Intelligent switching system for parallel capacitor bank of power distribution network
By designing a parallel capacitor group intelligent input and cutting system in the distribution network, combining the data acquisition module and intelligent input and cutting model, the refined control of reactive compensation of the distribution network is achieved, and overcompensation or insufficient problems caused by the established capacitor group design capacity is solved, and the power supply quality and reliability are improved.
Patent Information
- Application Number
- CN202411734507.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-03-04
AI Technical Summary
In the distribution network, when parallel capacitor banks are used for reactive compensation, the design capacity is set, resulting in overcompensation or insufficient problems in the early and later stages of operation, which in turn affects the stability of the bus voltage, increases equipment loss and reduces equipment life.
An intelligent switching system for parallel capacitor banks in distribution network is designed. By connecting capacitor banks in parallel on the main feeder and branch feeder and equipped with a circuit breaker, combining the data acquisition module and intelligent switching model, automatic switching control is achieved. The intelligent input and cutting model includes a long-term input and cutting model and short-term input and cutting model. By analyzing the real-time power factor, the input and cutting strategy of the capacitor bank is optimized to achieve reactive power compensation that is layered partitioned, on-site balance, and takes into account both length and short.
Through the intelligent input and cutting system, the reactive compensation of the distribution network is achieved, which avoids over-compensation or insufficient problems in the early and later stages of the capacitor bank's operation, reduces bus voltage fluctuations, extends the service time of the capacitor bank, and improves power supply quality and reliability.
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Figure CN119561077A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to reactive power compensation of a distribution network, and in particular to an intelligent switching system for parallel capacitor groups in a distribution network. Background Art
[0002] Among the factors affecting the power quality qualification rate, voltage deviation is one of the main factors. The more loads there are in the distribution network feeder, the greater the voltage deviation is, and the higher the demand for reactive load is.
[0003] Both reactive power and active power are essential factors to ensure the power quality of the distribution network system. In the distribution network system, active power and reactive power need to maintain a relative balance. If the reactive power is insufficient, the system voltage will drop, resulting in a decrease in network transmission capacity, increased losses, and even equipment damage and system disconnection.
[0004] Therefore, in order to maintain the balance between active power and reactive power in the distribution network system, a capacitor bank is usually connected in parallel to the main feeder of the distribution network system, and reactive power compensation for the distribution network system is achieved by putting the capacitor bank into operation.
[0005] However, when using parallel capacitor banks to compensate for reactive power in the distribution network system, since the capacity of the capacitor bank is designed based on the power supply conditions for 5-10 years at the time of the design, a design margin will be left to leave room for development.
[0006] In this way, when the capacitor bank is put into operation at the beginning, when the substation is in the valley load, the compensation capacity of the capacitor bank is bound to be too large, resulting in over-compensation, which will cause the bus voltage to rise. Since the compensation capacity of the capacitor bank is proportional to the actual power supply voltage, the increase in bus voltage will further increase the compensation capacity of the capacitor bank, causing the bus voltage to rise again, and so on, forming a vicious cycle, which will eventually lead to increased losses and reduced life of equipment such as transformers, motors, and capacitor banks.
[0007] In addition, when the capacitor bank is put into operation in the later stage and the substation is at peak load, the bus voltage level is lower than the rated supply voltage, and the compensation capacity of the capacitor bank decreases accordingly, further causing the bus voltage to drop, and ultimately leading to local voltage collapse. Summary of the invention
[0008] In order to solve the problems faced in the early and late stages of operation when a capacitor bank is connected in parallel to the main feeder of a distribution network for reactive power compensation as mentioned in the above background technology, since the design capacity of the capacitor bank is fixed, the present invention provides the following technical solutions:
[0009] An intelligent switching system for parallel capacitor banks in a distribution network, comprising:
[0010] The main feeder and the branch feeder in the distribution network system are each connected in parallel with a capacitor bank for reactive power compensation, and the capacitor bank connected in parallel with the main feeder and the capacitor bank connected in parallel with the branch feeder are both equipped with a circuit breaker for controlling their switching.
