In this paper, a simple and effective strategy is proposed for the coordination of protective devices in typical radial distribution networks embedding distributed generation units. The proposed strategy benefits from microprocessor-based reclosers and directional elements for feeder relays, and addresses the issues of blinding of protection, false tripping, recloserfuse and fuse-fuse miscoordination, and failed auto-reclosing. Another salient feature of the proposed strategy is that it does not require adaptive protective devices. The effectiveness of the proposed algorithm is demonstrated by simulation case studies conducted on a model of an example distribution network, in the PSCAD/EMTDC software environment. The paper also presents the steps taken to characterize the impact of DGs on the protection coordination, for host and neighboring feeders.

A strategy for protection coordination in radial distribution networks with distributed generators

This paper presents a new differential protection scheme based on support vector machine (SVM), which provides effective discrimination between internal faults in a power transformer with the other disturbances, such as various types of inrush currents and overexcitation conditions. The feature extraction is carried out using wavelet transform, which later, is given as input to the SVM classifier. Numerous simulation cases consisting of internal faults and other disturbances have been simulated with varying fault and system parameters for an existing power transformer of Gujarat Energy Transmission Corporation Ltd. (GETCO), Gujarat, India, using the PSCAD/EMTDC software package. The performance of the developed algorithm has been tested over a simulation data set of 5442 cases and the overall fault discrimination accuracy of more than 99% is achieved. It has also been observed that the SVM classifier gives highly promising results for CT saturation, different connection type, and various ratings of the transformer, even though it is trained only once for a single rating and connection of a transformer. At the end, a comparative evaluation of the proposed scheme is also carried out with other existing/proposed methods where it has been observed that the proposed method provides superior results.

Discrimination Between Internal Faults and Other Disturbances in Transformer Using the Support Vector Machine-Based Protection Scheme

Algorithm for harmonic restraint differential relaying based on the discrete Hartley transform

Protective relays have been designed with different technologies resulting in electromechanical, solid-state, and numerical devices. Speed and reliability are the two most important characteristics of a protective relay. Other capabilities such as monitoring and recording are supposed to be of secondary priority. Without any doubt, present-day numerical relays provide considerable capabilities and advantages but they have not improved speed of operation in comparison to their solid-state counterparts. With advancements in analog technology which has become more mature recently, the idea of using mixed signals in several applications has started. The new technology using combination of field-programmable analog arrays (FPAAs) and digital technologies seems to be a breakthrough and has the potential to provide better performance than the present-day numerical relays. In this paper, use of FPAAs for designing and implementing protective relays is investigated for the first time in literature. A distance relay design and its hardware implementation using FPAAs is described. Test results are reported.

Field-Programmable Analog Array Based Distance Relay

. Transformers are a vital part of the transmission and distribution system. Monitoring transformers for problems before they occur can prevent faults that are costly to repair and result in a loss of service. Current systems can provide information about the state of a transformer, but are either offline or very expensive to implement. Transformers being the essential part of power transmission system are expensive, as is the cost of power interruptions. Because of the cost of scheduled and unscheduled maintenance, especially at remote sites, the utility industry has begun investing in instrumentation and monitoring of transformer. On-line transformer diagnostics using conventional technologies like carrier power line communication, Radio frequency based control system, and Supervisory control and data acquiring systems, Distributed control systems and Internet based communications are having their own limitations. GSM is an open, digital cellular technology used for transmitting mobile voice and data services. This project objective is to develop low cost solution for monitoring health condition of remotely located distribution transformers using GSM technology to preent premature failure of distribution transformers and improving reliability of services to the customers. An Embedded based hardware design is developed to acquire data from electrical sensing system. It consists of a sensing system, signal conditioning electronic circuits, advanced embedded hardware for middle level computing, a powerful computer network for further transmission of data to various places. A powerful GSM networking is designed to send data from a network to other network for proper corrective action at the earliest. Any change in parameters of transmission is sensed to protect the entire transmission and distribution. The performance of prototype model developed is tested at laboratory for monitoring various parameters like transformer over load, voltage fluctuations, over temperature, oil quality and level etc.

https://www.ijser.org/researchpaper/Transformer-Health-Condition-Monitoring-Through-GSM-Technology.pdf

Transformer Health Condition Monitoring Through GSM Technology

Power System Protection: Static Relays

As the number of renewable energy sources increases worldwide, wind energy is one of themwho stand out from the crowd. With the development of technology, wind turbine projects have had a significant impact increased their capacity, reaching a higher capacity mainly for offshore installations. One of the most important challenges are power Converter, specifically semiconductor components that have limited voltage and current characteristics. This gave birth to the concept of multilevel Converter , which increased the voltage level and thus carried a higher power level. Apart from the application In multilevel converter , it is possible to increase the voltage and power level by using an generator. This context was investigated in this work the use of a multi-level converter (three-level cascaded H-bridge in series), which controlsan open coil of Generator Analysis of the proposed system was developed dynamicallySimulation of 1.71 MW WECS using PLECS software including basic system modeling components: generator, power converters, system control, filter and grid connection. The score show that the goal of achieving 5-level behavior of the output voltage is achieved by using OEW connection. In addition, a low harmonic concentration is achieved in the machine flow as such current supplied to the grid. In addition, it is possible to control the distribution of power between converter, indicating that lower power converter can be connected in a higher direction Wind power

Advanced Cascaded H-Bridge & Modular Multilevel Converter Applied to a Wind Energy Generation


The primary objective of the research article is to describe the functionality of wrist watch which acts as a digital stethoscope to measure health constraints such as heart pulse through blood pressure. The second objective is the detection of blockages of an artery due to fatty, cholesterol-deposited, over a period when the blood is passing through due to stress and exercise, etc. Pressure and velocity are two inputs with their respective results of contrast and expansion of veins at the outputs. The major parameters in detecting the laminar flow are pressure and velocity. These parameters of a vein are analyzed by integrating valves in the vein. The movement of blood laminar flow in the vein is captured by a MEMS-based piezoelectric sensor by its functionality. The proposed design performance accuracy is estimated by modeling of vein's laminar flow when blood is circulating. The coagulation effect of the vein is used to measure heart stroke by placing MEMS along with the stent, as MEMS are tiny in size. The functionality of a digital Stethoscope works on the piezoelectric effect that generates an electrical signal when pressure is applied from the vein. The accuracy, functionality, and performance of the design can be analyzed by COMSOL multi-physics. Applications of MEMS include detection, prevention, and alert during the second heart stroke, and also used in the bionic eye and automotive electronics.


Madhava Rao

Papers

Power System Protection: Static Relays

Advanced Cascaded H-Bridge & Modular Multilevel Converter Applied to a Wind Energy Generation

Detection and analysis of coagulation effect in vein using MEMS laminar flow for the early heart stroke diagnosis