Global digitalization and urbanization have increased the demand for electrical power supply. To fulfill this demand power generation and supply industry need to focus on developing advanced electric equipment such as power-generating substations. Its purpose is to step down high voltage electricity from the transmission system to lower voltage electricity, so it can be easily supplied to homes and businesses through lower voltage distribution lines.
A substation unit is an integral part of a power system. It is a bridge that transfers electricity from the power generation source unit to the end-user by transforming voltage from high to low and vice versa as needed. An electric substation system consists of much electrical equipment such as The power transformer, circuit breaker, bus bar, insulator, and a lightning arrester.
What Is a Substation?
A substation can be defined as an electrical system with high-voltage capacity which can be used to control the apparatus, generators, and other electrical circuits. It is mainly used to convert AC (alternating current) to DC (direct current). A basic electrical substation unit consists of a number of incoming circuits and outgoing circuits connected to common Bus-bar systems.
It receives electrical power from the generating station via incoming transmission lines and delivers electric power via the outgoing transmission lines. The electrical components in a substation are connected in a definite sequence which forms a proper circuit. This circuit can be switched off during normal operation by manual command and also automatically during abnormal conditions such as short-circuit.
Some types of substations are very small in size; they consist of an inbuilt transformer as well as related switches. Whereas some substations are very huge and contain different types of transformers, equipment, circuit breakers, and switches. Currently, substation automation is a cutting-edge technology in the electrical engineering field. It offers an intelligent, interactive power distribution network. Substation automation also helps to reduce operational and maintenance costs, increasing plant productivity with condition monitoring for circuit breakers, and power transformers.
Types of Substations
There are different types of substations that are classified in numerous ways, such as by nature of functions, service rendered, importance, and design. The classification of substations by nature of functions is discussed below.
- Step-Up or Primary Substations
A step-up or primary substation is utilized for the distribution of electricity over large distances. It receives power from a generating facility and then amplifies the voltage through a power transformer. Power in a primary substation is transmitted through transmission buses to transmission lines. Transformers in step-up substations increase the voltage of received power and lower the current to facilitate the transport of high amounts of electricity safely.
- Primary Grid Substations
This type of substation receives power from the step-up substation and lowers the voltage further for transmission. Primary grid substations are usually linked with bulk load centers next to primary transmission lines.
- Step-Down or Distribution Substations
These are located at different switching points on the electrical grid and are the source of distribution or sub-transmission lines. The step-down substation is used to change transmission voltage to a sub-transmission voltage ready for industrial utilization. It can also be transferred to a distribution substation, which is a step-down substation closest to the end user on the power grid.
The transformers in the distribution substation convert the transmission or sub-transmission voltage to lower levels for day-to-day purposes. Power received from a distribution substation is ready for household, industrial, and commercial use.
Role of Substation In Transmission And Distribution Systems
Substation plays an important role in electricity transmission and distribution. It performs major tasks of the system such as protection of the transmission system by controlling the exchange of energy. It also prevents loss of synchronism by maintaining the system frequency within the expected range. Substations ensure steady state and transient stability. It transmits data through power line carriers, which offers better control and protection and also helps in monitoring the network.
There are many driving factors responsible for innovation in substation technology such as increasing demand for efficient transmission of electricity, reduced operations and management costs for utilities, and ultimately lower power costs for consumers. In addition to this, the increasing integration of large-scale renewable energy systems requires more focus on research and development of automated substations.