Operation status means that the switch and knife switch of the equipment are in the closed position, and the circuit from the power supply to the receiving end is connected (including auxiliary equipment such as voltage transformer, lightning arrester, etc.);be-allrelay protectionThe control and operation circuits are normal.Operation status: it means that the disconnectors and circuit breakers of electrical equipment are in the closing state and have voltage.There are two kinds of power system operation states, namely, steady state and transient state.
Chinese name
running state
Foreign name
running state
Two
I.e. steady state and transient state
Transient process
Electromechanical transient
Transient cause
Mechanical torque and electromagnetic torque or power imbalance
Steady stateOperating parametersContinuously changes near a certain average value, with little change;Because the operation parameters of the disturbed system will change greatly, it is in a transient process;There are two kinds of transient processes. One is the rotating element in the power system, such asalternatorThe transient process of and motors is mainly caused by the imbalance between mechanical torque and electromagnetic torque (or power), which is usually called electromechanical process, namely electromechanical transient. The other is that in the components such as transformers and transmission lines, the transient process is called electromagnetic process, namely electromechanical transient, because it does not involve mechanical quantities such as angular displacement and angular speed.
classification
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The operation state of power system can be divided into steady state operation and transient process. The transient process can be divided into wave process, electromagnetic transient process and electromechanical transient process.The main research of wave process andAtmospheric overvoltageandSwitching overvoltageRelevant transmission process of voltage wave and current wave;The electromagnetic transition process mainly studies the changes of voltage and current related to various short circuit faults and broken line faults, and sometimes also involves the changes of power;Electromechanical transient process mainly studies the changes of generator speed, power angle and power when the power system is disturbed.
Four states
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The status of electrical equipment in the power plant is divided into four states: operation, hot standby, cold standby and maintenance.
running state
Operation status of electrical equipment: it means that the circuit breaker and disconnector (fuse, load switch, etc.) connected to the equipment are in the closing and connecting position, and the equipment has nominal voltage, andrelay protectionThe state that the automatic device and control power supply meet the equipment operation requirements.
Busbars, lines, circuit breakers, transformers, andVoltage transformerThe operation status of primary electrical equipment refers to that the circuit from the power supply of the equipment to the receiving end is connected and has corresponding voltage (whether with load or not), and the control power supplyrelay protectionAnd the automatic device is put into normal operation.Operation status of secondary equipment such as relay protection and automatic safety device: it means that the power supply of the equipment is put into operation, and the output function is correctly connected with the control circuit of the primary equipment.
Hot standby status
Hot standby state of electrical equipment: refers to that the electrical equipment has met the operating conditions, but the equipment has not been charged;There is only one disconnection point on each side connected to the equipment;And the relay protection, automatic device and control power supply meet the state of equipment operation requirements.
Hot standby state of the circuit breaker: it means that the circuit breaker itself is in the off position, but the disconnectors connecting each side of the circuit breaker are in the closed position;Relevant grounding switch is disconnected (or there is no grounding short line);And the relay protection, automatic device and control power supply meet the state of equipment operation requirements.Hot standby status of electrical equipment such as bus, transformer and line: it means that there are no safety measures on each side connecting the equipment;All circuit breakers connected to each side of the equipment are in the off position, but at least one group of disconnectors on both sides of the circuit breaker is in the on position;Relevant grounding switch is disconnected (or there is no grounding short line);And the relay protection, automatic device and control power supply meet the state of equipment operation requirements.
Cold standby status
Cold standby state of electrical equipment: it means that the circuit breaker and disconnector (fuse, load switch, etc.) connected to the equipment are in the off position, and the relay protection, automatic device and control power supply are out of operation;There are no safety measures on each side connected to the equipment, and there is no voltage on each side of the equipment.
Maintenance status
It means that all circuit breakers and disconnectors of electrical equipment are disconnected, and the electrical attendant arranges safety measures in accordance with the Electrical Safety Work Regulations and the requirements of the work ticket.
The switching operation law of electrical equipment is based on the above four stages. However, after the grounding wire of the maintenance equipment is removed, the insulation resistance should be measured to be qualified before it can be converted to another state.
Status and control measures
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Operation status of power system
From the macro point of view, the operation state of power system can be divided into normal state and abnormal state.In order to dispatch and control the power system, it is necessary to classify the operation state of the power system, so as to explain how to control the power system in different operation states.The operation state of the power system has not been strictly defined. In theory, the operation state of the power system is generally divided into two types, but there is no specific division standard for the specific operation state of different power systems under different conditions, so the management and control of the operation state of the power system is also lacking in pertinence,It is an urgent problem to divide the operation state of power system.According to the summary of practice, the operation state of power system can be divided into the following categories: normal state, alert state, emergency state, collapse state and recovery state.
