A Microgrid Variable Reactor with Filtering Function Using Transformer and Inverter

In this paper, a principle of microgrid variable reactor with filtering function using transformer and inverter is proposed to solve the problems of control deviation caused by harmonic pollution in microgrid and the variable reactor's discontinuous adjustment. Firstly, it introduces the principle of variable reactor. A transformer with air gap is chosen and the voltage of the transformer's primary winding is detected and functioned as the reference signal after filtering, phase shift and superposition. A voltage source PWM inverter is applied to produce a voltage source, which follows the reference signal and energizes the secondary winding of the transformer so that the equivalent impedance of primary winding can present a four-quadrant continuously variable impedance to fundamental and infinite impedance to harmonic. The stability condition is also analyzed. The simulation results show the effectiveness and excellent filtering characteristic of the proposed microgrid variable reactor with filtering function.