Research On Nonlinear Variable Structure Control Strategies For Single Machine System With SSSC

In the long transmission, the power is restricted by the impedance of the transmission mainly. The paper studies Static Synchronous Series Compensator (SSSC) to solve the problem about power supply quality and the non-stability resulting from the LC oscillation. SSSC is a very important device of FACTS. The fundamental principle of SSSC is the voltage source inverters. The series controllable voltage which is produced from SSSC can replace the performance of series capacitor or reactance. The compensator for line impedance could not cause resonance and oscillation. In this way, SSSC can provide smooth and rapid impedance compensation to power system, SSSC can regulate the power in the transmission line. Meanwhile, it can also damp the system oscillation and improve transient stability. In comparing with traditional series compensator, SSSC has the goodness such as continuous adjustability, faster response, wide scope of operation, lower harmonics, etc. The method of series compensator has brilliant prospect, and the new way to improve the performance attracts more and more scholars.This paper studies the controller for single machine infinite bus system with SSSC. The main contents have:In the theory respect, the series compensator technology is summarized properly, and the basic structure and effect to power system are introduced in detail. Then the current situation of SSSC and the study content of this paper are interpreted. Then the variable structure control based on inverse system theory is introduced. A lot of key theories and methods are presented, including the linearization based on inverse system method in SISO system, decoupling and linearization using inverse system in MIMO systems, and the basic theory and design process of variable structure control.In the respects of mathematic model and control, the SSSC is equipped in the two infinite-bus system, and the mathematic model of the SSSC is built. In the single machine system field, the relations of SSSC, excitation, and stream valve control system are studied, the MIMO control systems are built. The theories of inverse system and variable structure control are used for its design of control strategies. Finally, the results of MATLAB prove the feasibility and robustness of those control methods.