CN112436509A - Control method of intelligent capacitor in distribution transformer area - Google Patents

Control method of intelligent capacitor in distribution transformer area Download PDF

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Publication number
CN112436509A
CN112436509A CN202011220863.1A CN202011220863A CN112436509A CN 112436509 A CN112436509 A CN 112436509A CN 202011220863 A CN202011220863 A CN 202011220863A CN 112436509 A CN112436509 A CN 112436509A
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limit
voltage
control
capacitor
load
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CN112436509B (en
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王朝明
马春生
虞凡
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Nanjing Softcore Science & Technology Co ltd
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Nanjing Softcore Science & Technology Co ltd
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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
    • H02J3/003—Load forecast, e.g. methods or systems for forecasting future load demand
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
    • H02J3/144—Demand-response operation of the power transmission or distribution network
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • 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
    • H02J3/1807—Arrangements for adjusting, eliminating or compensating reactive power in networks using series compensators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • 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
    • Y02E40/30—Reactive power compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
    • Y04S20/20—End-user application control systems
    • Y04S20/222—Demand response systems, e.g. load shedding, peak shaving

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The invention discloses a control method of an intelligent capacitor of a distribution transformer area, which comprises the steps of circularly reading real-time data at the head end of the transformer area through the capacitor and judging whether a control mode is the control of a master station; if the control is the master station control, the control optimization limit is set by the master station; otherwise, calculating a voltage control optimization limit and a power factor control optimization limit according to the real-time data; if the voltage exceeds the check limit, adjusting the voltage and recording action information; otherwise, judging whether the voltage or the power factor exceeds the optimization limit; if the optimization limit is not exceeded, adjusting reactive compensation capacity according to a control target; otherwise, judging whether the load variation trend is reduced or not; if the optimization-exceeding condition is lightened, the control is cancelled; otherwise, adjusting the input capacity of the capacitor and recording the action information. The invention can make the control target more reasonable, and meanwhile, the change trend of the load is judged through load prediction, thereby effectively reducing the action times of the equipment.

Description

Control method of intelligent capacitor in distribution transformer area
Technical Field
The invention relates to the technical field of reactive power optimization of a power distribution network, in particular to a control method of an intelligent capacitor in a distribution transformer area.
Background
Most of the power loads are sensitive and need to consume reactive power, reactive compensation equipment is generally installed at a distribution transformer outlet to perform local compensation, and the flow of the reactive power in a power grid is reduced, so that the electric energy loss and the voltage loss of a circuit are reduced, the active power transmission capacity of a feeder line and a transformer is improved, and the electric energy quality is improved.
The common capacitor control strategy is that when the voltage or power factor is out of limit, the switching of the capacitor is controlled by the strategy, the capacitor is not controlled when the voltage and power factor reach the qualified range, and in order to reduce the action times, the voltage range and the power factor range are generally set to be larger, so that the basic qualified conditions of the national standard can be met, and the fine control of the capacitor cannot be realized.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above-mentioned conventional problems.
Therefore, the invention provides a control method of the intelligent capacitor in the distribution transformer area, which can realize the fine control of the capacitor.
