Method and system for determining reactive power compensation capacity of a transformer area and voltage out-of-limit treatment device

Abstract

The application discloses a kind of transformer area reactive power compensation capacity determination method, system and voltage out-of-limit management device, it is applied to rural transformer area voltage reactive power compensation, this method includes: obtaining transformer area daytime maximum reverse sending power, nighttime maximum load power and line basic parameters, and maximum voltage threshold, minimum voltage threshold;Line reactance and real-time line resistance are calculated in combination with line basic parameters;By maximum voltage and minimum voltage respectively compared with respective threshold, in combination with transformer area daytime maximum reverse sending power, nighttime maximum load power, line reactance and real-time line resistance, the reactive power compensation capacity of transformer area is calculated.The application is in work, according to transformer area relevant information, capacitor and reactor reactive power compensation capacity calculation is carried out, and relatively accurate reactive power compensation capacity is obtained, then voltage out-of-limit management device capacity is configured, so that reactive power voltage regulating effect can adapt to the actual situation requirement of transformer area, effectively governs transformer area voltage daytime and nighttime bidirectional out-of-limit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid operation control, and particularly relates to a transformer area reactive power compensation capacity determination method and system and a voltage out-of-limit treatment device. BACKGROUND

[0002] With the continuous expansion of the distribution network scale and the high proportion of distributed energy (such as distributed photovoltaic) access, the transformer area voltage out-of-limit problem is increasingly prominent. The distributed photovoltaic access stock and incremental scale expands rapidly, and the access of distributed photovoltaic leads to frequent voltage over-limit situation. The transformer area voltage out-of-limit situation has great uncertainty in long and short time scales and spatial distribution of transformer area, and is difficult to efficiently govern. Due to load fluctuation and source-load output mismatch, the voltage is bidirectional out-of-limit, which is difficult to govern. Voltage out-of-limit (too high or too low) affects the safe operation of electrical equipment, causes electrical equipment damage or efficiency reduction, and may also threaten the stability of the power grid.

[0003] Traditional treatment methods mainly rely on transformer tap adjustment, reactive power compensation device switching, etc. However, considering factors such as line impedance difference, the complexity of voltage control is increased. In the scene of high volatility load or high distributed power penetration rate, these methods often have response lag and insufficient adjustment capacity. SUMMARY

[0004] In view of the above problems, the present application provides a transformer area reactive power compensation capacity determination method, system and voltage out-of-limit treatment device.

[0005] The technical scheme of the present application is: a transformer area reactive power compensation capacity determination method applied to rural transformer area voltage reactive power compensation, comprising:

[0006] Obtaining the maximum reverse sending power during the day, the maximum load power at night and the line basic parameters of the transformer area, and the maximum voltage threshold and the minimum voltage threshold;

[0007] Calculating the line reactance and real-time line resistance in combination with the line basic parameters;

[0008] By comparing the maximum voltage and the minimum voltage with their respective thresholds respectively, and combining the maximum reverse sending power during the day, the maximum load power at night, the line reactance and the real-time line resistance, the reactive power compensation capacity of the transformer area is calculated, wherein,

[0009] In the daytime scenario of the transformer area, when the maximum voltage is greater than the maximum voltage threshold, the inductive reactive power compensation capacity of voltage over-limit is calculated according to the maximum reverse sending power during the day, the line impedance and the real-time line resistance;

[0010] In the nighttime scenario of the transformer area, when the minimum voltage is less than the minimum voltage threshold, the capacitive reactive power compensation capacity of voltage under-limit is calculated according to the maximum load power at night, the line reactance and the real-time line resistance.

[0011] The inductive reactive power compensation capacity exceeding the upper limit of the voltage is calculated according to the maximum daytime reverse power, the line impedance and the real-time line resistance, and is specifically calculated by the following formula:

[0012]

[0013] In the formula, Q c1 is the inductive reactive power compensation capacity, P PV is the maximum daytime reverse power, R 实时 is the real-time line resistance, and X is the line reactance.

