Weihang Yan

Inertial response of wind power plants: A comparison of frequency-based inertial control and stepwise inertial control

The frequency regulation capability of a wind power plant plays an important role in enhancing frequency reliability especially in an isolated power system with high wind power penetration levels. A comparison of two types of inertial control methods, namely frequency-based inertial control (FBIC) and stepwise inertial control (SIC), is presented in this paper. Comprehensive case studies are carried out to reveal features of the different inertial control methods, simulated in a modified Western System Coordination Council (WSCC) nine-bus power grid using real-time digital simulator (RTDS) platform. The simulation results provide an insight into the inertial control methods under various scenarios.

Inverter controller design based on model predictive control in microgrid

This paper presents a design of inverter controller based on the model predictive control (MPC) in the microgrid. The traditional PI controller is compared with the model predictive controller to demonstrate the advantage of MPC controller. The design concept of MPC controller is verified through several cases in this paper to demonstrate its control capability when microgrid works in grid-connected mode and islanded mode. The results confirm the effectiveness of designed MPC controller that has faster response speed and less overshoot.

Application of energy storage in high penetration renewable energy system

The application of energy storage technology in high penetration renewable energy systems are reviewed in this paper. Firstly, the characteristics of power system with high penetration renewable energy are analyzed. Secondly, the research direction and research status of domestic and international energy storage technology in high penetration renewable energy system are introduced. Then the application of energy storage technology in various fields is introduced in detail, and the advantages and disadvantages of energy storage in these fields are analyzed. At last, the problems and future development trend of energy storage technology are pointed out.

Distributed cooperative control of virtual synchronous generator based microgrid

As more and more distributed generators with intermittent characteristics are applied in microgrids, centralized control scheme encounters great challenges. In this paper, a fully distributed cooperative control scheme for Virtual Synchronous Generator based microgrid is proposed. Specifically, Virtual Synchronous Generator algorithm is developed as the primary controller of microgrid such that inverter of DG is capable of mimicking the dynamic behavior of a synchronous generator. Meanwhile, in order to eliminate the steady error caused by load disturbance which cannot be overcome through individual microgrids primary controller, the distributed cooperative secondary control strategy for microgrid is established considering the constraint and cost of communication network. Finally, simulation model of Virtual Synchronous Generator based microgrid is established in Matlab/Simulink platform. Simulation results demonstrate the validity and feasibility of the proposed method.

Assessment of system frequency support effect of PMSG-WTG using torque-limit-based inertial control

To release the “hidden inertia” of variable-speed wind turbines for temporary frequency support, a method of torque-limit based inertial control is proposed in this paper. This method aims to improve the frequency support capability considering the maximum torque restriction of a permanent magnet synchronous generator. The advantages of the proposed method are improved frequency nadir (FN) in the event of an under-frequency disturbance; and avoidance of over-deceleration and a second frequency dip during the inertial response. The system frequency response is different, with different slope values in the power-speed plane when the inertial response is performed. The proposed method is evaluated in a modified three-machine, nine-bus system. The simulation results show that there is a trade-off between the recovery time and FN, such that a gradual slope tends to improve the FN and restrict the rate of change of frequency aggressively while causing an extension of the recovery time. These results provide insight into how to properly design such kinds of inertial control strategies for practical applications.