Study Of Power Quality Control System Based On Dstatcom And Tsc Reactive Power Compensation

From the end of last century,power quality is gradually becoming concerned focus of electric power enterp rise ancd consumer.As two important power quality indicators,voltage fluctuation and flicker are inseparably related to the chan ge of reactive power in power grid.Generally,in order to suppress voltage fluctuation and flicker,reactive power compensator is usually used to compensate inductive reactive power or capacitive power that system is wanting and then maintain voltage stability.First of all,the principle and mathematical model of static synchronous compensator and thyristor switching capacitor are studied in this paper.The working principle of static synchronous compensator is analyzed for DSTATCOM steady state working vector diagram,the state-sp ace expressions of d-axis current,q-axis current and DC-side capacitance voltage are established,and then the compensation principle of static synchronous compensator is revealed.The relationship between the steady state current and the power supply of the circuit is established by using the sin gle-phase TSC connection circuit,then the expressions of the two differential equations are established from the point of view of time domain,the principle of thyristor zero-crossing switching capacitor is analyzed at the same time.Secondly,the detection method of reactive power and harmonic current and the control strategy of hybrid compensation system are desigied in detail.Thedetection of reactive power and harmonic current is based on ip-iq-based double-window-width sliding filter to adapt to both static and dynamic detection situations.The integral control of reactive current adopts the double closed loop structure of outer loop voltage control and inner loop current control.The DSTATCOM and TSC controllers receive respectively the given current value of the instruction front the coordination control center through the coordination distribution algorithm.The feedforward control strategy based on reactive current improves the response speed of the system and makes up for the defects of the hybrid compensation system.Fuzzy control is used to optimize the parameters of PI controller to adapt to the variable structure and nonlinear characteristics of power system and the simulation results show that the optimized controller improves the real-time performance of current response.Finally,the hardware and software system of coordinated control unit is designed and studied.In the hardware part,the microprocessor AM3354 based on Cortex-A8 architecture is used as the computing center of coordinated control.The sampling circuit based on RN7302 and transceivers part using to transmit 485 signal and CAN signal are designed.The software part adopts Linux operating system.The program of coordinating allocation of control center is written based on the underlying protocol driver of SPI,485,CAN and so on,and eventually the coordinated distribution of reactive current is realized.