[0014] And / or, the capacitive reactive power compensation capacity below the lower limit of the voltage is calculated according to the maximum nighttime load power, the line reactance and the real-time line resistance, and is specifically calculated by the following formula:

[0015]

[0016] In the formula, Q c2 is the capacitive reactive power compensation capacity, P load is the maximum nighttime load power.

[0017] The maximum daytime reverse power of the transformer area is obtained by the gateway table.

[0018] The line basic parameters include the line type and the distance between lines,

[0019] The line reactance is calculated as follows:

[0020] X = 2πf·L

[0021] In the formula, f is the frequency, and L is the line inductance.

[0022] The resistance of the line at the corresponding temperature is calculated in combination with the line basic parameters;

[0023] The real-time temperature of the line and the real-time current of the load are collected;

[0024] Based on the real-time temperature of the line and the real-time current of the load, the line resistance is dynamically corrected to obtain the real-time line resistance.

[0025] The resistance of the line at the corresponding temperature is calculated as follows:

[0026]

[0027] In the formula, R T is the resistance at T temperature, ρ T is the resistivity at T temperature, and S is the cross-sectional area of the conductor.

[0028] The real-time line resistance R 实时For:

[0029]

[0030] In the formula, α T is the temperature coefficient at T temperature, T 实时 is the line real-time temperature, k S-R is the skin effect coefficient of aluminum wire, I 实时 is the load real-time current, I N is the line rated current.

[0031] The voltage, load real-time current and line real-time temperature are obtained by the acquisition unit.

[0032] The transformer area reactive power compensation capacity determination system is applied to rural transformer area voltage reactive power compensation, comprising:

[0033] The acquisition module is used to acquire the transformer area daytime maximum reverse sending power, nighttime maximum load power and line basic parameters, and maximum voltage threshold and minimum voltage threshold.

[0034] The calculation module is used to calculate the line reactance and real-time line resistance in combination with the line basic parameters.

[0035] The capacity determination module is used to compare the maximum voltage and the minimum voltage with their respective thresholds respectively, and combine the transformer area daytime maximum reverse sending power, nighttime maximum load power, line reactance and real-time line resistance to calculate the reactive power compensation capacity of the transformer area, wherein,

[0036] In the daytime scene of the transformer area, when the maximum voltage is greater than the maximum voltage threshold, the inductive reactive power compensation capacity that exceeds the upper limit of the voltage is calculated according to the daytime maximum reverse sending power, the line impedance and the real-time line resistance.

[0037] In the nighttime scene of the transformer area, when the minimum voltage is less than the minimum voltage threshold, the capacitive reactive power compensation capacity that exceeds the lower limit of the voltage is calculated according to the nighttime maximum load power, the line reactance and the real-time line resistance.

[0038] The transformer area voltage limit management device is managed based on the reactive power compensation capacity determined by the transformer area reactive power compensation capacity determination method.

[0039] The management device comprises an intelligent controller, a capacitor bank, a reactor bank and a controllable switch bank,

[0040] The capacitor bank comprises at least one capacitor,

[0041] The reactor bank comprises at least one reactor,

[0042] The intelligent controller is connected with the capacitor bank and the reactor bank through the controllable switch bank,

[0043] The intelligent controller is used for triggering the controllable switch group group switching corresponding reactor or capacitor according to the voltage out-of-limit type, including over upper limit or over lower limit.

[0044] In the working process of the application, the capacitor and the reactor reactive power compensation capacity is calculated according to the maximum voltage, the minimum voltage and the line basic parameters, and the relatively accurate reactive power compensation capacity is obtained, and then the voltage out-of-limit management device capacity is configured, so that the reactive power voltage regulation effect can adapt to the actual situation requirements of the transformer area, and effectively manage the day and night two-way out-of-limit of the transformer area voltage. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0046] Figure 1 The flow chart for determining the reactive power compensation capacity of the transformer area,

[0047] Figure 2 The schematic diagram of the transformer area voltage out-of-limit management device,

[0048] Figure 3 The equivalent circuit diagram of photovoltaic integration into power grid. DETAILED DESCRIPTION

[0049] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail in conjunction with the drawings of the specification.

[0050] In the following description, many specific details are set forth in order to provide a thorough understanding of the application, but the application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the application, therefore the application is not limited to the specific embodiments disclosed below.

