A New Under-Frequency Load Shedding Technique Based on Combination of Fixed and Random Priority of Loads for Smart Grid Applications

Abstract

This paper presents a new under-frequency load shedding technique based on the combination of random and fixed priority of loads. It has been observed that placing all of the loads in the distribution system with fixed priority results in un-optimum load shedding. On the other hand, designing the load priority with a combination of random and fixed priority provides the technique with some sort of flexibility in achieving the optimal load shedding. The validation of the proposed scheme on different scenarios proves that the proposed technique is capable of achieving the optimal load shedding and recovering frequency to nominal value without any overshoot.Index Terms-Distributed generation (DG), fixed priority loads, optimum load shedding module (OLSM), random priority loads.

Coordinated Scheme of Under-Frequency Load Shedding with Intelligent Appliances in a Cyber Physical Power System

“…Because the power loads in the distribution network are 19% of the entire capacity in area B, a three-stage load shedding plan is adopted. The method in [16] is also modeled for comparison purposes. The process of the method is as follows: (1) calculate the load shedding amount based on the center of inertia frequency; (2) calculate all possible load combinations, and select the one with minimum absolute error.…”

“…When adopting the method of [16], the estimated power shortage exceeds the entire capacity of the distribution system; thus, the breakers of all 12 load buses are tripped as the frequency drops below 49.0 Hz. When adopting the traditional UFLS scheme, all of the power loads in the system are tripped with the three-stage actions.…”

“…However, lack of global information makes it difficult for conventional strategies to achieve an optimal result. As a suitable alternative, adaptive load shedding strategies have become the current research focus [14][15][16]. The estimation of frequency drops and the precise load shedding method are the two main concerns.…”

“…Gu et al [15] proposed a multi-agent system-based, decentralized UFLS scheme to maintain the frequency stability of an islanded distribution network, with only limited communication resources and information. To restrict the overshoot in the frequency response caused by extra load shedding, Laghari et al [16] provided a one-step optimal load shedding scheme, with accurate calculation of power imbalance after disturbance and selection of the load combination with the minimum absolute error. In this paper, this scheme is selected for comparison purposes because the simulation results in [16] demonstrate that it offers improved performance over other adaptive load shedding strategies.…”

“…To restrict the overshoot in the frequency response caused by extra load shedding, Laghari et al [16] provided a one-step optimal load shedding scheme, with accurate calculation of power imbalance after disturbance and selection of the load combination with the minimum absolute error. In this paper, this scheme is selected for comparison purposes because the simulation results in [16] demonstrate that it offers improved performance over other adaptive load shedding strategies. Using the minimum load shedding magnitude to achieve a better frequency recovery effect is the main purpose of the above studies.…”