Power capacitor service life balance switching scheduling method
By acquiring multi-dimensional parameters and real-time power factor of power capacitors, and combining them with switching scheduling algorithms to optimize capacitor switching strategies, the problem of uneven capacitor lifespan in reactive power compensation systems is solved, thereby extending capacitor lifespan and improving safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WEIYUAN ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2025-12-16
- Publication Date
- 2026-04-17
AI Technical Summary
Existing technologies have failed to effectively balance the lifespan of power capacitors in reactive power compensation systems, leading to premature failure of some capacitors that cannot be detected in time, posing a fire risk.
By acquiring multi-dimensional parameters of power capacitors, quantifying the degree of loss, and combining the real-time power factor of the power grid with switching and dispatching algorithms, the switching strategy of capacitors is optimized, taking into account the effects of temperature and voltage, to achieve balanced capacitor lifespan.
It effectively extends capacitor life, reduces switching frequency, lowers grid voltage fluctuations, promptly detects and replaces aging capacitors, and avoids fire risks.
Smart Images
Figure CN121886498A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power capacitor technology, and in particular to a method for balancing the switching of power capacitors throughout their lifespan. Background Technology
[0002] Power capacitors are electrical components used in power grids to compensate for inductive reactive power. Their capacity is measured in reactive power units, such as 5kvar, 10kvar, 20kvar, etc., representing a relatively fixed but discrete set of values. A typical reactive power compensation system consists of a smart capacitor controller and multiple power capacitors. The smart capacitor controller is responsible for collecting power grid operating parameters (voltage, current, active power, reactive power, power factor, etc.) and calculating and determining switching strategies and combinations based on the collected electrical parameters and switching parameters. The power capacitors are primarily responsible for receiving switching commands from the smart capacitor controller and for capacitor switching as well as their own protection functions. There are also reactive power compensation systems without a separate smart capacitor controller. In these systems, a host unit generated through an internal negotiation mechanism acts as the "smart controller," assuming the role of the smart capacitor controller and simultaneously performing the function of switching power capacitors.
[0003] A single power capacitor product can contain multiple sets of compensation capacitors. Depending on the electrical connection method of the capacitors within the power capacitor, different compensation methods are generated, which can be divided into phase-by-phase compensation, three-phase common compensation, and mixed compensation (phase-by-phase compensation + common compensation), etc. In practical applications, the ratio of common compensation to phase-by-phase compensation is generally between 6:4 and 8:2. Compared to phase-by-phase compensation capacitors, common compensation capacitors are relatively cheaper, so in practical applications, common compensation is preferred. When a three-phase imbalance occurs in the system, phase-by-phase compensation is needed to address the imbalance. After calculating the required compensation capacity for the current system, the intelligent capacitor controller allocates the capacitors according to the actual compensation amount needed. If multiple capacitors with the same capacitance value are required for a given capacitor capacity, they are switched on and off cyclically to ensure an equal opportunity for each capacitor to be connected. When there is already a connected power capacitor A in the system, and additional reactive power B needs to be added, and there is a power capacitor C in the system whose compensation amount satisfies C = A + B, A will not be switched off and C will not be connected. Instead, B will be connected directly to minimize the number of switching operations and reduce voltage fluctuations caused by switching. This will only be done if the newly calculated compensation amount cannot meet the demand without switching off the already connected capacitors. Currently, existing technologies balance the activation opportunities of various power capacitors through cyclic switching to extend the overall lifespan of the entire system. However, this balancing method fails to consider the following factors: First, the activation time of each capacitor varies, making sequential activation too simplistic. Second, temperature and voltage significantly impact capacitor lifespan, which current methods do not account for. Third, newly installed capacitors also participate in the cyclic switching with equal opportunities, negating the balancing effect on older capacitors that have been used for some time. Fourth, with existing balancing methods, some capacitors fail prematurely due to exceeding their usage opportunities, which is difficult to detect. The current method relies on manual measurement during inspections to check if the capacitance value has decreased beyond a threshold, or on replacing all capacitors based on their installation date. Failure to detect prematurely expired capacitors poses a fire risk. Therefore, a power capacitor lifespan balancing switching and scheduling method is urgently needed to address the technical challenge of balancing the lifespan of power capacitors in a reactive power compensation system. Summary of the Invention
[0004] The main objective of this invention is to propose a method for balancing the switching and dispatching of power capacitors based on their lifespan, aiming to solve the technical problem of how to balance the lifespan of each power capacitor in a reactive power compensation system.