[0051] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or selective embodiment which excludes other embodiments.

[0052] As Figure 1 As shown in the figure, the application provides a method for determining the reactive power compensation capacity of a transformer area, which is applied to rural transformer area voltage reactive power compensation, and includes:

[0053] Obtaining the maximum daytime reverse sending power, the maximum nighttime load power and the line basic parameters of the transformer area, and the maximum voltage threshold and the minimum voltage threshold;

[0054] The line reactance and real-time line resistance are calculated in combination with the line basic parameters;

[0055] The reactive power compensation capacity of the transformer area is calculated by comparing the maximum voltage and the minimum voltage with the respective threshold values, in combination with the maximum daytime reverse sending power, the maximum nighttime load power, the line reactance and the real-time line resistance, wherein,

[0056] In the daytime scenario of the transformer area, when the maximum voltage is greater than the maximum voltage threshold, the inductive reactive power compensation capacity that exceeds the upper limit of the voltage is calculated according to the daytime maximum reverse sending power, the line impedance and the real-time line resistance;

[0057] In the nighttime scenario of the transformer area, when the minimum voltage is less than the minimum voltage threshold, the capacitive reactive power compensation capacity that exceeds the lower limit of the voltage is calculated according to the nighttime maximum load power, the line reactance and the real-time line resistance.

[0058] In the working process of the present application, the characteristics of the voltage reactive power compensation of the rural transformer area are analyzed, the daytime and nighttime scenarios of the transformer area are distinguished, and the inductive and capacitive reactive power compensation capacities are calculated respectively; wherein, the daytime electricity consumption is small, the maximum reverse sending power is approximately equal to the maximum active output of the photovoltaic, the nighttime photovoltaic output is 0, and thus the maximum electricity consumption power is approximately equal to the maximum load power, thereby simplifying the calculation method of the voltage reactive power compensation of the transformer area. Specifically, in the daytime scenario of the transformer area, the inductive reactive power compensation capacity that exceeds the upper limit of the voltage is calculated according to the daytime maximum reverse sending power, the line impedance and the real-time line resistance; in the nighttime scenario of the transformer area, the capacitive reactive power compensation capacity that exceeds the lower limit of the voltage is calculated according to the nighttime maximum load power, the line reactance and the real-time line resistance. The present application is thus set, which is beneficial to improve the problems of the voltage reactive power compensation response lag and insufficient adjustment capacity, and thus, on the basis of ensuring accurate compensation, the response speed of the voltage reactive power compensation is improved.

[0059] The inductive reactive power compensation capacity that exceeds the upper limit of the voltage is calculated according to the daytime maximum reverse sending power, the line impedance and the real-time line resistance, and specifically calculated by using the following formula:

[0060]

[0061] In the formula, Q c1 is the inductive reactive power compensation capacity, P PV is the daytime maximum reverse sending power, R 实时 is the real-time line resistance, and X is the line reactance;

[0062] And / or, the calculating of the capacitive reactive compensation capacity of the voltage lower limit, according to the maximum night load power, the line reactance and the real-time line resistance, specifically adopts the following formula:

[0063]

[0064] In the formula, Q c2 is the capacitive reactive compensation capacity, P load is the maximum night load power.

[0065] Further, the embodiment of the present application combines the line parameters to calculate the real-time line resistance, which can further improve the accuracy of the reactive compensation capacity.

[0066] The present application specifically comprises the following steps:

[0067] 1.1) Obtain the maximum daytime reverse power Ppv (obtained by the gateway table, about equal to the maximum active output of photovoltaic in rural transformer area), the maximum night load power Pload and the line basic parameters, and the maximum voltage U max , the minimum voltage U min ;

[0068] 1.2) Calculate the line reactance and the resistance of the line at the corresponding temperature in combination with the line basic parameters;

[0069] The line basic parameters include the line type and the line distance,

[0070] According to the line type and the line distance of the overhead line, the conductivity at T temperature is calculated by the table lookup method (such as 280 examples of electrical engineering calculation application) to calculate the resistance R T of each kilometer of power supply line, and the line reactance X is calculated according to the line type and the line distance, and the calculation formula is as follows:

[0071]

[0072] In the formula, R T is the resistance at T temperature, p T is the resistivity at T temperature, S is the cross-sectional area of the conductor (which can be obtained by the conductor type), L is the line inductance, D j is the geometric distance between the phase lines, D UV , D VW , D WU is the center distance from each phase line to the neutral line, r is the radius of the line, and f is the frequency.

