High-voltage Ride Through Strategy for DFIG Considering Converter Blocking of HVDC System

Abstract

This paper presents a P-Q coordination based highvoltage ride through (HVRT) control strategy for doubly fed induction generators (DFIGs) based on a combined Q-V control and P-V de-loading control. The active/reactive power injection effect of DFIG on transient overvoltage is firstly analyzed and the reactive power capacity evaluation of DFIG considering its de-loading operation is then conducted. In the proposed strategy, the reactive power limit of DFIG can be flexibly extended during the transient process in coordination with its active power adjustment. As a result, the transient overvoltage caused by DC bipolar block can be effectively suppressed. Moreover, key outer loop parameters such as Q-V control coefficient and deloading coefficient can be determined based on the voltage level of point of common coupling (PCC) and the available power capacity of DFIG. Finally, case studies based on MATLAB/Simulink simulation are used to verify the effectiveness of the proposed control strategy. Index Terms-Active power de-loading control, high-voltage ride through (HVRT), inductive power absorption, transient overvoltage.

Optimal Power Distribution Method for Wind Farms to Enhance the FRT Capability of the LCC-HVDC System Under Commutation Failure

“…According to (9), the overvoltage of the sending AC grid under commutation failure can be suppressed by increasing the capacity of wind farms to absorb reactive power. According to Fig.…”

“…According to (8), the influence of the reactive power of the wind farm on the overvoltage of the sending AC grid under commutation failure can be analyzed. The influence of the reactive power of the wind farm on the bus voltage of the sending AC grid can be expressed as: (9) According to (9), the overvoltage of the sending AC grid under commutation failure can be suppressed by increasing the capacity of wind farms to absorb reactive power.…”

“…The transient reactive power of the wind farm on the sending AC grid is one of the main factors affecting the overvoltage of the sending AC grid [2] [6]. Considering the capacity limitation of wind turbines and converters, the transient reactive power of wind farms is limited by the active power of wind farms [9]. The power distribution method for wind farms is defined as the plan for the active power output of each wind farm in the regional power grid.…”

“…Jin et al [6] proposed a power command delay compensation strategy to speed up the power response speed of wind turbines to suppress the overvoltage of the sending AC grid under commutation failure. Zhou et al [17] proposed a cooperative power command strategy for wind turbines, which suppresses the active power output under commutation failure so as to increase the reactive power capacity of the wind turbines to suppress transient overvoltage. The existing improved control strategies are mostly aimed at a single wind turbine.…”

High Voltage Ride through Strategy of Wind Farm Considering Generator Terminal Voltage Distribution

“…AC failure at the sending-end grid may cause the DC blocking of the HVDC transmission system, and further lead to voltage swell problem for wind farms. To improve the high-voltage ride-through (HVRT) success rate of doubly-fed induction generators (DFIG), some papers have studied the reactive power compensation capability of DFIGs and proposed corresponding wind turbine reactive power compensation control strategies [5][6][7][8][9]. Reference [6] put forward a reactive current assignment strategy for a grid-side convertor (GSC) and rotor-side convertor (VSC), for two different ride-through scenarios, which improves the ride-through capability of the wind turbine based on DFIG.…”