Two-Stage Virtual Inertia Control Strategy with Coordination of Energy Storage System

To address the lack of effective cooperative control of each inertia support resource, the principles of cooperative inertia control in the power system with a high percentage of renewable energies are studied and the problems of cooperative inertia control are summarized. To make the wind turbine generator (WTG) participate in inertia response based on rotor kinetic energy method and the photovoltaic (PV) unit participate in inertia response based on capacitive energy storage method. The inertia response stage enables the energy storage system (ESS) based on sag control to collaborate with the WTG and PV unit for inertia support, and the frequency recovery stage enables ESS based on fuzzy control to improve the frequency response performance. The fuzzy control rules are formulated to propose a virtual inertia cooperative control method for the WTG, PV unit, and ESS. A case study is conducted to verify the effectiveness of the proposed strategy.

I. Introduction

The operating principle of wind power and photovoltaic units is different from that of traditional synchronous machines. Their large-scale grid connection reduces the equivalent inertia level of the power grid and exposes the power system frequency stability, especially transient stability, to greater risk. [1]–[3]. The lower cost of ESS and the rapid development of ESS technology make it a broader application prospect in new power systems, where multiple types of energy storage can be effective in different parts of the frequency response [4], [5].