Xu Jiazhu

LCL output filter design and the influence to the D-STATCOM compensation characteristic

As an important dynamic compensation device, the D-STATCOM is widely used in the power system, but its output current contains a lot of high-frequency harmonic composition. The LCL filter, a typical output filter, has good filter characteristics, but the compensation characteristic of D-STATCOM has strong sensitivity to the filter parameters. The paper firstly analysis the influence caused by the components of the output filter. Considering the compensation capacity of the D-STATCOM, the compensation current switching ripple, the grid THD, the resistance loss and the other factors, a method of designing LCL filter was presented, and then analysis the compensation characteristic of the D-STATCOM with the LCL filter, the results proved that the output filter designed in this method has very good inhibitory effect on high-frequency switching ripple, and greatly improved the compensation performance of the D-STATCOM.

An improved droop control strategy in the islanding operation

For maintaining the stability of voltage and frequency, the droop control is often adopted when micro-grid is in islanding operational mode. Although this method can control the fluctuation of voltage and frequency, when the loads change, its implementation effect is weak In order to solve the mentioned problem, an improved dynamic self-adjusting droop control strategy is proposed: on the basis of the traditional one, PI control of voltage and frequency is introduced to control flow. The principle and implementation steps of this method are analyzed. Finally, the operating characteristics of overloading connection, overloading cutting-off and loads disturbance are simulated and discussed based on an islanding mode built in Matlab/Simulink. The results show the proposed method can control the voltage and frequency more effectively and faster than traditional droop control, and can enhance the stability of micro-grid in islanding operational mode.

Application prospect of a new transformer inductive filtering technology

Different from passive and reactive filtering methods, this paper proposes a new transformer inductive filtering technology. Its characteristics is that it develops the potential electromagnetism capability of the transformer and makes use of the ampere-turn balance action of the interior coupling winding, which can suppress the harmonics in the secondary winding and avoid the harmonics flowing into the primary winding. In addition, it can effectively abate the negative effect of the harmonic magnetic potential on the transformer. This paper introduces three types of new supply transformers, expounds the interrelation and combined technical characteristics, then expands on its research progress and the industrialization condition. Furthermore, the paper summarizes the practical significance of new inductive filtering technology and its application prospect. The author adopts systematic analysis method, and carries out systematic research for the transformer inductive filtering technology. By means of various model experiments analysis, it verifies the good filtering influence that the new inductive filtering technology has.