Active power and reactive power regulation capacity study of DFIG wind turbine

In this paper, taking the doubly fed induction generator (DFIG) wind turbine as the research object, an electromagnetic transient simulation model is established in PSCAD/EMTDC simulation environment to analyze the active power and reactive power regulation capacity of DFIG wind turbine. Under different wind speed, maximum power point tracing (MPPT) control is implemented to ensure the optimum active power output, meanwhile the reactive power limits are calculated and combined with reactive power requirement of local load or the grid to determine the reactive power output. It can achieve operation optimization by making full use of a DFIG wind turbine capacity of the flexible power regulation.

I. Introduction

NOWADAYS, variable-speed constant-frequency (VSCF) wind-power doubly-fed induction generator is the most widely used for wind farms with the development of wind power generation technology. Compared with constant speed constant frequency (CSCF) wind generating system, variable speed constant frequency doubly fed wind power generator presents noticeable advantages such as, it can keep the optimum tip-speed ratio to get maximum wind-power during a low wind speed and improve the flexibility of the drive system by releasing or saving some energy during high wind speed, in order to ensure the active power output smooth [1]–[6]. At the same time, doubly fed induction generator wind turbines can achieve the decoupled control of active and reactive powers. So it not only can work as a power supply to the grid, it can also be used as reactive power supply to stabilize the power system voltage around a prescribed value and deliver the reactive power as compensation to local users near the wind farms. Therefore, calculation of the reactive power limits has important significance in selecting the reactive power control strategy and determining the set point of reactive power [7]–[10]. Hence, active power and reactive power regulation capacity study of DFIG wind turbine have attracted more attention.