Single-Phase Inverter for Grid-Connected and Intentional Islanding Operations in Electric Utility Systems

Abstract

Small distributed generation units are usually connected to the main electric grid through single-phase voltage source inverters. Grid operating conditions such as voltage and frequency are not constant and can fluctuate within the range values established by international standards. Furthermore, the requirements in terms of power factor correction, total harmonic distortion, and reliability are getting tighter day by day. As a result, the implementation of reliable and efficient control algorithms, which are able to adjust their control parameters in response to changeable grid operating conditions, is essential. This paper investigates the configuration topology and control algorithm of a single-phase inverter with the purpose of achieving high performance in terms of efficiency as well as total harmonic distortion of the output current. Accordingly, a Second Order Generalized Integrator with a suitable Phase Locked Loop (SOGI-PLL) is the basis of the proposed current and voltage regulation. Some practical issues related to the control algorithm are addressed, and a solution for the control architecture is proposed, based on resonant controllers that are continuously tuned on the basis of the actual grid frequency. Further, intentional islanding operation is investigated and a possible procedure for switching from grid-tied to islanding operation and vice-versa is proposed.

Review, analysis, and performance evaluation of the most common four active methods for islanding detection in grid-connected photovoltaic systems

“…A PWM-controlled single-phase power inverter [54], [82] with an LCL filter is used in this research. An inverter control system with a P&O-based MPPT controller [97], [98], DC voltage and current regulators, phaselocked loop (PLL) [99]- [101], measurements [9], and a PWM generator are used to control the PV power inverter [54]. The MPPT controller [102] collects the maximum electric power from the PV solar array under varying weather conditions [103].…”

Stability Analysis of Current Control based on Virtual Resistor for Single-Phase Grid Converters with LLCL Input Filters

“…신재생 에너지 의 급속한 성장에 따라 계통 연계를 위한 그리드 컨 버터가 널리 사용되고 있다 [1] . 계통 연계를 위해서는 PWM 스위칭에 의해 발생 되는 출력 고조파를 일정 수준 이하로 유지하여야 하 므로 일반적으로 컨버터와 계통 사이에 전력 필터가 사용된다.…”