Five-Level ANPC Converter for PMSG Based Wind Power System with Grid Power Factor Regulation

Abstract

This paper describes the implementation of Type-IV wind power generating system (WPGS) using a permanentmagnet synchronous-generator interfaced to a weak distribution grid. The power electronic interface in this system is built using a diode-rectifier, a dc-to-dc step-up converter and a dc-to-ac multi-level voltage source converter. This paper proposes the application of a 1-phase 5-Level Active Neutral-Point Clamped Converter (1P-5L-ANPCC) as the dc-to-ac converter in the WPGS. Phase disposition and shifting pulse width modulation technique with capacitor voltages balancing has been implemented to generate switching pulses for 1P-5L-ANPCC. To control the tip-speed ratio of the wind turbine, a closed loop controller is presented. The grid active power flow control is achieved using a modified Synchronous Reference Frame (SRF) closed loop controller for 1P-5L-ANPCC. In this paper, the closed loop controller also features a grid power factor regulation scheme, which is sometimes required in a weak distribution system. Hence, a separate D-STATCOM may not be needed in this system to supply the required reactive power. The proposed WPGS with its control scheme is verified using PSCAD software simulator for a 10-kW wind-turbine. The simulation results obtained are presented to verify the working of proposed WPGS using the 1P-5L-ANPCC. The power factor regulation feature of the controller is also verified using PSCAD and corresponding results are presented.