Electric Power System Dynamic Equivalence And Its Application

As more and more Ehv transmission lines being erected, more and more large generators being inputted, more and more subsystems interconnecting widely, our country power system is becoming larger and increasingly complex. If we still use full model of such electric power system to do analysis, which can't bear either in manpower resources or in time. Although we can give each power system element accurate mathematical model, we cannot provide parameters conforming to the actual network. Because of the lack of parameters, many special factors influencing the operation conditions will not be considered, leading to large discrepancy between calculation results and practical situation. Moreover, the external system data is more and more difficult to get. Coherency and model dynamic equivalence method need to know the whole date of the external system, whose disadvantages begin showing. Identification method dynamic equivalence is different, according to the measurement of the boundary data, it can identify external system equivalent model, which instead-s of the original system to study. Thus, identification method dynamic equivalence is well adapted to modern grid changes; its advantage is becoming more and more prominent.This paper chooses identification method dynamic equivalence for research object, does the following jobs:Summarizing the existing dynamic equivalence methods, which can be roughly divided into three types:coherency equivalence method,model equivalence method,identification equivalence method. The core work of coherency equivalence method is discriminating coherency units. According to the discriminate result, we merger generator buses, polymerize generator parameters, leading a coherency group to one unit. Model equivalence method, which based on the analysis on the roots of A array of external system linear model, reduces the rapid attenuation and high frequency modes, retain the dominant model to get one lower order external system. Identification equivalence method is the way, which uses the boundary measurement data to identify the equivalent parameters of the external system. Analyzing the equivalent model of three regional interconnection system. As our country power system is becoming larger and increasingly complex, when doing Equivalent simplification of interconnected system, if we still use single generator model with single load model, which is no longer appropriate. In order to deal with these changes, we should look for more accurate equivalent model than ever before.Using Genetic Algorithm to identify the parameters of three regional interconnection system dynamic equivalence type. This paper Chooses EPRI 36 for simulation system, identifies model parameters of external systems in the different conditions, verifies identification algorithm feasible by comparing the dynamic response of the research system before and after Equivalence in different conditions.