Research on Distributed PV Storage Virtual Synchronous Generator System and Its Static Frequency Characteristic Analysis

Abstract

The increasing penetration rate of grid connected renewable energy power generation reduces the primary frequency regulation capability of the system and poses a challenge to the security and stability of the power grid. In this paper, a distributed photovoltaic (PV) storage virtual synchronous generator system is constructed, which realizes the external characteristics of synchronous generator/motor. For this kind of input/output bidirectional devices (e.g., renewable power generation/storage combined systems, pumped storage power stations, battery energy storage systems, and vehicle-to-grid electric vehicles), a synthesis analysis method for system power-frequency considering source-load static frequency characteristics (S-L analysis method) is proposed in order to depict the system's power balance dynamic adjustment process visually. Simultaneously, an inertia matching method is proposed to solve the problem of inertia matching in the power grid. Through the simulation experiment in MATLAB, the feasibility of the distributed PV storage synchronous virtual machine system is verified as well as the effectiveness of S-L analysis method and inertia matching method.

Adaptive-MPPT-Based Control of Improved Photovoltaic Virtual Synchronous Generators

“…Picking up the PV system in the above typical PV micro-grid as an important research target, it is desirable for the PV system to achieve friendly access through the application of VSG technology. In a general way, in related works [19,20], a PV-VSG control strategy installed with an energy storage battery on the DC side was adopted, as shown in Figure 2. For traditional PV-VSG control, since PV output power is particularly influenced by environmental factors such as light intensity and temperature [13], the energy storage battery is primarily responsible for balancing power through a DC/DC converter so as to match the required power.…”

“…Secondly, the energy storage configuration of PV-VSG will greatly increase the expenses of investment, operation and maintenance [23,28]. The traditional PV-VSG (photovoltaic-virtual synchronous generator) control oriented for the energy storage battery [19,20].…”

“…Whether in off-grid mode or grid-connected mode, no matter when the power demand changes or the light intensity changes, PV power can operate in a stable area to adjust adaptively, and PV-VSG can provide the most effective output power matching under different load/dispatching power requirements, guaranteeing system stability in conditions of insufficient PV power. Accordingly, compared with traditional two-stage PV-VSG equipped with additional energy storage on the DC bus [19][20][21][22], the proposed control method reduces the cost of investment and operation on account of not configuring energy storage.…”

“…This type of PV-VSG research ignores the potential impact of PV dynamic characteristics on VSG control, hence limiting the development of PV-VSG. For this reason, the cooperative operation mode of PV and energy storage is discussed in [19][20][21][22], which is referred to as a PV-storage system for short, in which the PV system adds a bidirectional energy storage device at the DC side to stabilize the DC bus voltage and realizes VSG function through the inverter. In the above PV-storage system, the output power of energy storage compensates for the deficiency of the PV dynamic characteristics and the variations of the load or dispatching requirements.…”

Mechanism Analysis of PCC Harmonic Resonance Based on Nonlinear Self-Oscillation Concept in a High-Power Grid-Tied Photovoltaic Plant

“…The parameters of equivalent admittance/impedance of fundamental and harmonics of these equipment exist in uncertainty, which will significantly change the harmonic network admittance matrix of micro-grid [20]. Due to the rapid increase of photovoltaic systems in micro-grids, the problem of power quality associated with the intermittent nature of these systems had become more and more serious, and many efforts have been made already [21,22]. Most of the strategies about harmonic suppression in micro-grid focus on the power grid models containing one PV inverter, hence it is necessary to establish a model associated with a multi-inverter-based micro-grid [23,24].…”