Research On Coordination Control Of Combined Compensating By Static Var Generator

As the development of technology and the improvement of people's living standard, the problems of power quality became more an more prominent. Reactive power compensation and harmonic treatment have become an urgent means in the transmission and distribution system. As a new type of reactive power compensation device, SVG (Static Var Generator) has broad development prospects. However, the power semiconductor switching devices in the primary circuit of SVG has its rated voltage and rated current, this problem limits single SVG's capacity of compensation. When we need to compensate more reactive power, single SVG is hard to meet the compensation requirements.For the purpose of expanding the capacity and increasing the equipment's utilization, this paper does research on combined compensating of SVG, and selects an appropriate coordinated control strategy. Its aim is to make a rational distribution of compensation capacity according to the nominal capacity of each SVG, to optimize the allocation of resources, to compensate reactive power and harmonics and to improve the power quality.First, this paper analyses the principle of SVG when the SVG is compensating reactive power, describes the basic contents of the instantaneous reactive power theory, describes an method, ip-iq algorithm, which is based on the instantaneous reactive power theory, to detect the reactive power and harmonics'currents. Then, this paper proposes a new detection algorithm—modified sliding-window iterative of DFT. This algorithm is used to extract the fundamental information of the signal. Make SVG's model with Matlab/simulink. Analyses the advantages and disadvantages of control method of SVG. Analyses the features of hysteresis control method. Suggest a new control method which is based on hysteresis control method. This method is called dual-sampling time compare control. Using the method, we can improve the switching frequency of the system, optimize the current tracking, and reduce the pressure of the software designing. Design an artificial interface with LabVIEW. This interface can display three-phase current and voltage waveforms in real-time, and analyze the voltage and current harmonic content and power factor. Because of the excellent portability of LabVIEW, this program can run on the Wince system.Introduce the coordination control method of combined compensating of SVG. Build the platform of combined operation of SVG. Verify the algorithm of reactive and harmonic current's detection and the dual-sampling time compare control method. Verify the method of combined compensating of SVG and the effect of combined compensating of SVG.