In order to solve the technical problems, the invention provides the following technical scheme: the method comprises the steps of circularly reading three-phase voltage, active power, reactive power and power factor at the head end of a transformer area through a capacitor, and judging whether a control mode is master station control; if the control mode is the master station control, the control optimization limit is set by the master station; otherwise, calculating a voltage control optimization limit and a power factor control optimization limit according to the read value; if the three-phase voltage exceeds the assessment limit, adjusting the three-phase voltage and recording action information; otherwise, judging whether the three-phase voltage or the power factor exceeds the optimization limit; if the optimization limit is not exceeded, adjusting reactive compensation capacity according to a control target; otherwise, judging whether the load variation trend is reduced or not; if the optimization-exceeding condition is lightened, the control is cancelled; otherwise, adjusting the input capacity of the capacitor and recording the action information.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the voltage control optimization limit comprises when Smeas＜0.5SNThe method comprises the following steps:
uopt＝(Smeas-Smin)/(Smax-Smin) (u _ h _ limit-u _ l _ limit) + u _ l _ limit as Smeas≥0.5SNThe method comprises the following steps:
uopt＝u_h_limit
wherein S isNFor distribution of rated capacity, uoptTo an economic voltage, SmaxAnd SminRespectively maximum and minimum apparent power, S, that may occurmeasFor measured apparent power, u _ l _ limit and u _ h _ limit are the lower and upper threshold limits of the economic voltage, respectively.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the power factor control optimization limit comprises the following reactive power upper limit:
Figure BDA0002761973240000021
lower limit of reactive power:
Figure BDA0002761973240000022
wherein cosLTheta is the minimum power factor of the reactive power forward transmission, P is the active power, cosHTheta is the minimum power factor for reactive power reverse transmission.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the voltage adjustment comprises that the input compensation capacity is reduced if the three-phase voltage is more qualified than the upper limit, and the input compensation capacity is increased if the three-phase voltage is more qualified than the lower limit; the compensation capacity put into is:
Figure BDA0002761973240000023
wherein, Δ uneedFor the voltage change to be adjusted, Δ u0To throw in Qreal0Amount of temporal voltage change, Qreal0The actual capacity of the switching.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the action information comprises action time, adjustment capacity, a current voltage value, three-phase voltage variation and voltage variation caused by different voltages and different adjustment capacities.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the method is characterized in that: the reactive compensation capacity comprises the following components of,
Figure BDA0002761973240000031
wherein Q isrealFor the actual reactive compensation capacity of said capacitor, umeasFor actual measurement of voltage, UNFor rated voltage, Q, of said capacitorNFor rated capacity, L is the capacitor series reactance, and β is the capacitor efficiency.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the optimization-exceeding limit also comprises the steps that the number of times of the optimization-exceeding limit is increased by 1, and the number of times of the evaluation-exceeding limit and the number of times of qualified voltage are decreased by 1 when the three-phase voltage exceeds the optimization limit; and when the power factor is beyond the optimization limit, adding 1 to the number of times of exceeding the optimization limit, and subtracting 1 from the number of qualified times of the power factor.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the above-mentionedAdjusting the input capacity of the capacitor comprises adjusting the reactive compensation capacity if the three-phase voltage exceeds the check limit; if the three-phase voltage is qualified and the reactive power exceeds the check limit, determining the reactive power adjustment quantity through the reactive power range; defining the actual reactive power as QmeasIf said Q ismeas＞QHActually cutting off the capacitor capacity; if said Q ismeas＜QLThen the capacitor capacity should actually be put in.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the judging of the load change trend comprises the steps of calculating daily average load and linearly fitting the daily average load; predicting the average load of N +1 days; calculating a load change coefficient, and taking a weighted summation value of the load change coefficients of the previous N days as the load change coefficient of the N +1 day; and predicting the load of each time interval on the N +1 day.
As a preferable scheme of the control method of the intelligent capacitor in the distribution transformer area, the method comprises the following steps: the method also comprises the steps of carrying out linear fitting on the data of the current load and 6 subsequent prediction points, and if the load change rate is greater than a load increase threshold value, considering that the load is increased; if the load change rate is smaller than a drop threshold, the load is considered to be dropped; and if the load change rate is equal to a gentle threshold value, the load is considered to be in a gentle state.
