Performance of the OVP/UVP and OFP/UFP Method With Voltage and Frequency Dependent Loads

Abstract

In previous literature, constant RLC loads were assumed to impose, on the islanding detection method, the hardest detectable case. For this reason, distributed-generation (DG) islanding studies are usually analyzed and performed by using constant RLC loads. In this paper, different types of loads are taken into account by modeling the load's voltage and frequency dependence. The performance of the over/undervoltage and over/underfrequency protection (OVP/UVP and OFP/UFP) method is examined for the different load models and the results are compared with the constant RLC load case. The analysis is conducted on a constant power-controlled DG designed to operate at unity power factor. A generalized formula, for calculating the nondetection zone of the OVP/UVP and OFP/UFP method, is derived in terms of the load's voltage and frequency dependence parameters. The analysis is further extended on a constant current-controlled DG interface.

A Universal Islanding Detection Technique for Distributed Generation Using Pattern Recognition

“…Islanding detection methods can be divided into three main categories: communication based [5,6], active based [7][8][9][10][11][12][13][14][15], and passive based [16][17][18][19][20][21][22]. Communication based methods are very accurate but are the most expensive among islanding detection techniques.…”

“…Over/Under Frequency islanding detection technique relies on the frequency at the PCC of the island to detect islanding [16,17,18]. As discussed earlier, frequency deviation depends on the mismatch in reactive power.…”

“…If there is a large mismatch, then the frequency will deviate beyond a pre-defined threshold value (59.3 > f > 60.5) and the relay will trip and disconnect the DG. [18,19]. During grid-connected mode, there is no mismatch between the generated and consumed power at the PCC.…”

Metodologias de ajuste das proteções anti-ilhamento de geradores distribuídos considerando múltiplos eventos

“…Ajustes típicos estão na faixa de 0,5-0,8 e 1,1-1,2 pu [11], e essa proteção pode ser utilizada para detecção do ilhamento, como apresentado em [46]; [72].…”

“…As conclusões para um sistema com GD síncrono mostram que cargas de impedância constante apresentam resultados mais conservadores da proteção anti-ilhamento baseada em medidas de frequência, para condições de operação de excesso de potência ativa e reativa, ou déficit de potência ativa e reativa [46].…”