Small-Signal Modeling and Parameter Optimization Design for Photovoltaic Virtual Synchronous Generator

Abstract

With the continuous proliferation of renewable energy generation, distributed photovoltaic inverters operating at a maximum power point reduce the inertia of power systems, degrading system frequency stability and potentially causing severe oscillations in systems after being disturbed. The virtual synchronous generator (VSG) control method, which causes photovoltaic inverters to possess inertia and damping, now plays an important role in the field of distributed generation. However, while introducing the advantages of synchronous machines, problems with oscillations are also introduced and the stochastic fluctuation characteristic of photovoltaics results in the stochastic drifting of the operating point. This paper presents an adaptive controller parameter design method for a photovoltaic-VSG (PV-VSG) integrated power system. Firstly, a small-signal model of the PV-VSG is built and a state space model is deduced. Then, the small-signal stability and low frequency oscillation characteristics of the photovoltaic power generation system are analyzed. Finally, considering the limitations of system oscillations and the stochastic drifting of the operating point, a global optimization design method for controller parameters used to improve system stability is proposed. The time domain simulation shows that an optimized PV-VSG could provide sufficient damping in the case of photovoltaic power output changes across a wider range.

A Robust Design Method for Ultra-Low-Frequency Oscillation Suppression Control in Hydro–Photovoltaic Complementary Systems

“…The detailed model of PV is very complex, and some parameters involved are difficult to calculate directly, so it is not convenient to apply directly [27]. In order to facilitate research, the engineering approximate equivalent model is mainly used to solve it [28]. The model needs to be solved under rated light and temperature conditions (S ref = 1000 W/m 2 , T ref = 25 • C), and the calculation equation is:…”

Analysis of Synchronous Generators’ Local Mode Eigenvalues in Modern Power Systems

“…The need for knowledge in this area is confirmed by recent publications that address the damping of oscillations resulting from new solutions and equipment according to synchronous generators. The damping of oscillations produced due to the introduction of a photovoltaics virtual synchronous generator is considered in [14]. Reference [15] studies the oscillations of wind farms' synchronous generators.…”

A Model Predictive Control Strategy for Distribution Grids: Voltage and Frequency Regulation for Islanded Mode Operation

“…Specifically, two control modes are considered for the generation units: a voltage control mode, with an active droop control loop, and a power control mode, which allows setting the output power in advance. Some recent works that study virtual inertia are References [29][30][31][32][33].…”

“…In Reference [29], the authors study a novel control scheme for virtual inertia converters to operate in unbalanced settings, operating test on real hardware. In Reference [30], an adaptive controller method for a PV-based virtual inertia system is discussed.…”