The invention has the beneficial effects that: the invention dynamically adjusts the voltage threshold according to the load rate, and adjusts the power factor threshold range according to the actual measurement voltage condition, so that the control target is more reasonable; meanwhile, the load change trend is judged through load prediction, and when the voltage and the power factor are more optimal, if the load change trend enables the out-of-limit degree to be reduced, the equipment does not act, and the equipment action times are effectively reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
fig. 1 is a schematic flow chart of a control method of a distribution transformer area intelligent capacitor according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of a reactive load and reactive compensation capacity curve of a control method of an intelligent capacitor in a distribution transformer area according to a second embodiment of the present invention;
fig. 3 is a schematic diagram of reactive power curves before and after compensation of a control method for an intelligent capacitor of a distribution transformer area according to a second embodiment of the present invention;
fig. 4 is a schematic diagram of power factor curves before and after compensation of a control method for an intelligent capacitor of a distribution transformer area according to a second embodiment of the present invention;
fig. 5 is a schematic diagram of a reactive power and compensation capacity curve of an optimized control of a control method of an intelligent capacitor in a distribution transformer area according to a second embodiment of the present invention;
fig. 6 is a schematic diagram of a reactive power curve before compensation and a reactive power curve after optimization control of a control method for an intelligent capacitor in a distribution transformer area according to a second embodiment of the present invention;
fig. 7 is a schematic diagram of a power factor curve before compensation and a power factor curve after optimization control of a control method for an intelligent capacitor of a distribution transformer area according to a second embodiment of the present invention;
fig. 8 is a schematic diagram illustrating a reactive load and a load prediction result of a control method for an intelligent capacitor of a distribution transformer area according to a second embodiment of the present invention;
fig. 9 is a schematic view illustrating a load trend determination of a control method of an intelligent capacitor in a distribution transformer area according to a second embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1, a first embodiment of the present invention provides a method for controlling a smart capacitor of a distribution transformer area, including:
s1: and (4) configuring basic parameters.
Basic parameters such as transformer capacity, voltage assessment limit values, initial control modes and data sampling intervals are configured, the parameters to be configured are stored in a sqlite database in a control terminal, and configuration parameters are modified through a database client or SQL statements.
S2: and circularly reading the three-phase voltage, active power, reactive power and power factor at the head end of the transformer area through a capacitor.
According to the set data sampling interval, real-time data such as three-phase voltage, active power, reactive power, power factor and the like at the head end/distribution transformer outlet of the transformer area are read circularly through a capacitor or a controller.
S3: and reading the parameter configuration data, and judging whether the control mode is the master station control.
The control mode is divided into a main station control mode and a local control mode, the main station control mode is used for issuing a control target value by the main station, and the local control mode is used for calculating the control target value by a control program in the controller.
S4: if the control mode is master station control, the control optimization limit is set by the master station; otherwise, the economic voltage range and the reactive power range are calculated according to the real-time data.
(1) If the three-phase voltage is controlled by the master station, reading a control threshold value issued by the master station, and judging whether the three-phase voltage exceeds an optimization limit according to the control threshold value;
the control threshold value issued by the main station comprises a voltage target value, a power factor target value and a reactive power target value, and the parameters corresponding to the sqlite database in the control terminal are modified through SQL statements to complete issuing of the control target.
(2) And if the control mode is local control, calculating the load rate, the economic voltage range, the power factor and the reactive power optimization range to obtain a voltage control optimization limit and a power factor control optimization limit.
Specifically, (a) the load factor calculation formula is as follows:
Figure BDA0002761973240000061
wherein S ismeasFor measured apparent power, SNRated capacity is changed for distribution;
(b) the economic voltage range (i.e., voltage control optimization limit) is as follows:
when Smeas＜0.5SNThe method comprises the following steps:
uopt＝(Smeas-Smin)/(Smax-Smin)*(u_h_limit-u_l_limit)+u_l_limint
when Smeas≥0.5SNThe method comprises the following steps:
uopt＝u_h_limit
wherein S isNFor distribution of rated capacity, uoptTo an economic voltage, SmaxAnd SminRespectively maximum and minimum apparent power, S, that may occurmeasIs the measured apparent power;
threshold of economic voltage:
u_l_limit＝1.00p.u./220V
u_h_limit＝1.07p.u./235V
the above limits may be adjusted according to field operating requirements.
Further:
u_opt_h＝u_opt+u_ref*u_sen
u_opt_l＝u_opt-u_ref*u_sen
wherein u _ opt _ h is an upper optimized voltage limit, u _ opt _ l is a lower optimized voltage limit, u _ opt is a target voltage, u _ sen is a voltage regulation sensitivity, u _ ref is a reference voltage, and the voltage of the transformer area is 220V.