[0005] To achieve the above objectives, the present invention provides a method for balancing the switching and dispatching of power capacitors throughout their lifespan, wherein the method includes the following steps:
[0006] S1. Obtain multi-dimensional parameters of each power capacitor under the reactive power compensation system, and quantify the loss degree of each power capacitor.
[0007] S2. Obtain the compensation type, compensation capacity, and current switching status of each power capacitor;
[0008] S3. Collect the real-time three-phase active power, reactive power and power factor of the power grid, and calculate whether the current power grid needs to be put into or cut out for compensation based on the power factor, and calculate the power capacitor combination that needs to be put into or cut out this time according to the switching scheduling algorithm.
[0009] In one preferred embodiment, the loss level of the power capacitor is:
[0010] S=k1*k2*k3*k4*A
[0011] Where S is the loss level of the power capacitor, k1 is the temperature loss coefficient, k2 is the voltage loss coefficient, k3 is the voltage harmonic content loss coefficient, k4 is the current harmonic content loss coefficient, and A is the basic loss coefficient.
[0012] One preferred embodiment is that the compensation type of the power capacitor includes phase-by-phase compensation, three-phase common compensation, and hybrid compensation.
[0013] One preferred embodiment is that step S3 calculates whether the current power grid needs to be connected or disconnected for compensation based on the power factor, specifically as follows:
[0014] Set the upper and lower thresholds for the power factor;
[0015] If phase A is an inductive load and its power factor is below the lower threshold, then phase A needs to be compensated; if phase A is a capacitive or inductive load and its power factor is above the upper threshold, then phase A needs to be switched off for compensation. If phase B is an inductive load and its power factor is below the lower threshold, then phase B needs to be compensated; if phase B is a capacitive or inductive load and its power factor is above the upper threshold, then phase B needs to be switched off for compensation. If phase C is an inductive load and its power factor is below the lower threshold, then phase C needs to be compensated; if phase C is a capacitive or inductive load and its power factor is above the upper threshold, then phase C needs to be switched off for compensation.
[0016] The current switching demand is determined to be one of three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
[0017] In one preferred embodiment, step S3 calculates the combination of power capacitors to be switched in this operation based on the switching scheduling algorithm, specifically as follows:
[0018] S311. If the current input demand is three-phase input compensation, then first separate the three-phase common input demand amount as the common compensation demand amount;
[0019] S312. Treat all unused three-phase common-compensation type power capacitors as a capacitor resource pool. Sort each power capacitor in ascending order of loss level. Take the first percentage of power capacitors to solve the problem. If there is no solution, take the second percentage of power capacitors to solve the problem and obtain the first common-compensation solution.
[0020] S313. Subtract the compensation amount absorbed by the first common compensation solution from the current switching demand to obtain the first phase input demand amount; take all the un-input phase compensation type capacitors as the capacitor resource pool, sort each power capacitor in order of increasing loss degree, take the first percentage of power capacitors for solution, if there is no solution, take the second percentage of power capacitors for solution to obtain the first phase compensation solution.
[0021] S314. If the first sub-solution has a solution, then exit the switching scheduling algorithm and perform scheduling operations according to the solution situation; otherwise, add the compensation amount of all the already put power capacitors to the current switching demand as the new put-in demand, and treat all power capacitors as not put into operation.
[0022] S315. Repeat steps S311-S314, set a loop threshold. If the number of loops exceeds the loop threshold, no action will be taken in this scheduling.
