CN110571822A - Intelligent compensation control method for active power filter - Google Patents
Intelligent compensation control method for active power filter Download PDFInfo
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- CN110571822A CN110571822A CN201910801335.6A CN201910801335A CN110571822A CN 110571822 A CN110571822 A CN 110571822A CN 201910801335 A CN201910801335 A CN 201910801335A CN 110571822 A CN110571822 A CN 110571822A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/20—Active power filtering [APF]
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Abstract
The invention is suitable for the electronic and electrical technology, and provides an intelligent compensation control method for an active power filter, which comprises the steps of determining a reactive current value to be compensated, a harmonic current value and an unbalanced current value according to a detected load current, a preset target power factor, a target total harmonic distortion rate and a target unbalanced degree; judging whether the current output total current is larger than a rated current value or not; if so, sequentially reducing the output current correspondingly compensated by the low-priority sequencing sequence according to the preset priority sequencing compensated by reactive power, harmonic waves and unbalance until the current output total current is not greater than the rated current value; if not, according to the preset priority ranking, within the range of the rated current value, the compensated output current corresponding to the high-priority ranking is compensated to the target power factor, the target total harmonic distortion rate and the target unbalance degree corresponding to the high-priority ranking in sequence. The invention can improve the capacity utilization rate and the compensation efficiency of the equipment to the maximum extent.
Description
Technical Field
The invention belongs to the technical field of electronics and electricity, and particularly relates to an intelligent compensation control method for an active power filter.
Background
Converter, a large amount of consumer such as rectifier insert the electric wire netting, not only can consume active power, also can produce more reactive power, also can introduce the electric wire netting with the harmonic simultaneously, make electric wire netting electric energy quality variation, reduce distribution transformer's power supply efficiency, to three-phase four-wire system electric wire netting, if the three-phase load asymmetry that inserts the electric wire netting, can further arouse the three-phase voltage asymmetry of distribution transformer output, not only can increase the loss of circuit, can influence other consumer equally.
at present, in order to realize treatment of reactive power, harmonic waves and load unbalance, corresponding treatment is usually carried out through different power quality management devices, and each power quality management device independently solves the problem of specific power quality, so that resources are wasted, and cost is increased due to excessive equipment investment.
at present, reactive power, harmonic power and load imbalance are simultaneously compensated through one electric energy quality management device, but the compensated reactive power, harmonic power and load imbalance power need to be set respectively, so that the electric energy quality management device performs corresponding compensation according to each corresponding compensation power, however, when the load changes, the situation of insufficient reactive power, harmonic power and load imbalance compensation can occur, so that the device cannot be utilized to the maximum extent, the device capacity utilization rate is low, and the compensation efficiency is low.
disclosure of Invention
the embodiment of the invention provides an intelligent compensation control method for an active power filter, and aims to solve the problems of low equipment capacity utilization rate and low compensation efficiency in the existing scheme.
In order to achieve the above object, the present invention provides an active power filter intelligent compensation control method, including:
determining a reactive current value, a harmonic current value and an unbalanced current value to be compensated according to the detected load current, a preset target power factor, a target total harmonic distortion rate and a target unbalance degree;
Judging whether the current output total current is larger than the rated current value of the active power filter or not;
if so, sequentially reducing the output current correspondingly compensated by the low-priority sequencing sequence according to the preset priority sequencing compensated by reactive power, harmonic waves and unbalance until the current output total current is not greater than the rated current value;
If not, according to the preset priority sequence, within the range of the rated current value, sequentially compensating the output current correspondingly compensated by the high-priority sequence to the determined corresponding current value to be compensated, so as to sequentially compensate the target power factor, the target total harmonic distortion rate and the target unbalance degree corresponding to the high-priority sequence.
furthermore, the low priority ranking order is a third priority, a second priority, and a first priority in turn;
the step of sequentially reducing the compensated output current in the low priority sorting order comprises:
Judging whether the current output total current is larger than the rated current value or not when the compensated output current corresponding to the third priority is reduced to be within a first target threshold value of the rated current value;
if so, the output of the output current compensated corresponding to the third priority is closed, and the output current compensated corresponding to the second priority is reduced.
furthermore, after the step of reducing the compensated output current corresponding to the second priority, the method further includes:
judging whether the current output total current is larger than the rated current value or not when the compensated output current corresponding to the second priority is reduced to be within a first target threshold value of the rated current value;
If so, the output of the output current compensated corresponding to the second priority is closed, and the output current compensated corresponding to the first priority is reduced until the total output current is not greater than the rated current value.