(c) Range of power factor:
setting allowable power factor limit values under different load rates and voltages based on analysis and calculation results of distribution transformer historical operating data, wherein the power factor limit values support main station online adjustment, and default values are shown in the following table:
table 1: power factor limit versus voltage and duty cycle.
Figure BDA0002761973240000071
(d) The reactive power limit ranges are as follows:
upper reactive power limit (maximum reactive power of system input):
Figure BDA0002761973240000072
lower reactive power limit (reactive reverse, maximum reactive power transmitted to the system):
Figure BDA0002761973240000073
wherein cosLTheta is the minimum power factor of the reactive power forward transmission, P is the active power, cosHTheta is the minimum power factor for reactive power reverse transmission.
And (d) calculating and obtaining a voltage control optimization limit and a power factor control optimization limit according to (a), (b), (c) and (d).
And further, judging whether the three-phase voltage exceeds the evaluation limit.
S5: if the three-phase voltage exceeds the assessment limit, adjusting the three-phase voltage and recording action information; otherwise, judging whether the three-phase voltage or the power factor exceeds the optimization limit.
It should be noted that, according to the national standard "power quality supply voltage allowable deviation" GB 12325-2008, the upper limit of the voltage check is 235.4V, and the lower limit of the voltage check is 204.6V.
(1) If the three-phase voltage exceeds the assessment limit:
and if the three-phase voltage is more qualified, the input compensation capacity is reduced, and if the three-phase voltage is more qualified, the input compensation capacity is increased.
Specifically, the compensation capacity put into is:
Figure BDA0002761973240000081
wherein, Δ uneedFor the voltage change to be adjusted, Δ u0To throw in Qreal0Amount of temporal voltage change, Qreal0The actual capacity of the switching.
The reactive capacity Q to be adjustedreal0The power factor and reactive power optimization range constraints need to be met.
Further, recording action information; the action information includes action time, adjustment capacity, current voltage value and voltage variation, and records voltage variation caused by different voltages and different adjustment capacities in the reactive voltage sensitivity table, and then goes to step S2.
(2) If the three-phase voltage does not exceed the assessment limit:
and determining whether the three-phase voltage exceeds the optimization limit or whether the power factor exceeds the optimization limit or not through the voltage control optimization limit, the power factor control optimization limit and the set voltage adjustment sensitivity.
S6: if the optimization limit is not crossed, adjusting the reactive compensation capacity according to the control target; otherwise, judging whether the load variation trend is reduced or not.
(1) The three-phase voltage or power factor does not cross the optimal limit:
and adjusting the reactive compensation capacity according to the voltage target value and the power factor target value and according to the following formula:
Figure BDA0002761973240000082
wherein Q isrealFor the actual reactive compensation capacity of the capacitor, umeasFor actual measurement of voltage, UNFor rated voltage, Q, of the capacitorNTo ratedCapacity, L is the series reactance of the capacitor, and beta is the efficiency of the capacitor;
capacitor series reactance rate:
Figure BDA0002761973240000083
wherein, XLIs an inductive reactance, XCIs capacitive reactance;
capacitor efficiency:
Figure BDA0002761973240000084
wherein, the capacitor is complemented in total:
Figure BDA0002761973240000091
ua、ub、ucvoltages at points a, b, c, ia、ib、icThe currents at points a, b, c, respectively; and (3) separately compensating the capacitance:
Figure BDA0002761973240000092
ux，ixvoltage and current at x, respectively;
Figure BDA0002761973240000093
if the actual need is to compensate the capacity to be QrealThen corresponding rated capacity QNComprises the following steps:
Figure BDA0002761973240000094
further, after the adjustment is completed, the process returns to step S2.
Preferably, when the compensation capacity required to be adjusted by the compensation equipment is carried out, the influence of the actual voltage, the capacitor capacity attenuation and the series reactance is considered, so that the actual compensation capacity is closer to the target compensation capacity, and the control target is more reasonable.