Normal state and control measures
The understanding of the power system needs to be grasped on the whole. The power system is composed of engines, transformers and other electrical equipment, which integrates the functions of power generation, transmission and consumption.The load of the power system is constantly changing with the power consumption of users, and providing high-quality power consumption guarantee is an important goal and work content of the power enterprise, which needs to meet the requirements that the power and no power of the power system generator change within the safe range according to the change of the power load.To achieve this goal, electrical equipment needs to be able to operate normally, meet the needs of various situations, and ensure that the engines of all equipment can operate at the same frequency at the same time.
In practice, in order to ensure that the power system will not produce overload operation of equipment under normal interference and prevent the voltage deviation from being within the normal range, it is necessary to take corresponding adjustment measures. When the operation state transition changes, it is completed by adjusting the rotating standby or emergency standby.To ensure the normal operation of the power system is the guarantee of providing safe and reliable electricity, and is also the key to economic benefits.
Abnormal state and control measures
As mentioned above, the classification of power system operation state includes alert state, emergency state, collapse state and recovery state in addition to normal state, which belong to the category of abnormal state, and the following author will make a specific analysis of them.
First, alert status and control measures.The appearance of alert state is aimed at the overload operation of power system, the sudden failure of generator set, and the difficulty in ensuring normal operation, as well as the serious situations including shutdown, and the change of the operating environment of power system, which results in the reduction of the capacity of objective power operating equipment, and the external interference makes it difficult for the power system to operate normally.The operation of the power system in the alert state is unsafe, so it is necessary to take corresponding adjustment measures to adjust the load of the generator, temporarily eliminate the factors of economic interests, and take the safe operation of the power system as the primary goal.
Second, emergency and control measures.The emergency state is transformed from the alert state and the normal state. The faults in the emergency state are generally more serious. For example, sometimes the large capacity engine is tripped, resulting in a serious imbalance of power and no power in the power system;Or the synchronous operation of the generator has problems, and the emergency problems of the power system cannot be solved timely and effectively;Or if the emergency situation is not handled timely and effectively, it will lead to the operation imbalance, and the generator set will operate at different frequencies, which is a very serious threat to the power safety, and will lead to a large-scale power supply interruption.In addition, there are many fault manifestations, as well as natural disasters and weather caused by the operation of the power system into an emergency state.
Emergency state is a dangerous operation phenomenon, which needs to take timely and effective relay protection measures to control and deal with, so as to restore the power system to a safe and stable state as soon as possible and avoid accidents.
Third, collapse state and control measures.Collapse state is mainly aimed at the difficulty in taking timely and effective control measures under emergency state. In order to further expand the adverse effects of the power system, the dispatching staff take control measures to split the parallel system into several parts, which will cause the power system to enter a collapse state.
After the cracking measures are taken, several parts of the system after cracking have insufficient power, so all parts of the cracking are overloaded. Entering the collapse system is to ensure the normal operation of some important parts of the system, ensure normal power generation, and avoid the collapse of the entire power system.
Fourth, recovery status and control measures.In view of the problems, relevant dispatching personnel need to take relay protection and other measures for timely and effective control and dispatching to prevent the occurrence of accidents and the expansion of adverse effects. After the power system enters the collapse state, corresponding control measures need to be taken to restore the normal operation of the power system.To restore the state, the dispatcher needs to read the previously cracked generator sets for paralleling, and gradually restore the normal power supply to users.The control of recovery state needs to adopt gradual and progressive measures to recover the normal operation state according to the specific situation of failure.
The security control of the power system is mainly to adjust and control various abnormal states to make the power system return to the normal state as soon as possible. The dispatching staff should have a scientific plan for the operation of the power system and apply itcomputer control system Collect and process relevant information on the operation of the power system, monitor and adjust the operation of the power system in real time, and maintain the normal state of the power system.According to the summary, the security control of the power system can be divided into three categories according to the function. First, measures to improve the stable operation of the power system, including fast excitation, electric braking, series compensation, etc;The second is the measures to maintain the frequency of the power system, including low-frequency self starting, low-frequency voltage drop, high-frequency machine switching, etc;Third, measures to prevent overload operation of the line, including switching off power supply due to overload.