furthermore, the high priority sorting order is a first priority, a second priority and a third priority in sequence;
The step of sequentially compensating the output current corresponding to the high-priority sorting sequence to the determined corresponding current value to be compensated comprises the following steps:
Adjusting the output current compensated corresponding to the first priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion rate or the target unbalance degree corresponding to the first priority;
Judging whether the compensated current output total current corresponding to the first priority is smaller than a second target threshold value of the rated current value;
If so, adjusting the output current compensated corresponding to the second priority to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority;
if not, stopping adjusting the compensated output current corresponding to the second priority;
Judging whether the compensated current output total current corresponding to the second priority is smaller than a second target threshold value of the rated current value;
If so, adjusting the output current correspondingly compensated by the third priority to the corresponding current value to be compensated so as to enable the current output total current to be not greater than the rated current value;
if not, stopping adjusting the compensated output current corresponding to the third priority.
Furthermore, the step of adjusting the compensated output current corresponding to the first priority to the corresponding current value to be compensated includes:
judging whether the output current compensated corresponding to the first priority is larger than the corresponding current value to be compensated or not;
If so, reducing the output current compensated corresponding to the first priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion rate or the target unbalance degree corresponding to the first priority;
If not, the output current compensated corresponding to the first priority is increased to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the first priority.
Furthermore, the step of adjusting the compensated output current corresponding to the second priority to the corresponding current value to be compensated includes:
judging whether the output current compensated corresponding to the second priority is larger than the corresponding current value to be compensated or not;
If so, reducing the compensated output current corresponding to the second priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority;
if not, the output current corresponding to the second priority is increased to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority.
Further, the step of determining the reactive current value to be compensated, the harmonic current value, and the unbalanced current value according to the detected load current and preset target power factor, target total harmonic distortion rate, and target unbalance degree includes:
Detecting the current load current;
Determining a reactive current value to be compensated according to the load current and the target power factor;
determining a harmonic current value to be compensated according to the load current and the target total harmonic distortion rate;
And determining the value of the unbalance current to be compensated according to the load current and the target unbalance degree.
In the embodiment of the invention, the reactive current value, the harmonic current value and the unbalanced current value to be compensated are determined by detecting the load current, the preset target power factor, the preset target total harmonic distortion rate and the preset target unbalance degree, so that each output current required by the active power filter to be correspondingly compensated can be determined, whether the current output total current is greater than the rated current value or not is judged, and when the current output total current is greater than the rated current value, the current output total current is correspondingly reduced to be not greater than the rated current value, wherein the output current corresponding to the low priority in the preset priority sequence is mainly reduced, so that the maximum operation of the high priority can be ensured, and the overload problem caused by the fact that the system runs beyond the rated current value is avoided; when the current output total current is smaller than the rated current value, the output current correspondingly compensated by the high priority is preferentially compensated to the corresponding current value to be compensated while the compensation is carried out, so that the maximum operation of the high priority can be ensured. Meanwhile, the current is compensated to the corresponding current value to be compensated, so that the problem of insufficient compensation caused by preset compensated reactive power, harmonic power and unbalanced load power is avoided, the current output by the active power filter can be utilized to the maximum extent, and the problems that equipment cannot be utilized to the maximum extent, the equipment capacity utilization rate is low and the compensation efficiency is low are solved.
Drawings
FIG. 1 is a topology diagram of an active power filter compensation control system in an embodiment of the invention;
Fig. 2 is a flowchart illustrating an implementation of an intelligent compensation control method for an active power filter according to an embodiment of the present invention;
fig. 3 is a flowchart of an implementation of an intelligent compensation control method for an active power filter according to a second embodiment of the present invention;
fig. 4 is a flowchart of an implementation of an intelligent compensation control method for an active power filter according to a third embodiment of the present invention.
Detailed Description
in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
the invention provides an intelligent compensation control method of an active power filter, which comprises the steps of determining a reactive current value to be compensated, a harmonic current value and an unbalanced current value according to a detected load current, a preset target power factor, a preset target total harmonic distortion rate and a preset target unbalanced degree; judging whether the current output total current is larger than a rated current value or not; if so, sequentially reducing the output current correspondingly compensated by the low-priority sequencing sequence according to the preset priority sequencing compensated by reactive power, harmonic waves and unbalance until the current output total current is not greater than the rated current value; if not, according to the preset priority sequence, within the range of the rated current value, the output current corresponding to the compensation of the high-priority sequence is compensated to the determined corresponding current value to be compensated in sequence, so that the target power factor, the target total harmonic distortion rate and the target unbalance degree corresponding to the high-priority sequence are compensated in sequence, and the problems of low capacity utilization rate and low compensation efficiency of the existing equipment are solved.