(2) If the three-phase voltage or power factor crosses the optimization limit:
firstly, when the voltage is beyond the optimization limit, the number of times of exceeding the optimization limit is increased by 1, the number of times of exceeding the optimization limit and the number of times of qualified voltage are decreased by 1, and when the number of times of exceeding the optimization limit reaches the threshold value of the number of times of exceeding the optimization limit, the state of the system is judged to be the voltage exceeding the optimization limit.
And secondly, when the power factor is more optimized, adding 1 to the more optimized times, subtracting 1 from the qualified times of the power factor, and when the more optimized times reach the more optimized times threshold, judging that the system state is that the power factor is more optimized. The maximum value of the accumulated out-of-limit times is the corresponding out-of-limit times threshold value, and the minimum value is 0.
Further, whether the load change trend is reduced or not is judged.
Specifically, the load trend judgment comprises two steps of load prediction and trend judgment.
(1) Load prediction
Preferably, the forecast day is divided into a working day and a rest day, and the historical data of the reactive load on the load side are respectively stored, so that the forecast is more accurate. Specifically, historical data is stored every 5 minutes, data from monday to friday is stored on weekdays, data for 6 days on 3 weekends is stored on weekends, an N +1 day load curve is predicted according to the previous N calendar historical data, the load curve is divided into T time periods every day, and the load value of the ith day and the tth time period is recorded as xi，tIf the interval is 5 minutes, 288 sampling points are obtained.
The algorithm flow of the load prediction is as follows:
calculating daily average load:
Figure BDA0002761973240000095
wherein, yiAverage reactive power of ith day;
linear fitting daily average load:
Figure BDA0002761973240000101
wherein the content of the first and second substances,
Figure BDA0002761973240000102
predicting the average load of N +1 days:
Figure BDA0002761973240000103
calculating the load change coefficient (i day t time load value divided by i day average load):
Figure BDA0002761973240000104
weighting and summing the load change coefficients of the previous N days to obtain the load change coefficient of the N +1 day:
load change coefficient for the first N days:
Figure BDA0002761973240000105
load change coefficient for day N + 1:
Figure BDA0002761973240000106
predicting the load of each time interval of the N +1 day:
Figure BDA0002761973240000107
(2) trend determination
The historical data is stored every 5 minutes, the load trend of 30 minutes later is predicted every 5 minutes, wherein the load trend is divided into ascending, descending and gentle, and the abscissa is fixed for 0-30 min.
Specifically, linear fitting is performed on the data of the current load and the following 6 prediction points, if the slope k (i.e., the load change rate) is greater than an ascending threshold (configuration parameter), the load is considered to be increased, if the slope k is less than a descending threshold, the load is considered to be decreased, otherwise, the load is considered to be in a gentle state.
S7: if the situation of exceeding the optimization limit is lightened, the control is cancelled; otherwise, adjusting the input capacity of the capacitor and recording the action information.
(1) If the problem of the optimization limit is reduced by the load variation tendency, the control command for inputting or removing the compensation equipment is cancelled, the equipment control is not performed, and the process returns to step S2.
(2) If the load variation trend can not reduce the out-of-limit problem, the input capacity of the capacitor is adjusted according to the adjustment measure, and the action information is recorded.
Specifically, the input capacity of the capacitor is adjusted:
firstly, if the three-phase voltage exceeds the assessment limit, adjusting the reactive compensation capacity; if the three-phase voltage is qualified but the reactive power exceeds the check limit, the upper limit Q of the reactive power is passedHAnd upper and lower limits of reactive power QLDetermining reactive adjustment quantity;
② defining the actual reactive power as Qmeas：
If Qmeas＞QHThen, the capacitor capacity should actually be cut off: qreal＝Qmeas-QH；
If Qmeas＜QLThen, the capacitor capacity should be actually put in: qreal＝QL-Qmeas。
Further, the action information is recorded, and the process returns to step S2.
Example 2
In order to verify and explain the technical effects adopted in the method, the embodiment selects a common capacitor control method and adopts the method to perform a comparison test, and compares test results by means of scientific demonstration to verify the real effect of the method.
