Scheme For Distributed Systems Research Articles

Regional Area Protection Scheme for Modern Distribution System

More and more renewable energy sources (RESs) are integrated into the grid with inverter interfaces, which brings new challenges to protection systems. This paper proposes a directional overcurrent relay-based regional area protection scheme (RAPS) for a modern distribution system incorporating high penetration of RESs. Protection components and the sensitivity-preferred setting principle utilized in local relays are presented. Then, a RAPS is proposed to accelerate fault isolation and enhance protection coordination. It is achieved by exchanging the pick-up signal and fault direction information from local relays within each predefined regional area. Breaker tripping or relay holding decisions are made by several RAPS criteria. The effectiveness of the protection scheme is verified by the simulation of a modified IEEE 34-node distribution system with different types of RESs. Simulation results validate that the selectivity, and speed of protection system can be improved by this scheme. Compared to existing protection schemes for the distribution system with RESs, the proposed scheme can be applied in complicated scenarios, such as partial loss of communication or failure of a local relay.

Optimal Partitioning of Distribution Networks for Micro-Grid Operation

A great concern for the modern distribution grid is how well it can withstand and respond to adverse conditions. One way that utilities are addressing this issue is by adding redundancy to their systems. Likewise, distributed generation (DG) is becoming an increasingly popular asset at the distribution level and the idea of microgrids operating as standalone systems apart from the bulk electric grid is quickly becoming a reality. This allows for greater flexibility as systems can now take on exponentially more configurations than the radial, one-way distribution systems of the past. These added capabilities, however, make the system reconfiguration with a much more complex problem causing utilities to question if they are operating their distribution systems optimally. In addition, tools like Supervisory Control and Data Acquisition (SCADA) and Distribution Automation (DA) allow for systems to be reconfigured faster than humans can make decisions on how to reconfigure them. As a result, this paper seeks to develop an automated partitioning scheme for distribution systems that can respond to varying system conditions while ensuring a variety of operational constraints on the final configuration. It uses linear programming and graph theory. Power flow is calculated externally to the LP and a feedback loop is used to recalculate the solution if a violation is found. Application to test systems shows that it can reconfigure systems containing any number of loops resulting in a radial configuration. It can connect multiple sources to a single microgrid if more capacity is needed to supply the microgrid’s load.

Communication-based Adaptive Protection for Distribution Systems Penetrated with Distributed Generators

In this article, a communication-based adaptive over-current protection scheme for distribution systems penetrated with distributed generators is proposed. A communication network between the over-current relays, the distributed generators, and the utility grid is employed to automatically update the settings of the protective relays. Moreover, the communication reliability is increased through the addition of a backup communication system. The proposed scheme has the advantage of operating during grid-connected and islanding modes of operation. The scheme employs two simultaneous algorithms. The first algorithm works when the system configuration is changed due to the connection/disconnection of a distributed generator or the utility grid. The second algorithm efficiently uses the exchanged information between the relays to identify the faulted section and hence speeds up fault clearance. The proposed scheme is tested for difierent fault conditions as well as for different system configurations. The results demonstrated that relay operating times, including the communication delay, are greatly reduced when the faulted section is identified and relay settings are adjusted accordingly. In addition, a negligible time delay was experienced when the backup communication network was put in service.

Impact of Antyodaya Anna Yojana (AAY) on the Food Security of the Poorest of the Poor in Rural Areas – A Study Maharashtra, Uttar Pradesh and Jharkhand

One of the Public Distribution System schemes namely ‘Antyodaya Anna yojana’ (AAY) has been implemented in India from the end of the year 2000. This scheme ensures‘food security’, to create a hunger free India and to reform and improve the Public Distribution System so as to serve the poorest of the poor in rural and urban areas. Various reports and estimates reported around 5% of population of the country are unable to get two square meals a day throughout the year. This scheme proposed to cover poorest of the poor by supply of food grains free of cost and other important commodities on subsidized rates. Over a period of time, the performance of the scheme has been improved due to evolving various monitoring mechanism and other vigilance committees. Even though, the criticism of the various civil society organizations and reports of press on the status of implementation of the scheme by the different states brings out number of problems in the identification of beneficiaries and distribution of benefits. In this context, a study on the impact of the AAY programme on the food security of the poorest of the poor was conducted to bring out various untouched issues on the status of implementation, ability of the distributing agencies, problems faced by the implementing agencies and beneficiaries. The study was carried out in the states of Maharashtra, Uttar Pradesh and Jharkhand in India. This article brings field realities of the functioning of the scheme.

A Novel Approach to Tackle Miscoordination of Protective Device in Radial Distribution Network during DG Interconnections

Due to incorporation of Distributed Generation (DG), the traditional protection scheme for electric power distribution system lost its radial nature and behaves more like multifeed transmission system. Hence, there is a need to develop a new protection scheme for electric power distribution system which remains stable in all conditions. This paper presents a new directional protection scheme for distribution system containing DG. Authors have developed a laboratory prototype of the three-phase radial distribution system containing DG. The proposed scheme has also been simulated using the PSCAD/EMTDC software package with fault data generated by modeling the distribution systems. The proposed directional protection scheme has been tested for various types of faults in different sections of radial distribution network along with DG. At the end, a comparative evaluation of the results obtained using the developed laboratory prototype has been carried out with the simulation results obtained using PSCAD. It has been observed that the proposed scheme has the ability to isolate the faulted section without disturbing the healthy section in the presence of DG.