1 thought on “What are the basic knowledge of the power industry”
Rogelio
The power industry is an important energy industry for economic development. It provides support for the development of various industries of the national economy. The following is the content of the basic knowledge of the power industry compiled by me to provide your reference and understanding!
Basic knowledge of the power industry 1. Common bus wiring method 1. Single -bus wiring: Single -bus wiring has the advantages of simple and clear, small equipment, small investment, convenient operation, and beneficial to expansion, but reliable Sexuality and flexibility are poor. When the bus or bus is an isolated switch, it must be disconnected from all the power supply of the bus. 2. Double -bus wiring: The dual -bus wiring has the advantages of reliable power supply, convenient maintenance, flexible scheduling or easy expansion. However, there are many equipment (especially isolated switch) for this type of wiring. The distribution device is complex and the economy is poor; the seal switch is used as an operating appliance during operation, which is prone to misunderstanding and inconvenient to achieve automation; especially when the parent line system fails It must be removed in a short time, which is not allowed for particularly important large -scale power plants and substations. 3. The bus is bypass: its power supply reliability is high, and it is flexible and convenient to run, but the investment has increased, and the economy is slightly worse. Especially when the road breaking is used to bring the road, the operation is complicated, adding the chance of misunderstanding. At the same time, due to the installation of bypass the circuit breaker, the corresponding protection and automation systems are complicated. 4, 3/2, and 4/3 wiring: have high power supply reliability and running flexibility. Ren Yitian fault or maintenance will not cause power outages; except for the two -round lines that are connected to it when the circuit breaker fails, any other circuit breaker failure or maintenance will not interrupt the power supply; Under the extreme case of the group inspection, the power can continue to be transported. However, there are many use equipment for this wiring, especially the circuit breakers and current transformers. The investment is large, and the second -time control wiring and relay protection are more complicated. 5. Bare line-transformer-generator unit wiring: it has simple wiring, less switching equipment, simple operation, should be expanded, and because there is no motor export voltage bus, generator and main transformer low-voltage side short circuit current There are characteristics such as decrease. Basic knowledge of the power industry 2. The meaning of stability 1. Static stability of the power system refers to the non -periodic loss of the power system after being disturbed by small interference, and automatically restores to the starting operating state. . The temporary stability of the power system means that after the system suddenly suffers from large disturbances under certain operation methods, it goes through a new stable operating state through a temporary state of electromechanical or return to the original stable state. 3. The dynamic stability of the power system refers to the stroll that the power system does not increase the amplitude without an amplitude after being disturbed. Mainly: low -frequency oscillations of electrical systems, secondary synchronous oscillations of electromechanical coupling, and self -excitation of synchronous motors. 4. The voltage stability of the power system refers to the ability to maintain the load voltage within a certain specified operation limit of the power system. It is related to factors such as power configuration, network structure and operation method, load characteristics and other factors in the power system. When the voltage occurs is unstable, the voltage will collapse and cause a large -scale power outage. 5. Frequency stability refers to the ability to maintain the system frequency and a certain regulation of the operation limit of the power system. When the frequency is lower than a critical frequency, the balance between the power and the load will be completely destroyed, and some crews will withdraw from the operation one after another, resulting in a large -scale power outage, that is, the frequency collapse. Basic knowledge of the power industry 3. The arrangement of the transformer neutral grounding transformer neutral point connection method should be maintained as far as possible. When encountering a special way of changing the zero -sequence impedance of the substation due to transformer maintenance and other reasons, it should be temporarily processed in accordance with the regulations or actual conditions. 1. There is only one transformer in the substation, then the neutral point should be directly grounded. When calculating the normal protection fixed value, only the normal operation method of the transformer neutral point ground can be considered. When the transformer is maintained, it can be processed in a special operation method, such as changing the fixed value or discontinuation of the relevant protection section according to regulations. 