Tái cấu trúc lưới điện phân phối giảm tổn thất điện năng có tác dụng của dg

BỘ GIÁO DỤC VÀ ĐÀO TẠO TRƯỜNG ĐẠI HỌC KỸ THUẬT CÔNG NGHỆ TP HCM - HỒ DỰ LUẬT TÁI CẤU TRÚC LƯỚI ĐIỆN PHÂN PHỐI GIẢM TỔN THẤT ĐIỆN NĂNG CÓ TÁC DỤNG CỦA DG LUẬN VĂN THẠC SĨ Chuyên ngành : KỸ THUẬT ĐIỆN Mã số ngành: 60520202 HƯỚNG DẪN KHOA HỌC: TS TRƯƠNG VIỆT ANH TP HỒ CHÍ MINH, tháng 02 năm 2013 CƠNG TRÌNH ĐƯỢC HỒN THÀNH TẠI TRƯỜNG ĐẠI HỌC KỸ THUẬT CÔNG NGHỆ TP HCM Cán hướng dẫn khoa học : TS TRƯƠNG VIỆT ANH Luận văn Thạc sĩ bảo vệ Trường Đại học Kỹ thuật Công nghệ TP HCM ngày 02 tháng 02 năm 2013 Thành phần Hội đồng đánh giá Luận văn Thạc sĩ gồm: (Ghi rõ họ, tên, học hàm, học vị Hội đồng chấm bảo vệ Luận văn Thạc sĩ) TS Ngô Cao Cường ( Chủ tịch) PGS.TS Phan Thị Thanh Bình ( Phản biện 1) TS Huỳnh Châu Duy ( Phản biện 2) PGS.TS Lê Kim Hùng ( Ủy viên) TS Trần Vinh Tịnh ( Ủy viên, thư ký) Xác nhận Chủ tịch Hội đồng đánh giá Luận văn sau Luận văn sửa chữa (nếu có) Chủ tịch Hội đồng đánh giá LV TS Ngơ Cao Cường TRƯỜNG ĐH KỸ THUẬT CƠNG NGHỆ TP HCM PHÒNG QLKH - ĐTSĐH CỘNG HÒA XÃ HỘI CHỦ NGHĨA VIỆT NAM Độc lập - Tự - Hạnh phúc TP HCM, ngày 12 tháng 12 năm 2012 NHIỆM VỤ LUẬN VĂN THẠC SĨ Họ tên học viên: HỒ DỰ LUẬT Giới tính: Nam Ngày, tháng, năm sinh: 04 -07 – 1977 Nơi sinh: Long An Chuyên ngành: KỸ THUẬT ĐIỆN MSHV: 1181031036 I- TÊN ĐỀ TÀI: TÁI CẤU TRÚC LƯỚI ĐIỆN PHÂN PHỐI GIẢM TỔN THẤT ĐIỆN NĂNG CÓ TÁC DỤNG CỦA DG II- NHIỆM VỤ VÀ NỘI DUNG: - Nội dung : Tái cấu trúc lưới điện phân phối giảm tổn thất điện có tác dụng DG Luận văn giải nhiệm vụ sau:  Ngiên cứu việc tái cấu trúc lưới điện phân phối có DG kết nối  Giải tốn tái cấu trúc LĐPP có DG nhằm giảm thiểu tổn thất điện  Xây dựng hàm mục tiêu, áp dụng giải thuật heuristic để tìm cấu trúc tối ưu cho toán tái cấu trúc lưới điện phân phối có DG để giảm tổn thất điện  Đề suất thử nghiệm giải thuật lưới điện mẫu  Kiểm chứng kết trình TOPO PSS/ADEPT  So sánh kết giải thuật với số kết giải thuật khác  Đề xuất việc áp dụng giải thuật vào vận hành LĐPP - Phương pháp nghiên cứu : 1) Sử dụng phương pháp giải tích tốn học để xây dựng hàm mục tiêu F cực tiểu tổn thất điện LĐPP có DG 2) Xây dựng giải thuật heuristic để tìm cấu trúc tối ưu theo hàm mục tiêu giảm thiểu tổn thất điện LĐPP có DG 3) Sử dụng trình TOPO PSS/ADEPT để kiểm chứng kết - Kết đạt được: 1) Xây dựng giải thuật tái cấu trúc LĐPP có DG giảm tổn thất điện chứng minh lý thuyết lẫn kết tính tốn, kết kiểm chứng cho thấy lưới điện có cấu trúc giảm thiểu tổn thất điện năng, giảm chi phí vận hành hệ thống điện phân phối dẫn đến giảm giá thành điện cung cấp đến khách hàng sử dụng điện 2) Góp phần vào nghiên cứu liên quan đến toán tái cấu trúc lưới điện phân phối 3) Làm tài liệu tham khảo cho công tác nghiên cứu vận hành lưới điện phân phối 4) Tái cấu hình LĐPP có DG vận hành trực tuyến III- NGÀY GIAO NHIỆM VỤ: 18-04 - 2012 IV- NGÀY HOÀN THÀNH NHIỆM VỤ: 12 - 12 -2012 V- CÁN BỘ HƯỚNG DẪN: TS TRƯƠNG VIỆT ANH CÁN BỘ HƯỚNG DẪN TS TRƯƠNG VIỆT ANH KHOA QUẢN LÝ CHUYÊN NGÀNH i    LỜI CAM ĐOAN Tôi xin cam đoan cơng trình nghiên cứu riêng Các số liệu, kết nêu Luận văn trung thực chưa công bố cơng trình khác Tơi xin cam đoan giúp đỡ cho việc thực Luận văn cảm ơn thông tin trích dẫn Luận văn rõ nguồn gốc Học viên thực Luận văn (Ký ghi rõ họ tên) Hồ Dự Luật   ii    Lời cảm ơn Trong suốt trình học tập hồn thành luận văn này, tơi nhận hướng dẫn, giúp đỡ tận tình từ Thầy Cơ, gia đình, đơn vị chủ quản bạn bè Với lịng kính trọng biết ơn sâu sắc tơi xin bày tỏ lời cảm ơn chân thành tới: Tôi xin chân thành cảm ơn Tiến Sĩ Trương Việt Anh, người thầy trực tiếp hướng dẫn, truyền đạt kiến thức chuyên môn kinh nghiệm nghiên cứu để tơi hồn thành luận văn Tơi xin cảm ơn q Thầy Cơ giảng dạy chương trình cao học " Thiết bị mạng nhà máy điện” trường Đại Học Kỹ Thuật Công nghệ Tp.HCM giảng dạy, trang bị cho tơi kiến thức hữu ích quý báu suốt trình học tập nghiên cứu để làm đề tài Tôi xin bày tỏ lòng biết ơn chân thành đến Ban Giám Hiệu đặc biệt Hiệu trưởng Nhà Giáo Ưu Tú Tiến Sĩ Lê Văn Hiền Trường Cao Đẳng Nghề LILAMA tạo điều kiện thuận lợi hỗ trợ cho tơi nhiều q trình học tập, cơng tác đơn vị Xin cảm đồng nghiệp Khoa Điện - Điều Khiển hổ trợ nhiều thời gian qua Cuối xin gửi lời cảm ơn chân thành đến đại gia đình tơi đặc biệt bà xã Lê Thị Thanh Thủy trai Hồ Tuấn Minh quan tâm, động viên tạo điều kiện tốt cho Xin chân thành cảm ơn ! Tp Hồ Chí Minh, Ngày 12 tháng 12 năm 2012 Học viên Hồ Dự Luật iii TÓM TẮT Hệ thống điện phân phối thường quy hoạch quản lý theo hướng công suất từ nguồn đến phụ tải Hiện nay, với phát triển nguồn lượng máy phát phân tán (DG) kết nối nhiều vào hệ thống điện phân phối Việc kết nối DG vào lưới điện phân phối giúp nâng cao độ tin cậy khả cung cấp điện Tuy nhiên, địi hỏi cấu trúc lưới hợp lý để nâng cao hiệu cung cấp điện Luận văn xây dựng giải thuật tái cấu trúc lưới phân phối có máy phát phân tán DG giảm tổn thất điện Lưới điện phân phối có cấu trúc mạch vịng vận hành hở hình tia Với tham gia máy phát phân tán vào hệ thống điện phân phối có mạch vịng nhỏ, có dịng cơng suất theo hai chiều, đổ ngược nguồn Vì vậy, kết nối máy phát phân tán vào lưới điện phân phối gây số vấn đề lầm ảnh hưởng đến vận hành lưới điện phân phối Tái cấu trúc LĐPP có DG Một số phương pháp tái cấu trúc lưới Được xác định từ cấu trúc mạch vòng tuyến phân phối cách thay đổi trạng thái đóng mở khóa điện phân đoạn Tuy nhiên, với có mặt máy phát phân tán mạng phân phối, việc xác định cấu trúc lưới trở nên phức tạp Vấn đề thiết cần đặt để giải tối ưu lưới điện phân phối Luận văn xây dựng giải thuật tái cấu trúc lưới phân phối có tham gia máy phát phân tán hoạt động thời gian dài với mục tiêu giảm tổn thất điện Giải thuật đề xuất kiểm chứng PSS/ADEPT phù hợp tốt số nghiên cứu trước sau đề xuất áp dụng lưới điện phân phối thực tế Việt Nam iv  ABSTRACT Distribution networks are planned and managed for unidirectional power flows Nowadays, the marked increase in Distributed Generation (DG) will require a correct integration of the generators in distribution networks to guarantee and reliability of the electric system, with respect to the operation constraints This thesis discusses the network reconfiguration at the power distribution systems with dispersed generations (DG) for loss reduction The power distribution systems have a radial network and unidirectional power flows With the advent of dispersed generations, the power distribution systems have a locally looped network and bidirectional power flows Therefore, DG into the power