A DC chopper‐based fast active power output reduction scheme for DFIG wind turbine generators

Abstract

Increasing penetration level of renewable energy results in unprecedented operational challenges of AC grids due to generation uncertainty and reduced inertia. In grid emergencies, Fast active Power output Reduction (FPR) is demanded to drop wind turbine generator (WTG) power outputs faster than usual. However, the power mismatch between WTG mechanical power input and reduced electrical power output resulted from FPR can lead to rotor overspeed, which cannot be timely nullified by slow-responding pitch control. Therefore, this paper proposes a novel FPR scheme for doubly-fed induction generator (DFIG)-based WTG through coordinated control of DC chopper and pitch angle. Specifically, the FPR command is executed by DFIG rotor-side converter control, while rotor overspeed is restricted by triggering the DC chopper to dissipate the mismatched power. The pitch angle is actuated at a maximal rate to eliminate the mismatched power and switch off the DC chopper. The effectiveness of the proposed FPR scheme is verified through comparative simulation studies under FPR command execution and a grid fault. It shows the proposed scheme can achieve FPR in tens of milliseconds, avoid rotor overspeed and provide low-voltage ride-through capability in a fully-controlled manner.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Evaluating a Hybrid Circuit Topology for Fault-Ride through in DFIG-Based Wind Turbines

“…The DC chopper regulates the fault current through the chopper resistor by controlling the duty cycle of the semiconductor switch. When the voltage across the DC link exceeds the threshold voltage ( ) during a fault condition, the equation for can be expressed as [ 28 ]. where and are the PI controller coefficients.…”

Adaptive-Output-Voltage-Regulation-Based Solution for the DC-Link Undervoltage of Grid- Forming Inverters

“…In the overvoltage scenarios, many solutions have been reported to avoid this potential risk. One typical method is to use the dc-chopper circuit or the crowbar to consume the extra energy, thus making the dc-link voltage return back to the normal value [10]- [11]. Apart from this hardware-based solution, a modified controller-based solution is reported in [12].…”

An Overview of Control Method with Various Crowbar Techniques of Wind Turbines during Power System Faults

“…A review of published the crowbar protection techniques are discussed in [9][10][11][12][13]. [14][15][16] mentioned that both DC-brake chopper and crowbar are necessary for FRT capability to protect the DFIG components from over-current and over-voltage. However, the different protection techniques are turned on/off via control strategy called ANFIS.…”