2. When all two or more transformers are transformed, only one transformer should be grounded directly. When the transformer is stopped, the transformer is not grounded to directly ground. If some reasons, the substation must have two transformers in the normal ground and run directly. When one of the transformers directly grounded in the primary point of the primary point is stopped, if there is a third transformer, the third transformer will be changed to the third transformer to the third transformer to the third transformer to The neutral point is directly grounded. Otherwise, handle it in a special operation method. 3. When all three or more transformers running the transformer running on the dual parent line, it should be directly grounded according to the two transformer neutral points, and they should be connected to different bus lines. When the transformer is stopped directly, the transformer is not grounded directly. If you cannot keep a place on each parent line, it is treated as a special operation method. 4. In order to improve the protection of the protection and cooperation, when a short -line inspection is suspended, the number of increasing the number of neutral grounding transformers can offset the effects of line shutdown on the distribution of zero -order current. 5. The neutral point of the transformer required by auto -coupled transformers and insulation must be directly grounded. Basic knowledge of the power industry 4. The over -current protection of the three -phase star -shaped wiring of the large current connection system can also protect the ground short circuit, but its sensitivity is low and the protection time limit is longer. The use of zero -order protection can overcome this deficiency. This is because: 1. When the normal operation and occurring short circuit, zero -sequential current and zero -sequential voltage will not appear. Small, which is conducive to improving its sensitivity. 2. Y/△ wiring antihypertensive transformer, the failure after the △ side will not reflect the zero -sequential current on the Y side, so the time limit for zero -sequential protection can not be matched with the line protection of this transformer in the future. Take a shorter action time limit. Basic knowledge of the power industry 5. Protection of zero -sequential current 1. When the current circuit is disconnected, it may cause misunderstanding of protection. This is the common weakness of generally sensitive protection and needs to be paid to preventing it during operation. As far as the probability of a break is concerned, it is much smaller than the probability of protecting the voltage circuit disconnection. If necessary, you can also use the method of zero -sequential current at between adjacent current sensor to prevent this error. 2. When the power system runs asymmetrically, zero -sequential current also needs to occur, such as the asymmetric operation caused by the different three -phase parameters of the transformer. Different from the three broken circuit breakers during the manual gates, when the bus is poured to operate, the circuit breaker and isolation switch are connected in parallel or the circuit breaker normal ring. The circulation, and the imbalanced inspirational flow generated by the air dotter transformer, especially when the bus where the air documers are located have a neutral point grounding transformer, may occur for a long time of unbalanced inspirational flow and DC components. The protection of zero -sequential current may be started. 3. Parallel lines close to the geographical location. When one of the lines faults, the other line may cause a sensor zero -sequence current, resulting in the miscalculation of relay in the direction of the opposite direction. If there is such a possible, you can use a negative order relay to prevent the above -mentioned direction relay from mistakenly judged. 4. Due to the zero -sequential direction relay AC circuit usually does not have zero current and zero -sequential voltage, the circuit disconnection is not easy to find; when the relay zero -sequential voltage is taken from the side of the voltage transformer opening the triangle, it is not easy to use more intuitive more intuitive. The simulation method checks the correctness of its direction, so it is easier to cause protection and misunderstanding when the power grid fails due to the problem of the communication circuit. Basic knowledge of the power industry 6. The transformer differential protection transformer differential protection always has some differences at runtime (including off -area failure), which is generated by an unbalanced current. Stime imbalance current (need to escape by the threshold for differential motion): . Due to the different current transformer models of each side of the transformer, that is, the saturation characteristics and the saturation characteristics of the current transformers of each side Elephant current caused by different excitation currents. It must meet the requirements of the 10%error curve of the current transformer. 2. Due to the unbalanced current caused by the actual current transformer ratio and calculation ratio. 3. Unbalanced current caused by changing transformer regulatory segments. Installed currents in the case of temporary state (need to rely on ratio braking or second harmonic waves): . The non -cyclical component of short -circuit current is mainly an incentive current of the current transformer. , Make the iron core saturated, increasing errors, and unbalanced current. 2. The excitation surge flow of the transformer's empty loading gates is only current on the side of the transformer.
