Research On Structural Improvement And Parameter Optimization Of Power System Stabilizer

After the asynchronous interconnection operation of Yunnan Power Grid,the structure and operation mode of the grid are changed.Some of the existing PSS2 B gain of Yunnan Power Grid will affect the suppression ability of the low frequency band,and Some of PSS2 B parameters no longer be suitable for the new operation mode.These factors have led to low-frequency oscillations in the area near the DC power transmission line in Yunnan Power Grid.In this paper,theory of PSS2 B in Yunnan Power Grid is analyzed.PSS2 B parameters optimization and structure improvement improve the ability of the power system to suppress low frequency oscillation.It has good theoretical and practical value.In this paper,the mechanism of low frequency oscillation is studied on the basis of the single machine infinite linearization model,and the principle of PSS suppressing low frequency oscillation is analyzed.The working principle and characteristics of the self-shunt excitation system and PSS2 B controller currently used in Yunnan Power Grid are analyzed and studied.The properly simplified and linearized processing are carried out according to the working principle of both.The multi-machine linearization model of Yunnan Power Grid is established.The state matrix of multi-machine system is listed,which provides the theoretical basis for the subsequent PSS2 B parameter optimization.Firstly,this paper analyzes the existing structure and gain of PSS2 B in Yunnan Power Grid and finds that existing PSS2 B in some power generation units in Yunnan Power Grid has the problem that the gain in the high frequency gain growth soared and the gain in the middle and low frequency bands is limited.In this paper,New-PSS2 B is set up on PSASPUDM platform and added to single-machine infinite model which built in PSASP.The simulation results verify that New-PSS2 B can effectively solve the problem of high-frequency gain surge and improve the gain in the low band.Secondly,based on the standard biogeographic algorithm(BBO),the adaptive migration operation and the DE algorithm mutation operation are designed to improve the standard BBO algorithm,and the improved BBO algorithm(BBO-DE)is obtained.The performance of BBO-DE algorithm is tested by using the test function and compared with the original standard algorithm.The results show that the improved algorithm in this paper has the advantage of not easy to falling into the local optimum and converging faster.According to the negative damping mechanism and characteristics of excitation system,the damping ratio of the system is introduced as an objective function,and the different operating modes of the system are considered.It can effectively suppress the low-frequency oscillation and ensure that the PSS2 B parameters are robust.Finally,the classical 4-machine 2-areas system and partial regional model of Yunnan Power Grid are built in the PSASP simulation platform.Under different operating conditions,this paper compared with PSS2 B,BBO-SPSS and BBODE-MPSS through system of damping and time domain simulation of low frequency oscillation suppression effect.It verified that the optimized by BBODE-MPSS can effectively improve the system damping and has good robustness that can adapt to different working conditions of the system.