Overvoltage Suppression Strategy After Short Circuit Faults Applied to PV Systems

The high pressure on pollutant gas emission reduction and the positive incentives of the governments continue to speed up the global shift to renewable-based energy systems. In recent decades, the proportion of solar photovoltaic (PV) meets a continuous increase in renewable energy resources for the advantages of no noise, no pollution, and no geographical limitations. However, the PV systems that connect to the distribution network (DN) bring many challenges to the system's voltage stability. Especially when there is a short circuit fault in the DN, the characteristics of the PV system output may further deteriorate the voltage profile of the DN. In addition, owing to the inertia of the PI in the existing PV inverter, the overvoltage problem will be kept in the DN even after the short circuit fault is removed, which may significantly influence the DN operation stability. To suppress the overvoltage after clearing the short circuit faults in the AC line of the grid-connected PV system, an overvoltage suppression method of AC short circuit faults for PV systems is proposed in this paper. Based on the overvoltage suppression strategy, a novel overvoltage suppression control framework is developed to realize the integration with the existing PV control framework. In Matlab/Simulink, A real village DN in the east of China is implemented to verify the performance of the proposed overvoltage suppression method, where the results demonstrate that the overvoltage problem can be alleviated and the voltage stability can be effectively enhanced.

I. Introduction

Fossil energy occupies a considerable proportion in most countries' current energy systems, especially in the power system, causing significant environmental damage and energy shortages. To address this issue, the United Nations suggested that renewable sources can be adopted to alleviate the above energy problems [1]–[2]. For example, India has promised to increase renewable energy to 40% of total power production by 2030 [3]. China put forward the strategic goal in 2016 to reach 50% of non-fossil power generation in the entire power generation by 2030 [4]. And the European climate law makes reaching the climate goal of reducing EU emissions by at least 55% by 2030 a legal obligation [5]. Among various types of renewable power, the solar photovoltaic (PV) has been well developed due to the absence of pollution. PV systems can be divided into distributed PV and centralized PV, while in most countries, distributed PV has been more and more widely used without geographical limitations. By the end of 2020, the capacity of PV in China is , in which the distributed PV is , accounting for 33.5% of the total [6]–[7]. In the foreseeable future, distributed PV will undoubtedly be more extensively developed.