Analyses and Monitoring of Power Grid

Analyses and Monitoring of Power Grid

Rana A. Jabbar (Rachna College of Engineering and Technology, Pakistan), Muhammad Junaid (Rachna College of Engineering and Technology, Pakistan), M. A. Masood (Rachna College of Engineering and Technology, Pakistan), A. Bashir (Rachna College of Engineering and Technology, Pakistan) and M. Mansoor (Rachna College of Engineering and Technology, Pakistan)
DOI: 10.4018/978-1-61350-138-2.ch011
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Abstract

Power system analyses and monitoring of power system engineering are as essential as oxygen for human beings. This innovative approach deals with a 132 kV grid simulation in electrical transient analyzer program (ETAP). The existing power distribution system in Pakistan consists of approximately six thousand 11 kV feeders, which are mainly analyzed by software FDR-ANA (Feeder Analyses). This software does not have capability to provide comprehensive analyses for integrated power system. The case under study is 132 kV grid situated in Gujranwala electric power company (GEPCO), one of the distribution companies (DISCO’s) of Pakistan electric power company (PEPCO) which has been selected for comprehensive analyses using ETAP software. This software performs numerical calculations of large integrated power system with fabulous speed, besides generating output reports. In a developing country like Pakistan it is first time that analyses based Off-line monitoring has been made, which includes load flow, harmonic, transient, short circuit and ground grid analyses. In load flow analysis, current flowing in every branch, power factor, active and reactive power flow, line losses, voltage magnitude with angle etc. have been calculated. During harmonic analysis, distorted current and voltage waveforms along with their harmonic spectrum caused by non-linear loads have been recorded. Transient analysis has been performed to record different waveforms like variation in bus frequency, bus real power loading, bus voltage angle, and bus reactive power loading for short interval of time during transient conditions. In ground grid modeling, step, and touch potentials have been calculated in comparison with set standards. While performing short circuit analysis, all the possible short circuit faults like line to ground, double line to ground, 3-phase faults etc. on ½ cycle, 1.5 to 4 cycle, and 30 cycle networks have been performed to record the short circuit currents. These analyses have been executed using ETAP software, based upon historical data obtained from original system that will be very helpful for system security and reliability.
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Introduction

This book chapter comprises of two international conferences research papers published in ELECO’09 and PCO’10 in which first time in the history of Pakistan a practical 132 kV grid containing a large distribution network has been simulated for analyses purpose using ETAP software (Jabbar Khan et al, 2009; Bashir et al, 2010).

For the last few years electrical engineers have been focusing on the power system studies using software tools. Recent advances in engineering sciences have brought a revolution in the field of electrical engineering after the development of powerful computer based software. This research work high-lights the effective use of ETAP software for analyses of large electrical power system which comprises of large power distribution network emanating from 132 kV power grid (Lei et al, 2002; Inoue, 2007; Takimoto, 2005; Nagata & Inoue, 2008; Brown et al, 1990; Zhongxi & Xiaoxin, 1998; Stagg& El-Abiad, 1968).

Motivation to conduct the research work is to develop a prototype model which can be used as bench mark for comprehensive simulation of integrated network at national grid level to address power system stability under normal and abnormal operating conditions. PEPCO, the only power sector utility in Pakistan, consists of nine power distribution companies along with national transmission and power dispatch company but unfortunately no ON/OFF line monitoring is currently being performed. For this purpose a 132 kV grid station has been simulated using ETAP. PEPCO has been experiencing severe power shortage for last many years. Resultantly, the country is facing repeated and astonishing black outs. Despite the shortage of electricity, one of the main reasons of this energy crisis is deficiency in the field of analyses and monitoring of electrical power network. Keeping in view the above scenario, Rachna College of Engineering & Technology (RCET) Pakistan, has analyzed the complete 132 kV grid network which contains 11 kV feeders and rest of distribution network to predict the actual effects of load on the entire power system. These analyses include load flow analysis, harmonic analysis, transient analysis, ground grid analysis and short circuit analysis.

The data used for analyses purpose is in the form of one line diagram of complete power system network starting from power transformer at grid up-till the load. The ratings of power/distribution transformers are taken as they actually exist. Moreover, the conductors/cables, circuit breakers, CT’s, PT’s, and rest of power system elements are also modelled according to their actual ratings in ETAP.

This 132 kV Grid located in GEPCO region, having 6 power transformers, 32 feeders, 48 circuit breakers, 42 current transformers, 8 potential transformers and 2 incoming lines. Practical power system under study is a very antique grid which was inaugurated in 1952 and a centralized grid which feeds power supply to the other grids in this region, all the analyses and monitoring are concentrated on this grid (WAPDA, 2006).

A powerful computational software ETAP is used in this research paper for modeling and simulation purpose. The complete power system from grid to tail end load is modeled in this software. Although MATLAB is also used for power system simulation world widely, but ETAP has preferred here due to strong built-in properties regarding power system studies (Sybille & Hoang, 2002; Qinghuaz et al, 2009; Kjølle et al, 2002; Gatta et al, 2003; Gonen, 1968)

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