Frequency control using electric vehicles with adaptive latency compensation and variable speed wind turbines using modified virtual inertia controller

Abstract

In this paper, to reduce the effect of low inertia consequences, electric vehicle (EV) and variable speed wind turbine (VSWT) are adopted to collaborate in the power system frequency regulation. A virtual inertia controller based on the IEC 61851 standard is proposed to benefit from EV contribution in frequency regulation. In this controller, the rate-of-change-of-frequency (ROCOF) is measured and an appropriate EV current set point is obtained. Furthermore, to decrease the effect of frequency regulation on EVs owners, a stochastic allocation method of the regulation sequence among EVs parking lots is presented. One of the barriers of employing EV in the frequency regulation is the communication latency. To overcome this issue, according to the measured latency, a weighted combination of several compensators which is called adaptive latency compensator (ALC) is utilized. After compensating the delay, the output power of the EVs is calculated and collaborated in frequency regulation. In addition, an algorithm is proposed for collaborating VSWT in frequency control. In the proposed algorithm, according to the wind velocity, the output power of the VSWT increases to the maximum acceptable value and will be fixed. A method is developed to find the maximum acceptable increment power considering VSWT constraints. After a supportive part, a recovery part is started to return VSWT hub speed to a desired value. Two PID controllers are designed in this algorithm for support and recovery parts. During the recovery part, a second frequency dip emerges and a method is introduced which at first identifies the second frequency dip moment and EVs collaboration is applied to alleviate this unfavorable outcome. To evaluate the performance of the proposed algorithms and controllers, different simulation studies are conducted using the modified IEEE 39-bus test power system. Results confirm the effectiveness of the proposed methods in system frequency support.