fig. 1 shows a topology diagram of an active power filter compensation control system provided by an embodiment of the present invention, and for convenience of explanation, only the parts related to the embodiment of the present invention are shown. Referring to fig. 1, the Active power filter compensation control system includes Active Power Filters (APFs) connected to a utility power input side (distribution network side) and a load side, detection units connected to the utility power input side and the Active power filters, respectively, and a control unit connected to the detection units and the Active power filters, respectively. Wherein the commercial power current is input to the load for providing the load with work, and the detecting units respectively detect the current i on the side of the power gridSor the load current iLthe control unit obtains the load current i detected by the detection unitLAnd calculating to-be-compensated current i to be compensated through related reactive power and harmonic extraction algorithmCFurther, the compensation current i is output by controlling the active power filterCthe amplitude, the frequency and the phase position of the three-phase current compensation circuit are used for eliminating reactive harmonic current components contained in the side current is of the power distribution network, enabling active power of three-phase current input by the side of the power distribution network to be the same, and achieving the purposes of reactive power compensation, harmonic compensation and unbalance.
example one
fig. 2 shows an implementation flow of an intelligent compensation control method for an active power filter according to a first embodiment of the present invention, and for convenience of description, only the parts related to the first embodiment of the present invention are shown, which are detailed as follows:
In step S10, a reactive current value, a harmonic current value, and an unbalanced current value to be compensated are determined according to the detected load current, a preset target power factor, a target total harmonic distortion rate, and a target unbalanced degree.
The determination of the reactive current value, the harmonic current value and the unbalanced current value to be compensated can be realized by referring to the following steps:
Detecting the current load current;
Secondly, determining a reactive current value to be compensated according to the load current and a target power factor;
(III) determining a harmonic current value to be compensated according to the load current and a target total harmonic distortion rate;
and (IV) determining the value of the unbalance current to be compensated according to the load current and the target unbalance degree.
in the embodiment of the present invention, a target power factor, a target Total Harmonic Distortion (THDI Total Harmonic Current Distortion), and a target imbalance degree to be compensated are preset, and the detecting unit detects a load Current i of a Current load side at this timeLThe control unit determines a reactive current value to be compensated according to the obtained load current and the corresponding target power factor; the control unit determines an unbalanced current value to be compensated according to the active current of the extracted load current and the corresponding target unbalance; and the control unit obtains a synchronous phase through a PLL (phase locked loop), and determines a harmonic current value to be compensated by extracting each subharmonic current component of the load current and the corresponding target total harmonic distortion rate.
According to the detected load current and the phase of the grid voltage, an active current value, a reactive current value and a harmonic current value in the load current can be obtained through an active reactive and harmonic extraction algorithm, and further the reactive current value, the harmonic current value and the unbalanced current value to be compensated can be obtained through the following method, specifically:
The power factor of the grid current can be defined as:
Formula (1) IPRMSis the effective value of the active power of the current of the power grid,For compensated reactive effective value of grid current, PFtgtfor the set target power factor, the reactive effective value of the compensated grid current can be obtained through the formula (1):
let IQRMSFor the extracted reactive effective value of the load current, the reactive current I to be compensated can be obtained according to the formula (2)QCcomprises the following steps:
in the above formula IQCSin ω t is the reactive phase for the reactive current to be compensated.
the definition of THDI is shown in equation (4):
in the above formula IHtgtTo compensate for the post-harmonic current content, IFBeing the fundamental current content, THDItgtFor the set target power factor, further:
the harmonic current I to be compensated can be obtained according to the formula (5)HCis composed of
In the above formula IHin order to extract the load harmonic current,For each harmonic phase.
According to the definition of the degree of unbalance:
In the formula (7) IMIs the maximum phase current, IavgAverage current of three phases, YutgtFor a set target unbalance, further:
according to the formula, the unbalanced current value I of each phase to be compensated can be further obtaineduncComprises the following steps:
In the formula (9) IPRMSIs the active content of each phase.
in step S20, it is determined whether or not the present output total current is larger than the rated current value of the active power filter.
When the current output total current is judged to be larger than the rated current value of the active power filter, executing step S30; otherwise, step S40 is executed.
in the embodiment of the invention, when the control unit determines the reactive current value to be compensated, the harmonic current value and the unbalanced current value according to the detected load current, the control unit sends out control signals to the active power filter, so that the active power filter respectively sends out reactive compensation current for compensating reactive power, harmonic compensation current for compensating harmonic waves and unbalanced compensation current for compensating unbalanced, and the compensation of reactive power, harmonic waves and unbalanced is realized.
it should be noted that, when the active power filter has a rated current value, for example, the device capacity is 100A, the rated current value is 100A, and when the total output current of the reactive current value, the harmonic current value and the unbalanced current value to be compensated is determined according to the load current to be less than the rated current value, effective compensation can be achieved for the reactive power, the harmonic wave and the unbalance.
