Constrained operation zone of a VSG considering the DC-side power margin

Abstract

Recently, the virtual synchronous generator (VSG) has drawn considerable attention for its function of simulating the electromechanical transient of SG to make converters equip with the characters of inertia, damping, voltage regulating, and frequency regulating. Energy storage systems (ESSs), which are connected to the converter by a DC/DC circuit, are the basis of VSG. The output active power of VSG is restricted by the capacity margin of the grid-side converter and DC/DC circuit, and the output energy is bounded by the energy margin of ESS, which means that VSG is restrained by treble constraints: DC side power, DC-side energy, and AC-side power. A small signal model of VSG is built, and the method of getting the treble constraints is proposed. Through the analysis of the dynamic response characteristics of the VSG, the operating zone of VSG under constraints is confirmed. Simulations in power system computer aided design (PSCAD)/electromagnetic transient including DC (EMTDC) verified the theoretical analysis and the transient characteristics of VSG when the constraints are broken and simulated.

Keywords

• distributed power generation
• dynamic response
• frequency control
• synchronous generators
• power generation control
• energy storage
• voltage control
• power grids
• VSG
• DC-side power margin
• DC/DC circuit
• output active power
• DC-side energy
• virtual synchronous generator
• electromechanical transient
• energy storage systems
• inertia
• damping
• voltage regulation
• frequency regulation
• grid-side converter
• output energy
• transient characteristics