[0023] In one preferred embodiment, step S3 calculates the combination of power capacitors to be switched in this operation based on the switching scheduling algorithm, specifically as follows:
[0024] S321. If the current switching demand is three-phase switching compensation, then first separate the three-phase common switching demand amount as the common compensation demand amount;
[0025] S322. Treat all the three-phase common-compensation type power capacitors that have been put into use as a capacitor resource pool. Sort each power capacitor in descending order of loss. Take the first percentage of power capacitors to solve the problem. If there is no solution, take the second percentage of power capacitors to solve the problem and obtain the second common-compensation solution.
[0026] S323. Subtract the compensation amount absorbed by the second common compensation solution from the current switching demand to obtain the second phase input demand amount; take all the power capacitors of the phase compensation type that have been put into use as the capacitor resource pool, sort each power capacitor in descending order of loss degree, take the first percentage of power capacitors to solve, if there is no solution, take the second percentage of power capacitors to solve, and obtain the second phase compensation solution.
[0027] S324. If the second sub-solution has a solution, then exit the switching scheduling algorithm and perform scheduling operations according to the solution situation; otherwise, add the compensation amount of all the already put power capacitors to the current switching demand as the new switching demand, and treat all power capacitors as not put into operation.
[0028] S325. Based on the new switching requirements, determine whether the switching requirements are three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
[0029] One preferred embodiment, step S325, specifically includes:
[0030] If the new switching demand is three-phase switching compensation, then execute steps S311-S315, and compare and adjust the calculation results with the current actual power capacitors already in operation.
[0031] If the new switching requirement is three-phase switching compensation, then all power capacitors should be switched off.
[0032] If the new switching demand is a three-phase switching with both input and output compensation, then the output demand is set to 0, steps S311-S315 are executed, and the calculation results are compared and adjusted with the current actual power capacitors already in operation.
[0033] In one preferred embodiment, step S3 calculates the combination of power capacitors to be switched in this operation based on the switching scheduling algorithm, specifically as follows:
[0034] S331. If the current switching demand is three-phase with both input and switching compensation, then determine whether the compensation demand of each phase is input compensation or switching compensation.
[0035] S332. If it is an input compensation, then all the power capacitors of the un-input phase compensation type are regarded as the capacitor resource pool. The power capacitors are sorted in order of increasing loss degree. The first percentage of power capacitors are used for solution. If there is no solution, the second percentage of power capacitors are used for solution to obtain the first phase compensation solution.
[0036] If it is a phase-by-phase compensation, all the power capacitors that have been put into use are treated as a capacitor resource pool. The power capacitors are sorted in descending order of loss. The first percentage of power capacitors are used for the solution. If there is no solution, the second percentage of power capacitors are used for the solution to obtain the second phase-by-phase compensation solution.
[0037] S333. If all three phases have solutions for phase-by-phase compensation, then exit the switching and scheduling algorithm and perform scheduling operations according to the solution results; otherwise, add the compensation amount of all the power capacitors that have been put into operation to the current switching demand, and regard it as the new switching demand, and regard all power capacitors as not put into operation.
[0038] S334. Based on the new switching requirements, determine whether the switching requirements are three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
[0039] One preferred embodiment, step S334, specifically includes:
[0040] If the new switching demand is three-phase switching compensation, then execute steps S311-S315, and compare and adjust the calculation results with the current actual power capacitors already in operation.
[0041] If the new switching requirement is three-phase switching compensation, then all power capacitors should be switched off.
[0042] If the new switching demand is a three-phase switching with both input and output compensation, then the output demand is set to 0, steps S311-S315 are executed, and the calculation results are compared and adjusted with the current actual power capacitors already in operation.
[0043] One preferred embodiment is that the first percentage is 60% and the second percentage is 100%.
[0044] The above-described technical solution of the present invention includes the following steps in the method for balancing the lifespan of power capacitors during switching: acquiring multi-dimensional parameters of each power capacitor in the reactive power compensation system and quantifying the loss level of each power capacitor; acquiring the compensation type, compensation capacity, and current switching status of each power capacitor; collecting real-time three-phase active power, reactive power, and power factor of the power grid, calculating whether the power grid needs to be switched on or off based on the power factor, and calculating the combination of power capacitors to be switched on or off this time based on the switching scheduling algorithm. The present invention solves the technical problem of how to balance the lifespan of each power capacitor in a reactive power compensation system. Attached Figure Description
[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0046] Figure 1 This is a schematic diagram of a power capacitor lifetime equalization switching scheduling method according to an embodiment of the present invention.
