Priority-based Load Shedding Research Articles

Local Power Controller Based Load Shedding Scheme in Islanded Microgrids

To decrease the blackout risk due to the large disturbances, it is recommended to intentionally create islanded conditions in power systems. In this event, system elements will be insulated and the supply for creating the islands can be preserved. To do so, resources and generations in the islands are discharged and loads should be shed in case it is required. In this condition, voltage and frequency stay in their limits. In this paper, a priority-based load shedding technique is proposed using a Local Power Controller (LPC) for islanded microgrids. The suggested method utilizes frequency and rate of change of frequency (ROCOF) based approaches to activate the shredding procedure. Moreover, the proposed approach controls the islanded microgrids for developing support for the main grid in the case of frequency deviation events whereas supplying the local critical loads is mandatory. The advantages of the method are the minimum equipment requirement and suitability for end-users with critical loads. In the proposed methodology, a load addition mechanism is also considered. This mechanism automatically switches the shed loads when the system frequency recovers to a certain level. The proposed method scheme is verified and validated in a laboratory microgrid test bench under two operation modes, specifically allowing load shedding procedure in advance of and consequent to the islanded situation. In both cases, the results demonstrate that the scheme is able to sustain the islands.

A new demand response algorithm for solar PV intermittency management

This paper presents a new algorithm for managing solar PV intermittency in green buildings using demand response management (DRM) technique. The proposed DRM algorithm utilizes the building air conditioning and mechanical ventilation (ACMV) system to dynamically compensate for the deficit of power generated by solar PV system from its rated capacity. For example, the developed solution will reduce the load demand of the ACMV system equal to the drop of solar generation by controlling the speed of the fan. This will ensure that the amount of power supplied by the grid to the building will remain the same (as before the drop of solar generation) and thus no impact on the grid stability. However, since ACMV system is directly linked to building occupant comfort/health, the proposed solution will also include energy storage management and priority-based load shedding programs to provide support when room temperature (air conditioning) or CO level (ventilation) is above regulatory limit. A thermal model for building temperature variation is developed to test and analyze the proposed algorithm to dynamically manage solar PV fluctuation.

Overcoming Solar PV Intermittency using Demand Response Management in Buildings

Singapore’s National Climate Change Policy is aimed to make energy usage in Singapore more efficient, reduce pollution and expand the nation’s green spaces. Part of the plan is to promote the integration of solar photovoltaics (PVs) on rooftops of high-rise HDB residential and commercial buildings. This initiative contributed to the significant growth in the integration of solar PV systems in the last few years. However, large-scale integration of solar PVs will put at risk the reliability and stability of Singapore’s power system due to its intermittent nature. The intermittency problem of solar PV, typically in the range of minutes, will become very significant in Singapore as the installations of PV systems continue to increase. Conventionally, large energy storage systems are deployed as an energy buffer to compensate for the deficit or surplus of power supplied by solar PV systems. However, the high capital and maintenance costs as well as large space requirement for energy storage systems makes this an unfavorable option for building owners. This paper proposes a solution that utilizes the centrifugal fans in building air conditioning and mechanical ventilation (ACMV) system to dynamically compensate for the deficit or surplus of power supplied by solar PVs. For example, the developed solution will reduce the load demand of fans in the ACMV system equal to the drop of solar generation by controlling the speed of the fan. This will ensure that the amount of power supplied by the grid to the building will remain the same (as before the drop of solar generation) and thus no impact on the grid stability. However, since ACMV system is directly linked to building occupant comfort/health, the proposed solution will also include battery management and priority-based load shedding programs to provide support when room temperature (air conditioning) or CO level (ventilation) is above regulatory limit.

A Multiagent Framework for Self-Healing Mechanisms Considering Priority-Based Load Shedding and Islanding with Distributed Generation in Smart Distribution Grids

This paper proposes a methodology based on multi-agent system (MAS) to self-healing with priority-based load shedding and islanding with distributed generation (GD) in smart distribution grids. The operational process of the proposed self-healing model is composed of four stages respectively. The multi-agent system aims to solve the problem of self-healing in distribution network systems. The model is implemented in the platform JADE and Matlab. Case studies using a system composed of two substations, and seventy-four feeders buses are used in order to test the method proposed in this work. The simulations presented in this paper include fault in particular branches of the distribution network, the analysis of the results in terms of voltage, losses, and switching actions as well as load shedding. The results show that the proposed model is satisfactory and shows the importance of having a self-healing system with priority-based load shedding and islanding with distributed generation.

Grid Adaptive Power Management Strategy for an Integrated Microgrid With Hybrid Energy Storage

The penetration of growing microgrid systems within the ac distribution network is leading to several challenges to have a safe and reliable operation of the power system. For the utility system, it is mandatory to maintain the voltage and frequency within the prescribed limits at the local bus under diverse conditions of the renewable energy sources (RESs), loads, and grid. With these conditions, the need for energy storage system (ESS) becomes extremely important for effective operation of critical and frequency sensitive loads. The vital role of ESS based on dc-bus regulation and monitoring of grid frequency in the microgrid is a challenging task and needs to be investigated in detail. Therefore, in this paper, the storage and microgrid are scheduled to work in a grid supportive manner. Also, these ESSs need to be operated within its safe state of charge limits. Hence, based on all the above constraints, an appropriate grid adaptive power management strategy (GA-PMS) is formulated to generate current references for RES, ESS, and microgrid-connected converters. Furthermore, this algorithm includes seamless microgrid operation under abnormal conditions, priority-based load shedding, and ensuring power quality standards at the local bus. The performance of proposed GA-PMS is tested and validated through the simulation and experimental studies.

Hybrid islanding detection method and priority‐based load shedding for distribution networks in the presence of DG units

The integration of Distributed Generation (DG) units in the existing power system has made the reliable operation of the system more complex. This has necessitated a comprehensive approach in planning the expansion of the system with the incorporation of DG units for effective and reliable operation of the system. In this study, a robust Hybrid Islanding Detection Technique (HIDT) has been proposed for identifying the islanding event early and accurately in the distribution networks with DGs installed by a two-step Genetic Algorithm (GA) process. As the reliability of power supply to the customer is of utmost importance, a priority-based load shedding scheme is proposed. The proposed load shedding scheme sheds only the vulnerable loads in the island for regaining the frequency and voltage stabilities. By the proposed methods, a comprehensive solution for system planning and emergency control actions can be obtained for effective operation of the system with DG units. The proposed methods are investigated on standard IEEE 33 and 69 bus distribution systems under different loading conditions. The results obtained show that the proposed methods are able to identify the islanding event more effectively and also regain the stability in the island with less amount of load shedding.

Preemptive Demand Response Management for Buildings

A building energy management system (BEMS), which forms an integral part of a smart grid, enables building operators to monitor, manage, and control the energy utilized in their buildings, thus reducing the demand and consumption of energy. Building operators are responsible for the day-to-day maintenance and operation of their buildings’ heating, cooling, mechanical, and electrical systems. This paper proposes an intelligent preemptive demand response management (DRM) using the BEMS to ensure contracted capacity or demand limit (CC/DL) is not exceeded and at the same time reduce energy consumption in buildings. In this paper, dynamic electric vehicle (EV) charge scheduling, speed control of air conditioning (AC) system’s variable speed drive (VSD), and priority-based load shedding are considered in the DRM program. The performance of the proposed DRM program to keep the building power demand within the CC/DL and reduce the energy consumption is tested and analyzed using the BEMS.