Study On SVC Digital Regulator For Industrial Loads

In morden power system, reactive power control has become a necessary measure to ensure the power system realiable and economical. SVC (Static Var Compensator), due to its advantage of rapid, continuous and independent control of three phase reactive power, has become the best choice of reactive power compensator in power system supplying fluctuating loads.The electrical characteristics of industrial loads and the requirements of their reactive power compensation to SVC were analyzed firstly, and the basic conceptions, causes, negative effects, evaluation and solution of three phase unbalance were discussed in detail. Based on these, the algorithms of reactive power compensation and load balancing were generalized, and a new control algorithm based on single-phase instantaneous reactive power was proposed in this paper. In this algorithm, the single-phase instantaneous reactive power is detected by Hilbert phase-shifting transformation, and a half-cycle mean filter was adopted to filter the fluctuation of the results against current harmonics in the system. The simulation results verify that the compensation effects were improved significantly. For the comprehensive application of reactive power and asymmetric compensation, the relationship between the value of the parameter L, C, the reqirements of compensation capacity and three-phase degree of asymmetry was deduced theoretically from sequence-components and ideal compensation analysis, which provided theoretical warranty to design the parameters of SVC. The simulation results in different work conditions testify the correctness of the relationship. The mathematical model of SVC system was established, the stability conditions of close-loop control system were analyzed, and the parameters of PI regulator were adjusted.As to the overall structure, distributed structure was adopted in hardware design, and SVC experimental system was developed. The principle circuit and control algorithm of SVC control system based on DSP was designed. At last, the performances of the system were fully detected through experiments and simulation, and the advantages and disadvantages of open-loop and close-loop control schemes were compared in this paper. The experimental results indicate that the half-cycle mean filter can improve the compensation effects, the design method of SVC parameters was feasible, and the SVC experimental system can realize the reactive power compensation and the load balancing.