The power industry is an important energy industry for economic development. It provides support for the development of various industries of the national economy. The following is the content of the basic knowledge of the power industry compiled by me to provide your reference and understanding!
Basic knowledge of the power industry 1. Common bus wiring method 1. Single -bus wiring: Single -bus wiring has the advantages of simple and clear, small equipment, small investment, convenient operation, and beneficial to expansion, but reliable Sexuality and flexibility are poor. When the bus or bus is an isolated switch, it must be disconnected from all the power supply of the bus.
2. Double -bus wiring: The dual -bus wiring has the advantages of reliable power supply, convenient maintenance, flexible scheduling or easy expansion. However, there are many equipment (especially isolated switch) for this type of wiring. The distribution device is complex and the economy is poor; the seal switch is used as an operating appliance during operation, which is prone to misunderstanding and inconvenient to achieve automation; especially when the parent line system fails It must be removed in a short time, which is not allowed for particularly important large -scale power plants and substations.
3. The bus is bypass: its power supply reliability is high, and it is flexible and convenient to run, but the investment has increased, and the economy is slightly worse. Especially when the road breaking is used to bring the road, the operation is complicated, adding the chance of misunderstanding. At the same time, due to the installation of bypass the circuit breaker, the corresponding protection and automation systems are complicated.
4, 3/2, and 4/3 wiring: have high power supply reliability and running flexibility. Ren Yitian fault or maintenance will not cause power outages; except for the two -round lines that are connected to it when the circuit breaker fails, any other circuit breaker failure or maintenance will not interrupt the power supply; Under the extreme case of the group inspection, the power can continue to be transported. However, there are many use equipment for this wiring, especially the circuit breakers and current transformers. The investment is large, and the second -time control wiring and relay protection are more complicated.
5. Bare line-transformer-generator unit wiring: it has simple wiring, less switching equipment, simple operation, should be expanded, and because there is no motor export voltage bus, generator and main transformer low-voltage side short circuit current There are characteristics such as decrease.
Basic knowledge of the power industry 2. The meaning of stability 1. Static stability of the power system refers to the non -periodic loss of the power system after being disturbed by small interference, and automatically restores to the starting operating state.
. The temporary stability of the power system means that after the system suddenly suffers from large disturbances under certain operation methods, it goes through a new stable operating state through a temporary state of electromechanical or return to the original stable state.
3. The dynamic stability of the power system refers to the stroll that the power system does not increase the amplitude without an amplitude after being disturbed. Mainly: low -frequency oscillations of electrical systems, secondary synchronous oscillations of electromechanical coupling, and self -excitation of synchronous motors.
4. The voltage stability of the power system refers to the ability to maintain the load voltage within a certain specified operation limit of the power system. It is related to factors such as power configuration, network structure and operation method, load characteristics and other factors in the power system. When the voltage occurs is unstable, the voltage will collapse and cause a large -scale power outage.
5. Frequency stability refers to the ability to maintain the system frequency and a certain regulation of the operation limit of the power system. When the frequency is lower than a critical frequency, the balance between the power and the load will be completely destroyed, and some crews will withdraw from the operation one after another, resulting in a large -scale power outage, that is, the frequency collapse.
Basic knowledge of the power industry 3. The arrangement of the transformer neutral grounding transformer neutral point connection method should be maintained as far as possible. When encountering a special way of changing the zero -sequence impedance of the substation due to transformer maintenance and other reasons, it should be temporarily processed in accordance with the regulations or actual conditions.
1. There is only one transformer in the substation, then the neutral point should be directly grounded. When calculating the normal protection fixed value, only the normal operation method of the transformer neutral point ground can be considered. When the transformer is maintained, it can be processed in a special operation method, such as changing the fixed value or discontinuation of the relevant protection section according to regulations.