[0073] 1.3) Real-time parameter acquisition: the real-time temperature T 实时 of the line is acquired by the temperature sensor built in the intelligent controller, and the real-time current I 实时 of the load is acquired by the gateway table.

[0074] 1.4) Line resistance R and reactance X dynamic correction: Where, R T is the resistance at temperature T, a T is the line temperature coefficient at temperature T, k S-R = 0.018 (as the skin effect coefficient of the aluminum wire with a cross-sectional area of 185 mm 2 ), I N is the line rated current. The reactance is negligible by temperature and skin effect.

[0075] The temperature T can be selected and set according to actual conditions, such as 20℃ or 25℃, etc.

[0076] 1.5.1) When U max > 1.05U, calculate the voltage over-limit compensation capacity (daytime scenario): calculate the inductive reactive power compensation capacity according to the reverse sending power

[0077] 1.5.2) When U min < 0.95U, calculate the voltage under-limit compensation capacity (nighttime scenario): calculate the voltage deviation according to the load rate Determine the capacitive reactive power compensation capacity

[0078] The principle of the present application is as follows: when applied to the voltage reactive power compensation of a transformer area, the reactive power compensation capacity needs to be determined according to the on-site conditions of the transformer area, and needs to be calculated according to the following conditions, including the maximum reverse sending power of the transformer area during the day, the maximum power consumption during the night, and the power supply line specifications.

[0079] For a rural distributed photovoltaic transformer area, generally speaking, the daytime power consumption is small, the maximum reverse sending power is approximately equal to the maximum active power output of the photovoltaic Ppv, and the nighttime photovoltaic output is 0, so the maximum power consumption is approximately equal to the maximum load power Pload.

[0080] As Figure 3 shown, first analyze the relationship between voltage power and line parameters based on the photovoltaic grid-connected equivalent circuit. Figure 3 In U is the reference voltage, U PV is the grid-connected point voltage, Ppv and Qpv are the active power and reactive power sent by the photovoltaic, Pload and Qload are the active power and reactive power absorbed by the load, Qc is the reactive power of the reactive power compensation device, R and X are the line resistance and reactance, respectively.

[0081] After the photovoltaic is connected to the grid, set the reference voltage U as the reference vector, and the line voltage drop formula (1) can be obtained, as follows:

[0082]

[0083] Assuming the reference voltage remains constant, the line voltage gradually decreases along the direction of feeder power flow before the photovoltaic system is connected. With the increasing scale of photovoltaic power stations, when the photovoltaic active power output is much larger than the local load consumption, i.e. P pV >P load And ignoring the photovoltaic reactive power and the load reactive power consumption, formula (2) can be obtained as follows:

[0084]

[0085] When the photovoltaic system adopts a reactive power control strategy to maintain the grid-connected point voltage unchanged, ignoring the longitudinal axis increment of the grid-connected point voltage, the required reactive power support amount is formula (3) as follows:

[0086]

[0087] After simplification, it is formula (4) as follows:

[0088]

[0089] In the formula, ΔU1 represents the voltage deviation value caused by the photovoltaic.

[0090] Further, considering that the daytime Qload and Pload are very small and can be basically ignored, formula (4) is simplified to formula (5) as follows:

[0091]

[0092] At night, the photovoltaic output stops, Qpv and Ppv are 0, and formula (4) is simplified to formula (6) as follows:

[0093]

[0094] In the formula, ΔU2 represents the voltage deviation value caused by the user load.

[0095] The following analyzes the reactive power compensation capacity calculation method of the voltage over-limit.