When the total current to be compensated is larger than the rated current value, the phenomenon that the total current output by the active power filter exceeds the rated current value can occur in the output process, so that the current limiting control is correspondingly performed on the active power filter at the moment, namely, the current output total current is correspondingly controlled to be reduced to reach the range of the rated current value, and the problem that the active power filter is damaged when the total current output by the active power filter is larger than the rated current value for a long time is solved. Therefore, first, it detects whether or not the total current currently output by the active power filter is larger than the rated current value of the active power filter.
in step S30, the output currents compensated for the low priority ranking order are sequentially reduced according to the preset priority ranking for compensation of reactive power, harmonic wave, and unbalance until the current output total current is not greater than the rated current value.
in the embodiment of the present invention, the compensated priority ranking is preset according to the actual use requirement, specifically, for example, the ranking from the highest priority to the lowest priority in the embodiment is reactive, harmonic, and unbalanced. It is understood that in other embodiments of the present invention, other priorities may be ordered according to actual usage requirements, and are not limited herein.
Further, when it is determined that the current output total current of the active power filter is greater than the rated current value, the current limiting control of the active power filter is required, that is, the output total current is controlled to be reduced to be within the rated current value, and at this time, the output currents compensated for according to the preset priority ranking for reactive power compensation, harmonic compensation and imbalance compensation are sequentially reduced according to the low priority ranking Harmonic compensation current, and unbalance compensation current. When the output current compensated corresponding to the lowest priority is completely reduced and the current output total current is still greater than the rated current value, the output current compensated corresponding to the second priority is reduced, namely the harmonic compensation current (the output current used by the active power filter for compensating the harmonic) is reduced.
and step S40, according to the preset priority sequence, within the range of the rated current value, sequentially compensating the output current correspondingly compensated by the high priority sequence to the determined corresponding current value to be compensated, so as to sequentially compensate the target power factor, the target total harmonic distortion rate and the target unbalance degree corresponding to the high priority sequence.
in the embodiment of the present invention, when it is determined that the current output total current of the active power filter is not greater than the rated current value, the reactive power, the harmonic wave, and the imbalance are dynamically compensated at the same time, but during the compensation process, the output current compensated corresponding to the high priority ranking order is compensated to the determined current value to be compensated preferentially, for example, when it is determined that the compensated output current corresponding to the highest priority is not compensated to the determined current value to be compensated, the output current compensated corresponding to the highest priority is compensated preferentially, that is, the reactive power compensation current is compensated to the reactive power current value to be compensated preferentially, so that the active power filter compensates the reactive power to the corresponding target power factor.
specifically, in the embodiment of the present invention, the active power filter needs to compensate the reactive power, the harmonic wave, and the imbalance to the corresponding target power factor, the target total harmonic distortion and the target imbalance, so the indexes to be detected are the target power factor, the target total harmonic distortion and the target imbalance, when the load changes, the reactive current value, the harmonic current value, and the imbalance current value to be compensated correspondingly change, therefore, in the embodiment of the present invention, the active power filter needs to dynamically and sequentially compensate to the target power factor, the target total harmonic distortion and the target imbalance according to the priority order, that is, the reactive power is preferentially compensated to the corresponding target power factor, when the compensation is completed and the compensation can be performed, the harmonic wave is compensated to the corresponding target total harmonic distortion, and the above compensation is performed sequentially, which can be understood, when the priority order of idle work, harmonic wave and unbalance is other, the compensation of other corresponding high priority orders is correspondingly carried out.
Specifically, for example, when the current reactive compensation current is greater than the reactive current value to be compensated, the current reactive compensation current is reduced; and when the current reactive compensation current is smaller than the reactive current value to be compensated, increasing the current reactive compensation current. Within the range of the rated current value, when the reactive compensation is finished preferentially, the total output current of the active power filter is smaller than the rated current, at the moment, the active power filter continues to preferentially compensate the output current corresponding to the second priority to the determined current value to be compensated, for example, the active power filter continues to compensate the harmonic wave, at the moment, the harmonic wave compensation current is controlled to compensate to the determined harmonic wave current value to be compensated, and therefore, the reactive compensation, the harmonic wave compensation and the unbalance are finished completely within the rated current value, or the adjustment of the corresponding compensated output current is stopped when the total output current is not finished completely and is equal to the rated current value.
