Tripping Risk Analysis of Wind Turbines under Insufficient Margin of Reactive Power and Impact Load

When wind turbines encounter a short-time withdrawal of the main reactive power source of the system, the access of large impact loads have a great influence on the voltage of the wind turbines, increasing the risk of wind turbines tripping. This paper analyzes the scenario when the thermoelectric generating set of the wind-thermal bundled system are withdrawn from operation, resulting in wind turbines experiencing short-time voltage disturbances with weak reactive power support. The probability distribution model of the electrified traction load is established, and the reactive power regulation range of the doubly fed induction generator is calculated. By identifying the equivalent parameters of the power system, a time-domain simulation model of the wind turbines is constructed, and the critical value of tripping is adjusted accordingly, then the operational risk index of the wind turbines is calculated. The simulation results illustrate that the risk of tripping due to the access of impact load is high when the main reactive power source of the system is withdrawn, and it is urgent to develop corresponding emergency control strategies to reduce the operational risk level of wind turbines.