The Nonlinear Control Strategy Of DSTATCOM Based On The Theory Of Feedback Linearization

Power quality problems on distribution system were became a growing emphasis. Distribution Static Synchronous Compensator(DSTATCOM) as an important user of electrical installations, can be integrated to solve power quality problems. Due to it's compensation results primarily depend on control system performance, DSTATCOM control strategy to become a hot research scholars at home and abroad.In this paper, According to three-phase four-wire three-level DSTATCOM, a variety of three-phase four-wire system of DSTATCOM main circuit structure was analysed at first. Then DSTATCOM main circuit was determined to be the midpoint of bridge arm three-level inverter. After that, the basic working principle of DSTATCOM was analysised in the ideal situation and the non-ideal conditions. Then the state-space model of DSTATCOM was established in the a-b-c coordinate system and d-q-0 coordinate system.According to the p-q-o reactive current detection method in three-phase four-wire system based on the instantaneous reactive power theory and three-dimensional space vector (3-D SVM) modulation strategy based on the reference voltage decomposition, the PI controller of DSTATCOM was integrated design. And then, using PSCAD/EMTDC simulation software to verify its control effect. Simulation results reflected the characteristics of the PI controller and the existing problems.The theory of input-output feedback linearization was systematic analysed, so DSTATCOM nonlinear control strategy was to determine like:useing p-q-o reactive current detection method to calculate three-phase four-wire DSTATCOM reference current, then according to feedback linearization control technique derived reference voltage vector, and using 3-D SVM modulation to control three-level NPC inverter. The simulation experiments verified the effectiveness of non-linear control strategy.Due to changes in system parameters were able to cause errors, affect the dynamic response of the system and reduce compensation effect. Through the load mutation of distribution power system, the three-phase four-wire three-level DSTATCOM non-linear control system have been simulated, the compensation effects and dynamic response of controller aslo have been analysed.