In the embodiment of the invention, the reactive current value, the harmonic current value and the unbalanced current value to be compensated are determined by detecting the load current, the preset target power factor, the preset target total harmonic distortion rate and the preset target unbalance degree, so that each output current required by the active power filter to be correspondingly compensated can be determined, whether the current output total current is greater than the rated current value or not is judged, and when the current output total current is greater than the rated current value, the current output total current is correspondingly reduced to be not greater than the rated current value, wherein the output current corresponding to the low priority in the preset priority sequence is mainly reduced, so that the maximum operation of the high priority can be ensured, and the overload problem caused by the fact that the system runs beyond the rated current value is avoided; when the current output total current is smaller than the rated current value, the output current correspondingly compensated by the high priority is preferentially compensated to the corresponding current value to be compensated while the compensation is carried out, so that the maximum operation of the high priority can be ensured. Meanwhile, the current is compensated to the corresponding current value to be compensated, so that the problem of insufficient compensation caused by preset compensated reactive power, harmonic power and unbalanced load power is solved, the current output by the active power filter can be utilized to the maximum extent, the single active power filter can simultaneously compensate the reactive power, the harmonic power and the unbalanced load power, the compensated reactive power, the compensated harmonic power and the unbalanced load power can be intelligently distributed, and the problems of low capacity utilization rate and low compensation efficiency of the existing equipment are solved.
Example two
Fig. 3 shows an implementation flow of the intelligent compensation control method for the active power filter according to the second embodiment of the present invention, and for convenience of description, only the parts related to the second embodiment of the present invention are shown, and the implementation principle and the generated technical effects are the same as those of the first embodiment. The active power filter intelligent compensation control method is different from the active power filter intelligent compensation control method shown in fig. 2 in that in the method, the low priority sorting order is a third priority, a second priority and a first priority in sequence, and the step of reducing the output current compensated corresponding to the low priority sorting order in sequence according to the preset priority sorting compensated for reactive power, harmonic wave and unbalance until the current output total current is not greater than the rated current value comprises the following steps:
Step S31, determining whether the current output total current is greater than the rated current value when the compensated output current corresponding to the third priority level decreases to within the first target threshold of the rated current value.
when it is determined that the compensated output current corresponding to the third priority is reduced to the first target threshold of the rated current value and the current output total current is greater than the rated current value, performing step S32;
in the embodiment of the present invention, when the current output total current is greater than the rated current value, the compensated output current corresponding to the third priority is first reduced according to the priority ranking order, for example, when the priority ranking order is the first priority idle, the second priority harmonic, and the third priority is unbalanced in sequence from high to low, the compensated output current corresponding to the third priority is first reduced, that is, the unbalanced compensation current is reduced in the embodiment. When the reduced unbalance compensation current enables the output total current not to be larger than the rated current value, stopping reducing the unbalance compensation current; when the reduced unbalance compensation current is reduced to be within a first target threshold range of the rated current value, it is determined whether the currently output total current is still greater than the rated current value, wherein, for example, in the present embodiment, the rated current value is 100A, and the first target threshold value is 5%, when the unbalance compensation current is reduced to be 5A, it is determined whether the currently output total current is still greater than 100A, wherein when the current output total current is not greater than 100A, the reduction of the unbalance compensation current is stopped.
step S32, the output of the compensated output current corresponding to the third priority is turned off, and the compensated output current corresponding to the second priority is decreased.
When the current output total current is larger than the rated current value, the output of the output current compensated corresponding to the third priority is closed, namely the unbalanced compensation current is closed, the active power filter prohibits the compensation of the unbalance, and meanwhile, the output current compensated corresponding to the second priority is reduced, namely the harmonic compensation current is reduced until the current output total current is not larger than the rated current value.
Step S33, determining whether the current output total current is greater than the rated current value when the compensated output current corresponding to the second priority level is reduced to be within the first target threshold of the rated current value.
when it is determined that the compensated output current corresponding to the second priority is reduced to the first target threshold of the rated current value and the current output total current is greater than the rated current value, performing step S34;
When the reduced harmonic compensation current enables the output total current not to be larger than the rated current value, the reduction of the harmonic compensation current is stopped; when the reduced harmonic compensation current is reduced to be within a first target threshold range of the rated current value, whether the current output total current is still larger than the rated current value is judged, for example, when the harmonic compensation current is reduced to 5A, whether the current output total current is still larger than 100A is judged, and when the current output total current is not larger than 100A, the reduction of the harmonic compensation current is stopped.
and step S34, the output of the compensated output current corresponding to the second priority is closed, and the compensated output current corresponding to the first priority is reduced until the total output current is not greater than the rated current value.