[0096] The low-voltage distribution network generally has reactive power close to 0, and the daytime voltage deviation is caused by the distributed photovoltaic active power, while the reactive power output is generally 0. At this time, the voltage deviation formula (5) changes to:

[0097]

[0098] If the voltage deviation value ΔU needs to be reduced, the reactive power Q can be compensated by acting on the line reactance X to offset the voltage deviation. According to formula (5), Qpv is equivalent to the compensation reactive power Qc, and the voltage deviation after reactive power compensation is formula (8):

[0099]

[0100] where ΔU3 is the voltage deviation caused by the reactive power of the reactive power compensation device, Q C1 is the inductive reactive power of the reactive power compensation device, X is the line reactance, and U is the reference voltage.

[0101] Only the voltage deviation on the line caused by the active power of the photovoltaic needs to be offset by the reactive power of the reactive power compensation device. That is:

[0102]

[0103] That is:

[0104]

[0105] where the resistance of the line dynamically changes with temperature and skin effect, and the dynamic change of the reactance with temperature and skin effect can be ignored. That is:

[0106]

[0107] The inductive reactive power compensation capacity for treating the voltage deviation exceeding the upper limit can be obtained through the above calculation.

[0108] The following analyzes the calculation method of the reactive power compensation capacity for treating the voltage deviation below the lower limit.

[0109] In general, the reactive power of the low-voltage distribution network is close to 0, and the voltage deviation at night is caused by the load power consumption, and the reactive power output is generally 0. At this time, the voltage deviation formula (6) changes to:

[0110]

[0111] If the voltage deviation value ΔU2 needs to be raised, the voltage deviation can be offset by compensating the reactive power Q acting on the line reactance X. According to formula (6), Qload is equivalent to the compensating reactive power Qc, and the voltage deviation after reactive power compensation is formula (12):

[0112]

[0113] where Q C2 is the capacitive reactive power of the reactive power compensation device, X is the line reactance, and U is the reference voltage.

[0114] Only the voltage deviation on the line caused by the active power of the photovoltaic needs to be offset by the reactive power of the reactive power compensation device. That is:

[0115]

[0116] That is:

[0117]

[0118] The circuit resistance dynamically changes with temperature and the skin effect, while the reactance dynamically changes negligibly with temperature and the skin effect. That is:

[0119]

[0120] The capacitive reactive power compensation capacity for controlling voltage exceeding the lower limit can be obtained through the above calculations.

[0121] This invention provides a system for determining the reactive power compensation capacity of a transformer substation, comprising:

[0122] The acquisition module is used to acquire the maximum daytime backflow power, maximum nighttime load power, and basic line parameters of the transformer area, as well as the maximum voltage threshold and minimum voltage threshold.

[0123] The calculation module is used to calculate the line reactance and real-time line resistance by combining the basic line parameters;

[0124] The capacity determination module is used to calculate the reactive power compensation capacity of the transformer area by comparing the maximum and minimum voltages with their respective thresholds, combined with the maximum daytime backflow power, maximum nighttime load power, line reactance, and real-time line resistance.

[0125] In the daytime scenario of the transformer area, when the maximum voltage is greater than the maximum voltage threshold, the inductive reactive power compensation capacity for voltage exceeding the upper limit is calculated based on the maximum backfeed power during the daytime, the line impedance, and the real-time line resistance.

[0126] In a nighttime scenario in a transformer substation, when the minimum voltage is less than the minimum voltage threshold, the capacitive reactive power compensation capacity for voltage exceeding the lower limit is calculated based on the maximum nighttime load power, the line reactance, and the real-time line resistance.

[0127] like Figure 2 As shown, the present invention provides a voltage over-limit control device for transformer areas, including a capacitor bank, a reactor bank, a controllable switch bank, an intelligent controller, a communication controller, and a heat dissipation device.

[0128] The capacitor bank may include one or more capacitors, supporting both common compensation and separate compensation modes. The capacitor compensation capacity is determined according to the above reactive power capacity compensation calculation method.

[0129] The reactor group may include one or more reactors, adopting a common compensation mode, and the reactor compensation capacity is determined according to the above reactive power capacity compensation calculation method.

[0130] The number of controllable switch groups is the same as the total number of capacitors and reactors, and it has at least three control nodes, which can control the opening and closing of the switches in separate phases.

[0131] The intelligent controller is provided with voltage sampling function, outgoing node control, control software programming interface and man-machine interactive interface.