In order to reduce the number of times of actions, the voltage range and the power factor range of the common capacitor control method are generally set to be larger, and fine control cannot be achieved.
In order to verify that the method can effectively reduce the number of equipment actions and improve the operation state of the capacitor compared with a common capacitor control method, the common capacitor control method and the method are adopted in the embodiment to respectively control and compare actual operation data of a certain area during summer load peak.
The parameter values for a certain area before compensation is performed are shown in the following table.
Table 1: and (5) a parameter setting table before compensation.
Average reactive power Average power factor Capacity of transformer Capacity of container group Minimum regulating capacity
49.4kvar 0.884 400kVA 120kvar 10kvar
According to the parameters shown in the table 1, respectively adopting a common capacitor control method and the method to carry out simulation test on a python platform; and reading in operation data through python programming, analyzing and calculating the distribution transformer voltage quality of different discontinuous surfaces, controlling the input quantity of the capacitor, and outputting new operation data of distribution transformer after the capacitor is added and a control strategy of the capacitor is added.
The reactive power result curve before and after compensation by adopting a common capacitor control method is shown in figure 3, and the power factor curve before and after compensation is shown in figure 4.
The reactive power result curve before and after compensation by adopting the control method of the intelligent capacitor of the distribution transformer area is shown in fig. 6, and the power factor curve before and after compensation is shown in fig. 7.
The control results of the two control methods can be obtained by combining fig. 3, fig. 4, fig. 6 and fig. 7, and the specific numerical values are shown in table 2.
Table 2: and respectively adopting a control result comparison table of a common capacitor control method and the control result comparison table of the method for actual operation data of a certain area.
Method of producing a composite material Compensating reactive power of rear system side Compensated power factor
Common capacitor control method 14.3kvar 0.979
Method for producing a composite material 4.2kvar 0.987
As can be seen from the above table, the control of the reactive power by the common capacitor control method is improved by 35.1kvar, and the control of the reactive power by the method is improved by 45.2 kvar; the common capacitor control method improves the power factor by 0.095, and the method improves the power factor by 0.103; the running state and the voltage quality of the capacitor are better and the energy is saved after the method is adopted.
The load prediction result of the invention is shown in fig. 8, the abscissa is the data point serial number, the ordinate is the reactive load capacity, the unit is kvar, and the predicted load trend is basically consistent with the actual load trend.
The result of the load change trend determined by the trend determination algorithm is shown in fig. 9, where an ordinate value of 1 indicates an increase in load, an ordinate value of 0 indicates a gradual change in load, and an ordinate value of minus 1 indicates a decrease in load. The gray curve is the load trend calculated according to the trend judgment algorithm, and the black curve is the result obtained by further analysis on the basis, so that part of short-term load fluctuation is filtered, and the equipment action times are effectively reduced.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims (10)

1. A control method of an intelligent capacitor in a distribution transformer area is characterized by comprising the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
circularly reading three-phase voltage, active power, reactive power and power factor at the head end of the transformer area through a capacitor, and judging whether the control mode is master station control;
if the control mode is the master station control, the control optimization limit is set by the master station; otherwise, calculating a voltage control optimization limit and a power factor control optimization limit according to the read value; if the three-phase voltage exceeds the assessment limit, adjusting the three-phase voltage and recording action information; otherwise, judging whether the three-phase voltage or the power factor exceeds the optimization limit;
if the optimization limit is not exceeded, adjusting reactive compensation capacity according to a control target; otherwise, judging whether the load variation trend is reduced or not;
if the optimization-exceeding condition is lightened, the control is cancelled; otherwise, adjusting the input capacity of the capacitor and recording the action information.