When the current output total current is larger than the rated current value, the output of the output current compensated corresponding to the second priority is closed, namely the harmonic compensation current is closed, at the moment, the active power filter prohibits the compensation of the harmonic, and meanwhile, the output current compensated corresponding to the first priority is reduced, namely the reactive compensation current is reduced until the current output total current is not larger than the rated current value. At the moment, the active power filter only compensates reactive power, and when the reactive compensation current output by the rated current value is smaller than the reactive current value to be compensated, the active power filter operates in a reactive compensation current limiting mode, so that the total current output by the active power filter is completely used for compensating the reactive power of the first priority.
In this embodiment, when the output total current is greater than the rated current value, the output current compensated in the low priority sorting order is reduced first, so that the high priority corresponding compensation can be performed to the maximum extent, the problem that the active power filter compensates reactive power, filtering and imbalance, but each has no good compensation, and the damage to the equipment caused by overload due to the fact that the active power filter operates beyond the rated current value is avoided.
EXAMPLE III
Fig. 4 shows an implementation flow of an intelligent compensation control method for an active power filter according to a third embodiment of the present invention, and for convenience of description, only the parts related to the third embodiment of the present invention are shown, and the implementation principle and the generated technical effects are the same as those of the second embodiment of the present invention, and for briefly describing the places not mentioned in the embodiments of the present invention, reference may be made to the corresponding contents in the second embodiment of the present invention, and the intelligent compensation control method for an active power filter is different from the intelligent compensation control method for an active power filter shown in fig. 3 in that, in the method, the step of sequentially compensating the output currents compensated by the high priority ranking order to the determined corresponding current values to be compensated includes:
step S41, adjusting the compensated output current corresponding to the first priority to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target imbalance corresponding to the first priority;
the adjustment of the compensated output current corresponding to the first priority to the corresponding current value to be compensated can be realized by referring to the following steps:
judging whether the compensated output current corresponding to the first priority is larger than the corresponding current value to be compensated;
if yes, reducing the output current compensated corresponding to the first priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the first priority;
and (III) if not, increasing the compensated output current corresponding to the first priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the first priority.
In the embodiment of the invention, when the current output total current is judged to be smaller than the rated current value, the reactive power, the harmonic wave and the unbalance of the current output total current are intelligently compensated at the same time, the output current corresponding to the compensation in the high priority sorting sequence is preferentially compensated to the determined current value to be compensated at the same time of the intelligent compensation, and the priority sorting sequence of the output current is the first priority reactive power, the second priority harmonic wave and the third priority unbalance from high to low.
At this time, when the reactive compensation current of the first priority output by the active power filter is greater than the reactive current value to be compensated, the reactive compensation current is correspondingly reduced to the reactive current value to be compensated, so that the compensation is reactive to the corresponding target power factor.
When the reactive compensation current output by the active power filter is smaller than the value of the reactive current to be compensated, the reactive compensation current is correspondingly increased, it should be noted that, when the reactive compensation current is increased so that the current total output current is larger than the rated current value, the corresponding reduction of the third priority imbalance compensation current, as described with reference to embodiment two, when imbalance compensation is disabled, the harmonic compensation current of the second priority is correspondingly reduced until the reactive compensation current of the first priority is increased to the reactive current to be compensated, so that the reactive power of the first priority can be completely compensated to the corresponding target power factor, the incomplete compensation caused by the output current of the compensation corresponding to the first priority being lower than the corresponding current value to be compensated is avoided, and the problem of resource waste caused by the fact that the output current compensated corresponding to the first priority is higher than the corresponding current value to be compensated.
It should be noted that, when the total current output is greater than the rated current value, the output current corresponding to the low priority sorting order is correspondingly dynamically decreased according to the second embodiment, and when the reactive compensation current that is decreased to only output the first priority is still greater than the rated current value, the active power filter cannot perform full reactive compensation, the reactive compensation current of the active power filter operates in a current-limited manner at the rated current value, and only the reactive power of the first priority is compensated and compensated in a current-limited manner, so that the full total output current of the active power filter is used for compensating the reactive power of the first priority.
step S42, judging whether the compensated current output total current corresponding to the first priority is smaller than a second target threshold value of the rated current value;
When the compensated current output total current corresponding to the first priority is judged to be smaller than the second target threshold value of the rated current value, the step S43 is executed; otherwise, stopping adjusting the compensated output current corresponding to the second priority.
in the embodiment of the present invention, after the output current compensated by the first priority is compensated to the corresponding current value to be compensated, it is determined whether the current output total current is smaller than a second target threshold of the rated current value, in this embodiment, the second target threshold is specifically 95%, that is, it is determined that the current output total current is greater than 95% of the rated current value and is smaller than the rated current value, for example, when the rated current value is 100A, the current output total current is 98A, the current output total current is between 95 and 100A, at this time, the second priority is not compensated, the active power filter stops adjusting the output current compensated by the second priority, that is, at this time, only the reactive power of the first priority is fully compensated, and a certain current margin is reserved for the active power filter, so as to ensure stable operation of the system.