distribution system can cause operational problems and impact on existing operational schemes In reconfiguration problem distribution networks with DG, One of these operational schemes is network reconfiguration, which is defined as altering the topological structures of distribution feeders by changing the open/closed states of the switches However, with the introduction of DG in power distribution systems, this increases the complexity of this problem This necessary problem is established to optimal operational distribution networks In thesis, an operational scheme is presented which uses network reconfiguration at the power distribution systems with DG as long-time operation tool for power loss reduction The solution procedure is verified on PSS/ADEPT, and applied on Viet Nam distribution networks v MỤC LỤC Trang Lời cam đoan i Lời cảm ơn ii Tòm tắt iii Summary iv Mục lục v Danh sách từ viết tắt vii Danh mục bảng viii Danh mục hình ix CHƯƠNG 0: GIỚI THIỆU 1 Đặt vấn đề Mục tiêu nhiệm vụ luận văn 3 Phạm vi nghiên cứu 4 Phương pháp giải toán Điểm luận văn Giá trị thực tiễn luận văn Bố cục luận văn CHƯƠNG 1: TỔNG QUAN VỀ TÁI CẤU TRÚC LĐPP CÓ DG 1.1 Tổng quan lưới điện phân phối 1.2 Tổng quan DG 1.3 Tái cấu trúc lưới điện phân phối có DG 11 1.4 Các tốn tái cấu trúc lưới điện phân phối 13 1.5 Thực trạng lưới phân phối Việt Nam 15 1.6 Các nghiên cứu khoa học tái cấu trúc lưới phân phối 15 1.7 Phương án giải luận văn 25 vi CHƯƠNG 2: CƠ SỞ LÝ THUYẾT 26 2.1 Đặt vấn đề 26 2.2 Cơ sở toán học 26 2.2.1 LĐPP đơn giản 27 2.2.2 Lưới điện tổng quát 36 CHƯƠNG 3: XÂY DỰNG GIẢI THUẬT CỰC TIỂU TỔN THẤT ĐIỆN NĂNG 3.1.Giới thiệu 3.2 Hàm mục tiêu 3.3 Thuật toán CHƯƠNG 4: ÁP DỤNG GIẢI THUẬT TRÊN LƯỚI ĐIỆN PHÂN PHỐI 42 42 42 44 49 4.1 Lưới điện mẫu 16 bus 49 4.2 Lưới điện 33 nút 58 4.3 So sánh kết với giải thuật khác 64 4.4 Tái cấu hình LĐPP có DG vận hành trực tuyến 65 4.5 Kết luận 70 CHƯƠNG 5: KẾT LUẬN VÀ ĐỀ XUẤT 5.1 Kết luận 5.2 Những hạn chế đề xuất hướng phát triển đề tài TÀI LIỆU THAM KHẢO PHỤ LỤC 72 72 73 74 The 2012 international conference on green technology and sustainable development (GTSD2012) STUDY THE EFFECT OF DISTRIBUTED GENERATION TO THE RECONFIGURATION OF ELECTRICITY DISTRIBUTION NETWORKS Truong Viet Anh, Lai Minh Hoc1, Trinh Trong Chuong2, Ho Du Luat3 HCMC University of Technical Education1 Hanoi University of Industry2,; HCM University of Technical3 ABSTRACT Distributed generation (DG) in the future will play an important role in the medium voltage network (MVN), of DG capacity from a few hundred kW to tens of MW But, when connected to the local power network, DG will have certain influence on the power quality of the power network One of the most significant effects is that they will change the reconfiguration of the local power network as well as affecting the operation mode of the network This paper presents a method of finding the optimal open loop, analyze and select the appropriate mode of operation to reduce power losses of power distribution networks considering DG KEYWORD: Medium voltage network, distribution network, power loss reduction, reconfiguration INTRODUCTION Medium voltage network (MVN), also known as power distribution networks are usually designed as closed form, but in fact they are required to operate with the beam form to reduce short circuit current and increase simple operation When DG appears and connects to the MVN, the electric current distribution on the branch line will change and affect the optimal configuration of MVN, which brings up the task is: To find new optimal configuration (reconfiguration of MVN with DG) This new configuration is in place with multiple objectives: Improving the quality of bus voltages on MVN, reducing power loss, improving reliability of power supply, and preventing line overload This article only focuses reconfiguring MVN with DG to reduce power loss (P) There are many methods to perform reconfiguration problem of power distribution networks, reducing P, taking into consideration the DG These methods are based on two algorithms such as: The algorithm of A.Merlin & Back [1] (technical loop cut) represents the heuristic method combined with optimization techniques; Civanlar algorithm [3] (technical branch exchange) represents the pure heuristic methods Applications [1], the methods which are subsequently developed base on the idea as turn open the branches with the smallest capacity running through, the process will end when the network obtains the opening operator DG is described as a negative power load button Advantage of [1] is simple, after examining all the search space, reducing configuration P will be found However, the algorithm still has the disadvantage of waste of time in calculations because there are 2n configuration occurring if there are n lines are equipped with Electronic switch, final configuration [2], [6] is not optimal In which, Civanlar’s algorithm is based on heuristic rules to reconfigure the MVN This algorithm is highly appreciated because of Defining rules to reduce the number of power switch considered and building empirical function that describes the decrease of P when there is a change the status of a pair of electric switches in the process of reconfiguration Reconfiguration Technical of power distribution networks in the algorithm is shown in the process of replacing 01 opening switch by 01 closing 527 The 2012 international conference on green technology and sustainable development (GTSD2012) switch in the same loop to reduce P Loops that are chosen to change branches have a pair of switches on/off with the largest decrease of P The process is repeated until P can not be reduced any more The algorithm has the advantage as: Quickly identifying the reconfiguration plan with smaller P by heuristic rules and using empirical formulas However, The bad point of this algorithm is that in each calculating step, only a pair of power in a switch loop is considered, and we not solve the global minimum problem P in the network [6] completely To overcome the limitations above, this article will develop an algorithm based on ideas of [1], however, instead of reducing directed P = I2R (takes a lot of calculating time), we build the objective function of reducing productivity and increasing P (function G) that contains information about the MVN and DG, Then the biggest most reduction of function G found will mean that an optimal configuration with the smallest P is found APPROACH