how do power substations work

**Answer: The working principle of a power substation is to adjust the voltage and distribute the electric 

power through transformers and electrical equipment, ensuring the efficient transmission of electrical energy

 from power plants to households and enterprises. The following are its core working processes and key functions:**

 I. The Core Functions of a Power Substation

1. **Voltage Conversion**

   - **High-voltage Transmission**: The electricity generated by a power plant (usually 10-30 kV) is raised to

 110-765 kV through a step-up substation to reduce the energy loss during long-distance power transmission

 (the higher the voltage, the lower the current, and the lower the resistance loss).

   - **Low-voltage Power Distribution**: The high-voltage electricity is gradually reduced to 10-35 kV 

(distribution lines) through a step-down substation, and finally reduced to 220-480 V for use by households

 and enterprises.

2. **Power Distribution**

   Shunt the power from the main power grid to the distribution lines in different regions to ensure that

 multiple users can use electricity simultaneously.

 II. Classification and Working Processes of Power Substations

1. Transmission Substations (High-voltage Substations)

- **Function**: Connect the power plant to the main power grid and be responsible for stepping up or stepping 

down the voltage.

- **Process**:

  ① Power plant → Step-up transformer (10kV→220kV) → High-voltage transmission line

  ② High-voltage electricity from the main power grid → Step-down transformer (220kV→110kV) → Regional

 power grid

2. Distribution Substations (Low-voltage Substations)

- **Function**: Distribute the power from the regional power grid to end-users, finally step down the voltage, 

and control the stability of power supply.

- **Typical Process**:

  110kV transmission line → Transformer (reduced to 10kV) → Distribution line → Community substation 

(further reduced to 220V) → Households/Enterprises

III. Key Equipment and Principles of Power Substations

1. Transformers

- **Function**: Change the voltage through electromagnetic induction.

- **Structure**:

  - **Primary Winding** (connected to the input power source)

  - **Secondary Winding** (connected to the output line)

  - **Core** (enhance the magnetic field coupling)

- **Formula**:

2. Switchgear Equipment

- **Circuit Breaker**: Automatically cut off the circuit in case of a fault (such as overload, short circuit).

- **Isolating Switch**: Isolate the circuit without load for maintenance purposes.

3. Protection Devices

- **Lightning Arrester**: Prevent equipment from being damaged by lightning strikes or voltage surges.

- **Relay**: Monitor the current/voltage and trigger the circuit breaker to operate.

IV. Examples of Working Scenarios of Power Substations

1. **From Power Plant to Household**:

   Power plant (10kV) → Step-up substation (220kV) → High-voltage transmission line → Regional substation

 (step down to 10kV) → Distribution line → Community substation (step down to 220V) → Household.

2. **Fault Handling**:

   If a certain line has a short circuit, the relay detects the abnormal current, triggers the circuit breaker to trip,

 isolates the faulty area, and avoids affecting the entire power grid.

 V. Conclusion

A power substation is the "hub" of the power system. Through transformers to regulate the voltage, switchgear

 equipment to control the on-off, and protection devices to ensure safety, it realizes the efficient transmission 

and distribution of electrical energy. Its core logic is: **Transmit electricity at high voltage to save energy, and 

distribute electricity at low voltage for safety**.