2. The method for controlling the intelligent capacitor of the distribution transformer area according to claim 1, wherein: the voltage control optimization limits may include,
when S ismeas＜0.5SNThe method comprises the following steps:
uopt＝(Smeas-Smin)/(Smax-Smin)*(u_h_limit-u_l_limit)+u_l_limint
when S ismeas≥0.5SNThe method comprises the following steps:
uopt＝u_h_limit
wherein S isNFor distribution of rated capacity, uoptTo an economic voltage, SmaxAnd SminRespectively maximum and minimum apparent power, S, that may occurmeasFor measured apparent power, u _ l _ limit and u _ h _ limit are the lower and upper threshold limits of the economic voltage, respectively.
3. The method for controlling the intelligent capacitor of the distribution transformer area as claimed in claim 2, wherein: the power factor control optimization limit comprises a power factor control optimization limit,
upper limit of reactive power:
Figure FDA0002761973230000011
lower limit of reactive power:
Figure FDA0002761973230000012
wherein cosLTheta is the minimum power factor of the reactive power forward transmission, P is the active power, cosHTheta is the minimum power factor for reactive power reverse transmission.
4. The control method of the distribution transformer area intelligent capacitor as claimed in claim 1 or 3, characterized in that: the voltage adjustment includes the steps of,
if the three-phase voltage is more checked to be in an upper limit, reducing the input compensation capacity, and if the three-phase voltage is more checked to be in a lower limit, increasing the input compensation capacity;
the compensation capacity put into is:
Figure FDA0002761973230000021
wherein, Δ uneedFor the voltage change to be adjusted, Δ u0To throw in Qreal0Amount of temporal voltage change, Qreal0The actual capacity of the switching.
5. The method for controlling intelligent capacitors of distribution transformer areas according to claim 4, wherein: the action information includes, in a form of a message,
the voltage variation of the three-phase system is determined according to the voltage variation of the three-phase system, the current voltage value, the voltage variation of the three-phase system and the voltage variation caused by different voltages and different adjustment capacities.
6. The method for controlling the intelligent capacitor of the distribution transformer area as claimed in any one of claims 2, 3 and 5, wherein: the reactive compensation capacity comprises the following components of,
Figure FDA0002761973230000022
wherein Q isrealFor the actual reactive compensation capacity of said capacitor, umeasFor actual measurement of voltage, UNFor rated voltage, Q, of said capacitorNFor rated capacity, L is the capacitor series reactance, and β is the capacitor efficiency.
7. The method for controlling intelligent capacitors of distribution transformer areas according to claim 6, wherein: the out-of-optimization limit may further include,
when the three-phase voltage exceeds the optimization limit, the number of times of exceeding the optimization limit is increased by 1, and the number of times of exceeding the examination limit and the number of times of qualified voltage are decreased by 1;
and when the power factor is beyond the optimization limit, adding 1 to the number of times of exceeding the optimization limit, and subtracting 1 from the number of qualified times of the power factor.
8. The method for controlling the intelligent capacitor of the distribution transformer area according to claim 3 or 7, wherein: the adjusting of the input capacitance of the capacitor comprises,
if the three-phase voltage exceeds the check limit, adjusting the reactive compensation capacity;
if the three-phase voltage is qualified and the reactive power exceeds the check limit, determining the reactive power adjustment quantity through the reactive power range;
defining the actual reactive power as QmeasIf said Q ismeas＞QHActually cutting off the capacitor capacity; if said Q ismeas＜QLThen the capacitor capacity should actually be put in.
9. The method for controlling intelligent capacitors of distribution transformer areas according to claim 8, wherein: the judging of the load variation tendency includes,
calculating daily average load, and linearly fitting the daily average load;
predicting the average load of N +1 days;
calculating a load change coefficient, and taking a weighted summation value of the load change coefficients of the previous N days as the load change coefficient of the N +1 day;
and predicting the load of each time interval on the N +1 day.
10. The method for controlling intelligent capacitors of distribution transformer areas according to claim 9, wherein: also comprises the following steps of (1) preparing,
taking data of the current load and 6 prediction points behind the current load to perform linear fitting, and if the load change rate is greater than a load increase threshold, determining that the load is increased; if the load change rate is smaller than a drop threshold, the load is considered to be dropped; and if the load change rate is equal to a gentle threshold value, the load is considered to be in a gentle state.
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