[0011] The data acquisition module is installed at intervals on each feeder of the distribution network system to collect circuit parameter information.
[0012] The intelligent switching model sends closing and opening commands to the circuit breaker to automatically switch the capacitor banks connected in parallel to the main feeders and the capacitor banks connected in parallel to the branch feeders.
[0013] Furthermore, the intelligent switching model includes a long-line switching model and a short-line switching model.
[0014] The long-line switching model is used to analyze the changes in the overall power factor of the distribution network system and control the switching strategy of the capacitor group connected in parallel to the main feeder.
[0015] The short-line switching model is used to analyze the change of power factor of branch feeders in the distribution network system and control the switching strategy of capacitor banks connected in parallel to the branch feeders.
[0016] The short-line switching model performs cross compensation based on the switching of the long-line switching model. The two models each include an independent single-layer compensation model and a cross-layer compensation model. The single-layer compensation model is used to decide the switching strategy of the capacitor group for reactive power compensation at this layer. The cross-layer compensation model re-decides the result of the single-layer compensation model of the other layer based on the decision result of the single-layer compensation model of the current layer. Among them, the current layer refers to the single-layer compensation model that makes the decision first in the cross-layer compensation model, and the other layer refers to the single-layer compensation model that makes the decision later in the cross-layer compensation model.
[0017] Furthermore, the single-layer compensation model of the long-line switching model is a conditional function, and its expression is:
[0018] PF i <PF imin
[0019] In the formula, PF i is the real-time power factor of the main feeder, PF imin It is the minimum power factor value allowed for the main feeder when designing the line. When the function condition is met, the circuit breaker of the capacitor bank connected in parallel to the main feeder is closed, the capacitor bank is put into operation, and the overall power factor of the distribution network is improved.
[0020] Furthermore, the step-out compensation model of the long-line switching model is divided into local-layer expressions and other-layer expressions.
[0021] The expression of this layer is:
[0022] PF i<PF imin
[0023] In the formula, PF i is the real-time power factor of the main feeder, PF imin It is the minimum power factor value allowed for the main feeder when designing the line.
[0024] The other expression is:
[0025] PF j <PF ijmin
[0026] In the formula, PF j is the real-time power factor of the branch feeder, PF ijmin It is the minimum power factor value allowed for branch feeders when capacitor banks are put into operation on the main feeder during line design.
[0027] Only when the function conditions of this layer are met, the function conditions of other layers will be judged.
[0028] Furthermore, the single-layer compensation model of the short-line switching model is a conditional function, and its expression is:
[0029] PF j <PF jmin
[0030] In the formula, PF j is the real-time power factor of the branch feeder, PF jmin It is the minimum power factor value allowed for the branch feeder when designing the line. When the function condition is met, the circuit breaker of the capacitor bank connected in parallel to the branch feeder is closed, the capacitor bank is put into operation, and the power factor of the branch feeder of the distribution network is improved.
[0031] Furthermore, the step-out compensation model of the short-line switching model is divided into local-layer expressions and other-layer expressions.
[0032] The expression of this layer is:
[0033] PF j <PF jmin
[0034] In the formula, PF j is the real-time power factor of the branch feeder, PF jmin It is the minimum power factor value allowed for branch feeders when designing a line.
[0035] The other expression is:
[0036] PF i <PF ji min
[0037] In the formula, PFi is the real-time power factor of the main feeder, PF jimin It is the minimum power factor value allowed for the main feeder under the premise of putting capacitor banks into operation on the branch feeder when designing the line.
[0038] Only when the function conditions of this layer are met, the function conditions of other layers will be judged.
[0039] Furthermore, the operation of the intelligent switching model is divided into two types: fully automatic operation and semi-automatic operation. The operation priority within each type is:
[0040] Fully automatic calculation, that is, the system monitors the PF in real time i and PF j Automatically switch capacitor banks. The priority is to calculate the long-line switching model first and then the short-line switching model, and to transport the single-layer compensation model first and then the cross-layer compensation model.