In reconfiguration problem MVN with DG, choosing the optimal configuration is based on the development chart of DG and additional charge over time chart Because of the nature, MVN reconfiguration problem arises because there is a change of modes (addition load or power) The smallest P diagram with load current will become non-optimal in next load mode Need to change the structure optimized with the mode of new loading source Therefore, the selection process is conducted on the calculating the biggest reduction efficient of P or the smallest power loss costs (c.A) graph following of combination among sources - DG - load In specific cases, the process of building methods will be considered at the time of DG capacity and additional load capacity In other cases, the relationship between DG - additional load capacity will be calculated as [7] Because of this, most research up to now on MVN restructuring has focused on finding a final configuration of MVN with the smallest P when DG considered as a PQ node connected to MVN [4] 2.1 Building power loss function (P) as MVN with DG In simple medium voltage network not have DG (Figure 1), if branch current i is IPi and IQi (i = n) and constant, the P before MVN configuration is:  P befor  n  R I i i 1 Pi  I Qi  (1) When redistributing the additional load, that means transferring an amount of current IQj and IPj (j = k, if MVN with loop k) from the old configuration to the new one, we can be done generally by: With drawing/ pumping into an amount of current IQj and IPj at the open- switch MNj on all loops of the network [2] Aij is Called as the indicator of correlation between the current direction No j and natural capacity distribution direction No i in the opening branch in the network: Aij = 1: The direction of loop j is the same as IPI and IQi; Aij = -1: The direction of loop j opposite to the IPI and IQi; Aij = if branch No i does not belong to the loop j After reconfiguration (Do the action of with drawing/ pumping into at switch MNj an amount of current of IPj, IQj respectively), the power loss of MVN in Figure would be: n n 2 P    IPi  Ai1IP1  Ri    IQi  Ai1IQ1  Ri   IP1  IQ1  RMN1  i1 i1      P P NBAO MN1 iLoop1    IPi  Ai1IP1  Ai2IP2  Ri    IQi  Ai1IQ1  Ai2IQ2  Ri i1 i1    n n P MO iLoop1    IPi  Ai2IP2  Ri    IQi  Ai2IQ2  Ri   IP1  IQ1  RMN2  i1 i1     P n n P MO2 iLoop2 2 MN2 With complex MVN with multiple loops connect several DG shown in Figure IPlDG and IQlDG is Called as 528 The 2012 international conference on green technology and sustainable development (GTSD2012) the total current of the DG behind the branch i with the direction from the electric source to open-switch MNj (j = k), the action of redistributing the additional load is equivalent to the pumping into/ withdrawing the same amount of electric current IPj, IQj in open - switch P on the branch are: (3) and (4) reached minimum following the variations IPjMN; IQjMN; value IPjMN; IQjMN; be calculated from expression (3) and (4) as follows: n  L K K MN  MN MN Pafter   IPi   Bil IDG Pl  Aij  IPj  Ri    IPj  R j i 1  l1 j1 j1  n  L K K DG MN  MN    IQi   Bil IQl  Aij  IQj IQj   RMN j  Ri   i 1  l1 j1 j   (2) IMN Pj  n L i 1 i 1 K Aij  IPi R i  Aij  Bil IDG Pi R i R MN  Aij  R j j n  Aij  IPi R i R i 1 LoopMN j L  Aij  Bil IDG Pi R i i 1 LoopMN j R (5) j1 I MN Qj  n L i 1 i 1 K DG Aij  IQi R i  Aij  Bil IQi Ri R MN  Aij  R j j L n  Aij  IQi R i R i 1 LoopMN j  DG Aij  Bil IQi Ri i 1 LoopMN j R (6) j1 Of which: IPi, IQi:The current component of the branch i in the network with n branches IPjMN; IQjMN: Current component injected / with drawing in the branch with open- switch MNj in the network with K loops RjMN: Resistance of the branch with open switch MN on the first loop j IQlMN: Current component of reactive power l in the network L DG (l = 1…L); The indicator of relationship Bil: between DG and branch i, value (0, +1: respectively is not relative, DG behind from the source to the branch I ) Necessary condition for (2) minimized following the variables IPjMN; IQjMN is represented by two expressions (3) and (4): n  L K Pafter MN MN   IMN  Aij   IPi   Bil IDG Pj R j Pl  Aij  I Pj  R i  i l j   1 IMN   Pj (3) n  L K Pafter MN DG MN  R MN  IQj  Aij   IQi   Bil IQl  Aij  IQj j  Ri  MN i 1  l 1 j1 IQj  (4) According to (2) there is always  j  h (h = K and i = n) in order that the second derivative by the current variation are greater than to reach the minimum objective function [7] Hence it always satisfies the enough condition in order that Expression (7) can be created when adding expression (5) and (6) after two sides of the (6) and j P P j   I  jI  R I I MN Pj MN Qj MN Pj MN Qj MN j n  L K DG DG DG  Aij   IPi  jIQi   j Bil  IDG Pl  jIQl   Aij   I Pj  jI Qj  R i  i 1  l 1 j1  (7) 2.2 Comment Equation (7) describes the total pressure drop on the independent loop j including all the branches on the MVN that becomes closed This shows the current value IPjMN; IQjMN pumping into / with drawing in order that P in (2), the minimum current value on a switch branch MNj at the close - MVN with DG (electric switch on the branch MNj is at closing status)  Expression (5), (6) shows that the pumping into / with drawing current at two ends of switch MN equivalent to load redistribution, so the user can know the redistribution of the additional load of the switch MN and the amount of electrical current that needs to be transferred from branch OMj to branch ONj following the value of IPjMN; IQjMN with j = K  Current value IPjMN; IQjMN in (5) and (6) 529 The 2012 international conference on green technology and sustainable development (GTSD2012) is the consequent quantity, while the current values as the distributing additional load is the discrete values (when closed switch MNj and open switch MHj) So it is difficult to find an operational state after distributing additional load of MVN with IPNHj = and IQNH= at MHj switch, which can only be IPNHj  and IQNHj  If IPNHj and IQNHj are smaller and smaller the right hand side of expression (3) and (4) are smaller and smaller or P approaches the smallest value  In (5) and (6), the influence of DG on the current IPMN and IQMN will affect the results of reconfiguration problem MVN In other words, the configuration of MVN with DG will be very much different from the configuration of MVN without DG with a minimum target P BUILDING ALGORITHM OF MINIMIZING POWER LOSS Rewriting (5) and (6) in the loop j as follows: I MN Pj