generation transmission and distribution

... load currents during peak and emergency conditions, performing coordination studies that include source and low side protection equipment, and expected transformer size and winding configuration ... maintenance and cost advantages found with power fuses Protection and control devices, circuit breakers, and station batteries are required The overcurrent relays are a small part of the total cost and ... size, cost, and application, which could range from generator step-up to a position in the transmission= distribution system, or perhaps as an auxiliary unit When protective relays trip and isolate...

Ngày tải lên: 21/03/2014, 12:08

... above a small set-value SET_4 and the negative and zero sequence currents I2 and I2 not exceed a small set-value SET_3, then a fuse failure condition will pick up to one and remain in that state thanks ... in case of a loss of VT signal and contrary to a fault condition, there should not be any change in the current’s magnitudes and phases Therefore, the negative and zero sequence currents should ... recommended by the ANSI=IEEE guides and standards Fig 2.10 represents a typical dual definite-time characteristic whereas Fig 2.11 represents a combined definite and inverse-time characteristic One...

Ngày tải lên: 21/03/2014, 12:08

... at 138 kV and above, subtransmission lines are 34.5 kV to 138 kV, and distribution lines are below 34.5 kV These are not rigid definitions and are only used to generically identify a transmission ... systems become more complex and the fault current varies with changes in generation and system configuration, directional overcurrent relays become difficult to apply and to set for all contingencies, ... multiphase fault between phases x and y, Ex À Ey ¼ Z1 Ix À Iy (3:1) where x and y can be a, b, or c and Z1 is the positive sequence impedance between the relay location and the fault For ground distance...

Ngày tải lên: 21/03/2014, 12:08

... the transmission lines, varying the operating conditions such as voltage profile and generation dispatch, coordinating relays and controls, and load shedding Most utilities rely on planning and ... bandwidth, usually expressed in bits per second (BPS), latency in data transmission, reliability, and communication error handling Presently, electrical utilities use a combination of analog and ... PMUs, and performs data checks, records disturbances, and rebroadcasts the combined data stream to other monitor and control applications This type of unit fulfills the need for both hard and soft...

Ngày tải lên: 21/03/2014, 12:08

... ANSI=IEEE Standard C37.90, provides the standard for the Surge Withstand Capability (SWC) to be built into protective relay equipment The standard consists of both an oscillatory and transient ... in time and Eq (5.44) represents the measurements The terms wk and vk are discrete time random processes representing state noise, i.e., random inputs in the evolution of the parameters, and measurement ... state x, and recursively updates the estimate of state The initial assumption about the state is that it is a random vector independent of the processes wk and vk and with a known mean and covariance...

Ngày tải lên: 21/03/2014, 12:08

... ‘‘off ’’ initially and cut ‘‘on’’ shortly after fault initiation It stayed ‘‘on’’ for a few cycles after the fault cleared and stayed ‘‘off ’’ all during the reclose ‘‘dead’’ time and after restoration ... This restrike cannot be extinguished and will last until the oil becomes badly carbonized and a subsequent fault occurs between the bus breaker terminal and the breaker tank (ground) In Fig 6.15 ... response for permanent faults upon reclosure, and a ‘‘stuck’’ breaker In Fig 6.3 two waveforms are shown that depict adequate carrier response for internal and external faults The first waveform shows...

Ngày tải lên: 21/03/2014, 12:08

... rotor angle instability and voltage instability go hand in hand One may lead to the other, and the distinction may not be clear However, distinguishing between angle stability and voltage stability ... restore power consumption beyond the capability of the transmission system and the connected generation (Kundur, 1994; Taylor, 1994; Van Cutsem and Vournas, 1998) While the most common form of voltage ... also exists and has been experienced at least on one system (Van Cutsem and Mailhot, 1997) It can occur when EHV transmission lines are loaded significantly below surge impedance loading and underexcitation...

Ngày tải lên: 21/03/2014, 12:08

... or island, a power system into areas with ß 2006 by Taylor & Francis Group, LLC balanced generation and load Some load shedding or generation tripping may also be required in selected islands ... Load and generation forecast: The design process must use forecast information about the amount, distribution, and characteristics of the connected loads as well as the location and amount ... traditional positive sequence powerflow model, which defines the transmission topology, line reactances, connected loads and generation, and predisturbance voltage profile Generators can be represented...

Ngày tải lên: 21/03/2014, 12:08

... changed rather suddenly in the 1960s, when the process of interconnection accelerated and more transmission and generation extended over large areas Perhaps, the most important aspect was the wider ... capacitor and reactor banks, tapchanging transformers, and SVCs Modulation controls to enhance power system stability have been applied extensively to generator exciters and to HVDC, SVC, and TCSC ... predictable by simulation, its nonlinear character and vast size lead to challenging demands on system planners and operating engineers The experience and intuition of these engineers is generally...

Ngày tải lên: 21/03/2014, 12:08

... in Fig 10.7 In this model (Xu and Mansour, 1994), x is the state variable Pt(V ) and Ps(V ) are the transient and steady-state load characteristics, respectively, and can be expressed as Pt ¼ ... these Jacobians, and their sensitivities with respect to various system parameters Bus voltage profiles and their sensitivity to variations in active and reactive power of the load and generators, ... by generators, synchronous condensers, and static-var compensators and its sensitivity to variations in load bus active and= or reactive power These indices and sensitivities, as well as their associated...