[0041] Semi-automatic operation means that the circuit breaker is manually closed and opened to switch the capacitor bank. At this time, the system exits full automation and the system still operates according to the real-time monitored PF. i and PF j It is determined whether the capacitor bank needs to be switched, and whether the capacitor bank needs to be switched is determined in a fully automatic operation mode. However, the judgment result is sent to the terminal device through the network, and the circuit breaker is no longer automatically closed or opened.
[0042] Compared with the prior art, the present invention has the following beneficial effects:
[0043] 1. In the present invention, not only capacitor banks for long-line reactive power compensation are connected in parallel on the main feeder lines of the distribution network, but also capacitor banks for short-line reactive power compensation are connected in parallel on the branch feeder lines where key users are located, so as to achieve the purpose of hierarchical zoning, local balance, and consideration of both long and short lines.
[0044] 2. In the present invention, by setting up a capacitor bank for short-line reactive power compensation, it is possible to quickly compensate for the needs of key users, reduce line losses, and ensure the power supply quality and reliability of key users.
[0045] 3. In the present invention, by setting a capacitor group for short-line reactive power compensation, the upper limit of the capacity of the capacitor group for reactive power compensation of the main feeder can be lowered during design, thereby avoiding the adverse effects caused by the large capacity design of the capacitor group for reactive power compensation of the main feeder in the early and late stages of its operation.
[0046] 4. In the present invention, by monitoring the peak and valley electricity consumption behaviors of key users, the power factors of various levels of the distribution network are optimized using an intelligent switching model, so that the power supply quality of users at all levels can be adaptively adjusted accordingly, thereby improving the power supply quality and reliability.
[0047] 5. In the present invention, by putting into operation a capacitor bank for short-line reactive power compensation, a part of reactive power compensation capacity of the trunk feeder can be released for other users. According to actual needs, a capacitor bank for short-line reactive power compensation is set near each key user, further releasing reactive power compensation capacity of the capacitor bank for long-line reactive power compensation, so that the capacitor bank for long-line reactive power compensation can compensate more loads of other users, thereby extending the service life of the capacitor bank for long-line reactive power compensation in disguised form. BRIEF DESCRIPTION OF THE DRAWINGS
[0048] Figure 1 This is a schematic diagram of a capacitor bank connected in parallel to the main feeder of a distribution network;
[0049] Figure 2 It is a schematic diagram of a shunt capacitor bank for a branch feeder of a distribution network;
[0050] Figure 3 It is a decision logic diagram of the intelligent switching model of the present invention. DETAILED DESCRIPTION
[0051] The preferred specific embodiments for implementing the present invention are described in detail below, and a clear and complete description is made in conjunction with the accompanying drawings.
[0052] The voltage of the trunk feeder of the urban distribution network system is 35KV, which is the main line in the urban area. According to the different electricity demand of the user groups, the trunk feeder is divided into branch feeders of different voltage levels. For example, the voltage of the branch feeder in the urban commercial center and industrial park is generally 10KV, and the branch feeder in the residential area is generally 220V.
[0053] As the power load of users on each branch feeder line in the urban area increases, peak load appears in the urban area, and the power factor in the power transmission line from the substation to the user side will decrease accordingly, that is, the power supply quality will be reduced.
[0054] See also Figure 1 ,The figure shows the principle of using parallel capacitor groups for reactive power compensation in the main feeder of the urban distribution network system.
[0055] In the prior art, in order to ensure the power supply quality of the urban distribution network system, one of the measures is to connect a capacitor bank for reactive power compensation in parallel to the 35KV trunk feeder of the urban substation. The commissioning of the capacitor bank can compensate for reactive power in the urban distribution network system, improve the overall power factor of the urban distribution network system, thereby reducing line losses, improving power supply quality and improving the stability of the urban distribution network system.
