A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Between the generating station and consumer, electric power may flow through several substations at different voltage levels. A substation may include transformers to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages.
Substations may be owned and operated by an electrical utility or may be owned by a large industrial or commercial customer. Generally, substations are unattended, relying upon remote supervision and control.
The word substation comes from the days before the distribution system became a grid. As central generation stations became larger, smaller generating plants were converted to distribution stations, receiving their energy supply from a larger plant instead of using their own generators. The first substations were connected to only one power station, where the generators were housed and were subsidiaries of that power station.
Substation panel board
Substations may be described by their voltage class, their applications within the power system, the method used to insulate most connections, and by the style and materials of the structures used. These categories are not disjointed; for example, to solve a particular problem, a transmission substation may include significant distribution functions. In distributed generation projects such as a wind farm, a collector substation may be required. It resembles a distribution substation although power flow is in the opposite direction, from many wind turbines up into the transmission grid. Usually, for the economy of construction, the collector system operates around 35 kV, and the collector substation steps up voltage to a transmission voltage for the grid. The collector substation can also provide power factor correction if it is needed, metering, and control of the wind farm. In some special cases, a collector substation can also contain an HVDC converter station.
Collector substations also exist where multiple thermal or hydroelectric power plants of comparable output power are in proximity. Examples of such substations are in Germany and Hradec in the Czech Republic, where power is collected from nearby lignite-fired power plants. If no transformers are required for increasing the voltage to transmission level, the substation is a switching station. The electrical substation is an assemblage of electrical components including busbars, switchgear, power transformers, auxiliaries etc. These components are connected in a definite sequence such that a ckt. can be switched off during normal operation by manual command and also automatically during abnormal conditions such as short-cut.
Basically, an electrical substation consists of a number of incoming ckt. and outgoing ckt. connected to a common Bus-bar system. A substation receives electrical power from generating station via incoming transmission lines and delivers elect. power via the outgoing transmission lines. The switchgear assembly comprises one or more busbar assemblies and a number of bays each connecting a circuit to the busbar assembly. Normally the busbars and bays should be mapped individually, see below. However, sometimes the layout of the switchgear is not known, such as when the switchgear is inside a building or when no good aerial imagery is available. In such cases, the switchgear may be mapped as an area. Only map switchgear in this way if it cannot be mapped in more details. If the entire substation is located indoor don’t map the switchgear separately
A power transformer is a static piece of apparatus with two or more windings which, by electromagnetic induction, transforms a system of alternating voltage and current into another system of voltage and current for the purpose of transmitting electrical power.