R LoopMN j   n L  R    A ij  I Pi R i  A ij  Bil I DG Pi i   Pj   i 1 i 1 i j     n L MN DG    A ij  IQi R i  A ij  Bil IQi IQj R LoopMN R i   Qj (8) j   i 1 i 1 i j   Function (8) includes two components: The current of the additional load on the MVN without DG and current DG impacting on MVN IPMN and IQMN defined by (5) and (6) is the condition of minimizing P If you reduce this value that will make the objective function value decrease However, the reduction of G from (2) will face some difficulties due to consider interaction between branch current and DG impacting the MVN, moreover we also notice that when IPMN and IQMN is smaller and smaller, P will be the best Starting from the idea put G = [Pj2 + Qj2] with j = K, then: LoopMN LoopMN G    IMN    IQjMN.RLoopMN    j1 IMN   min(9) Pj R j j j Rj j1  K K The objective function in (9) is a rate rise function P, abbreviated as a function G From comments 2.1.b.ii and 2.1.b.iii that MVN operators at the opening status with P that is the smallest if the function G is indicated in the MVN decreasing the most So in the process of calculating of decreasing the function G, we just solve the power distribution on the MVN operators with DG one time only This reduces the volume and increase speed of calculation However, minimizing the function G is a difficult problem, this section will present a search algorithm to reduce the function G as follows: i In an independent loop, if we can find a branch with the current that is less than IjMN (assuming that the current branch IjNH), if we open branch MH we will have P that is smaller than that we open branch MN Therefore, in order to minimize the function G in (9) we can replace the value with IPjMN and IQjMH by IPjNH and IQjNH with smaller value and in the same loop j, value is RjLoop by the formula (10) Here:    2 MN NH   NH GMN   RLoopMN   IPjNH    IQj    IMN   j j Pj    IQj  2 NH  (10)   RLoopMN   IMN j j    Ij    ii Because the MVN has many independent loops, reducing the function G should be carried out step by step Independent loop is chosen for opening first is the loop with the decreasing level G that is the most comparing to all remaining independent loops in MVN with DG In the independent circuit, The power switch that is opened the switch with the smallest current running through in the independent loop iii Iterative process is done to reduce the function G until we not found the pair of switch / open switch MNj and NHj and we cann’t reduce the function G more Flowchart decrease function G is presented in Figure on the basis of additional volume decrease in G and the algorithm of [1], then test P levels decrease to achieve optimal configuration with the smallest P 530 The 2012 international conference on green technology and sustainable development (GTSD2012) In essence, stage of the algorithm is based on the algorithm [1], but has added the function G on blocks in the algorithm, so in essence, the branch is open at this stage is the smallest electric current running through At the end of stage 1, power distribution networks have completely radial, but also could not confirm the MVN has the smallest P (such as weakness of the algorithm stated [1]) In stage 1, determining speed MVN configuration very rapidly, the decrease P in each redistribution load is very high, but not consider interaction of independent loops of MVN at this stage is not really the least However, by the flash of a speed reduction of the function G at the impact of each pair of switch can be used to build algorithms operate online MVN In stage 2, P reduction is not high after every redistribution load should only be worth pointing out that the structure MVN with the smallest P, but it means when operating MVN in a very long time After each closing/opening a switch pair to reduce the power function G, power distribution problem is made on the remaining closed MVN, considering the DG Because of this difference that the current composition of the Ip and Iq of DG effects consideration on IPMN and IQMN components during the remaining iterations decrease G The comments above will be clarified by example verifiable MVN 16 nodes Stage is actually a stage of opening the check on the network optimization by: Play each switch power is on, solve power distribution branch to check if it is selected to open the stream running through the smallest or not If correct, it will accept the results, if wrong, will choose the branch with smaller line to open This work was conducted for each independently loop (play each switch in turn is open) CALCULATING APPLICATIONS MVN 16 nodes, a nominal voltage of kV has 21 branches and open switches with DG by G Celli in [4] is described in Figure 4, data for the branches and nodes are shown in [4] In power distribution networks, increasing powers are DG 450kW at node 9, and 630KW at node 13 The process of finding the configuration operation in order to reduce power loss is investigated in two cases that have DG and no DG Results of finding the configuration optimal are compared with the results of [4] 531 The 2012 international conference on green technology and sustainable development (GTSD2012) and compare them with TOPO in the PSS / ADEPT 5.0 [5] to verify the advantages of the algorithm Synthesis results in Table  Solving the problem of distributed calculating power on MVN close Conduct to decrease G function at stage by the proposed algorithm The G function decreases (G1 = 18342) when considering independent loop L1 (close K21 and open K2) The other independent loops not reduce the G function Power loss at the moment is  Pstage1 = 96.4kW  Carry out stage 2, this configuration of power distribution networks has open switches as: K2, K17, K18, K20, K10, K19 We solve the problem of power distribution as close each switch opening and open switch the smallest electric current running through The result 4.1 Description the searching process of network configuration without DG:    Radial power distribution networks initially [4] have the open switches K21, K17, K18, K20, K10, K19 Power loss is first calculated by PSS / ADEPT 5.0:  Pold = 171.6kW Solving the problem of distributing power on MVN close Conduct to decrease G function at stage by the proposed algorithm The G function decreases (G1 = 18342) when considering independent loop L1 (close K21 and open K2) The other independent loops not reduce the G function Power loss at the moment is  Pstage1 = 94.6kW Carry