Study On Sliding Model Variable Structure Control In DSTATCOM

With the development of modern industrial, power quality becomes more and more important to customers. The technology of Flexible AC Transmission Systems (FACTS) is gradually utilized for distribution system (Custom Power), which forms power quality control technology based on inverter. In this paper, the typical custom power device, i.e. Distribution Static Synchronous Compensator (DSTATCOM), is studied. The paper includes the main circuit configuration and fundamental principle of DSTATCOM, reactive power and harmonic current detecting methods based on instantaneous reactive power theory, pulse width modulation technique and control strategy for DSTATCOM.As a non-linear control method, Sliding mode variable structure control (SMC) exhibits increasing attraction to power electronics control. SMC has a natural accordance to the non-linear characteristic of power electronics device. The SMC control for inverter has many advantages such as wide stability range, quick dynamic response, good robustness and easy realization. In this paper, sliding mode variable structure control is used for DSTATCOM based on research with the traditional PI control. Two novel control strategies are presented. One is sliding mode variable structure with integral action underαβframe for voltage source inverter based DSTATCOM, the other is exponential reaching law sliding mode control strategy for current source inverter based DSTATCOM. With the control strategies presented in this paper, the disadvantages of PI control are overcome, the device capability are realized more sufficiently, reactive power compensation, harmonics and imbalance suppression become more effective.The control performances of the two proposed control strategies and PI control strategy are simulated and analyzed with power system analysis software PSCAD/EMTDC, and the control strategies are compared. The simulation results verified the effectiveness of the proposed methods.