Control strategy to improve damping and transient response of VSG-based renewable power plants

Abstract

This paper presents a control strategy for renewable power plants with converter-interfaced generation (CIG) units. The proposed strategy uses virtual synchronous generator (VSG) control in CIG units to provide inertia and frequency support, and a centralized control to achieve high-performance control of active and reactive power at the point of interconnection with the grid. The centralized control is an observer-based state-feedback controller designed using system identification and model-matching techniques. First, an identification method is applied to obtain a system model. Thus, models and data from equipment used in nonconventional renewable power plants are not required for the control design. Then, a model-matching method is used to shape the transient response of the power delivered to the grid. This method improves the reference tracking performance and the response speed of the plant output power. The centralized control is formulated in the discrete-time domain to allow proper representation of time delays and direct digital implementation. The proposed control strategy can handle different time delays in the power plant communication system. The design methodology aims to improve the power control of nonconventional power plants and support the integration of renewable energy sources into the power grid.