Abstract: This paper expounds the concept of hidden danger in substation operation and its pre-control. Aiming at the dangerous points and hidden dangers in substation operation, this paper puts forward effective solutions and preventive measures, such as strengthening the prevention of dangerous points, strengthening the safety education and training of personnel, and integrating new technologies such as infrared thermal imager into substation operation.

Paper Keywords: substation operation; Hidden danger; solution

With the accelerating pace of China's economic construction, as the forefront of power grid security, substation operation safety management has attracted more and more attention from enterprises, society and researchers. One of the characteristics of substation operation is that there are many equipments, the probability of dangerous points or hidden dangers is high, and it is hidden. Any nonstandard working procedure in substation operation will affect the normal operation of power and even the safety of the whole power grid and the occurrence of major personal accidents. Therefore, how to find the dangerous points of equipment operation, analyze and discuss the potential safety hazards, and formulate strict and scientific safety protection measures has become a hot issue in the operation of power system substations.

First, the concept of hidden dangers in substation operation and precontrol.

Places, components, working tools and operations where safety accidents may occur in substation operation are called safety hazards.

Security risks are divided into three aspects.

First, the workplace is not set according to the requirements of environment and occupational health and safety, and the harmful working environment such as high temperature, noise and smell will directly or indirectly endanger the health of workers and induce occupational diseases.

Second, the mechanical equipment protection in the job site is not in place. If there are no danger signs and mechanical sprockets have no safety cover, it will directly cause harm to human body.

Third, the safety management is not in place, and the operators are indifferent to safety awareness, which violates the safety operation procedures.

Pre-control of hidden dangers of dangerous points is to find the dangerous points in the operation by technical means before operation, make scientific analysis and evaluation, formulate strict and feasible control schemes, and adopt active and effective prevention methods. It is not only an effective way to nip accidents in the bud or minimize the risks and losses caused by security risks, but also an effective way to ensure the normal operation of the power grid.

Second, the analysis of dangerous points and hidden dangers in substation operation and management

1. transformer

(1) operation hazards and hidden dangers. Transformer operation is one of the most common and typical operations in substation operation, including charging transformer, load transformer and cutting off no-load transformer. Usually, when the transformer is in operation, in the process of adapting to the no-load transformer, there will be the phenomenon that the running overvoltage will affect or endanger the transformer insulation, and there are dangers and hidden dangers that the transformer insulation will be damaged due to the increase of the no-load voltage.

(2) Preventive measures. The operation of transformer should be careful to avoid irreparable consequences due to negligence. Transformer adopts neutral grounding mode to avoid operating overvoltage.

Principles to be followed in neutral grounding switching of transformer;

1) When multiple transformers are running in parallel on different buses, it is required that each bus should have a neutral point of 1 or more transformers directly grounded, so as to prevent the bus from being ungrounded due to bus coupler switch tripping.

2) When the low-voltage side of the transformer is equipped with power supply, the neutral point of the transformer must be directly grounded to prevent the transformer from becoming a neutral point insulation system when the switch on the high-voltage side trips, causing potential safety hazards.

3) Put the reactor into operation, reduce the terminal voltage, and change the tap of the on-load voltage regulating transformer to avoid the no-load voltage increase of the transformer.

2. Bus trip

The dangerous point of (1) operation. Bus is the gathering place of substation operation equipment, which is characterized by many connecting elements and heavy workload. The power transmission and power failure of the bus and the switching process of the equipment on the bus between two buses will produce dangerous points and hidden dangers, so the operation should be carried out in strict accordance with the operation requirements.

The potential danger points of bus operation are as follows:

1) On-load switch accident.

2) misoperation caused by incorrect switching of relay protection or automatic device.

3) When the no-load bus is charged, series resonance is formed between the inductive voltage transformer and the switch fracture capacitor.

(2) Preventive measures.

1) When the standby bus fails, it can be cut off by the bus coupler switch to prevent the accident from expanding.

2) In the process of bus switching, the operating power supply of bus coupler switch should be opened to avoid misoperation of bus coupler switch in operation, which may cause safety accidents of on-load switch.

3) When all elements on one bus are switched to another bus, the following two switching sequences should be used correctly according to the position of the operating mechanism and the habits of the operators: one is to connect the circuit breaker of a certain element to one bus and open the circuit breaker of the other bus; The other is to combine all the components on one bus and then disconnect all the circuit breakers on the other bus.

4) When the voltage transformer on the bus is cut off due to equipment switching, the relay protection and automatic device can't malfunction due to voltage loss, and the uncharged bus is charged reversely, causing the fuse of the voltage circuit to blow and the relay protection to malfunction.

5) Because the equipment is switched to another bus or the voltage transformer on the bus is out of power, when the voltage circuit of relay protection and automatic device needs to be switched to another voltage transformer for power supply, attention should be paid to avoid misoperation of relay protection and automatic device caused by voltage loss. Avoid the phenomenon of poor contact of voltage circuit and secondary charging of dead bus through voltage transformer.

