Power system (pdf file)

The system starts with the generation, by which electrical energy is produced in the power plant and then transformed in the power station to high voltage the electrical energy that is m

Ho Chi Minh City University of Technology and Education Faculty for High Quality Training

Electrical and Electronic Engineering Technology

POWER SYSTEM

Assoc.Prof Le My Ha

Submitted by Dinh Xuan Tien Bach Quoc Khanh Nguyen Dang Phuong Hua Hong Minh Quan

J anuary 7th , 2022

2.1.1The configuration of a typical power system .5

2.1.2The working principle of power system 7

2.2MATLAB design 8

2.2.1Idea .8

2.2.2Applications of power system in MATLAB 8

In this final project, we develop the project according to the electricity system in a country The application is used by Matlab software through the Simulink tool to run simulations We use renewable energy and solar energy is used as the main source And is connected to the national system through loads and power stations Experimental results show that solar cells can work in different temperature and time conditions.

List of Figures

1.1 On grid power system 4

2.1 Configuration of a typical power system 6

2.2 The distribution network in power system 6

2.3 Structure of power system 7

2.4 Converter 8

2.5 Cascading control block diagram 9

2.6 Block diagram of control method V–I 10

2.7 Block diagram Control method V–f 11

2.8 PV block model connected to Boost Converter 11

2.9 MPPT algorithm 12

2.10 System of loads, transformers and grids 13

2.11 Block diagram of 3 phase motor 13

2.12 Block diagram of Rectifier circuit (Diot) 14

2.13 Block diagram of Pulse generator circuit (PWM); Inverter Circuit (IGBT) 14

2.14 Block diagram of the three-phase motor 15

3.1 Our power system via Matlab simulink 18

Assignment of work

Member Private work Work in pairs Work in group

Dinh Xuan Tien

Prepare code for Latex and find information

about power system

Write report and Bach Quoc Khanh Code of MPPT and present

Nguyen Dang Phuong Find information about

power system Design powerpoint Hua Hong Minh Quan Find information about

power system Design powerpoint

Chapter 1 Overview

1.1Introducing of standard of power system

Electric power systems are real-time energy delivery systems Real-time means that power is generated, transported, and supplied the moment you turn on the light switch Electric power systems are not storage systems like water systems and gas systems Instead, gener-ators produce the energy as the demand calls for it The system starts with the generation, by which electrical energy is produced in the power plant and then transformed in the power station to high voltage the electrical energy that is more suitable for efficient long-distance transportation The power plants transform other sources of energy in the process of pro-ducing electrical energy For example, heat, mechanical, hydraulic, chemical, solar, wind, geothermal, nuclear, and other energy sources are used in the production of electrical energy High-voltage (HV) power lines in the transmission portion of the electric power system effi-ciently transport electrical energy over long distances to the consumption locations Finally, substations transform this HV electrical energy into lower-voltage energy that is transmitted over distribution power lines that are more suitable for the distribution of electrical energy to its destination, where it is again transformed for residential, commercial, and industrial consumption.

1.2Objective of study

We have looked up references on the internet and YouTube, but their make are complicated systems we have consulted and re-implemented the process of making an electrical system - Creation of an electrical system through MATLAB simulink.

- Source starts from solar energy.

- Transformed through loads to reach the point of consumption - Monitor the power transmission of the system.

- The running process depends on the environmental impact.

On Grid solar system is a solar power system connected to the electricity grid The basic structure of a grid-tied power system includes the following basic components:

+ Solar panel

+ The inverter is capable of synchronizing the frequency of the grid

A grid-tied solar power system allows the AC power produced by the PV system to be supplied to local electrical loads or re-supply to the grid when the output of the PV system is greater than the demand of the PV system load However, in the event of a grid outage due to a power failure or maintenance, at this time, the solar power system will be disconnected, the load will no longer have electricity to use Therefore, this system is suitable for customers who are using electricity from Electricity’s grid without ensuring uninterrupted power supply The installation of grid-tied solar power system has the following advantages: Low initial investment cost; no energy storage is used, so the system life is longer and the operating and maintenance costs are low; maximum savings on monthly electricity costs; selling excess electricity to electricity through 2-way meters at preferential prices; Support Electricity in reducing power transmission.

