Optimal Placement of PMUs & Development of Adaptive Relaying Scheme

Abstract

Currently, rapid change in power, drastic change in Power generation and transmission system , power system restructuring and other factor affecting on loading condition of existing network. In such circumstances to make stable operation, an accurate measurement and monitoring is essential. Mainly monitoring is performed by the Supervisory Control and Data Acquisition (SCADA) system. The limitation of the said system is that the measurements acquired are not time synchronised. To overcome this limitation, Recently developed synchrophasor based technique is utilized. This improves wide system operation, monitoring and system protection. The synchrophasor technology implements PMU (Phasor Measurement Unit), a device for fast and synchronised measurement based on Global Positioning System (GPS). PMU reports phasor data of voltage and current. Further, PMU data is applicable for calculation of other phasor data. Such as, frequency, Rate of change of frequency(ROCOF), positive, negative and zero sequence- voltage and current, active power, reactive power at phasor data concentrator. It will be useful for Analytical study to improve overall reliability and security of power system network. But the major problem associated is identification of location of the PMU in a network to make network fully observable and at the same time it should be cost efficient as well. It can be achieved by typical mathematical method. In the emerging power system network, it is observed that most of the transmission lines are operating near their stability limits. Under such conditions in appropriate operation of relays during the disturbance can result into calamitous loss and cascaded tripping. The traditional first zone of the protection which is operate at power swing as primary protection was found to be main culprit in many literatures and field. Therefore, there is a need to have a defensive system which can give strong assistance to system operators and can become an informative tool that can help in tacking suitable decisions on stable power swing. As a part of development process, the specific area of work can be enlisted as Study of measurement process of Synchrophasor Technology, Study of optimization method, Development of algorithm to identify optimal location of PMUs, Synchrophasor measurement signal applicable for abnormal condition in network, Study of existing distance protection scheme, Study of PMU data and calculation from application data, Based on the Phasor data, algorithm will be differentiate stable power swing and fault of EHV transmission line and it is helping to blocking distance relay's first zone of protection.