[0056] See also Figure 2, the figure shows the principle of the intelligent switching system of parallel capacitor banks in the distribution network given by the present invention. This scheme adopts the principles of hierarchical zoning, local balance, and long-term and short-term consideration, and proposes a reactive power compensation method for branch feeders for key users. Among them, key users refer to but are not limited to urban commercial centers and industrial parks. Such users have the characteristics of large electricity demand, large peak and valley electricity consumption differences, high dependence on power supply quality, and obvious periodic changes in electricity consumption patterns.
[0057] The reactive power compensation equipment is set up as follows:
[0058] Connect a capacitor bank C for reactive power compensation in parallel on the 35KV main feeder line of the urban substation i , and the capacitor bank C i By circuit breaker K a Through the capacitor bank C i The commissioning of the power distribution network will improve the overall power factor of the urban distribution network system.
[0059] Connect capacitor group C in parallel for reactive power compensation on branch feeder lines of key users in urban areas j , and the capacitor bank C j By circuit breaker K b Through the capacitor bank C j The commissioning of the branch feeder can improve the power factor of the branch feeder.
[0060] Based on the construction of the above reactive power compensation equipment, the application strategy is as follows:
[0061] In the urban distribution network system, in addition to key users with characteristics such as large electricity demand, large difference between peak and valley electricity consumption, high dependence on power supply quality, and obvious periodic changes in electricity consumption patterns, there are also some users with small peak and valley differences, scattered and irregular electricity demand, and relatively low dependence on power supply quality.
[0062] During the peak hours of urban power consumption, the load at the end of the urban distribution network system doubles significantly. Under the given voltage and current of the urban substation, the active power in the urban distribution network system decreases, resulting in a decrease in power supply quality. In order to ensure the power supply quality, the urban substation closes the circuit breaker K a , the capacitor bank C i After being put into operation, the power factor of the overall urban distribution network system is improved by performing reactive power compensation on the trunk feeder, thereby achieving the purpose of improving the power supply quality.
[0063] During the peak hours of urban power consumption, the load at the end of the urban distribution network system drops significantly. i The commissioning of the capacitor bank C resulted in excessive reactive power compensation capacity of the trunk feeder, resulting in overcompensation and an increase in bus voltage. iThe compensation capacity is proportional to the actual supply voltage. The increase of bus voltage will cause the capacitor group C i The compensation capacity is further increased, resulting in a further increase in bus voltage, and this cycle forms a vicious cycle, eventually leading to the transformer, motor, capacitor group C i In order to avoid this situation, the circuit breaker K is used during the off-peak hours of urban power consumption. a , the capacitor bank C i Exit, thereby rebalancing the active power and reactive power in the urban distribution network system and ensuring power supply reliability.
[0064] The capacitor bank C is put into operation in the urban distribution network system i After that, due to the capacitor C i For reactive power compensation across layers and regions of long lines, as the line length and the span across layers and regions increase, the capacitor group C i The reactive power compensation loss also increases accordingly. At this time, the key users continue to increase the load put into use. When the increased load exceeds the capacitor bank C i After the load limit that the urban distribution network system can supply is reached, the active power in the urban distribution network system drops again, resulting in a decline in power supply quality, making it impossible for key users to operate normally.
[0065] Therefore, the closing circuit breaker K b , the capacitor bank C j The branch feeder to the key user is put into operation to make it perform short-line reactive power compensation on the feeder, improve the power factor of the feeder, and achieve the purpose of improving the power supply quality of the feeder. If the key user re-enters the off-peak period, in order to rebalance the power factor of the feeder, the circuit breaker K can be opened b , the capacitor bank C j Exit from the branch route of this key user.
[0066] In this case, due to the capacitor group C j The commissioning of the capacitor bank C in the trunk feeder i The reactive power compensation supply pressure, the original capacitor group C i Of the capacity required for reactive power compensation for key users, part of it is used by capacitor bank C j The reactive power compensation is replaced, and the replaced part can be used to supply other users except the key user. In this way, the power supply reliability of the key users is guaranteed and the power supply quality of other users is improved.