2. When all two or more transformers are transformed, only one transformer should be grounded directly. When the transformer is stopped, the transformer is not grounded to directly ground. If some reasons, the substation must have two transformers in the normal ground and run directly. When one of the transformers directly grounded in the primary point of the primary point is stopped, if there is a third transformer, the third transformer will be changed to the third transformer to the third transformer to the third transformer to The neutral point is directly grounded. Otherwise, handle it in a special operation method.
3. When all three or more transformers running the transformer running on the dual parent line, it should be directly grounded according to the two transformer neutral points, and they should be connected to different bus lines. When the transformer is stopped directly, the transformer is not grounded directly. If you cannot keep a place on each parent line, it is treated as a special operation method.
4. In order to improve the protection of the protection and cooperation, when a short -line inspection is suspended, the number of increasing the number of neutral grounding transformers can offset the effects of line shutdown on the distribution of zero -order current.
5. The neutral point of the transformer required by auto -coupled transformers and insulation must be directly grounded.
Basic knowledge of the power industry 4. The over -current protection of the three -phase star -shaped wiring of the large current connection system can also protect the ground short circuit, but its sensitivity is low and the protection time limit is longer. The use of zero -order protection can overcome this deficiency. This is because:
1. When the normal operation and occurring short circuit, zero -sequential current and zero -sequential voltage will not appear. Small, which is conducive to improving its sensitivity.
2. Y/△ wiring antihypertensive transformer, the failure after the △ side will not reflect the zero -sequential current on the Y side, so the time limit for zero -sequential protection can not be matched with the line protection of this transformer in the future. Take a shorter action time limit.
Basic knowledge of the power industry 5. Protection of zero -sequential current 1. When the current circuit is disconnected, it may cause misunderstanding of protection. This is the common weakness of generally sensitive protection and needs to be paid to preventing it during operation. As far as the probability of a break is concerned, it is much smaller than the probability of protecting the voltage circuit disconnection. If necessary, you can also use the method of zero -sequential current at between adjacent current sensor to prevent this error.
2. When the power system runs asymmetrically, zero -sequential current also needs to occur, such as the asymmetric operation caused by the different three -phase parameters of the transformer. Different from the three broken circuit breakers during the manual gates, when the bus is poured to operate, the circuit breaker and isolation switch are connected in parallel or the circuit breaker normal ring. The circulation, and the imbalanced inspirational flow generated by the air dotter transformer, especially when the bus where the air documers are located have a neutral point grounding transformer, may occur for a long time of unbalanced inspirational flow and DC components. The protection of zero -sequential current may be started.
3. Parallel lines close to the geographical location. When one of the lines faults, the other line may cause a sensor zero -sequence current, resulting in the miscalculation of relay in the direction of the opposite direction. If there is such a possible, you can use a negative order relay to prevent the above -mentioned direction relay from mistakenly judged.
4. Due to the zero -sequential direction relay AC circuit usually does not have zero current and zero -sequential voltage, the circuit disconnection is not easy to find; when the relay zero -sequential voltage is taken from the side of the voltage transformer opening the triangle, it is not easy to use more intuitive more intuitive. The simulation method checks the correctness of its direction, so it is easier to cause protection and misunderstanding when the power grid fails due to the problem of the communication circuit.
Basic knowledge of the power industry 6. The transformer differential protection transformer differential protection always has some differences at runtime (including off -area failure), which is generated by an unbalanced current.
Stime imbalance current (need to escape by the threshold for differential motion):
. Due to the different current transformer models of each side of the transformer, that is, the saturation characteristics and the saturation characteristics of the current transformers of each side Elephant current caused by different excitation currents. It must meet the requirements of the 10%error curve of the current transformer.
2. Due to the unbalanced current caused by the actual current transformer ratio and calculation ratio.
3. Unbalanced current caused by changing transformer regulatory segments.
Installed currents in the case of temporary state (need to rely on ratio braking or second harmonic waves):
. The non -cyclical component of short -circuit current is mainly an incentive current of the current transformer. , Make the iron core saturated, increasing errors, and unbalanced current.
2. The excitation surge flow of the transformer's empty loading gates is only current on the side of the transformer.