[0047] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0049] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0050] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.
[0051] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.
[0052] See Figure 1 According to one aspect of the present invention, a method for balancing the switching and dispatching of power capacitors throughout their lifespan is provided, wherein the method includes the following steps:
[0053] S1. Obtain multi-dimensional parameters of each power capacitor under the reactive power compensation system, and quantify the loss degree of each power capacitor.
[0054] S2. Obtain the compensation type, compensation capacity, and current switching status of each power capacitor;
[0055] S3. Collect the real-time three-phase active power, reactive power and power factor of the power grid, and calculate whether the current power grid needs to be put into or cut out for compensation based on the power factor, and calculate the power capacitor combination that needs to be put into or cut out this time according to the switching scheduling algorithm.
[0056] Specifically, in this embodiment, the loss level of the power capacitor is quantified using multi-dimensional data. By quantifying the loss level of the power capacitor, the horizontal comparison between each connected power capacitor in the switching scheduling algorithm has a certain error tolerance regarding whether it reflects the true loss of the power capacitor. By adjusting the coefficients in the loss index calculation, the reflected loss level is closer to the true loss, and only a single loss index is output, which can effectively reduce the complexity of the lifetime balancing control method. The loss level of the power capacitor is:
[0057] S=k1*k2*k3*k4*A
[0058] Where S is the loss level of the power capacitor, k1 is the temperature loss coefficient, k2 is the voltage loss coefficient, k3 is the voltage harmonic content loss coefficient, k4 is the current harmonic content loss coefficient, and A is the basic loss coefficient.
[0059] The value of A differs depending on whether the operation is in operation or out of operation. For example, A is 5 when in operation and 3 when out of operation. Furthermore, k2, k3, and k4 are all 1 when the operation is not in operation. The loss rate is calculated once per minute. If a power capacitor is in operation 50% of the time and out of operation 50% of the time during this period, then:
[0060]
[0061] S = S1 + S2
[0062] Specifically, in this embodiment, each power capacitor has a calculated quantification index of its loss level. The intelligent controller calculates the combination of power capacitors that need to be switched this time based on the current switching requirements through a switching scheduling algorithm. Before performing the switching scheduling calculation, the power capacitors are regarded as a capacitor resource pool, and the compensation type, compensation capacity, and current switching status of each power capacitor are obtained. The compensation types of the power capacitors include phase-by-phase compensation, three-phase common compensation, and hybrid compensation. In order to meet the principles of prioritizing common compensation, balancing lifespan, and reducing the number of switching times to reduce grid voltage fluctuations, the intelligent controller performs switching scheduling according to different situations.
[0063] Specifically, in this embodiment, step S3, calculating whether the current power grid needs to be connected or disconnected for compensation based on the power factor, specifically involves:
[0064] Set the upper and lower thresholds for the power factor;
[0065] If phase A is an inductive load and its power factor is below the lower threshold, then phase A needs to be compensated. If phase A is a capacitive or inductive load and its power factor is above the upper threshold, then phase A needs to be switched off for compensation. If phase B is an inductive load and its power factor is below the lower threshold, then phase B needs to be compensated. If phase B is a capacitive or inductive load and its power factor is above the upper threshold, then phase B needs to be switched off for compensation. If phase C is an inductive load and its power factor is below the lower threshold, then phase C needs to be compensated. If phase C is a capacitive or inductive load and its power factor is above the upper threshold, then phase C needs to be switched off for compensation. The current switching requirement is one of three-phase compensation, three-phase switching off compensation, or three-phase compensation with both compensation and switching off.
[0066] Specifically, in this embodiment, step S3 calculates the power capacitor combination that needs to be switched this time according to the switching scheduling algorithm, which specifically involves:
[0067] S311. If the current input demand is three-phase input compensation, then first separate the three-phase common input demand amount as the common compensation demand amount;
[0068] S312. Treat all unused three-phase common-compensation type power capacitors as a capacitor resource pool. Sort each power capacitor in ascending order of loss level. Take the first percentage of power capacitors to solve the problem. If there is no solution, take the second percentage of power capacitors to solve the problem and obtain the first common-compensation solution.