Chapter 2 Design

2.1Theoretical basis

2.1.1The configuration of a typical power system

The basic structure of a power system is it contains a generating plant, a transmission system, a sub transmission system and a distribution system These subsystems are intercon-nected through transformers T1 , T2 and T3 Let us consider some typical voltage levels to understand the functioning of the power system The electric power is generated at a thermal plant with a typical voltage of 22 kV (voltage levels are usually specified line-to-line) This is boosted up to levels like 400 kV through transformer T1 for power transmission Transformer T2 steps this voltage down to 66 kV to supply power through the sub transmission line to industrial loads that require bulk power at a higher voltage Most of the major industrial cus-tomers have their own transformers to step down the 66 kV supply to their desired levels The motivation for these voltage changes is to minimize transmission line cost for a given level Distribution systems are designed to operate for much lower power levels and are supplied with medium level voltages.

The power distribution network starts with transformer T3, which steps down the voltage from 66 kV to 11 kV The distribution system contains loads that are either commercial type (like office buildings, huge apartment complexes, hotels etc) or residential (domestic) type Usually, the commercial customers are supplied power at a voltage level of 11 kV whereas the domestic consumers get power supply at 400-440 V Note that the above figures are given for line-to-line voltages Since domestic customers get single-phase supplies, they usually receive 230-250 V at their inlet points While a domestic customer with a low power consumption gets a single-phase supply, both industrial and commercial consumers get three-phase supplies not only because their consumption is high but also because many of them use three-phase motors For example, the use of induction motor is very common amongst industrial customers who run pumps, compressors, rolling mills etc.

2.1.2The working principle of power system

The power system is a network which consists of generation, distribution and transmis-sion system It uses the form of energy (like coal and diesel) and converts it into electrical energy The power system includes the devices connected to the system like the synchronous generator, motor, transformer, circuit breaker, conductor, etc The power plant, transformer, transmission line, substations, distribution line, and distribution transformer are the six main components of the power system The power plant generates the power which is step-up or step-down through the transformer for transmission The power system is the complex enter-prise that may be subdivided into the following sub-systems The subsystems of the power system are explained below in details.

Figure 2.3: Structure of power system

2.2MATLAB design

In this project, we had a lot of ideas such as designing a power system with solar energy or wind energy After a period of debate, we chose the source as solar energy Then connect that energy source into an electricity network through loads, sources, transformers, etc to transmit to the loads, places of consumption and link to the national grid However, our system also incorporates a three-phase electric motor via diodes and IGBT/diots.

2.2.2Applications of power system in MATLAB

Converter (DC – DC)

DC switch - DC is installed between PV array and inverter frequency The main function of the converter is to create a separation between the two voltage levels by increasing or de-creasing the PV array output voltage to match the inverter input voltage level The structural basis of a converter consists of diodes, capacitors, inductors and switching electronics that can be controlled and act as a switch This commonly used component is MOSFET or IGBT The tool converts each option type, and the way these events are connected is also different.

Figure 2.4: Converter

Converter control (MPPT)

MPPT (short for Maximum Power Point Tracker) or maximum power point tracker is an electronic converter to optimize the match between solar panels and solar batteries, or grid Simply put, they convert the higher voltage DC current from the solar panels to the lower voltage needed to charge the solar battery.

There are a lot of type of MPPT, but in this project, we have consulted and selected P&O (Perturbation and observation), which is a cascaded linear control method, with the outer stage being a DC voltage control loop and the inner stage a current control loop This algorithm is applied to the boost converter This algorithm alters the operating voltage to ensure maximum power Although there are some more advanced and optimized variations of this algorithm, the basic P&O MPPT algorithm is shown below.