6) When the bus is running, the bus differential should be protected according to the Operating Rules for Bus Differential Protection. Bus differential protection should run through the bus phase inversion operation process, and the bus is equipped with automatic reclosing. During operation, the reclosing mode should be changed accordingly as needed.

3. Dangerous points in 3.DC circuit operation and their prevention

DC loop operation is a common operation item for substation operators. Incorrect operation method of DC circuit leads to some dangers and hidden dangers such as misoperation of protection and automatic devices.

(1) When removing DC control fuse, in order to prevent the parasitic circuit and protection device from misoperation, the operation sequence of taking the positive electrode first and then the negative electrode should be strictly followed; When installing DC control fuse, the operation of installing negative electrode first and then installing positive electrode should be strictly implemented. When assembling and disassembling fuses, we should be decisive and quick after correct judgment, avoiding repeated operation modes of connection and disconnection, and the time interval between disassembly and reassembly should not be less than 5s. ? (2) When the DC power supply needs to be stopped in operation, the correct sequence of stopping the protection outlet connector first and then stopping the DC circuit should be adopted; The reverse operation sequence is adopted during recovery.

(3) When the circuit breaker is powered off, it should be removed after confirming that safety measures are taken to turn on the switch.

(4) In the power transmission operation of the circuit breaker, the control fuse of the circuit breaker should be installed before the safety measures are removed. This is because after installing the control fuse, you can check whether the protection device and the control circuit are in good working condition.

4. Dangerous points of parallel and parallel operation of ring network and its prevention

The parallel operation of ring network, that is, closed loop and open loop, is a common operation to switch from one mode to another in substation operation of power system. In the switching operation of ring network, in addition to meeting the general requirements of line and transformer operation, the power flow distribution of each step should be correctly predicted and the allowable range of each component should be safely controlled to ensure the safe operation of power system after the switching operation of ring network.

The operation of ring network and column network shall meet the following conditions:

(1) When the loop is closed for the first time, or after the maintenance that may cause the phase change of the line, in order to ensure the consistency of the phase, phase measurement must be carried out at any time.

(2) The voltage difference should be adjusted and controlled to ensure that the maximum allowable voltage difference does not exceed 20%; Under special circumstances, the maximum voltage difference between ring networks should be controlled within 30%.

(3) After the loop is closed, ensure that all components of the line are not overloaded, and control and monitor the voltage of each node so that it does not exceed the specified value.

(4) The relay protection system should meet and adapt to the ring network.

(5) During open-loop operation, the influence of open-loop on power flow voltage, load transfer and automatic device relay protection should be considered comprehensively.

These potential danger points constitute the hidden danger of substation operation, and if pre-control cannot be carried out in time and effectively, safety accidents will occur.

Three, substation operation dangerous points and hidden dangers prevention measures

In the daily work of substation operation, it is necessary to strengthen the prevention of dangerous points while establishing rules and regulations to control dangerous points.

1. Improve the awareness of danger point prevention.

In the operation of substation, it is necessary to strengthen the safety concept, constantly improve the safety awareness of operators and realize innovative management. Bring the psychological state and changing factors of operators into the scope of risk point prevention.

2. Implement humanized management.

"Humanized" safety management is widely expected, which is the key to the long-term stability of enterprises and the lubricant of rigid constraints and flexible management. Rational use of humanized management can enhance the sense of responsibility and honor of operators and stimulate the dedication of employees.

3. Strengthen the efforts of employees to perform standardized operations.

Strict implementation of standardized operation modes such as operation ticket and process card work system is a powerful guarantee to avoid dangerous points and eliminate hidden dangers.

4. Strengthen personnel risk education and training.

Let employees truly feel the dangers in reality. Carrying out practical technical training is an important means to improve the overall quality of personnel, prevent misoperation and effectively prevent and control dangerous points. In addition, an effective incentive mechanism should be established to improve the learning ability of employees.

5. Integrate new technologies such as infrared thermal imager into substation operation.

Infrared thermal imager can diagnose the high and low voltage electrical equipment in substation in a long-distance and non-contact way. Compared with traditional preventive power outage detection, infrared thermal imager can effectively and truly check equipment defects. Because infrared temperature measurement only receives infrared rays emitted by objects, no infrared light source is added to the equipment, which will not damage or affect the normal power production and operation continuity of the operating equipment.

Four. conclusion

To sum up, safety in production is the eternal theme of power enterprises and the center of power system work. Defining the concept and composition of hidden dangers is the first link to realize pre-control of dangerous points and ensure the operation of substations. Only by comprehensively controlling and preventing potential safety hazards can we ensure the normal operation of substation operation and create benefits for enterprises while bringing stability to society.

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