[0069] S313. Subtract the compensation amount absorbed by the first common compensation solution from the current switching demand to obtain the first phase input demand amount; take all the un-input phase compensation type capacitors as the capacitor resource pool, sort each power capacitor in order of increasing loss degree, take the first percentage of power capacitors for solution, if there is no solution, take the second percentage of power capacitors for solution to obtain the first phase compensation solution.
[0070] S314. If the first sub-solution has a solution, then exit the switching scheduling algorithm and perform scheduling operations according to the solution situation; otherwise, add the compensation amount of all the already put power capacitors to the current switching demand as the new put-in demand, and treat all power capacitors as not put into operation.
[0071] S315. Repeat steps S311-S314, set a loop threshold. If the number of loops exceeds the loop threshold, no action will be taken in this scheduling.
[0072] Specifically, in this embodiment, step S3 calculates the power capacitor combination that needs to be switched this time according to the switching scheduling algorithm, which specifically involves:
[0073] S321. If the current switching demand is three-phase switching compensation, then first separate the three-phase common switching demand amount as the common compensation demand amount;
[0074] S322. Treat all the three-phase common-compensation type power capacitors that have been put into use as a capacitor resource pool. Sort each power capacitor in descending order of loss. Take the first percentage of power capacitors to solve the problem. If there is no solution, take the second percentage of power capacitors to solve the problem and obtain the second common-compensation solution.
[0075] S323. Subtract the compensation amount absorbed by the second common compensation solution from the current switching demand to obtain the second phase input demand amount; take all the power capacitors of the phase compensation type that have been put into use as the capacitor resource pool, sort each power capacitor in descending order of loss degree, take the first percentage of power capacitors to solve, if there is no solution, take the second percentage of power capacitors to solve, and obtain the second phase compensation solution.
[0076] S324. If the second sub-solution has a solution, then exit the switching scheduling algorithm and perform scheduling operations according to the solution situation; otherwise, add the compensation amount of all the already put power capacitors to the current switching demand as the new switching demand, and treat all power capacitors as not put into operation.
[0077] S325. Based on the new switching requirements, determine whether the switching requirements are three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
[0078] Specifically, in this embodiment, step S325 is as follows:
[0079] If the new switching demand is three-phase switching compensation, then execute steps S311-S315, and compare and adjust the calculation results with the current actual power capacitors already in operation. Specifically, adjust the actual power capacitors already in operation according to the calculation results.
[0080] If the new switching requirement is three-phase switching compensation, then all power capacitors should be switched off.
[0081] If the new switching demand is a three-phase switching with both input and output compensation, then the output demand is set to 0, steps S311-S315 are executed, and the calculation results are compared and adjusted with the current actual power capacitors already in operation.
[0082] Specifically, in this embodiment, step S3 calculates the power capacitor combination that needs to be switched this time according to the switching scheduling algorithm, which specifically involves:
[0083] S331. If the current switching demand is three-phase with both input and switching compensation, then determine whether the compensation demand of each phase is input compensation or switching compensation.
[0084] S332. If it is an input compensation, then all the power capacitors of the un-input phase compensation type are regarded as the capacitor resource pool. The power capacitors are sorted in order of increasing loss degree. The first percentage of power capacitors are used for solution. If there is no solution, the second percentage of power capacitors are used for solution to obtain the first phase compensation solution.
[0085] If it is a phase-by-phase compensation, all the power capacitors that have been put into use are treated as a capacitor resource pool. The power capacitors are sorted in descending order of loss. The first percentage of power capacitors are used for the solution. If there is no solution, the second percentage of power capacitors are used for the solution to obtain the second phase-by-phase compensation solution.
[0086] S333. If all three phases have solutions for phase-by-phase compensation, then exit the switching and scheduling algorithm and perform scheduling operations according to the solution results; otherwise, add the compensation amount of all the power capacitors that have been put into operation to the current switching demand, and regard it as the new switching demand, and regard all power capacitors as not put into operation.
