Stochastic Model for Preventing Blackouts: A Live Case

Stochastic Model for Preventing Blackouts: A Live Case

Michael Sony (Namibia University of Science and Technology, Windhoek, Namibia) and V. Mariappan (Agnel Institute of Technology and Design, Goa, India)
DOI: 10.4018/IJORIS.2019010103

Abstract

Power system blackouts cause huge financial losses for the society and power utilities. Two types of blackouts have been identified. One involving load loss due to transmission lines reaching its limits and other involving failures of multiple transmission lines. Technologically advanced electricity transmission networks work in a financially just manner if a high rate of availability of the transmission networks is accomplished. Keeping this concept in mind, it is imperative to conduct the examination of transmission network availability, to design reliable electrical systems. This article discusses the stochastic availability modeling and analysis in transmission lines. The same is applied to a case of GED and the results obtained are discussed with the proper conclusion.
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Introduction

Power is one of the fundamental needs of human beings. As the country grows economically there is a continuous demand for power (Bhagwat & Tiwari, 2017; Mudakkar, Zaman, Khan, & Ahmad, 2013; Sony & Mekoth, 2014; Michael Sony & Mekoth, 2017). Economic growth of the country coupled with continued increase in demand for power makes the power transmission system increasingly complex in the process of evolution over the process of time. The evolution and reliability of power systems are leading engineering accomplishments of the last century that underpin developed societies (Carreras, Lynch, Dobson, & Newman, 2004). However, widespread disturbances of power transmission systems result in significant cost to society and the power utilities (Michael Sony & Mekoth, 2015). To study the complex dynamics of blackouts in power transmission systems, a dynamic model of such a system must be developed. In principle, improving system reliability and reducing operation and maintenance costs are top priorities of electrical utilities. Power scenario assessment of the reliability of transmission lines and assurance of quality power to consumers becomes a vital issue, health of equipment is of utmost importance of industries and society alike, because revenue is affected by the condition of equipment, when demand is high, and equipment is in working order, substantial revenues can be realized. To date in the power systems context, continuous parameter Markov models have been applied most extensively to model power system, reliability, and maintenance models. Stochastic models have been used in very widely used power systems (Aghamohammadi & Salimian, 2017; Alsammarae, 1989; Gupta, Kazi, Wagh, & Singh, 2018; Sony Michael, Mariappan, & Kamat, 2011), this paper intends to analyze a live case of power blackout situation using stochastic models, for optimum prevention strategies.

System Description

The power to Goa is coming from Western and southern region load dispatch centre. The power is wheeled through two 220kV transmission lines. Due to the apprehension expressed by officials, we do not give the exact names of transmission lines. The power transmission is utilizing the overhead lines. From substation AM two 220kV transmission lines emanate. They terminate in Substation CM and MB which are in Goa region. The network arrangement is given in Figure 1. In Goa region, these lines are in parallel. The transmission line protection relays are employed at substations.

Figure 1.

Block diagram of the system

IJORIS.2019010103.f01

A fault will be detected and the line at fault will be isolated and other lines will continue to feed non-faulty regions. As such the line which is not at fault will continue to be alive and transmit the power. The fault on line can occur anywhere along 118 Kilometer distance of the length of line. The different types of faults noted are earth faults, overcurrent, decapping of insulators, flashover of insulators, conductor related faults, transmission tower related faults which are permanent in nature. The various protections schemes at substations indicate the nature of the fault and the distance protection gives the location of the fault. It is noted that as there is little coordination between state power utilities in India and as such protection coordination studies are not meticulously done (Azavedo, 2017; Dubash & Rajan, 2001; S Michael, Mariappan, Amonkar, & Telang, 2009). It results in erroneous distance protection and nuisance tripping of transmission lines. The fault-finding crews have trouble in locating the faults and rely on manual patrolling of transmission lines in zones to ascertain the exact fault location.

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