Impact of Distributed Generation Grid Code Requirements on Islanding Detection in LV Networks

Abstract

Abstract:The recent growing diffusion of dispersed generation in low voltage (LV) distribution networks is entailing new rules to make local generators participate in network stability. Consequently, national and international grid codes, which define the connection rules for stability and safety of electrical power systems, have been updated requiring distributed generators and electrical storage systems to supply stabilizing contributions. In this scenario, specific attention to the uncontrolled islanding issue has to be addressed since currently required anti-islanding protection systems, based on relays locally measuring voltage and frequency, could no longer be suitable. In this paper, the effects on the interface protection performance of different LV generators' stabilizing functions are analysed. The study takes into account existing requirements, such as the generators' active power regulation (according to the measured frequency) and reactive power regulation (depending on the local measured voltage). In addition, the paper focuses on other stabilizing features under discussion, derived from the medium voltage (MV) distribution network grid codes or proposed in the literature, such as fast voltage support (FVS) and inertia emulation. Stabilizing functions have been reproduced in the DIgSILENT PowerFactory 2016 software environment, making use of its native programming language. Later, they are tested both alone and together, aiming to obtain a comprehensive analysis on their impact on the anti-islanding protection effectiveness. Through dynamic simulations in several network scenarios the paper demonstrates the detrimental impact that such stabilizing regulations may have on loss-of-main protection effectiveness, leading to an increased risk of unintentional islanding.

Evaluation of the Use of Class B LoRaWAN for the Coordination of Distributed Interface Protection Systems in Smart Grids

“…Although the anti-islanding mechanisms defined by current regulatory frameworks proved to be effective in most cases, recent studies demonstrated that, under the different stabilizing functions required by national and international grid codes, the measurement techniques implemented in current IPSs could be inadequate [9]. Anti-islanding protection functions could in fact fail, particularly during transients, due to the masking effect of stabilizing functions on IPSs [10].…”

Comparative Study of Different Approaches for Islanding Detection of Distributed Generation Systems

“…Thus, a thorough study is needed in solving this issue. Hence, anti-islanding with fast response time is essential for a DG connected grid system [10,16]. To overcome the challenges from islanding DGs, researchers proposed a numerous model that deals with the consequences of intentional islanding, and clears it as fast as possible [11,12,[17][18][19][20][21][22][23][24][25][26][27][28][29].…”

Comparison of the reactive control strategies in low voltage network with photovoltaic generation and storage

“…The highest penetration of PV systems is at the distribution level, in fact 95% of the PV systems are connected to the medium voltage (MV) and low voltage (LV) level [4], in which the topology of the network is essentially radial. At micro-generating level, the European Standard CENELEC EN 50438 contains the rules for the connection of electrical power plants with a rated current below 16 A, to the LV distribution network [5,6]. For what concerns the voltage quality, the European Standard EN 50160 limits the voltage deviation to an interval of ±10% of the rated value [7].…”