[0087] S334. Based on the new switching requirements, determine whether the switching requirements are three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
[0088] Specifically, in this embodiment, step S334 is as follows:
[0089] If the new switching demand is three-phase switching compensation, then execute steps S311-S315, and compare and adjust the calculation results with the current actual power capacitors already in operation.
[0090] If the new switching requirement is three-phase switching compensation, then all power capacitors should be switched off.
[0091] If the new switching demand is a three-phase switching with both input and output compensation, then the output demand is set to 0, steps S311-S315 are executed, and the calculation results are compared and adjusted with the current actual power capacitors already in operation.
[0092] Specifically, in this embodiment, the first percentage is 60% and the second percentage is 100%.
[0093] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
Claims
1. A method for balancing the switching and dispatching of power capacitors throughout their lifespan, characterized in that, Includes the following steps: S1. Obtain multi-dimensional parameters of each power capacitor under the reactive power compensation system, and quantify the loss degree of each power capacitor. S2. Obtain the compensation type, compensation capacity, and current switching status of each power capacitor; S3. Collect the real-time three-phase active power, reactive power and power factor of the power grid, and calculate whether the current power grid needs to be put into or cut out for compensation based on the power factor, and calculate the power capacitor combination that needs to be put into or cut out this time according to the switching scheduling algorithm.
2. The power capacitor lifetime equalization switching scheduling method according to claim 1, characterized in that, The loss level of the power capacitor is as follows: S=k1*k2*k3*k4*A Where S is the loss level of the power capacitor, k1 is the temperature loss coefficient, k2 is the voltage loss coefficient, k3 is the voltage harmonic content loss coefficient, k4 is the current harmonic content loss coefficient, and A is the basic loss coefficient.
3. A power capacitor lifetime equalization switching scheduling method according to any one of claims 1-2, characterized in that, The compensation types for the power capacitors include phase-by-phase compensation, three-phase common compensation, and hybrid compensation.
4. A power capacitor lifetime equalization switching scheduling method according to any one of claims 1-2, characterized in that, Step S3, which calculates whether the current power grid needs to be switched on or off for compensation based on the power factor, specifically involves: Set the upper and lower thresholds for the power factor; If phase A is an inductive load and its power factor is below the lower threshold, then phase A needs to be compensated; if phase A is a capacitive or inductive load and its power factor is above the upper threshold, then phase A needs to be switched off for compensation. If phase B is an inductive load and its power factor is below the lower threshold, then phase B needs to be compensated; if phase B is a capacitive or inductive load and its power factor is above the upper threshold, then phase B needs to be switched off for compensation. If phase C is an inductive load and its power factor is below the lower threshold, then phase C needs to be compensated; if phase C is a capacitive or inductive load and its power factor is above the upper threshold, then phase C needs to be switched off for compensation. The current switching demand is determined to be one of three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
5. The power capacitor lifetime equalization switching scheduling method according to claim 4, characterized in that, Step S3 calculates the power capacitor combination that needs to be switched this time according to the switching scheduling algorithm, specifically as follows: S311. If the current input demand is three-phase input compensation, then first separate the three-phase common input demand amount as the common compensation demand amount; S312. Treat all unused three-phase common-compensation type power capacitors as a capacitor resource pool. Sort each power capacitor in ascending order of loss level. Take the first percentage of power capacitors to solve the problem. If there is no solution, take the second percentage of power capacitors to solve the problem and obtain the first common-compensation solution. S313. Subtract the compensation amount absorbed by the first common compensation solution from the current switching demand to obtain the first phase input demand amount; take all the un-input phase compensation type capacitors as the capacitor resource pool, sort each power capacitor in order of increasing loss degree, take the first percentage of power capacitors for solution, if there is no solution, take the second percentage of power capacitors for solution to obtain the first phase compensation solution. S314. If the first sub-solution has a solution, then exit the switching scheduling algorithm and perform scheduling operations according to the solution situation; otherwise, add the compensation amount of all the already put power capacitors to the current switching demand as the new put-in demand, and treat all power capacitors as not put into operation. S315. Repeat steps S311-S314, set a loop threshold. If the number of loops exceeds the loop threshold, no action will be taken in this scheduling.