Step S43, adjusting the compensated output current corresponding to the second priority to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target imbalance corresponding to the second priority;
The adjustment of the output current compensated corresponding to the second priority to the corresponding current value to be compensated can be realized by referring to the following steps:
judging whether the compensated output current corresponding to the second priority is larger than the corresponding current value to be compensated;
If yes, reducing the output current compensated corresponding to the second priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority;
and (III) if not, increasing the compensated output current corresponding to the second priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance corresponding to the second priority.
In the embodiment of the present invention, when it is determined that the compensated output current corresponding to the second priority is greater than the corresponding current value to be compensated, the harmonic compensation current of the second priority is correspondingly reduced to the harmonic current value to be compensated, so that the harmonic is compensated to the target total harmonic distortion rate, and at this time, the reactive power of the first priority and the harmonic of the second priority can be fully compensated.
In the embodiment of the present invention, when it is determined that the current output total current after compensation corresponding to the first priority is smaller than the second target threshold of the rated current value, that is, after the reactive power of the first priority is completely compensated, a certain current remains in the active power filter for compensation output, and at this time, the harmonic of the second priority can be compensated, that is, the harmonic compensation current is increased.
In the process of increasing the harmonic compensation current, when the harmonic compensation current is increased to a harmonic current value to be compensated, the current output total current is smaller than a rated current value, so that the reactive power of the first priority and the harmonic of the second priority can be completely compensated, and at the moment, the active power filter can further continuously use residual current for compensating unbalance; or it may occur that when the current output total current is increased to reach the rated current, the harmonic compensation current of the current output total current does not reach the harmonic current value to be compensated, and at this time, the active power filter outputs at the rated current value to realize the reactive full compensation of the first priority and the partial compensation of the harmonic of the second priority.
Therefore, in the process of increasing the harmonic compensation current, it needs to determine whether the rated current value is reached first or the harmonic compensation current value to be compensated is reached first. When the harmonic compensation current of the second priority is increased to the harmonic compensation current value to be compensated and the compensated current output total current is smaller than the rated current value, whether the imbalance of the third priority is further compensated or not can be correspondingly judged. When the unbalanced compensation current of the third priority is reduced to close the output of the unbalanced compensation current, the increase of the harmonic compensation current of the second priority is correspondingly stopped, so that the current output total current is not greater than the rated current value. The active power filter is now output at a rated current value to achieve full compensation of reactive power of a first priority and partial compensation of harmonics of a second priority.
step S44, judging whether the compensated current output total current corresponding to the second priority is smaller than a second target threshold value of the rated current value;
when it is determined whether the compensated current output total current corresponding to the second priority is smaller than the second target threshold of the rated current value, step S45 is executed; otherwise, stopping adjusting the compensated output current corresponding to the third priority.
In the embodiment of the present invention, when the compensated output current corresponding to the second priority is increased to the corresponding current value to be compensated, and the current output total current is smaller than the rated current value, it is determined whether the current output total current after compensation corresponding to the second priority is smaller than the second target threshold value of the rated current value, wherein, when the current output total current is larger than the second target threshold value of the rated current value, the compensation is not performed on the third priority, for example, in the embodiment, the second target threshold value is specifically 95%, the rated current value is 100A, when the current output total current is 98A, the compensation is not performed on the third priority, at this time, the adjustment of the compensated output current corresponding to the third priority is stopped, that is, at this time, the reactive power of the first priority and the harmonic of the second priority are completely compensated, and at the active power filter keeps a certain current margin, to ensure stable operation of the system.
And step S45, adjusting the compensated output current corresponding to the third priority so that the current total output current is not greater than the rated current value.
in the embodiment of the present invention, when it is determined that the current output total current compensated for the second priority is smaller than the second target threshold of the rated current value, the output current compensated for the third priority is increased, so that the total output current is not greater than the rated total current, and the active power filter can implement complete compensation for the reactive power of the first priority and the harmonic of the second priority, and partial compensation for the imbalance of the third priority.
