Load Shedding Application within a Microgrid to Assure Its Dynamic Performance during Its Transition to the Islanded Mode of Operation

Dorel Soares Ramos,Ricardo Leon Vasquez-Arnez,Tesoro Elena Del Carpio-Huayllas

doi:10.4236/epe.2013.57047

Abstract

This article presents the simulation results and analysis related to the response of the generators within a microgrid towards an accidental overload condition that will require some load shedding action. A microgrid overload can occur due to various reasons ranging from poor load schedule, inadequate switching of circuits within the microgrid, outage of one or more generators inside the microgrid, illegal load connections by some low voltage consumers, etc. It was observed that among the main factors that determine the survival of the microgrid during its transition from the grid connected mode to the islanded mode of operation are the size and type of the load connected (passive or dynamic load) as well as the length of time during which the unexpected load is connected. Models of a speed and voltage regulators of a diesel generator, and important for coping with the overload conditions are provided in the paper. The novelty of the work lies in the load shedding simulation and analysis of the specific generators studied herein, regarding that in many countries the microgrid technology is seen as an important alternative towards the ever increasing load demand and also to assist the system during periods of blackout.

Highlights

At present, the establishment of microgrid systems is regarded by the power industry as one of the alternatives to keep running critical loads and provide electricity to some regular consumers during periods of prolonged interruptions
This article presents the simulation results and analysis related to the response of the generators within a microgrid towards an accidental overload condition that will require some load shedding action
The novelty of the work lies in the load shedding simulation and analysis of the specific generators studied regarding that in many countries the microgrid technology is seen as an important alternative towards the ever increasing load demand and to assist the system during periods of blackout

Summary

Introduction

The establishment of microgrid systems is regarded by the power industry as one of the alternatives to keep running critical loads and provide electricity to some regular consumers during periods of prolonged interruptions (e.g. blackouts). Reference [1], for example, provides a comprehensive coverage on the load shedding issue, load restoration and generator protection schemes using underfrequency relays during abnormal frequency conditions. The transition from a grid-connected to an islanded mode of operation of a microgrid can occur due to reasons like the presence of faults in the system, or due to some pre-planned conditions like the system (grid) maintnance, energy costs, etc During such a transition the power control of the microgrid generators must act quickly as they start controlling the frequency of the islanded section. The sequence of the load shedding procedure is as follows: initially, all loads are primarily being fed by the utility when, due to any reason (e.g. a three-phase fault), the circuit-breaker (CB) is open At this moment all three generators start running and taking up their respective loads.

Diesel Generator Overloading

Wind Generator Load Shed

Findings

Conclusion