Ngày tải lên: 21/03/2014, 12:08

... studies and is limited to the analysis of first swing transients For more details regarding the model, the reader is referred to Anderson and Fouad (1994), Fouad and Vittal (1992), Kundur (1994), and ... stability methods: Pai (1981), Pai (1989), Fouad and Vittal (1992), Ribbens-Pavella (1971), and Pavella and Murthy (1994) These references provide a thorough and detailed review of the evolution of the ... TEF method can also be found in Padiyar and Sastry (1987), Padiyar and Ghosh (1989), and Abu-Elnaga et al (1988) In Chiang (1985), Chiang et al (1987), and Chiang et al (1988), a significant contribution...

Ngày tải lên: 21/03/2014, 12:08

... stability and transfer capability problems must be solved by new controls and new substation equipment, rather than by new transmission lines Different ownership of generation, transmission, and distribution ... two 330-MW units and two 700-MW units The microprocessor-based controller measures rotor speed and generator power and computes acceleration and angle Tripping of 16–100% of plant generation is ... 157–168, 1998 57 Zhou, X and Liang, J., Overview of control schemes for TCSC to enhance the stability of power systems, IEE Proceedings Generation, Transmission and Distribution, 146(2), 125–130,...

Ngày tải lên: 21/03/2014, 12:08

... equivalent circuit, and Ll represent the resistance and leakage inductance of the generator stator, Lad and Laq represent the mutual inductance between stator and rotor, and the remaining elements ... analysis, the transient and steady-state variation of the load P and Q with changes in bus voltage and frequency must be modeled Accurate load modeling is difficult due to the complex and changing nature ... resistance and inductance and the shunt capacitance Transformers are normally represented by their leakage inductance, resistance, and tap ratio Transformer magnetizing inductance and eddy current...

Ngày tải lên: 21/03/2014, 12:08

... problems, trade-offs, and strategic issues carry over directly to the EPRI flexible AC transmission system (FACTS), and to any similar effort using wide area control to extend transmission capabilities ... both its network performance, and its performance as an RMS transducer for steady stand and dynamic information on the power system All of these are major issues, and attention here is focused ... identifying important data and for generation of operator alerts Functions for this are the following: Signal conditioning and data repair, to assure the measurement quality and prompt observability...

Ngày tải lên: 21/03/2014, 12:08

... References Anderson, P.M and Bose, A., A probabilistic approach to power system stability analysis, IEEE Transactions on Power Apparatus and Systems, PAS-102(8), 2430–2439, August 1983 Anderson, P.M and ... security: (a) feature extraction and (b) classification The first stage includes off-line generation of a training set of stable and unstable operation states and a space transformation process ... limits (El-Keib and Ma, 1995; Chauhan and Dava, 1997; Chen et al., 2000) The essential idea is to select a set of representative features (such as line flows, loads, and generator limits) and then train...

Ngày tải lên: 21/03/2014, 12:08

... Terms, definitions and symbols for subsynchronous resonance, IEEE Transactions, PAS-104, June 1985, 1326–1334 Kilgore, L.A., Ramey, D.G., and Hall, M.C., Simplified transmission and generation system ... Inter-Harmonics and Generator Torsional Impacts, July 1996, Denver, Colorado 52 IEEE=ANSI Standard C50.13, Standard for Cylindrical-Rotor 50 and 60 Hz, Synchronous Generators Rated 10 MVA and Above, ... increase transient and steady-state stability limits, in addition to being a near perfect means of var and voltage control One transmission project, consisting of 1000 miles of 500 kV transmission...

Ngày tải lên: 21/03/2014, 12:08

... Instructional System Energy management is the process of monitoring, coordinating, and controlling the generation, transmission, and distribution of electrical energy The physical plant to be managed includes ... transform to subtransmission and distribution levels These lower-voltage circuits typically operate radially, i.e., no normally closed paths between substations through subtransmission or distribution ... Since transmission systems provide negligible energy storage, supply and demand must be balanced by either generation or load Production is controlled by turbine governors at generating plants, and...

Ngày tải lên: 21/03/2014, 12:08

... through the forces of supply and demand Economic theory and common sense tell us that if the total supply is high and the demand is low, the price is likely to be low, and vice versa If the price ... Sheble and Fahd (1994) and Wood and Wollenberg (1996) Another heuristic technique that has shown much promise and that offers many advantages (e.g., time-to-solution for large systems and ability ... through the markets (and their associated reserves and losses) While the GENCO is determining the optimal unit commitment schedule, the energy demanded by the market (i.e., market demand) can be represented...

Ngày tải lên: 21/03/2014, 12:08

... i and bus j, gij and bij are the conductance and susceptance of line i-j, respectively, and gish and bish are the shunt conductance and susceptance at bus i, respectively Using Eqs (19.4) and ... performs data acquisition and remote control of a power system Energy Management System (EMS)—A computer system that monitors, controls, and optimizes the transmission and generation facilities with ... illustrates the effect of standard deviation on the normal density function Standard deviation, s, is a measure of the spread of the normal distribution about the mean (m) and gives an indication...

Ngày tải lên: 21/03/2014, 12:08

... specified power demand occurs), the practically observed version of the standard OPF solution will have a higher total power demand, and hence a higher fuel cost, and total revenue, and net revenue ... in a few cases (Dias and El-Hawary, 1990; El-Hawary and Dias, Jan 1987; El-Hawary and Dias, 1987; El-Hawary and Dias, July 1987) In all these studies, the specified power demand of the modeled loads ... OPF solution and hence there will be more cases with a decrease in the power demand, fuel cost, and total and net revenues in the observed version of the results than for its standard counterpart...

Ngày tải lên: 21/03/2014, 12:08