1.1 Introduction
Reliable electricity supply has become an important part of the electric power system along with the mutual benefits of power utility companies and the consumers (Fagbohun et al., 2012). A reliable and uninterrupted power supply at an optimum cost is a basic factor for industrial and socio-economic development for any place. As a matter of fact, the electricity consumption per capita of a nation is a measure of the standard of living of its citizens (Adebanji et al., 2017).
The major goal of power system is to ensure continuous supply of electricity at declared service quality to meet up with the demand of its customers. However, interruptions which sometimes may be unavoidable, tends to negate this trend. Hence, the needs for reliability assessment of power system components in ensuring continuity of power supply to cope with the increasing teeming population and the need for rapid industrial growth (Fasina et al., 2017; Adebanji et al., 2020).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitation of the study and Definition of technical terms.
1.2 Background of Study
The electricity utility industry is moving towards a deregulated, competitive environment where utilities must have accurate information about system performance to ensure that maintenance money are spent wisely and that customer expectations are met (Okorie et al., 2020). It is of utmost importance to assess the reliability of power system networks especially the distribution system, in order to be able to make informed decisions in planning and maintenance operations. Power system reliability can therefore be said to be the probability that power system will be able to perform its intended role of delivering continuous electrical energy at an acceptable service quality. As the major aim of power system is to ensure continuous supply of electricity at a declared service quality to its consumers, informed knowledge on reliability assessment will indeed improve the performance of the system components. The assessment of distribution feeders should be a routine exercise considering its major role in power system design, operation, control, and maintenance.
In terms of reliability evaluation and modeling, generating stations have justifiably received more attention than the other systems because they are individually capital intensive. In addition, in the event of generation inadequacy and generation loss there is usually widespread catastrophic effects on the society and environment. It impacts directly on the whole system and even distribution system will not be able to perform its duty because there will be no electricity to supply to customers. However based on published research work and studies, distribution systems have begun to receive moderate attention compared to past decades. In most cases, when there is disturbance in form of failure which results in outages in the distribution system it affects only the localized territory. Only in few cases does the fault move up in to the system largely as a result of protection failure. Analysis of the customer failure statistics of most electricity companies shows that the distribution system makes the greatest individual contribution to the unavailability of supply to a customer (Gonen, 2014).
One of these is the issue of serving its main purpose which is to supply quality electricity with little or no interruptions. This problem is inevitable in power systems across the world but the way they are managed is what makes it different from country to country. Electric power system is basically set up to supply electricity with little or no interruptions to its customers. The number of interruptions that occur while the system performs its intended function is part of what determines the overall reliability of the system. The other factor that determines its reliability is the quality of electricity delivered. Furthermore, the capability of a power system to continuously deliver quality electricity means that the customers are satisfied and the electricity providers are having favorable returns on their investment as they continue their business of supplying electricity. As electricity consumption has become an important factor that affects the drive needed for technology to grow and to facilitate the development of modern society, it is very important therefore to take seriously the issue of reliability of an electric power system.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to evaluate the Secondary Distribution Systems Reliability.
1.3 Statement of Problems
Investigation revealed that in Nigeria, the daily electric power interruption is largely becoming a consistent phenomenon in wide area network of electricity distribution and this is basically due to insufficient power generation, transmission faults and distribution system faults and failures. Unavailability of power supply to customers can occur several times a day and sometimes for weeks and in worst cases for months. There are instances where several interruptions occur in a day especially at the residential loads, which causes untimely failure of home gadgets, darkening of light bulbs, and reduced efficiency and performance of high-power appliances. Damage of electronic devices and burning of light bulbs have also occurred due to over voltages. There are also few cases of deliberate outages due to weather especially rainfall.
This is to protect most residential areas from voltage surge that may enter into the power system when lightning occurs owing to the fact that not all residential areas were inspected and certified by the electrical companies when the buildings were completed. Most electrical designs in residential houses are usually not done by professional engineers especially in the middle-class and low-income earner’s settlements.
1.4 Aim and Objectives of Study
The aim of the study is to evaluate the Secondary Distribution Systems Reliability in Nigeria using Ayetoro 1 Substation, Aguda, Lagos State as a case study. In achieving this aim, the following specific objectives were laid out as follows:
- To determine the reliability of each component in the substation system;
- To examine the overall reliability of the distribution substation; and
- To find out how the substation unavailability contributes to the loss of supply to the customers by interpreting the results obtained after analysis.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- Does the substation unavailability contribute to the loss of supply to the customers by interpreting the results obtained after analysis?
- What is the overall reliability of the distribution substation?
- What is the reliability of each component in the substation system?