out stage 2, this configuration of power distribution networks has open switches as: K2, K17, K18, K20, K10, K19 We solve the problem of power distribution as close each switch opening and open switch the smallest electric current running through The result is: + Close K2: Independent loop has the smallest current I2 (41.1A) + Close K17: Independent loop has current I17 (30.9A) + Close K18: Independent loop has the smallest current I16 (8.1A)  close K16 open K18 + Close K20: Independent loop has the smallest current I20 (30.5A) + Close K10: Independent loop has the smallest current I10 (9.6A) + Close K19: Independent loop has the smallest current I19 (11.1A) So after stage 2, the switch to open the MVN will be: K2, K17, K16, K20, K10, K19, so the power loss from Pstage1 = 97.1kW reduced Pstage2 = 93.06kW 4.2 Description of the searching process of network configuration with DG at node and node 13  Radial power distribution networks initially [4] have the open switches K21, K17, K18, K20, K10, K19 Power loss is first calculated by PSS / DEPT: Pold = 120.5kW  Solving the distributed calculating power on power distribution networks close Conduct stage function G decrease by the proposed algorithm after iteration reduce G function (G1 = 13437) when considered independent loop L1 (closed K21and open K2: P1 = 67.5kW) and iteration (G2 = 20) when considering independent loop L3 (closed K18 and K5 open:  P2 = 68.4kW) Power loss in the second iteration G function increased but decreased as the power loss decreases as expression (4) and (5) simultaneously equal to  Carry out stage 2, this configuration of power distribution networks is the switch to open: K2, K17, K5, K20, K10, K19 Solve the power distribution as close every switch is open and open switch electric current running through the smallest The result: 532 The 2012 international conference on green technology and sustainable development (GTSD2012) + Close K2: Independent loop has the smallest current I2 (33.6A) + Close K17: Independent loop has current I17 (21.7A) + Close K5: Independent loop has the smallest current I18 (11.5A)close K5 open K18, P3=67.5kW + Close K20: Independent loop has the smallest current I15 (28.2A)  close K20 open K15, P4 = 66.4kW + Close K10: Independent loop has the smallest current I10 (6.7A) + Close K19: Independent loop has the smallest current I9 (1.3A)  close K19 open K9,  P5 = 66.3kW So after stage 2, the open switch of MVN will be: K2, K17, K18, K15, K10, K9, so the power loss from Pstage1 = 68.4kW reduced Pstage2 = 66.3kW 4.3 Description of the search network configuration when there is a DG at node Radial power distribution networks initially [4] had the open switches as: K21, K17, K18, K20, K10, K19 Power loss is first calculated by PSS / ADEPT is Pold = 166.9kW Solving the distributed calculating power on power distribution networks close Carry out Process of decreasing the G function (stage 1) following the proposed algorithm after iteration reduce G function (G1 = 13006) when considering independent loop L1 (closed K21 and opening K2,  P1 = 89.8kW) Carry out stage 2, this configuration of power distribution networks have open switches as: K2, K17, K18, K20, K10, K19 We solve the power distribution as close each switch opening and open switch the smallest electric current running through The result is: + Close K2: Independent loop has the smallest current I2 (33.6A) + Close K17: Independent loop has current I17 (30.9A) + Close K18: Independent loop has the smallest current I16 (8.1A)  close K18 open K16,  P3 = 85.8kW + Close K20: Independent loop has the smallest current I15 (28.2A)  close K20 open K15, P4 = 84.0kW + Close K10: Independent loop has the smallest current I10 (12.1A) + Close K19: Independent loop has the smallest current I9 (1.3A)  close K19 open K9, P5 = 83.7kW So, after stage 2, the open switch of the MVN will be: K2, K17, K16, K15, K10, K9, so the power loss from Pstage1 = 89.8kW reduced Pstage2 = 83.7kW 4.4 Description of the searching process of network configuration with a DG at node 13 Radial power distribution networks initially [4] had the switches to open K21, K17, K18, K20, K10, K19 Power loss is first calculated by PSS / ADEPT is Pbandau = 125.2kW Solving the distributed calculating power on power distribution networks closed Carry out Process of decreasing the G function (stage 1) following the proposed algorithm after iteration reduce G function (G1 = 14405) when considering independent loop L1 (close K21 and open K2:  P1 = 74.3kW) and iteration (G2 = 4) when considering independent loop V3 (closed K18 and K5 open:  P2 = 75.2kW) Power loss in the second iteration increases but function G decreases because the power loss decreases as expression (3) and (4) simultaneously equal to Carry out stage 2, this configuration of power distribution networks have open switches as: K2, K17, K5, K20, K10, K19 We solve the power distribution as closing each open switches open and open switch the smallest electric current running through The result is: + Close K2: Independent loop has the smallest current I2 (35.5A) 533 The 2012 international conference on green technology and sustainable development (GTSD2012) + Close K17: Independent loop has current I17 (21.7A) + Close K5: Independent loop has the smallest current I18 (11.3A)  close K5 open K18, P3 = 74.3kW + Close K20: Independent loop has the smallest current I20 (23.5A) + Close K10: Independent loop has the smallest current I10 (9.6A) + Close K19: Independent loop has the smallest current I19 (11.1A) So, after stage 2, the open switches of the MVN will be: K2, K17, K18, K20, K10, K9, so the power loss from Pstage1 = 75.2kW reduces Pstage2 = 74.3kW Summarizing the survey results on power distribution networks for 16 nodes in the table below CONCLUSION DG resource has great influence on the electric current distribution across whole the MVN, so after connecting DG, the reconfiguration of power distribution networks is very important in order to ensure that MVN has DG with the smallest P With DG with power changing strongly seasonally (such as small hydropower), the expression (3) to (6) shows this clearly Therefore MVN configuration that needs to change to get the biggest reduction P after having DG The algorithm proposed appropriates to the online mode of operation of power distribution networks with DG on the basis of comparing the deviation c.A with switching costs When moderators have information