Power control flexibilities for grid‐connected multi‐functional photovoltaic inverters

Abstract

This study explores the integration issues of next-generation high-penetration photovoltaic (PV) systems, where the grid is becoming more decentralised and vulnerable. In that case, the PV systems are expected to be more controllable with higher efficiency and reliability. Provision of ancillary and intelligent services, such as fault ride-through and reactive power compensation, is the key to attain higher utilisation of solar PV energy. Such functionalities for the future PV inverters can contribute to reduced cost of energy, and thus enable more cost-effective PV installations. To implement the advanced features, a flexible power controller is developed in this study, which can be configured in the PV inverter and flexibly change from one to another mode during operation. Based on the single-phase PQ theory, the control strategy offers the possibilities to generate appropriate references for the inner current control loop. The references depend on system conditions and also specific demands from both system operators and prosumers. Besides, this power control strategy can be implemented in commercial PV inverters as a standardised function, and also the operation modes can be achieved online in predesigned PV inverters. Case studies have verified the effectiveness and flexibilities of the proposal to realise the advanced features.

Influence of Dynamic Efficiency in the DC Microgrid Power Balance

“…The renewable energy sources, such as photovoltaic (PV) generation and wind turbines, have quite different characteristics from the conventional fossil sources: they are highly variable and intermittent; therefore they cannot directly generate the desired sinusoidal current with a fixed frequency [1]. Thus, besides the high installation cost, there is extra cost to integrate the renewable energy into the conventional electrical power grid, because the needed rapid regulation service is generally provided by natural-gas-fueled power plants.…”

A Novel Multi-Function PV Micro-Inverter with an Optimized Harmonic Compensation Strategy

“…The remaining capacity of these inverters can be used for other functions. Since some active power quality conditioners have a structure that is similar to that of PV inverters in the DC/AC stage, some researchers have tried to multiplex them to achieve multi-function [16]- [19]. Wu T.F.…”

“…et al have also proposed an enhanced current-control DC unit, which can achieve harmonic compensation without using any local harmonic extraction or harmonic voltage detection at the point of connection (POC) [18]. A flexible power controller based on the single-phase p-q theory is developed, which can improve the controllability of grid-connected multi-functional photovoltaic inverters with advanced features, such as low voltage ride-through and reactive power compensation [19]. Generally, the primary task for a PV inverter is to inject active power current into the grid while the secondary task is to compensate harmonic currents with the remaining capacity.…”

Universal Fractional-Order Design of Linear Phase Lead Compensation Multirate Repetitive Control for PWM Inverters

“…uninterrupted power supply system [1], [2], grid-connected photovoltaic power source [3], [4], etc. Repetitive control, which is based on internal model principle, is an effective way to improve inverter performance with low total harmonic distortion (THD), fast transient response, and low steady state error [5]- [7].…”