[0067] Construction of data acquisition module:
[0068] The data acquisition module is installed at intervals on each feeder of the distribution network system in a distributed manner to collect parameter information of the circuit in which it is located, such as voltage, current, phase difference, power factor, frequency, harmonics, etc. Among them, the data acquisition module includes but is not limited to various types of intelligent instruments and sensors, such as voltage sensors, current sensors, frequency monitors, harmonic analyzers, smart meters, etc. In addition, the data acquisition module is connected to Internet servers, cloud storage media, etc. through the Internet of Things.
[0069] The intelligent switching model is loaded into the substation server and can retrieve the information collected by the data acquisition module. The intelligent switching model makes decisions on the switching of capacitor banks by analyzing the real-time information collected by the data acquisition module, and controls the circuit breakers corresponding to the capacitor banks to close and open according to the decisions.
[0070] See also Figure 3 ,The figure shows the decision logic of the intelligent switching model.
[0071] The intelligent switching model includes a long-line switching model and a short-line switching model.
[0072] The long-line switching model is used to analyze the changes in the overall power factor of the distribution network system and control the switching strategy of the capacitor group connected in parallel to the main feeder.
[0073] The short-line switching model is used to analyze the change of power factor of branch feeders in the distribution network system and control the switching strategy of capacitor banks connected in parallel to the branch feeders.
[0074] The short-line switching model performs cross-compensation based on the switching of the long-line switching model. Both of them contain independent single-layer compensation model and cross-layer compensation model. The single-layer compensation model is used to decide the switching strategy of the capacitor group for reactive power compensation in this layer. The cross-layer compensation model re-decides the results of the single-layer compensation model of other layers based on the decision results of the single-layer compensation model of this layer.
[0075] Among them, the current layer refers to the single-layer compensation model that makes decisions first in the cross-layer compensation model, and the other layer refers to the single-layer compensation model that makes decisions later in the cross-layer compensation model.
[0076] Preferably:
[0077] The single-layer compensation model of the long-line switching model is a conditional function, and its expression is:
[0078] PF i <PF imin
[0079] In the formula, PF i is the real-time power factor of the main feeder, PF iminIt is the minimum power factor value allowed for the main feeder when designing the line. When the function condition is met, the circuit breaker of the capacitor bank connected in parallel to the main feeder is closed, the capacitor bank is put into operation, and the overall power factor of the distribution network is improved.
[0080] The expression of the step-out compensation model of the long-line switching model is:
[0081] PF i <PF imin
[0082] In the formula, PF i is the real-time power factor of the main feeder, PF imin It is the minimum power factor value allowed for the main feeder when designing the line.
[0083] The other expression of the step-out compensation model of the long-line switching model is:
[0084] PF j <PF ijmin
[0085] In the formula, PF j is the real-time power factor of the branch feeder, PF ijmin It is the minimum power factor value allowed for the branch feeder when the capacitor bank is put into operation on the main feeder during line design. Only when the function conditions of this layer are met, the function conditions of other layers will be judged.
[0086] Preferably:
[0087] The single-layer compensation model of the short-line switching model is a conditional function, and its expression is:
[0088] PF j <PF jmin
[0089] In the formula, PF j is the real-time power factor of the branch feeder, PF jmin It is the minimum power factor value allowed for the branch feeder when designing the line. When the function condition is met, the circuit breaker of the capacitor bank connected in parallel to the branch feeder is closed, the capacitor bank is put into operation, and the power factor of the branch feeder of the distribution network is improved.
[0090] The expression of the step-out compensation model of the short-line switching model is:
[0091] PF j <PF jmin
[0092] In the formula, PF j is the real-time power factor of the branch feeder, PF jmin It is the minimum power factor value allowed for branch feeders when designing a line.
[0093] The other expression of the step-out compensation model of the short-line switching model is:
[0094] PF i <PF jimin
[0095] In the formula, PF i is the real-time power factor of the main feeder, PF jimin It is the minimum power factor value allowed for the main feeder when the capacitor bank is put into operation in the branch feeder during line design. Only when the function conditions of this layer are met, the function conditions of other layers will be judged.