6. The power capacitor lifetime equalization switching scheduling method according to claim 5, characterized in that, Step S3 calculates the power capacitor combination that needs to be switched this time according to the switching scheduling algorithm, specifically as follows: S321. If the current switching demand is three-phase switching compensation, then first separate the three-phase common switching demand amount as the common compensation demand amount; S322. Treat all the three-phase common-compensation type power capacitors that have been put into use as a capacitor resource pool. Sort each power capacitor in descending order of loss. Take the first percentage of power capacitors to solve the problem. If there is no solution, take the second percentage of power capacitors to solve the problem and obtain the second common-compensation solution. S323. Subtract the compensation amount absorbed by the second common compensation solution from the current switching demand to obtain the second phase input demand amount; take all the power capacitors of the phase compensation type that have been put into use as the capacitor resource pool, sort each power capacitor in descending order of loss degree, take the first percentage of power capacitors to solve, if there is no solution, take the second percentage of power capacitors to solve, and obtain the second phase compensation solution. S324. If the second sub-solution has a solution, then exit the switching scheduling algorithm and perform scheduling operations according to the solution situation; otherwise, add the compensation amount of all the already put power capacitors to the current switching demand as the new switching demand, and treat all power capacitors as not put into operation. S325. Based on the new switching requirements, determine whether the switching requirements are three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
7. The power capacitor lifetime equalization switching scheduling method according to claim 6, characterized in that, Step S325 specifically includes: If the new switching demand is three-phase switching compensation, then execute steps S311-S315, and compare and adjust the calculation results with the current actual power capacitors already in operation. If the new switching requirement is three-phase switching compensation, then all power capacitors should be switched off. If the new switching demand is a three-phase switching with both input and output compensation, then the output demand is set to 0, steps S311-S315 are executed, and the calculation results are compared and adjusted with the current actual power capacitors already in operation.
8. The power capacitor lifetime equalization switching scheduling method according to claim 5, characterized in that, Step S3 calculates the power capacitor combination that needs to be switched this time according to the switching scheduling algorithm, specifically as follows: S331. If the current switching demand is three-phase with both input and switching compensation, then determine whether the compensation demand of each phase is input compensation or switching compensation. S332. If it is an input compensation, then all the power capacitors of the un-input phase compensation type are regarded as the capacitor resource pool. The power capacitors are sorted in order of increasing loss degree. The first percentage of power capacitors are used for solution. If there is no solution, the second percentage of power capacitors are used for solution to obtain the first phase compensation solution. If it is a phase-by-phase compensation, all the power capacitors that have been put into use are treated as a capacitor resource pool. The power capacitors are sorted in descending order of loss. The first percentage of power capacitors are used for the solution. If there is no solution, the second percentage of power capacitors are used for the solution to obtain the second phase-by-phase compensation solution. S333. If all three phases have solutions for phase-by-phase compensation, then exit the switching and scheduling algorithm and perform scheduling operations according to the solution results; otherwise, add the compensation amount of all the power capacitors that have been put into operation to the current switching demand, and regard it as the new switching demand, and regard all power capacitors as not put into operation. S334. Based on the new switching requirements, determine whether the switching requirements are three-phase input compensation, three-phase cut-out compensation, or three-phase input and cut-out compensation.
9. The power capacitor lifetime equalization switching scheduling method according to claim 8, characterized in that, Step S334 specifically includes: If the new switching demand is three-phase switching compensation, then execute steps S311-S315, and compare and adjust the calculation results with the current actual power capacitors already in operation. If the new switching requirement is three-phase switching compensation, then all power capacitors should be switched off. If the new switching demand is a three-phase switching with both input and output compensation, then the output demand is set to 0, steps S311-S315 are executed, and the calculation results are compared and adjusted with the current actual power capacitors already in operation.
10. The power capacitor lifetime equalization switching scheduling method according to claim 5, characterized in that, The first percentage is 60%, and the second percentage is 100%.