Research On Theories And Technologies Of Distribution Static Synchronous Compensator (D-STATCOM)

Distribution Static Synchronous Compensator (D-STATCOM) is an important "Custom Power" device, which can be an effective solution to power quality problems such as voltage fluctuation and flicker, three-phase voltage imbalance and harmonics pollution. Based on laboratory±50kvar D-STATCOM devices for the development background, D-STATCOM voltage control strategy, unbalanced control strategy, compensation current detection and control technology, power switching device drivers and snubber circuit design parameter optimization theory and key technology for the system in-depth were studied.Reactive compensation and voltage control are the basic functions of D-STATCOM. D-STATCOM can make the voltage of PCC maintain the voltage reference voltage value through reactive power exchange with the power system. For D-STATCOM devices with good voltage compensation performance, voltage controller design is crucial. In the second chapter aims at the shortcomings of the traditional voltage control strategy of D-STATCOM, on the basis of instantaneous reactive power theory, power exchange from the perspective of a detailed analysis of the D-STATCOM system of power exchange, derived from the D-STATCOM output voltage instructions and directives for conversion between the current relationship thus the balance of power based on instantaneous voltage direct control strategy. As the realization of the control strategy the connect reactor equivalent electrical parameters are used. Therefore, the performance of the controller will be influenced by equivalent electrical parameters. At the same time taking into account the D-STATCOM mathematical model of accuracy, the adaptive fuzzy PI control is used in D-STATCOM control system, which makes not only simple, easy to implement, but also robust adaptive performance, simulation results prove this point.Unbalanced control is a technical difficulties when D-STATCOM realization of the project application. Grid voltage imbalance prevailing in power system, power system voltage imbalance will give D-STATCOM adversely affected. In the third chapter the output performance of inverter for D-STATCOM and the overcurrent phenomena of D-STATCOM are analyzed detailed under power system voltage is imbalance. A comprehensive utilization of improved switching function modulation and negative sequence voltage feedforward control the imbalance control strategy overcome alone improve the switching function modulation and negative sequence voltage feedforward control strategy to control the imbalance, the defects solve the D-STATCOM output current harmonics of the device and overcurrent problems. In order to take advantage of D-STATCOM improve the supply voltage imbalance positive and negative sequence control loop superimposed imbalance control strategy is proposed in the third chapter is. From simulation and the experimental results, this imbalance control strategy is feasible.D-STATCOM devices in addition to compensation of reactive power and voltage, but also can be used for load comprehensive compensation. Broaden D-STATCOM scope of application enhance D-STATCOM device's cost-effectiveness is D-STATCOM future development of a direction. When using D-STATCOM to achieve a load comprehensive compensation, compensation current detection and control technology is one of the two key technologies. In the fourth chapter a modified vector based on the supply voltage synchronous reference coordinate transformation method is proposed. This method is no need PLL circuit and the voltage imbalance conditions can be accurately detected by the load current of reactive, harmonic and negative sequence to meet D-STATCOM load compensation requirements. Consideration of the irregular non-sinusoidal signal of D-STATCOM's direct current, the conventional current tracking control technology is very difficult to achieve without static error tracking. Because of this, in the fourth chapter based on the vector space hysteresis current control technology is introduced to the D-STATCOM which achieves comprehensive load compensation and achieves good control effect.D-STATCOM devices to achieve security, stability operations depends to a large extent on the main circuit power switching device operation. In order to ensure that the power switching devices stable can reliably work, we must design its excellent performance driving circuit and the snubber circuit. Chapter 5 of the papers from the point of view of project development cycle and drive circuit performance, integrated use of intelligent integrated driving module SD315A as D-STATCOM power switching device IGBT drive circuit, the driving circuit has the function of driving, isolation and protection of integration and development cycle is short so suitable for D-STATCOM practical device development. In the fifth chapter also designed a D-STATCOM new main circuit structure, the main circuit inductance makes smaller and better transient voltage suppression. In addition, a fuzzy-based multi-objective optimization of the design parameters of the snubber circuit, practice has proved that the method is feasible. In the sixth chapter of the paper under the guidance of the above theories and technologies a±50kvar D-STATCOM prototype is development. A large number of experiments are implemented on the experimental prototype. The experimental results match with the simulation results. The correction and effective of the theories and technologies are verified by the experimental results.