on additional load forecast, DG as well as % industrial additional load ratio and switching time they will decide whether to change the configuration of power distribution networks or not REFERENCES A Merlin and H Back; Search for a minimum loss operating spanning reconfiguration for urban power distribution system; Proc 5th Power Syst Computation Conf (PSCC) Cambridge, U.K, 1975 Baran, M E and F F Wu; Network Reconfiguration in Distribution Systems for Loss Reduction and Load Balancing; IEEE Transactions on Power Delivery, April 1989, pp 1401- 1407 Civanlar; Distribution feeder reconfiguration for loss reduction; IEEE Trans PWRD, Vol-3, July 1988 G Celli; Online network reconfiguration for loss reduction in distribution networks with distributed generation; 18th International Conference on MVN; CIRED - Turing, 6-9 June 2005 Shaw Power Technologies Inc (2004), PSS-ADEPT User Manual, New York T.V Anh, Viet N.H; An effective algorithm for loss reduction by recofiguration distribution feeder; The 2004 International Symposium on Advanced Science and Engineering; HCM city 5/2004 Trương Việt Anh, Trịnh Trọng Chưởng; Research and propose some solutions for reducing power loss MVN - connected small hydropower in Lao Cai thread-level Ministry of Science Trade, Ha Noi 2011 Contact address: Truong Viet Anh, Phone: 0913117659, Email: tvanhspkt@yahoo.com 534 The 2012 international conference on green technology and sustainable development (GTSD2012) PRINCIPAL GUIDANCE FOR DEVELOPMENT OF MEDIUM VOLTAGE POWER NETWORK IN NORTHERN VIETNAM BASED ON COMPARING ECONOMIC AND TECHNICAL NETWORK PARAMETERS Truong Viet Anh1, Lai Minh Hoc, Nguyen Duc Hanh 2, Ho Du Luat3 HCMC University of Technical Education Institue of Energy, Ministry of Industry anh Trade HCM University of Technical ABSTRACT Current status of Vietnamese medium voltage network (MVN) existed too much the voltage levels There are many aspects in MVN of Viet Nam such as selection of voltage level, improvement plan of 22kV level, continued using 35kV or not in some areas Rehabilitation plans need to base scientific basis with the quantitative factor of economic and technical comparison This paper introduces research methods orientation MVN The method is based on ensuring the overall economy target based on studying a typical area has an area suitable to calculate, since then expanded for overall study area Research results has show that can use the LRMC as a general economic indicators to calculate the comparison of the planning network developed typical structure Based on the calculated results for the typical areas that can develop recommendations for the North Vietnam MVN in the coming period KEYWORD: Medium voltage network, distribution network, plan, LRMC, typical structure impeded by the lack of indicators, reasonable parameters, thus this leads to inaccuracy in the forecast, the equipment selection and a waste of investment capital Moreover, it is accompanied with the increase of power losses and low power quality Although there was decision of changing different delivering electric voltages in to the level of 22kV [2], the changing period carries out very slowly and it does not bring high effect of economic There are many points: Must we change the electric network of 35kV in Northern mountain areas into 22kV or not? How we change the electric network of 6, 10, 15kV into 22kV? That causes many difficulties in setting up the project, building and operation INTRODUCTION Investment capital for MVN accounts for nearly 1/3 the overall investment for electrical system Currently, the ratio of distribution lines / power consumption and put power ratio distribution Transformer / power consumption in Vietnam is 2.4 km/GWh and 0.64 MVA/GWh lower than reasonable target of 4.0 km / GWh and 0.85 MVA / GWh in comparison with Japanese standard [1] This leads to enormous energy losses (8%-10%) and low quality of power supply It is necessary to have enough capitals for MVN development in order to ensure sufficient high quality power output in the coming periods Due to historical conditions, there are many voltage levels of MVN in Vietnam that the existence of multiple voltage levels requires a variety of devices from different origins; therefore this actually creates problems in the operation process and also in establishment of economic working conditions In addition, the improvement and planning process is also The method of researching the orientation of developing electric network In order to choose the voltage levels for the power supply systems in general, 435 The 2012 international conference on green technology and sustainable development (GTSD2012) itinerary, select different voltage levels should provide long-term marginal cost compared to the performance evaluation there were many various methods of researching and many results announced [3] Each method has advantages and disadvantages and difficulties In recent years, method of calculating and choosing for a particular line that considers the ability of fluctuation of additional charge, electric cost Hence, we can choose the suitable voltage level for the power supply systems The above method is the most reasonable in calculating and choosing suitable voltage level MVN So, the method of researching the orientation of developing MVN based on the idea of ensuring general economic by researching particular areas with reasonable square for calculating Hence, we can enlarge and set up the orientation of transformation and developing whole the researching area In this article, we propose more target of long-term boundary expense (LRMC) That becomes the general economic target when comparing the projects of electrical network The formula of calculating longterm boundary expense as below [4]: n Ct  t LRMC = t 1 (1  i ) n E t  t t 1 (1  i ) Where: - Ct is differential of year expense, - t, Et is differential of additional charge need following year t (kWh) - i is discount coefficient, n is time period of calculating 2.1 Economic target applied for MVN project [8] 2.1.1 Method of minimizing calculating expense function By solving analytically target function, we can compare series of factors as: Additional charge density, length of line … That is still used to assessment, compare and choose the parameters of electrical network 2.2 Researching model [8] The problem is solved in general such as: “The voltage level of 35kV should exist or not”, “We need to apply fast or