Research On Control Strategies Of Current Source Converter-Based STATCOM

With the development of electric power industry, the problems of electrical power energy and power use efficiency have been paid more and more attention. Compensating reactive power for the power network is an effective way to improve the power quality. Static Synchronous Compensator (STATCOM) plays an important role in improving power quality and power use efficiency as well as promoting energy-saving and environmental protection. Because of its rapid dynamic response and excellent compensation performance, STATCOM has been a hot issue in reactive power compensation area around the world. STATCOM includes VSC-STATCOM and CSC-STATCOM, this paper focuses on CSC-STATCOM. The main research work of this paper is as follows:Firstly, the basic topology structure and operation principle are introduced, and the mathematical modeling of system is built. In order to reduce the switching frequency and switching losses of SPWM modulation strategy, a new SVPWM modulation strategy based on sawtooth carrier is introduced, the comparative analysis with traditional SPWM modulation technique based on triangular carrier is made, and the simulations are established.And then, the control strategy for three-phase CSC-STATCOM system is studied in detail. Dual closed-loop control structure is adopted in the control system. The traditional PI control is used in the outer current loop to stabilize the DC side current, and state feedback linearization control method is applied in the inner loop to tracking reactive command current. Aiming at the disadvantages of conventional phase locked loop (PLL), a control method without PLL is proposed, which is suitable for three-phase CSC-STATCOM system, the superiority of this no phase-locked loop control method is showed by simulation results.Lastly, the Matlab/Simulink simulations of three-phase CSC-STATCOM system are established. Meanwhile the experiment platforms are set up, the rapid dynamic response and excellent compensation performance of three-phase CSC-STATCOM system are demonstrated by the simulation and experiment results.