In the embodiment of the invention, the current value to be compensated of the first priority is compensated by the active power filter in priority, and when the rated current value is smaller than the current value to be compensated corresponding to the first priority, the active power filter outputs all current to compensate the first priority, so that the partial compensation of the first priority is realized; after the first priority is completely compensated, judging whether the total output current is close to a rated current value, if so, not compensating the other current so as to keep a certain current margin and realize the stable operation of the system; if not, the compensation of the second priority is continued, and in turn, the sequential compensation can be performed according to the priority until the rated current value is reached, so that one or more of the active power filters can be effectively compensated, and the problem that the active power filters compensate the reactive power, the filtering power and the unbalance, but each of the active power filters does not have good compensation is solved. Meanwhile, the high priority is compensated to the corresponding current value to be compensated, so that the problem of insufficient compensation or excessive compensation caused by the existing reactive power, harmonic power and load unbalanced power according to preset compensation is avoided, and the current output by the active power filter can be utilized to the maximum extent.
the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. an active power filter intelligent compensation control method, characterized in that the method comprises:
Determining a reactive current value, a harmonic current value and an unbalanced current value to be compensated according to the detected load current, a preset target power factor, a target total harmonic distortion rate and a target unbalance degree;
judging whether the current output total current is larger than the rated current value of the active power filter or not;
If so, sequentially reducing the output current correspondingly compensated by the low-priority sequencing sequence according to the preset priority sequencing compensated by reactive power, harmonic waves and unbalance until the current output total current is not greater than the rated current value;
if not, according to the preset priority sequence, within the range of the rated current value, sequentially compensating the output current correspondingly compensated by the high-priority sequence to the determined corresponding current value to be compensated, so as to sequentially compensate the target power factor, the target total harmonic distortion rate and the target unbalance degree corresponding to the high-priority sequence.
2. the active power filter intelligent compensation control method of claim 1, wherein the low priority is sorted in order of a third priority, a second priority, and a first priority;
the step of sequentially reducing the compensated output current in the low priority sorting order comprises:
Judging whether the current output total current is larger than the rated current value or not when the compensated output current corresponding to the third priority is reduced to be within a first target threshold value of the rated current value;
if so, the output of the output current compensated corresponding to the third priority is closed, and the output current compensated corresponding to the second priority is reduced.
3. The active power filter intelligent compensation control method of claim 2, wherein after the step of reducing the compensated output current corresponding to the second priority, the method further comprises:
Judging whether the current output total current is larger than the rated current value or not when the compensated output current corresponding to the second priority is reduced to be within a first target threshold value of the rated current value;
if so, the output of the output current compensated corresponding to the second priority is closed, and the output current compensated corresponding to the first priority is reduced until the total output current is not greater than the rated current value.
4. The active power filter intelligent compensation control method of claim 1, wherein the high priority is ordered as a first priority, a second priority, and a third priority;
The step of sequentially compensating the output current corresponding to the high-priority sorting sequence to the determined corresponding current value to be compensated comprises the following steps:
Adjusting the output current compensated corresponding to the first priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion rate or the target unbalance degree corresponding to the first priority;
judging whether the compensated current output total current corresponding to the first priority is smaller than a second target threshold value of the rated current value;
If so, adjusting the output current compensated corresponding to the second priority to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority;
if not, stopping adjusting the compensated output current corresponding to the second priority;
judging whether the compensated current output total current corresponding to the second priority is smaller than a second target threshold value of the rated current value;
If so, adjusting the output current correspondingly compensated by the third priority to the corresponding current value to be compensated so as to enable the current output total current to be not greater than the rated current value;
if not, stopping adjusting the compensated output current corresponding to the third priority.
5. The active power filter intelligent compensation control method of claim 4, wherein the step of adjusting the output current compensated for the first priority to the corresponding current value to be compensated comprises:
Judging whether the output current compensated corresponding to the first priority is larger than the corresponding current value to be compensated or not;
If so, reducing the output current compensated corresponding to the first priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion rate or the target unbalance degree corresponding to the first priority;
If not, the output current compensated corresponding to the first priority is increased to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the first priority.
6. the active power filter intelligent compensation control method of claim 4, wherein the step of adjusting the output current compensated for the second priority to the corresponding current value to be compensated comprises:
Judging whether the output current compensated corresponding to the second priority is larger than the corresponding current value to be compensated or not;
If so, reducing the compensated output current corresponding to the second priority to the corresponding current value to be compensated so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority;
if not, the output current corresponding to the second priority is increased to the corresponding current value to be compensated, so as to compensate to the target power factor, the target total harmonic distortion or the target unbalance degree corresponding to the second priority.
7. the active power filter intelligent compensation control method of claim 1, wherein the step of determining the reactive current value, the harmonic current value, and the unbalance current value to be compensated according to the detected load current and preset target power factor, target total harmonic distortion rate, and target unbalance degree comprises:
Detecting the current load current;
determining a reactive current value to be compensated according to the load current and the target power factor;
determining a harmonic current value to be compensated according to the load current and the target total harmonic distortion rate;
and determining the value of the unbalance current to be compensated according to the load current and the target unbalance degree.
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