slow route of transform voltage level chosen”…for areas So, the proposing a close math model is not feasible The research bases on the method of directive calculating and comparing the particular projects That is in fact finding out minimum of term boundary expense in limited set of considering projects, those are particular in area, chosen voltage level, and transformation route 2.1.2 Method of analyzing economicfinance of project With this method, we can not only compare and choose a project but also assess the economic effect of the project This method is rather effective when assessing a particular project Considering area: The edge of urban; Rural plain, highland - Voltage level: 22kV or 35kV; 22kV and 35kV - Exchange route: Fast transform; medium transform; slow transform - In each area, choosing a real electrical network for particular calculating Composing voltage level and transform route will make a set of comparing calculating method 2.1.3 Marginal cost method Marginal cost method that targets shortterm marginal cost and long term This method has advantages: norm per unit of production should be able to compare performance for different projects (same type), with the number of relatively specific plans are still pretty much applied, convenient Improvement and MVN development plan can disparate due to 435 436 The 2012 international conference on green technology and sustainable development (GTSD2012) 2.3 Choosing researching area Load density and distribution of the area is the main factor, creating specific network areas as well as selected voltage level 2.3.1 The edge of urban Additional charge density of Urban and edge of urban is from 20 to 30VA/m2 [5] So, choosing voltage level of 22kV for MVN in this area has the best target of economic-technical [3] The problem given in this area is choosing the suitable transform route for current electrical network with different voltage levels that change into the voltage level of 22 kV The speed of transformative is fast, medium or slow that depends on the life of the equipments Figure1 Flow chart of researching orientation of MVN 2.3.3 High land In this area, additional charge density is very low, the route of transforming the voltage level from (6, 10, 35) kV to 22kV is a problem considered more about the ability of applying the voltage of 35kV So, we consider some methods as: rebuild, transform the current electrical network into 22kV; rebuild, transform the current electrical network in to 35kV; both electrical network of 35kV and electrical network of 22kV exist 2.3.2 Rural plain With these areas, additional charge density of some areas is more than 10 VA/m2, other areas is less than 10VA/m2 [6], [7] The voltage levels of (6, 10) kV has a big rate of station and line of 35kV that is effective for a long time So, the suitable transformative route may be different from that in urban, edge of urban The calculation methods are the same as those in urban, edge of urban However, we need to mention more the particular factors as: Urgent character of economictechnical factors in area; ability of the finance; the current character of electrical network; the ability of supplying the need of material and equipment… Regarding the improvement of methods for this area, given the ability to renovate the existing network (6, 10, 35kV) to 22kV voltage level by three routes: move fast on 22kV network, gradually shift or extend the time converted to 22kV network The result of calculating the method of transforming the particular areas Depend on analyzing of the character of the electrical network; choose particular areas in North area for researching  Area I: Hoan Kiem district – Ha Noi City  Area II: Dong Hung district – Thai Binh province  Area III: Vi Xuyen district – Ha Giang province In area I and Area II, we research the transformative speed, compare and infer the conclusion between high and medium additional charge density, fast speed, 435 437 The 2012 international conference on green technology and sustainable development (GTSD2012) medium speed or low speed of transformation, and decide that which speed is reasonable In Area III, research the methods of transforming current electrical network into electrical network of 22kV; method of transforming current electrical network into electrical network of 35kV; the method of that both electrical network of 35kV and 22kV exist We consider each small area of developing only one voltage level in order to infer the conclusion of which method is reasonable for high land 3.1 Calculating with Hoan Kiem District [5] Hoan Kiem District has a current medium voltage line of 207 km (100% underground cable), in which the electrical network of kV occupies 30%, the electrical network of 10kV occupies 8%, the electrical network of 22kV occupies 62% The electrical network of this District is contributed from Tran Hung Dao station (4 routes of 10 kV); Yen Phu station (2 routes of 6kV, routes of 22kV); Giam station (5 routes of 6kV); Bo Ho Station (3 routes of 6kV, routes of 22kV) Currently, there are routes that don not get technical standard The methods of developing the electrical network in Hoan Kiem district are below: - Method 1: transform the electrical network of 6kV in to 22kV; - Method 2: transform with considering the change of equipment; - Method 3: transform at low speed depending on life of equipment Thus, after calculating the network development plan Hoan Kiem soon find that the uniform network will bring the greatest economic efficiency Table1 Collection of economic – technical targets of electrical network developing No Category Unit I plan II plan III plan 574,34 590,86 549,2 Billion (VND) Capital investment 271 277,5 286,2 Billion (VND) Period up to 2015 a 303,34 313,36 263 Billion (VND) b Period 2016-2020 Power loss 23,5 22,3 18,5 Million (kWh) Period up to 2015 a 26,8 23,1 23,1 Million (kWh) b Period 2016-2020 262 260 248,8 VND / kWh LRMC 1106 1112 1138 Billion (VND) NPV 3.2 Calculating with Dong Hung district, Thai Binh province [6] Dong Hung district has a current medium voltage line the length of which is 226 km In which, the electrical network of 10kV occupies 84%, the electrical network of 35kV occupies 16% The electrical network of this District is contributed from Long Boi station of 110kV (4 routes of 35kV, routes of 10kV); Thang Long station (3 routes of 10kV) Currently, there are routes of 10kV that not reach technical standard The methods of