Study on Voltage Stability and Control Strategy of Grid-Connected Wind Farm

Xinyu Liu,Xianwei Li,Guofang Wu

doi:10.1109/access.2019.2945195

Abstract

Aiming at the Low voltage ride through capability of doubly-fed wind farm when it is merged into a weak grid, this paper researches the theory of rotor excitation control and proposed an additional control model of DFIG grid-connected rotor flux based on structure decentralization theory. In this model, the Low voltage ride through capability of the doubly-fed wind farm is enhanced by designing the d-axis and q-axis adaptive terminal sliding mode controllers for the synchronous rotating coordinate system. Simulation results show that the proposed control model not only can better realize the rapid regulation of reactive power of doubly-fed wind farms, but also improve the ability of the system to resist grid voltage fluctuations, and improve the transient stability of power systems. It has certain theoretical significance and practical application value.

Highlights

Wind power generation is a renewable energy generation method
This paper proposes an adaptive terminal sliding mode additional control strategy for rotor flux linkage by the basic grid-connected operation model of DFIG
By analyzing the integral terminal sliding surface shown in equation (16), it is known that if the doubly-fed wind turbine system satisfies the condition of the generalized perturbation term |Fd | < kd, the following control law can be obtained under the adaptive switching gain ηd

Summary

INTRODUCTION

Wind power generation is a renewable energy generation method. It has many advantages. Literature [16] proposed a method to improve the low voltage ride through capability In this method, the stator and rotor electromotive force models in the wind turbine are designed, and the new stator-damping resistor unit (SDRU) and rotor current control (RCC) are combined with the stator and rotor electromotive force models. Literature [20] introduced a control method to enhance the capability of Fault ride-through (FRT) It studies the application of positive-negative-sequence dynamic modeling (PNSDM) and supercapacitor in DFIG-based wind farms. The DFIG using this control strategy can quickly generate reactive power and reduce the bus voltage, thereby improving low voltage ride through capability

DFIG STRUCTURE DECENTRALIZED DYNAMIC MATHEMATICAL MODEL

DFIG ADDITIONAL ROTOR MAGNETIC LINKAGE

ANALYSIS AND DISCUSSION

CONCLUSION