An Intelligent Fuse-box for use with Renewable Energy Sources integrated within a Domestic Environment

This paper outlines a proposal for an intelligent fuse-box that can replace existing fuse-boxes in a domestic context such that a number of renewable energy sources can easily be integrated into the domestic power supply network, without the necessity for complex islanding and network protection. The approach allows intelligent control of both the generation of power and its supply to single or groups of electrical appliances. Energy storage can be implemented in such a scheme to even out the power supplied and simplify the control scheme required, and environmental monitoring and load analysis can help in automatically controlling the supply and demand profiles for optimum electrical and economic efficiency. Simulations of typical scenarios are carried out to illustrate the concept in operation

Line protection in inverter supplied networks

New protection methods are required to protect a distribution system when supplied by current limited converters. In this paper, a method of converter control is proposed to limit the current by reducing the voltage in the faulted phase or phases while keeping the voltage of the healthy phases unaltered. Unsymmetrical fault analysis is performed to calculate the sequence currents and voltages at the relay location, when system is supplied by a converter. Based on that converter control, distance relay performances have been evaluated in both grid-connected and islanded mode operations. Distance relay, combined with MHO and negative sequence impedance directional characteristics, is proposed as a protection scheme for the distribution system for different types of faults under the current limited environment. The results are validated through PSCAD/EMTDC simulation and MATLAB calculations

Distributed photovoltaic systems: Utility interface issues and their present status

Major technical issues involving the integration of distributed photovoltaics (PV) into electric utility systems are defined and their impacts are described quantitatively. An extensive literature search, interviews, and analysis yielded information about the work in progress and highlighted problem areas in which additional work and research are needed. The findings from the literature search were used to determine whether satisfactory solutions to the problems exist or whether satisfactory approaches to a solution are underway. It was discovered that very few standards, specifications, or guidelines currently exist that will aid industry in integrating PV into the utility system. Specific areas of concern identified are: (1) protection, (2) stability, (3) system unbalance, (4) voltage regulation and reactive power requirements, (5) harmonics, (6) utility operations, (7) safety, (8) metering, and (9) distribution system planning and design

Reliability analysis of distribution systems with photovoltaic generation using a power flow simulator and a parallel Monte Carlo approach

This paper presents a Monte Carlo approach for reliability assessment of distribution systems with distributed generation using parallel computing. The calculations are carried out with a royalty-free power flow simulator, OpenDSS (Open Distribution System Simulator). The procedure has been implemented in an environment in which OpenDSS is driven from MATLAB. The test system is an overhead distribution system represented by means of a three-phase model that includes protective devices. The paper details the implemented procedure, which can be applied to systems with or without distributed generation, includes an illustrative case study and summarizes the results derived from the analysis of the test system during one year. The goal is to evaluate the test system performance considering different scenarios with different level of system automation and reconfiguration, and assess the impact that distributed photovoltaic generation can have on that performance. Several reliability indices, including those related to the impact of distributed generation, are obtained for every scenario.Postprint (published version

International White Book on DER Protection : Review and Testing Procedures

This white book provides an insight into the issues surrounding the impact of increasing levels of DER on the generator and network protection and the resulting necessary improvements in protection testing practices. Particular focus is placed on ever increasing inverter-interfaced DER installations and the challenges of utility network integration. This white book should also serve as a starting point for specifying DER protection testing requirements and procedures. A comprehensive review of international DER protection practices, standards and recommendations is presented. This is accompanied by the identifi cation of the main performance challenges related to these protection schemes under varied network operational conditions and the nature of DER generator and interface technologies. Emphasis is placed on the importance of dynamic testing that can only be delivered through laboratory-based platforms such as real-time simulators, integrated substation automation infrastructure and fl exible, inverter-equipped testing microgrids. To this end, the combination of fl exible network operation and new DER technologies underlines the importance of utilising the laboratory testing facilities available within the DERlab Network of Excellence. This not only informs the shaping of new protection testing and network integration practices by end users but also enables the process of de-risking new DER protection technologies. In order to support the issues discussed in the white paper, a comparative case study between UK and German DER protection and scheme testing practices is presented. This also highlights the level of complexity associated with standardisation and approval mechanisms adopted by different countries

Protection Considerations of Future Distribution Networks with Large Penetration of Single Phase Residential Rooftop Photovoltaic Systems

Solar Photovoltaics now constitute a significant part of electrical power generation for many utilities around the world. This penetration of PVs introduces many technical challenges. This thesis has investigated the impact of high penetration level of single phase rooftop PVs on protection of low voltage and medium voltage and distribution networks and proposed necessary recommendation to improve the performance of protection systems of these networks

Over current protection of distribution system with impact of solar and wind generation using DIgSIlent power factory

The utilization of renewable resources has been growing very fast worldwide recently to manage the increasing energy gap, but it also raises some challenges like protection issues, transient stability issues and security issues in the power system operation. Mainly, wind and solar photovoltaic renewable power generation sources are account for bulky renewable energy share. The transients in power systems including renewables are reduced and have recently attracted wide attention. The impact of renewables generation on power system transients should be effectively analyzed and evaluated to improve power system reliability, stability, operation and security. DIgSILENT Power Factory software is more powerful and useful for providing phasor of fundamental power frequency components better than other existing software’s; therefore, DIgSILENT Power Factory is proposed for modeling and analysis of the system.&nbsp

Impact of distributed PV generation on relay coordination and power quality

Distributed generation (DG) has gained popularity among electricity end users who are determined to contribute to a cleaner environment by conforming to green and sustainable energy sources for various daily needs. The power system impact of such trends (e.g. roof-top solar-PV) need thorough investigation, such as impact on fault current levels on the distribution network. Varying fault current levels could adversely affect the operation of protection relays, which may lead to localized blackouts. Therefore, it is imperative to avoid localised blackouts due to mal-operation of protective relays under high penetration of DGs in distribution network. The focus of this research is to study the importance and implications of protective relays and over-current protection in the presence of distributed generation; where the impact of distributed generation on distribution network is identified. Relay coordination is observed to determine their operation characteristics to avoid mal-operation with the presence of DGs (e.g. solar-PV). This paper uses the UK generic distribution network model to simulate different scenarios in DIgSILENT Power Factory. The resulting power quality measures, such as voltage levels, short-circuit current levels and frequency are presented and discussed in the paper. The research highlights that small-scale DG penetration allows for existing protection infrastructure to continue operation and expensive upgrades for overall network are not required as fault levels remain the same

Time-Series Analysis of Photovoltaic Distributed Generation Impacts on a Local Distributed Network

Increasing penetration level of photovoltaic (PV) distributed generation (DG) into distribution networks will have many impacts on nominal circuit operating conditions including voltage quality and reverse power flow issues. In U.S. most studies on PVDG impacts on distribution networks are performed for west coast and central states. The objective of this paper is to study the impacts of PVDG integration on local distribution network based on real-world settings for network parameters and time-series analysis. PVDG penetration level is considered to find the hosting capacity of the network without having major issues in terms of voltage quality and reverse power flow. Time-series analyses show that distributed installation of PVDGs on commercial buses has the maximum network energy loss reduction and larger penetration ratios for them. Additionally, the penetration ratio thresholds for which there will be no power quality and reverse power flow issues and optimal allocation of PVDG and penetration levels are identified for different installation scenarios.Comment: To be published (Accepted) in: 12th IEEE PES PowerTech Conference, Manchester, UK, 201