developing the electrical network in Dong Hung district are below: 435 438 - - Method 1: Depend on the idea of soon completing the changing the electrical network from 10kV in to 22kV; Method 2: Depend on the idea of salvaging the current electric network, base on identifying the areas that not get technical target, we change the electrical network into 22kV and change the electrical network of 10kV into 22kV Method 3: Do not transform the electric of 10, 35kV in to 22kV Because the electrical network of Dong Hung district was very old, we need to increase line section and put deeply the station with the source power of 110kV The 2012 international conference on green technology and sustainable development (GTSD2012) in order to decline electric supplying diameter So for Dong Hung district, the gradual improvement of 22kV or 10kV network will bring the greatest economic efficiency Table2 Collection of economic – technical targets of electrical network developing No Category Unit I plan II plan III plan 265,31 252,65 277,7 Capital Investment Billion (VND) 104,98 114,86 162,91 a Period up to 2015 Billion (VND) 160,33 137,79 11,479 b Period 2016-2020 Billion (VND) Power loss 6,69 5,1 4,8 Million (kWh) a Period up to 2015 11,01 9,04 8,01 Million (kWh) b Period 2016-2020 251 243 271 VND / kWh LRMC 337 344 317,6 Billion (VND) NPV in wards with low additional charge That will bring the greatest economic efficiency 3.3 Calculating with Vi Xuyen district, Ha Giang province [7] Vi Xuyen district has a current medium voltage line of 243 km In which the electrical network of 10kV occupies 33,2%, the electrical network of 35kV occupies 66,8% The electrical network of this district is contributed from Vi Xuyen station of 110kV (3 routes of 35kV, routes of 10kV); Intermediate Vi Xuyen station (1 routes of 10kV Currently, there are routes that not reached technical standard The methods of developing the electrical network depends on the life of equipments are below: - Method 1: transform the electrical network of 10, 35kV in to 22kV; - Method 2: transform the electrical network of 10kV in to 35kV; - Method 3: considering the MVN, both of 22kV and 35kV In which, we develop the electrical network of 22kV in industrial areas, urban, and the electrical network of 22kV in promote areas CONCLUSION: Target long-term marginal costs (LRMC) comparison, because it was determined in units of the product The application of additional criteria LRMC in improving the planning problem MVN is more appropriate Especially, LRMC can use as a general economic indicator to compare the planning schemes for power networks in a typical structure-oriented research and development MVN improvement Based on the calculating results for particular areas, we can propose the orientation of transforming and developing the MVN in the North of Viet Nam in next stage such as : - For suburban areas, we should be quickly renovated and converted into 22kV network Identifying the MVN in these areas in to 22kV not only brings the most economic advantage, but also make good condition for construction, operating management, and increase reliability of electric supply - For plain Rural, we need to transform following suitable routes (medium speed) into the electrical network of 22kV, salvage equipments (replace, exchange) in order to avoid waste of investment capital - With high land, we need to compare and choose the voltage level of 35kV or 22kV, in each small area, we should develop a Hence, with Vi Xuyen district, there is the method of both electrical network of 35kV and 22kV existing However, in each small area we should develop an electrical network of MVN In which, we develop the electrical network of 22kV in industrial zone, urban with high density of additional charge, and the electrical network of 35kV 435 439 The 2012 international conference on green technology and sustainable development (GTSD2012) Institute of Energy, Electricity Development Plan periods 2010-20152020 Hanoi City, Hanoi, 2010 Institute of energy, The electricity development planning in Thai Binh province period 2010-2015-2020, lowering it in 2010 Institute of Energy, Electrical network development plan period 2011-20152020 Ha Giang, Hanoi, 2010 Nguyen Duc Hanh, Advanced Research economic efficiency, voltage quality and reliability in the medium voltage network planning, engineering doctoral thesis, Hanoi, 2011 voltage level We develop the electrical network of 22kV in industrial zone, and electrical network of 35kV in village and hamlet REFERENCES The Tokyo Electrical network Co Power Development Planning, Inc, Tokyo, 2003 Department of Energy, Decision No 149 NL / Science and Technology March 24, 1993 on the selection of the medium standard voltage is 22kV for the country, Hanoi, 1993 B.A.Koзлов, гopoдckиe распpeдeлитeльныe электpичeckиe ceти, лeнингpaд, энepгoиэдaт, 1982 Nghiem Sy Thuong, Establishment of corporate financial management, summarizes the content of lectures, Hanoi, 1997 Contact: Truong Viet Anh; Tel 0913117659, Email: tvanhspkt@yahoo.com 440 435 GREEN TECHNOLOGY AND SUSTAINABLE DEVELOPMENT (Volume 1) Nhiều tác giả NHÀ XUẤT BẢN ĐẠI HỌC QUỐC GIA TP HỒ CHÍ MINH Khu phố 6, Phường Linh Trung, Quận Thủ Đức, TPHCM Số Công Trường Quốc Tế, Quận 3, TP HCM ĐT: 38 239 172 – 38 239 170 Fax: 38 239 172 – E – mail: vnuhp@vnuhcm.edu.vn *** Chịu trách nhiệm xuất TS HUỲNH BÁ LÂN Tổ chức thảo chịu trách nhiệm tác quyền TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT TPHCM Biên tập NGUYỄN HUỲNH Sửa in THÙY DƯƠNG Thiết kế bìa HƯNG PHÚ ISBN: 978-604-918-021-7 TK.01.KTh(V) ĐHQG.TPHCM-12 1127-2012/CXB/08-47 KTh.TK.478-12(T) In 200 khổ 19x27cm, công gty TNHH In Và Bao Bì Hưng Phú, Số đăng ký kế hoạch xuất bản: 1127-2012/CXB/08-47/ĐHQGTPHCM Quyết định xuất số: 150/QĐ-ĐHQGTPHCM/TB cấp ngày 21/9/2012 Nhà Xuất ĐHQGTPHCM In xong nộp lưu chiểu tháng 9, 2012 ... CHƯƠNG 1: TỔNG QUAN VỀ TÁI CẤU TRÚC LĐPP CÓ DG 1.1 Tổng quan lưới điện phân phối 1.2 Tổng quan DG 1.3 Tái cấu trúc lưới điện phân phối có DG 11 1.4 Các tốn tái cấu trúc lưới điện phân phối 13 1.5... THUẬT ĐIỆN MSHV: 1181031036 I- TÊN ĐỀ TÀI: TÁI CẤU TRÚC LƯỚI ĐIỆN PHÂN PHỐI GIẢM TỔN THẤT ĐIỆN NĂNG CÓ TÁC DỤNG CỦA DG II- NHIỆM VỤ VÀ NỘI DUNG: - Nội dung : Tái cấu trúc lưới điện phân phối giảm. .. giảm tổn thất điện có tác dụng DG Luận văn giải nhiệm vụ sau:  Ngiên cứu việc tái cấu trúc lưới điện phân phối có DG kết nối  Giải tốn tái cấu trúc LĐPP có DG nhằm giảm thiểu tổn thất điện