[0096] In the present invention, the operation of the intelligent switching model is divided into two types: fully automatic operation and semi-automatic operation. The operation priority within each type is:
[0097] Fully automatic calculation, that is, the system monitors the PF in real time i and PF j Automatic switching of capacitor banks is performed with the priority of calculating the long-line switching model first and then the short-line switching model, and transporting the single-layer compensation model first and then the cross-layer compensation model.
[0098] Semi-automatic operation means that the circuit breaker is manually closed and opened to switch the capacitor bank. At this time, the system exits full automation and the system still uses the real-time monitored PF i and PF j It is determined whether the capacitor bank needs to be switched, and whether the capacitor bank needs to be switched is determined in a fully automatic operation mode. However, the judgment result is sent to the terminal device through the network, and the circuit breaker is no longer automatically closed or opened.
[0099] More specifically:
[0100] When the urban distribution network is in the power consumption valley, PF i and PF j None of them meet the conditions, K a and K b In other words, C i and C j All are in the exit state. At this time, the power factor of the distribution network has not reached the designed minimum value. The distribution network can stably transmit electricity to users at all levels and ensure the quality of electricity.
[0101] More specifically:
[0102] When the urban distribution network is at its peak, first determine the PF i Whether the conditions are met, if PF i If the conditions are met, the power factor of the entire network will drop and be lower than the designed minimum value, and the K a, so that C i After being put into operation, the power factor of the entire network can be improved. i After being put into operation, PF is judged again i Whether the conditions are met, if PF i If the conditions are still met, the power factor of the entire network is still lower than the designed minimum value, and the distribution network cannot stably transmit electricity to users at all levels and ensure the quality of electricity.
[0103] This will lead to PF j To ensure the quality and reliability of power supply to key users, close the switch K b , so that C j The power factor of the branch feeder where the key users are located has been improved. Furthermore, C i The reactive power compensation is partially released, and the released part can be used to adjust the power factor of the branch feeders where other non-key users are located, so that the quality of electric energy supplied by the substation to other users is improved.
[0104] In the present invention, the capacitor group C i and capacitor bank C j The switching coordination can achieve the balance between long-line reactive power compensation and short-line reactive power compensation, and optimize the reactive power compensation scheme of the distribution network system, as follows:
[0105] Since the capacitor bank C j In the design of capacitor bank C i When the capacitor group C i Compared with the prior art, the design margin of can be reduced appropriately. i In the initial operation, when the substation is at low load, the capacitor group C i The over-compensation of the compensation capacity is limited, thereby limiting the increase in bus voltage.
[0106] Since the capacitor bank C j When the capacitor bank C i In the later stage of operation, when the substation is at peak load, if the bus voltage level is lower than the rated supply voltage, the capacitor group C j To ensure the power supply quality of key users and make capacitor bank C i The released reactive power is supplied to other users to ensure their power supply quality. In this way, the voltage deviation between the bus voltage and the rated power supply voltage is reduced, avoiding local voltage collapse caused by the bus voltage level being far lower than the rated power supply voltage.
[0107] Based on the above content and the accompanying drawings, those skilled in the art can understand and implement the present invention. In addition, any non-creative modifications made to the present invention by those skilled in the art without creative work still fall within the protection scope of the present invention.
Claims
1. A distribution network parallel capacitor bank intelligent switching system, comprising a capacitor bank for reactive power compensation connected in parallel to a trunk feeder in a distribution network system, characterized in that: Also includes: A capacitor bank connected in parallel to a branch feeder in a distribution network system for short-line reactive power compensation, and both the capacitor bank connected in parallel to the main feeder and the capacitor bank connected in parallel to the branch feeder are equipped with circuit breakers for controlling their switching; Data acquisition modules are installed at intervals on each feeder of the distribution network system to collect circuit parameter information; The intelligent switching model sends closing and opening commands to the circuit breaker to automatically switch the capacitor banks connected in parallel to the main feeders and the capacitor banks connected in parallel to the branch feeders.
