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The operating status of the power system refers to the working conditions of each part of the power system (such as power generation, transmission, distribution, load, etc.) during operation, which is usually characterized by electrical parameters (such as voltage, current, frequency, power, etc.). These states indicate whether the system is operating normally, whether there are abnormalities or faults, and affect the safety, stability and reliability of the power system.
The operating status of the power system is usually divided into the following categories:
1. Normal state
This is the ideal operating state of the power system. Under normal conditions, all parameters of the system (such as voltage, current, frequency) are within the allowable range, and the power generation, transmission, distribution and load are balanced, and the system operates stably and reliably.
Features:
- The voltage and frequency remain within the specified standard range.
- The power generation and load are matched, and the system power supply is sufficient.
- The transmission lines and equipment work within a safe load range.
2. Overload state
In the overload state, the load of the system exceeds the rated capacity of the generator set, transmission line or other equipment, causing the current or power of some equipment to exceed its design limit.
Features:
- Excessive current may cause equipment to heat up and be damaged.
- Voltage may drop.
- If not handled in time, it may cause equipment damage or system crash.
Causes:
- Sudden increase in load.
- Unreasonable system operation mode.
3. Emergency state
When a system fails, an accident or extreme conditions occur, it enters an emergency state. For example, a short circuit, a line break, an equipment failure or other sudden events may cause system instability or power outage. At this time, emergency measures must be taken to avoid the expansion of the accident.
Features:
- Severe fluctuations in current, frequency or voltage.
- Some equipment or lines lose function or protective devices operate.
- It may cause partial or complete power outage of the system.
Countermeasures:
- Take automatic or manual measures to isolate the fault.
- Start backup equipment or adjust the system operation mode.
4. Instability state
Instability refers to the loss of stability of the power system, causing parameters such as voltage and frequency to quickly deviate from the normal range, and even cause the system to crash. Common forms of instability are:
- Voltage instability: The voltage drops rapidly and cannot be restored to normal levels.
- Frequency instability: The balance between power generation and load is destroyed, and the frequency fluctuates sharply.
- Power angle instability: The relative power angle between synchronous generators loses synchronization, causing the generators to lose synchronous operation.
Causes:
- Load surge, equipment failure, insufficient power generation, etc. may cause instability.
Countermeasures:
- Start the protection device to isolate the fault area.
- Increase reactive power compensation, or reduce the load.
5. Recovery state
When the power system passes through a fault, certain recovery measures are taken to gradually restore the system to normal operation, which is called the recovery state.
Features:
- System parameters gradually return to the normal range.
- It may be necessary to restart some generators, reclose the line, etc.
Recovery measures:
- Manually or automatically adjust the equipment to restore the power balance.
- Gradually restore power supply according to the established recovery procedures.
6. Power outage state
The power outage state refers to the complete cessation of power supply to a part of the power system or the entire system, usually due to serious faults, equipment damage or human operation errors.
Features:
- All or part of the power equipment stops operating.
- Users cannot get power supply.
Causes:
- System faults cannot be isolated.
- The entire system loses stability, resulting in large-scale power outages.
In a word, the safe and stable operation of the power system depends on quickly identifying these states and taking corresponding control and protection measures.