[0132] The intelligent controller acquires voltage, current and line temperature through the acquisition unit.

[0133] The intelligent controller samples three-phase voltage in real time, and triggers controllable switch group grouping switching corresponding reactor or capacitor according to voltage overrun type, including over upper limit or over lower limit. By adjusting the input reactive compensation capacity, the line voltage deviation is offset, and the grid-connected node voltage is maintained within the standard range.

[0134] The communication controller realizes the remote communication function of the intelligent controller, and can read running data and remotely control the intelligent controller.

[0135] The heat dissipation device monitors the temperature of the running equipment and the internal environment temperature, and starts heat dissipation when the temperature is out of limit, so as to ensure the normal and stable operation of the equipment.

[0136] In the working process, the comprehensive voltage regulation capacity of the reactor and capacitor bank in the transformer area is considered, the capacitor and reactor reactive compensation capacity is calculated according to the related information of the transformer area, including maximum voltage, minimum voltage, line specification and the like, the relatively accurate reactive compensation capacity is obtained, and then the voltage overrun treatment device capacity is pre-configured, so that the reactive voltage regulation effect can adapt to the actual situation requirements of the transformer area, and the day and night two-way overrun of the transformer area voltage is effectively treated.

[0137] In actual use, the transformer area voltage overrun treatment device operation includes:

[0138] The line temperature is acquired through the built-in temperature sensor (sampling frequency 1Hz), and the real-time current is read through the intelligent controller (sampling frequency 50Hz);

[0139] R is updated every 100ms 实时 ;

[0140] The corrected R 实时 / X ratio is used to calculate the formula of the input reactive compensation capacity, so that the reactive compensation capacity is dynamically adjusted with the working condition (such as sudden increase of photovoltaic output in daytime, parameter updating and correction of switching strategy are completed within 50ms);

[0141] The intelligent controller samples three-phase voltage at a frequency of ≥100Hz, compares with the threshold value, U max >1.05U when the voltage is over the upper limit, U min <0.95U when the voltage is over the lower limit;

[0142] According to the over-limit scene, the reactive power switching control is carried out, and the number of reactors / reactor switching groups is determined according to the "real-time reactive power compensation capacity / single group capacity" (for example, if 42kVar is required after correction, 4 groups of 10kVar reactors are switched, and 2kVar redundancy is reserved); when R 实时 When the temperature rises suddenly (such as direct sunlight at noon) by more than 10%, the switch action interval is shortened to 50ms (originally 100ms), to avoid rapid voltage over-limit.

[0143] The communication controller uploads data and receives remote instructions through HPLC / LORA, and the heat dissipation device starts the fan cooling when the temperature exceeds the threshold value (such as 55°C).

[0144] In specific applications,

[0145] Taking a typical rural area as an example, the capacity of the distribution transformer is 200kVA, the maximum reverse power is 80kW, the maximum load is 100kW, the line specification is 185mm aluminum wire, the power supply radius is 700m, and the overhead line temperature is 45°. The real-time phase voltage effective value is 851A.

[0146] Using the power supply line specification, 185mm 2 aluminum core wire, by referring to the data, T=20° temperature per kilometer impedance R T =0.16Ω / km, reactance X=0.31Ω / km, main line resistance about 0.112Ω, reactance about 0.217Ω. That is:

[0147]

[0148] The inductive compensation capacity is:

[0149]

[0150] Through the above calculation, the inductive reactive power compensation capacity for treating voltage over-limit is 44.48kVar. For practical application, the capacity of a single reactor is generally 10kVar, so 5 groups can be configured, a total of 50kVar.

[0151] Similarly, taking the above typical area as an example, the capacitive compensation capacity is:

[0152]

[0153] Among them, the voltage lower limit usually occurs at night, if the user load is 100kW, at this time, excluding the light factor, the overhead line temperature drops to 35°, at this time the real-time current is 1110A, that is:

[0154]

[0155] Also considering the impedance change caused by the field condition, the ratio of resistance and reactance is still taken as 0.5 between, and 20% reactive power compensation safety margin is set:

[0156]

[0157] Through the above calculation, the capacitive reactive power compensation capacity range of the lower limit of the treatment voltage is [50-60]kVar, and for practical application, generally, the capacitor single group capacity is 10kVar, therefore, 6 groups can be configured, and a total of 60kVar.

