- Generation
- Transmission
- Distribution
🔌 What is an Electrical Power System?
- An electrical power system refers to the network of components used to supply, transmit, and use electric power. It consists of generating stations, transmission lines, substations, and distribution networks.
- In most modern grids, a three-phase, three-wire AC system is used for both generation and transmission due to its cost-effectiveness and efficiency. However, a three-phase, four-wire AC system is commonly used in power distribution for consumer loads.
- Note: Although underground systems are more secure, they are also expensive. Hence, in countries like India, overhead lines are widely used for both transmission and distribution.
⚙️ Structure of Electrical Power System
Below is a breakdown of each stage in the structure of the electrical power system:
- The three main divisions of an electric power system are generation, transmission, and distribution. These stages work together to produce electricity, deliver it over long distances, and supply it safely to consumers.
🔋 (i) Generating Station
Electricity is produced at generating stations using different types of power plants, including:
- Thermal Power Plant
- Hydropower Plant
- Nuclear Power Plant
Here, electricity is generated by alternators running in parallel. The standard generation voltage is around 11 kV. To reduce transmission losses and improve efficiency, this voltage is stepped up using a step-up transformer to 132 kV or higher.
🔌 (ii) Primary Transmission
From the generating station, the stepped-up voltage (e.g., 132 kV) is transmitted through overhead 3-phase, 3-wire transmission lines. This process is called primary transmission.
⚡ (iii) Secondary Transmission
The primary transmission lines terminate at the receiving station, where the voltage is stepped down from 132 kV to 33 kV using step-down transformers. This reduced voltage is then transmitted to local substations, marking the stage of secondary transmission.
🔄 (iv) Primary Distribution
At the local substations, the 33 kV voltage from the secondary transmission is further reduced to 11 kV through another step-down transformer. This voltage is now ready for primary distribution to different areas.
🏠 (v) Secondary Distribution
The 11 kV supply from the primary distribution system is transformed into 400 V (line-to-line) or 230 V (line-to-neutral) using distribution transformers. This is done through a three-phase, four-wire system, making it suitable for direct supply to residential, commercial, and industrial consumers.
📌 People Also Read:
📷 Visual Representation: Electrical Power System
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| Structure of Electrical Power System |
Components of Power System
1. Generation
- Prime Movers (Steam Turbine, Water Turbine, Gas Turbine, Diesel Engine)
- Alternators / Generators
- Excitation System
- Boiler / Furnace (in thermal plants)
- Cooling Towers & Condensers
- Generator Step-up Transformers
- Switchgear (Isolators, Circuit Breakers)
2. Transmission
- Transmission Lines (Overhead Conductors / Underground Cables)
- Transmission Towers
- Insulators
- Substations
- Power Transformers
- Switchgear (Circuit Breakers, Isolators)
- Protective Relays
- Lightning Arresters
- Capacitors & Reactors (for reactive power compensation)
3. Distribution
- Distribution Transformers
- Feeder Lines
- Distributors
- Service Mains
- Pole-Mounted Switchgear
- Fuses and Circuit Breakers
- Consumer Energy Meters
- Pole Structures / Cables
4. Utilization (Loads)
- Lighting Equipment
- Electric Motors
- Heaters & Furnaces
- Air Conditioning & Refrigeration
- Traction Equipment (Electric Trains, Metro)
- Agricultural Pumps
- Domestic Appliances
5. Protection & Control
- Protective Relays
- Circuit Breakers
- Fuses
- Lightning Arresters
- SCADA (Supervisory Control and Data Acquisition)
- Load Dispatch Centers (LDC)
6. Energy Storage (Modern Systems)
- Battery Energy Storage Systems (BESS)
- Pumped Hydro Storage
- Compressed Air Storage
- Supercapacitors
- Flywheels
📝 Conclusion
The electrical power system is a well-structured network ensuring efficient electricity delivery. From generation at power stations to distribution at consumer level, each stage plays a vital role in maintaining stability, voltage regulation, and energy efficiency.
For aspirants of competitive exams like SSC JE, RRB JE, or GATE, understanding this structure is essential.