2. The intelligent switching system for parallel capacitor banks in distribution network according to claim 1, characterized in that: Intelligent switching models include: Long-line switching model, used to analyze the change of the overall power factor of the distribution network system and control the switching strategy of the capacitor bank connected in parallel to the main feeder; The short-line switching model is used to analyze the change of the power factor of the branch feeder of the distribution network system and control the switching strategy of the capacitor bank connected in parallel with the branch feeder; The short-line switching model performs cross compensation based on the switching of the long-line switching model. The two models each include an independent single-layer compensation model and a cross-layer compensation model. The single-layer compensation model is used to decide the switching strategy of the capacitor group for reactive power compensation of the layer. The cross-layer compensation model re-decides the result of the single-layer compensation model of the other layer based on the decision result of the single-layer compensation model of the current layer. Among them, the current layer refers to the single-layer compensation model that makes decisions first in the cross-layer compensation model, and the other layer refers to the single-layer compensation model that makes decisions later in the cross-layer compensation model.
3. The intelligent switching system for parallel capacitor banks in distribution network according to claim 2, characterized in that: The single-layer compensation model of the long-line switching model is a conditional function, and its expression is: PF i <PF imin In the formula, PF i is the real-time power factor of the main feeder, PF imin It is the minimum power factor value allowed for the trunk feeder when designing the line; When the function condition is met, the circuit breaker of the capacitor group connected in parallel with the main feeder is closed, the capacitor group is put into operation, and the overall power factor of the distribution network is improved.
4. The intelligent switching system for parallel capacitor banks in distribution network according to claim 2, characterized in that: The step-out compensation model of the long-line switching model is divided into: At this level, the expression is: PF i <PF imin In the formula, PF i is the real-time power factor of the main feeder, PF imin It is the minimum power factor value allowed for the trunk feeder when designing the line; The other layer is expressed as: PF j <PF ijmin In the formula, PF j is the real-time power factor of the branch feeder, PF ijmin It is the minimum power factor value allowed for branch feeders under the premise of putting capacitor banks into operation on trunk feeders when designing lines; Only when the function conditions of this layer are met, the function conditions of other layers will be judged.
5. The intelligent switching system for parallel capacitor banks in distribution network according to claim 2, characterized in that: The single-layer compensation model of the short-line switching model is a conditional function, and its expression is: PF j <PF jmin In the formula, PF j is the real-time power factor of the branch feeder, PF jmin It is the minimum power factor value allowed for the branch feeder when designing the line; When the function condition is met, the circuit breaker of the capacitor group connected in parallel with the branch feeder is closed, the capacitor group is put into operation, and the power factor of the distribution network branch feeder is improved.
6. The intelligent switching system for parallel capacitor banks in distribution network according to claim 2, characterized in that: The step-out compensation model of the short-term switching model is divided into: At this level, the expression is: PF j <PF jmin In the formula, PF j is the real-time power factor of the branch feeder, PF jmin It is the minimum power factor value allowed for the branch feeder when designing the line; The other layer is expressed as: PF i <PF jimin In the formula, PF i is the real-time power factor of the main feeder, PF jimin It is the minimum power factor value allowed for the main feeder under the premise of putting capacitor banks into operation on the branch feeder when designing the line; Only when the function conditions of this layer are met, the function conditions of other layers will be judged.
7. The intelligent switching system for parallel capacitor banks in a distribution network according to any one of claims 2 to 6, characterized in that: The operation of the intelligent switching model is divided into two types: fully automatic operation and semi-automatic operation. The operation priority within each type is: Fully automatic calculation, that is, the system monitors the PF in real time i and PF j Automatically switch capacitor banks, with the priority of calculating long-line switching model first and short-line switching model second, and transporting single-layer compensation model first and cross-layer compensation model second; Semi-automatic operation means that the circuit breaker is manually closed and opened to switch the capacitor bank. At this time, the system exits full automation and the system still uses the real-time monitored PF i and PF j It is determined whether the capacitor bank needs to be switched, and whether the capacitor bank needs to be switched is determined in a fully automatic operation mode. However, the judgment result is sent to the terminal device through the network, and the circuit breaker is no longer automatically closed or opened.