Substation
Category : electrical , Elétrica
A substation can be defined as a set of switching and/or transformation equipment, and possibly reactive power compensation equipment, used to direct the flow of energy in a power system and enable its diversification through alternative routes, possessing protection devices capable of detecting the different types of faults that occur in the system and isolating the sections where these faults occur.
A substation can be classified according to its function, voltage level, type of installation, and mode of operation.
Classification according to function
Transformer Substation: This is a substation that converts the supply voltage to a different level, higher or lower, and is designated, respectively, as a step-up transformer substation and a step-down transformer substation. Generally, a transformer substation near generation centers is a step-up transformer substation (it raises the voltage to transmission and sub-transmission levels, providing economical transport of electrical energy).
Substations at the end of a transmission system, close to load centers or supplying an industry, are Step-Down Transformer Substations (they reduce voltage levels), avoiding inconveniences for the population such as radio interference, intense magnetic fields, and very wide right-of-way.
Sectionalizing, Switching or Disconnecting Substation
It is the type of circuit that interconnects supply circuits under the same voltage level, enabling their multiplication. It is also used to allow for the sectioning of circuits, permitting their energization in successive shorter sections.
Classification according to voltage level
High-voltage (HV) substations: these are substations with a nominal voltage below 230 kV;
Extra-high voltage (EHV) substations: these are substations with a nominal voltage above 230 kV. It is important to emphasize that additional studies considering the Corona Effect are necessary for this type of substation.
Classification according to its type of installation
Open-air substations
They are built in large outdoor areas and require the use of equipment and machinery suitable for operation in adverse weather conditions (rain, wind, pollution, etc.);
Indoor substations
They are built in sheltered locations and the equipment is placed inside buildings, so they are not subject to adverse weather conditions like those in open areas;
Armored substations
Built in sheltered locations, the equipment is completely protected and isolated in oil, with solid material, or in gas (compressed air or SF6).
In the case of enclosed substations, some advantages and disadvantages can be highlighted. Enclosed substations have advantages such as reduced footprint (up to 10% of a conventional substation), low maintenance, and safe operation (entirely contained within metal enclosures), and are available in voltage levels up to 500kV. However, they also have certain disadvantages, such as the need for personnel with specialized training and the fact that switching and maneuvering operations cannot be visualized (only monitored by indicator lights).
Solar Power Substation
See article Solar Energy.
Classification according to the mode of operation
Operator-controlled substations: require a high level of personnel training and the use of computers for local supervision and operation; only justified for larger installations.
Semi-automatic substations
They have local computers or electromechanical interlocks that prevent improper operations by the local operator.
Automated substations
They are supervised remotely via computers.
TRANSFORMATION EQUIPMENT
Transformation equipment includes power transformers and instrument transformers – Potential Transformers (PTs), Capacitive or Inductive, and Current Transformers (CTs). Without transformers, the economic use of electrical energy would be practically impossible, as they allow transmission at increasingly higher voltages, enabling significant savings in transmission lines over increasingly longer distances. Instrument transformers (CTs and PTs) serve to reduce current and voltage, respectively, to levels compatible with the operating voltage and current of electricity meters.
VOLTAGE TRANSFORMERS
Voltage transformers are classified according to their insulating medium, which can be mineral oil-filled, liquid-filled with low-flammability synthetic insulators (silicone), or dry-type.
Mineral oil (derived from petroleum) and synthetic insulating liquids used in transformers have two main functions: to insulate, preventing the formation of an arc between two conductors that have a potential difference, and to cool, dissipating the heat generated by the operation of the equipment.
Dry-type transformers use air as both an insulating and cooling medium, and have insulation class B, class F, or class H.
Potential Transformers
Used to lower the voltage for the purpose of measuring electrical energy.
CURRENT TRANSFORMERS
A current transformer (CT) is an instrument transformer whose primary winding is connected in series with an electrical circuit and whose secondary winding is intended to supply current coils of electrical measuring, protection, or control instruments.
Images and some text extracted from Google.
Adolpho Eletricista – Seu Eletricista em São Paulo