Figure 2.5: Cascading control block diagram

Inverter (DC – AC)

Inverters are used to convert DC to AC in PV systems Different types of inverters produce different “quality” of electricity Therefore, based on the amount of electricity that the load requires, the user must choose the appropriate inverter to achieve the best possible efficiency Simple storage consists of semiconductor tools such as BJT, IGBT Operates on the fre-quency of the inverter and turns off the switches at the required frefre-quency f However, when operating, the harmonic generator can generate overheating in case of no higher dynamic load

as well as uneven magnetic field affecting the overall operation Harmonics can be reduced by using high frequency tuning techniques to reduce harmonics and provide load voltage testing.

Inverter control method

The operation and control of inverters of distributed renewable energy sources, such as Photovoltaic in microgrids, is a real challenge, especially when it comes to maintaining both low grid voltage and frequency within the allowed range There are many methods that have been studied, of which three are common: the V–I cascade control method, the V–f voltage-frequency control method and the PQ power control method In this section, two methods of cascading V-I control and V-f control are introduced Note, the control methods consider the coordinate system transformation abc-dq and vice versa, which will be analyzed in the following section.

Figure 2.6: Block diagram of control method V–I

Modeling a PV system using Simulink

In this section, a stand-alone PV system will be modeled including PV array, MPPT, Boost converter and inverter.

Figure 2.8: PV block model connected to Boost Converter

Pv system is designed to endure with different weather circumstances The parameters are shown in the table below.

The MPPT algorithm used is the P&O (Perturbation and observation) that we mention in section Converter control (MPPT) above.

Figure 2.9: MPPT algorithm

The power system

The PV–converter Block is then connected to the inverter (DC-AC) Then it is connected to a transformer to increase the voltage (22kv) and directly connected to the transmission line (designated in the form of ) and carries the high voltage power to the loads used ( we use in this project is the load R) A part is continued to be connected to the national grid.

Three-phase motor

Figure 2.11: Block diagram of 3 phase motor

Besides connecting to the system of loads and the power grid, we also connect to a three-phase motor system to see the operation of solar energy.

The input source is a three-phase AC source (50Hz) The structure of a three-phase motor consists of these parts:

+ Rectifier circuit (Diot)

+ Pulse generator circuit (PWM) + Inverter Circuit (IGBT) + Electric motor

Figure 2.12: Block diagram of Rectifier circuit (Diot)

The operation is as follows: Before the power source enters the motor, it must pass through the rectifier circuit (Diot) Then connect to intermediate d.c voltage (L) And continue through an inverter circuit (Including 6 IGBT) Through the inverter circuit, the intermedi-ate DC voltage will be converted into AC voltage Finally, current will be supplied to the stator of the 3-phase AC motor.

To control the inverter circuit, we must have a pulse generator (PWM) circuit.

Figure 2.14: Block diagram of the three-phase motor

persistent Dprev Pprev Vprev % record values for next recall

Chapter 3 Results

Despite many controversies and disagreements, we did this project completely Although there were many controversies and disagreements, we did this project completely MATLAB simulink completed within the time we set The hardest part was the MPPT algorithm that we had to consult and learn from a lot of people Second, it is rearranging the blocks so that they link to form a complete system There are times when the run fails but we still find a way to fix it Third, is a three-phase motor system And connect them to the Solar power source Besides, thanks to the MPPT algorithm and the Intensity Adjustment Block, our system runs normally and produces numerical and sine results.

In the process of mounting blocks and running the system is very complicated We often have system errors We were shocked by what we went through We don’t know where to start over and especially in the process of learning online We are difficult to connect with each other to solve the problem But thanks to Mr Tu (a graduate student from Polytechnic University) who helped us in installing the loads, sources and even the code for MPPT.

Although, we are under the guidance of Mr Tu and the system runs well, but we only understand part of the MPPT algorithm, still do not fully understand the algorithm, so we need to study that part more.

Solar power is mainly used to operate residential equipment, commercial equipment, light-ing and air conditionlight-ing for all types of buildlight-ings Through stand-alone systems, it is also very suitable for remote areas where there is no power source PV solar panels can be mounted on the ground, installed on the roofs of buildings or installed floating on a lake This chapter discussed solar PV arrays, converters, inverters and control methods, MPPT techniques along with MATLAB/SIMULINK blocks describing PV system components.