The term power flow calculation in electric power science refers to calculating the distribution of active power, reactive power and voltage in the power network under the conditions of given power system network topology, component parameters and power generation and load parameters.
Power flow calculation opening report topic: power flow calculation design and analysis of power system
Science: Department of Information Science Major: Electrical Engineering and Automation Class: 07 Electrical Engineering and Automation ScienceNo.: 7022807042 Last name: Xia Runjie Instructor: Zheng
Completion date: 20 10 12.7.
First, the basis and significance of the topic:
Power flow calculation of power system is the basic electrical calculation to study the steady operation of power system. The task of power flow calculation in power system is to find out the operation state of power grid according to the given network structure and operation conditions, including the voltage of each bus, the power distribution and power loss of each branch. Power flow calculation is the most extensive, basic and important electrical calculation in power system, and it is an indispensable part of power planning and operation.
With the development and expansion of power system, computers have been fully applied in power flow calculation of power system. The powerful matrix processing function of MATLAB brings great convenience to the analysis and calculation of power system.
Newton-Raphson power flow calculation method is the most widely used one. Newton-Raphson method is divided into polar coordinate form and rectangular coordinate form, which has good convergence and needs suitable initial values.
Importance of power flow calculation;
(1) Before power grid planning, the power supply capacity and power grid can be reasonably planned by power flow calculation, and at the same time, the reactive power compensation scheme can be selected to meet the requirements of power flow exchange control, peak shaving, phase modulation and voltage regulation at different planning levels.
(2) During the operation, it is expected that the load will increase and new equipment will be put into operation, and different power flow calculations will be selected to find the weak links in the power grid for the reference of the dispatcher's daily dispatching control, and suggestions will be put forward to the relevant departments to improve the power grid structure and speed up the progress of infrastructure construction.
(3) Power flow calculation under normal maintenance and special operation mode is used to compile daily operation mode, guide power plant startup mode, active and reactive power adjustment scheme and load adjustment scheme, and meet the thermal stability and voltage quality requirements of lines and transformers. (4) Analyze the influence of expected accidents and equipment outage on static safety, and formulate the adjustment scheme of expected operation mode.
It is concluded that in the study of power system operation mode and planning scheme, power flow calculation is needed to compare the feasibility, reliability and economy of operation mode or planning power supply scheme. At the same time, in order to monitor the operation state of power system in real time, a lot of fast power flow calculation is needed. Therefore, power flow calculation is the most widely used, basic and important electrical operation in power system. When planning, designing and arranging the operation mode of the system, off-line power flow calculation is adopted; In the real-time monitoring of power system operation state, online power flow calculation is adopted.
Second, the research status and development trend at home and abroad (including literature review):
There are many kinds of power flow algorithms, but generally they must meet four basic requirements: reliable convergence, fast calculation speed, convenient and flexible use and less memory occupation. They are also the main basis for evaluating power flow algorithms.
Development status: In recent years, most of the research focuses on the improved Newton method and P-Q decomposition method. In addition, with the development of artificial intelligence theory, genetic algorithm, artificial neural network and fuzzy algorithm are gradually introduced into power flow calculation. However, so far, these new models and algorithms can not replace Newton method and P-Q decomposition method. Due to the continuous expansion of power system scale, the requirement for calculation speed is also increasing, and the parallel computing technology of computer will also be widely used in power flow calculation, becoming an important research field.
After more than 30 years of development, the power flow algorithm has matured, but there are still many problems to be solved, such as the non-convergence of various Newton power flow algorithms under certain conditions, the phenomenon and mechanism of multiple solutions in power flow calculation, and the relationship between adjacent roots and voltage instability under heavy load. Because the optimal power flow can integrate the safety and economy of the system and provide decision-making basis for improving the safety and economy of the system, it will become one of the core application software of modern energy management system. At present, there are many problems to be solved, whether in practice or in theory, especially how to solve the large-scale nonlinear programming problem with thousands of variables quickly.
Development trend: In recent years, the research on power flow algorithm is still how to improve the traditional power flow algorithm, Newton Raphson method. Because it adopts the method of successive linearization when solving the nonlinear power flow equation, in order to further improve the convergence and calculation speed of the algorithm, people consider the higher-order term or nonlinear term of Taylor series, so the second-order power flow algorithm is produced. Then, according to the characteristics that the power flow equation in rectangular coordinates is quadratic algebraic equation, a nonlinear fast power flow algorithm in rectangular coordinates is proposed.
Third, the research content of this topic.
1. Significance and common calculation methods of power flow calculation.
2. Understand the origin of node admittance matrix, grasp the physical meaning and calculation method of elements, and the characteristics of node admittance matrix, thus
And its application.
3. Mainly study the principle, classification and characteristics of Newton's Raphson Law.
4. Application of Newton-Raphson method in power flow calculation in rectangular coordinate system and polar coordinate system. 5. Realization of power flow calculation in MATLAB.
6. Write a computer program with MATLAB software to analyze Newton-Raphson power flow calculation. 7. Check the selected examples of compiled programs, and analyze and summarize the results in detail.
Fourth, the research plan
1. Compile the block diagram and program to form the node admittance matrix of power network.
On the premise of mastering the basic concepts, the program block diagram of forming the admittance matrix of power network nodes is drawn, and the application program for processing the formation of the admittance matrix of power network nodes is compiled. The program should be based on the branch data of the power grid. 2. The calculation block diagram and program of Newton Raphson method for power flow analysis are compiled.
On the premise of mastering the basic concepts and mathematical principles of Newton's Raphson's law, the program block diagram is drawn, and the application program is compiled to deal with the power flow calculation of general power system. In the process of compiling, it is required to choose the best solution of linear equations as far as possible, find the regularity of calculation formulas, and make the program as concise as possible. The required power flow calculation results include: node voltage, node power, line power, network loss, iteration times, etc. 3. An example verifies the program results.
Choose a suitable example to test the compiled program. The test results are analyzed and summarized. Step 4 write a graduation thesis
The paper should include a description of basic concepts and principles. Program block diagram and list. Use examples and test results examples to program. And experiences.
Verb (abbreviation for verb) work progress
Reference of intransitive verbs
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[2] Dong Wang, Visual Basic Programming Practical Course (2nd Edition) [M]. Tsinghua University Publishing House, 2002.
Zhu Junwei, Power System Analysis [M]. China Electric Power Press, 1995.
Wang Xifan, calculation of power system [M]. Water resources and electric power press, 1978.
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