[0158] The above-mentioned voltage limit treatment device for the transformer area,

[0159] The capacitor group can include 6 10kVar capacitor groups, and all are configured in a common compensation mode.

[0160] The reactor group can include 5 10kVar reactor groups, and all adopt a common compensation mode.

[0161] The number of controllable switch groups is 11.

[0162] The intelligent controller supports three-phase voltage sampling, and the number of node outputs is 11 groups.The human-computer interface includes keys and a liquid crystal display.The liquid crystal display is a monochrome liquid crystal screen with a resolution of 480*240.

[0163] The intelligent controller sets the voltage upper limit value, the upper limit return value, the lower limit value and the lower limit return value respectively, and samples the three-phase voltage in real time.When the voltage is higher than the upper limit, the controllable switch is triggered to gradually put in the reactor, and when the voltage is lower than the upper limit return value, the reactor is gradually withdrawn; when the voltage is lower than the lower limit, the controllable switch is triggered to gradually put in the capacitor, and when the voltage is higher than the lower limit return value, the capacitor is gradually withdrawn.

[0164] The present application has the following advantages:

[0165] 1、The present application distinguishes between day and night scenes, and calculates the reactive power compensation capacity based on the maximum reverse power during the day and the maximum load power during the night respectively, and dynamically corrects the compensation value in combination with the real-time parameters of the line, accurately adapts to the source-load space-time mismatch characteristics of the rural transformer area "daytime photovoltaic reverse power is large, and nighttime load fluctuation is severe", and avoids the problem of insufficient compensation accuracy caused by fixed line parameters, and significantly improves the adaptation ability to source-load uncertainty.

[0166] 2、The present application establishes a dynamic correlation model of "temperature-current-line resistance", and dynamically corrects the line resistance by using the aluminum wire temperature coefficient and the skin effect coefficient through real-time acquisition of the line temperature and the load current, and updates R 实时The X / R ratio is substituted into the compensation capacity calculation formula, the limitation of static X / R ratio is broken, the deviation of compensation amount and actual demand is greatly reduced, and the over-compensation (high voltage at night) or under-compensation (voltage out of limit during the day) is effectively avoided.

[0167] 3、The voltage out of limit management device of the district area can realize high frequency sampling (voltage≥100Hz, current 50Hz, temperature 1Hz) through the intelligent controller, the line real-time resistance is updated once every 100ms, the parameter updating and correction switching strategy can be completed within 50ms, and the switching action interval can be shortened to 50ms according to the sudden temperature rise and other sudden conditions, the dynamic adjustment and fast response of the reactive power compensation capacity are realized, the problem of response lag of the traditional device depending on the preset strategy is solved, and the suddenness of the voltage out of limit can be effectively coped with.

[0168] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and all of them should be covered in the scope of the claims of the present application.

Claims

1. A method for determining reactive power compensation capacity of a transformer area, characterized by, The application is applied to rural transformer area voltage reactive power compensation, comprising: obtaining the maximum reverse power during the day, the maximum load power at night and the line basic parameters, and the maximum voltage threshold and the minimum voltage threshold; calculating the line reactance and the real-time line resistance in combination with the line basic parameters; comparing the maximum voltage and the minimum voltage with the respective thresholds respectively, and calculating the reactive power compensation capacity of the transformer area in combination with the maximum reverse power during the day, the maximum load power at night, the line reactance and the real-time line resistance, wherein, in the transformer area daytime scenario, when the maximum voltage is greater than the maximum voltage threshold, the inductive reactive power compensation capacity of the voltage exceeding the upper limit is calculated according to the maximum reverse power during the day, the line impedance and the real-time line resistance; in the transformer area nighttime scenario, when the minimum voltage is less than the minimum voltage threshold, the capacitive reactive power compensation capacity of the voltage exceeding the lower limit is calculated according to the maximum load power at night, the line reactance and the real-time line resistance; the inductive reactive power compensation capacity of the voltage exceeding the upper limit is calculated according to the maximum reverse power during the day, the line impedance and the real-time line resistance, and the calculation is specifically performed according to the following formula: ； wherein Pmax is the maximum daytime feed-forward power, R is the real-time line resistance, and X is the line reactance. the capacitive reactive power compensation capacity of the voltage exceeding the lower limit is calculated according to the maximum load power at night, the line reactance and the real-time line resistance, and the calculation is specifically performed according to the following formula: ； In the formula, is the maximum night load power.

