why is power distribution frequency to low

In the power distribution system, **excessively low frequency** (for example, in a 50Hz system dropping below 49Hz or in a 60Hz system

 dropping below 59Hz) is usually caused by **an imbalance between the supply and demand of active power**. The following are the 

specific causes, impacts, and solutions:

I. Core Cause: Insufficient Active Power

The frequency of the power system is determined by **the rotational speed of the generator**, and the rotational speed depends on 

**the balance of active power** (generated power vs. load power).

**Frequency formula**: \( f = \frac{P_{\text{mechanical}} - P_{\text{electrical}}}{K} \), where \( K \) is the system inertia constant.

**The essence of excessively low frequency**: **Generated power < Load power**, leading to a decrease in the rotational speed of the 

generator.

II. Specific Causes

1. Generator Failure or Insufficient Output

- **Power plant equipment failure**: Such as failures of steam turbines, boilers, or generator tripping, resulting in a reduction of the

 connected grid power sources.

- **Interruption of fuel supply**: Insufficient fuel in coal-fired and gas-fired power plants, or too low water levels in hydropower stations.

- **Fluctuations in the output of new energy sources**: Wind power and photovoltaic power are affected by the weather (such as no wind, 

cloudy conditions), and the output suddenly drops.

2. Sudden Increase in Load

- **Surge in industrial load**: When large motors (such as those in steel plants and chemical plants) start up, they consume a large amount 

of active power.

- **Extreme weather**: The air conditioning load in summer or the heating load in winter surges suddenly, exceeding the system's prediction.

3. Transmission Network Failure

- **Line tripping or short circuit**: This causes some power sources to be unable to be transmitted to the load center, resulting in local power

 imbalance.

- **Power grid disconnection**: The fault causes the system to split into multiple islands. Small islands have low inertia, and the frequency is

 prone to fluctuations.

 4. Failure of Automatic Control

- **Failure of the Automatic Generation Control (AGC) system**: It is unable to adjust the generator output according to the frequency deviation.

- **Failure of the primary frequency regulation function**: The generator governor fails to respond promptly to frequency changes (such as

 the governor getting stuck).

5. System Design Defects

- **Insufficient reserve capacity**: Insufficient spinning reserve (hot standby generators) or non-spinning reserve (power sources that can be

 quickly started).

- **Low inertia of small power grids**: In distributed microgrids or island systems, load changes have a more significant impact on the frequency.

III. Impacts of Excessively Low Frequency

1. **Equipment Damage**:

   - The rotational speed of the motor decreases (rotational speed ∝ frequency), the efficiency decreases, and the temperature rise is too high.

   - The iron loss of the transformer increases, and it may overheat.

2. **Chain Reactions**:

   - Excessively low frequency triggers the low-frequency load shedding device (Load Shedding), which automatically cuts off part of the load,

 leading to power outages.

   - In severe cases, it may cause the system to collapse (such as the major power outage in Texas in 2021).

 IV. Solutions

1. Rapidly Increase Generated Power

- **Start standby generators**: Such as gas turbines and diesel generators.

- **Deploy energy storage systems**: Battery energy storage and pumped-storage hydroelectricity can release power quickly.

- **Adjust the output of hydropower**: Increase the opening of the turbine guide vanes to rapidly increase the active power.

2. Reduce Load

- **Manually/automatically cut off non-critical loads**: Such as industrial users and commercial air conditioners.

- **Demand Response (DR)**: Encourage users to actively reduce the load through electricity price incentives.

3. Optimize Grid Operation

- **Parallel operation**: Synchronize the island system with the main grid and use the inertia of the large grid to stabilize the frequency.

- **Inspect and repair transmission lines**: Restore the faulty lines and balance the power between regions.

4. Long-term Prevention

- **Increase reserve capacity**: Configure spinning reserve according to 10%-15% of the maximum system load.

- **Upgrade the AGC system**: Improve the sensitivity and response speed of frequency regulation.

- **Strengthen grid interconnection**: Through cross-regional grid support, share the impact of load fluctuations.

V. Case: The Frequency Collapse of the Indian Power Grid in 2022

- **Cause**: The load in the northern power grid surged (the increase in air conditioning load due to high temperatures), and at the same 

time, there was a shortage of coal in thermal power plants, resulting in insufficient generated power.

- **Result**: The frequency dropped sharply from 50Hz to 48Hz, triggering low-frequency load shedding and causing a power outage for

 200 million people.

- **Lesson**: Insufficient reserve capacity, a fragile fuel supply chain, and a lagging AGC response.

 VI. Summary

Excessively low power frequency is a direct manifestation of **active power imbalance**, which needs to be addressed through **real-time

 adjustment of power generation/load** and **optimization of the system design**. For operation and maintenance personnel, the key is to

 quickly locate the source of the fault (such as generators, lines, or control devices) and activate emergency response plans (such as standby

 power sources and load shedding).