2. The method of claim 1, wherein the maximum reverse power during the day is obtained through a gateway table.

3. The transformer area reactive power compensation capacity determination method according to claim 1, characterized in that, the line basic parameters comprise a line type and a line distance, wherein the line reactance is calculated as follows: ； where X is the line reactance, is the frequency, is the line inductance.

4. The method of claim 1, wherein calculating the resistance of the line at the corresponding temperature in combination with the line basic parameters; collecting the real-time temperature of the line and the real-time current of the load; based on the real-time temperature of the line and the real-time current of the load, dynamically correcting the line resistance to obtain the real-time line resistance.

5. The transformer area reactive power compensation capacity determination method according to claim 4, characterized in that, the resistance of the line at the corresponding temperature is calculated as follows: ； wherein is the resistance at temperature T, is the resistivity at temperature T, is the cross-sectional area of the wire.

6. The method of claim 5, wherein, The real-time line resistance is: ； wherein T is the temperature coefficient at temperature T, T is the line real-time temperature, T is the skin effect coefficient of the aluminum wire, the load real-time current, T is the line rated current.

7. The method of claim 4, wherein the method further comprises: determining the reactive power compensation capacity of the transformer based on the load of the transformer and the load of the distribution area. the voltage, the real-time current of the load and the real-time temperature of the line are obtained through a collection unit.

8. A system for determining reactive power compensation capacity of a transformer area, characterized by The application is applied to rural transformer area voltage reactive power compensation, comprising: an acquisition module, configured to acquire the maximum reverse power during the day, the maximum load power at night and the line basic parameters, and the maximum voltage threshold and the minimum voltage threshold; a calculation module, configured to calculate the line reactance and the real-time line resistance in combination with the line basic parameters; a capacity determination module, configured to compare the maximum voltage and the minimum voltage with the respective thresholds respectively, and calculate the reactive power compensation capacity of the transformer area in combination with the maximum reverse power during the day, the maximum load power at night, the line reactance and the real-time line resistance, wherein, in the transformer area daytime scenario, when the maximum voltage is greater than the maximum voltage threshold, the inductive reactive power compensation capacity of the voltage exceeding the upper limit is calculated according to the maximum reverse power during the day, the line impedance and the real-time line resistance; in the transformer area nighttime scenario, when the minimum voltage is less than the minimum voltage threshold, the capacitive reactive power compensation capacity of the voltage exceeding the lower limit is calculated according to the maximum load power at night, the line reactance and the real-time line resistance; the inductive reactive power compensation capacity of the voltage exceeding the upper limit is calculated according to the maximum reverse power during the day, the line impedance and the real-time line resistance, and the calculation is specifically performed according to the following formula: ； wherein Pmaxis the maximum daytime feed-forward power, R is the real-time line resistance, and X is the line reactance. The capacitive reactive power compensation capacity of the voltage lower limit is calculated according to the night maximum load power, the line reactance and the real-time line resistance, and the calculation formula is as follows: ； In the formula, is the maximum night load power.

9. A device for managing the over-limit of the voltage of a transformer area, characterized in that, Governance is performed based on the reactive power compensation capacity determined according to the transformer area reactive power compensation capacity determination method in any one of claims 1-7; The governance device comprises an intelligent controller, a capacitor bank, a reactor bank and a controllable switch bank, The capacitor bank comprises at least one capacitor, The reactor bank comprises at least one reactor, The intelligent controller is connected to the capacitor bank and the reactor bank through the controllable switch bank, The intelligent controller is used to trigger the controllable switch bank to switch the corresponding reactor or capacitor according to the voltage limit type, including the upper limit or the lower limit.

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