Active power distribution network voltage control method and system

Abstract

The invention discloses an active power distribution network voltage control method. The method comprises the steps of obtaining data information of a target power distribution network; performing sensitivity analysis to determine a pressure regulating range; optimization of an AVC control strategy and an operation mode is carried out; suggesting equipment type selection based on voltage regulation sensitivity analysis; and completing the final voltage control of the target active power distribution network. The invention also discloses a system for realizing the active power distribution network voltage control method. According to the invention, through multi-angle analysis and calculation of the active power distribution network, voltage regulation step lengths under different main transformer operation and voltage regulation modes are calculated, an AVC control strategy is optimized, and corresponding equipment type selection suggestions are provided; therefore, voltage control of the active power distribution network can be completed, the reliability is high, and the accuracy is good.

Description

Technical Field

[0001] The present invention belongs to the field of electrical automation, and in particular relates to a voltage control method and system for an active power distribution network. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring the stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] At present, as environmental problems become more and more serious, more and more distributed photovoltaic power generation systems are being integrated into the power system to generate electricity. However, as the penetration rate of distributed photovoltaics in the distribution network continues to increase, the problem of overvoltage for users is becoming more and more serious.

[0004] At present, the commonly used voltage control schemes in power systems generally adopt the scheme of seasonal gear adjustment of distribution transformers and changing the control mode of photovoltaic inverters; at the same time, it also requires that the bus voltage of substations be kept in a low and narrow range. However, in the specific implementation process of existing technical schemes, it is easy to produce a large voltage fluctuation range and cause frequent or ineffective operation of the main transformer gear and capacitors. Such situations increase the safe operation risk of the power system to a certain extent. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for controlling voltage of an active power distribution network with high reliability and good accuracy.

[0006] A second objective of the present invention is to provide a system for implementing the active power distribution network voltage control method.

[0007] The active power distribution network voltage control method provided by the present invention comprises the following steps:

[0008] S1. Obtain data information of the target distribution network;

[0009] S2. Perform sensitivity analysis based on the data information obtained in step S1 to determine the voltage regulation range;

[0010] S3. Optimize the AVC control strategy and operation mode according to the data information obtained in step S2;

[0011] S4. According to the data information obtained in step S3, based on the voltage regulation sensitivity analysis, make recommendations on equipment selection;

[0012] S5. Complete the voltage control of the final target active distribution network.

[0013] Step S2, based on the data information obtained in step S1, performs sensitivity analysis to determine the voltage regulation range, specifically including the following steps:

[0014] The voltage drop formula of the power system is expressed as

[0015]

[0016] Where ΔU is the voltage drop value; U1 is the source voltage; U2 is the terminal voltage; P is the active power; R is the resistance; Q is the reactive power; X is the reactance; U is the rated voltage;

[0017] Assume that the active power supplied by the 10 kV busbar is P, the reactive power is Q, and the capacitor capacity is Q. c , then the reactive power change after the capacitor is put into operation is QQ c ; The voltage difference from the power source to the 10 kV bus changes, expressed as

[0018]

[0019] Where U Δ is the voltage difference change value;

[0020] Set the voltage regulation sensitivity k to Then the voltage difference after the capacitor is put into operation changes to -kQ c ; The voltage at the first end remains unchanged, and the voltage difference decreases kQ c , indicating that the tail voltage changes to kQ c ;

[0021] System-side voltage regulation includes power plant voltage regulation, main transformer tap-changer voltage regulation and capacitor / reactor voltage regulation:

[0022] Voltage regulation: The power system sets the voltage control assessment curve for the power plant, requiring the power plant to adjust its own reactive power output to ensure that the grid voltage does not exceed the limit and absorb reactive power as much as possible;

[0023] Main transformer tap changer voltage regulation: For transformers of 110 kV and above, set the voltage regulation of each gear on the high-voltage side to 1.25% to 1.5%, corresponding to a 10 kV voltage fluctuation of 0.125 to 0.15 kV; for 35 kV transformers, set the voltage regulation of each gear on the high-voltage side to 2.5%, corresponding to a 10 kV voltage fluctuation of 0.25 kV; considering the dead zone system of the AVC system, set the 10 kV voltage limit range of 110 kV and above substations to not less than 0.25 kV, and the 10 kV voltage limit range of 35 kV substations to not less than 0.35 kV;

[0024] Capacitor / reactor voltage regulation: Set the voltage regulation scheme for capacitors / reactors.

[0025] The step S3 described in which the AVC control strategy and operation mode are optimized according to the data information obtained in the step S2 includes the following steps:

[0026] Determine whether the unit is controllable based on the circuit breaker status, bus voltage measurement value and switch telemetering value;

[0027] Determine whether the voltage exceeds the limit;

[0028] Determine whether the reactive power and power factor are reasonable;

[0029] According to the above judgment results, the AVC control strategy is optimized.

[0030] The step S3 specifically includes the following steps:

[0031] According to the circuit breaker status, bus voltage measurement value and switch remote signal value, determine whether the unit is controllable:

[0032] A single main transformer or two main transformers running in parallel form a unit; the topological relationship is determined according to the positions of the three-measurement circuit breakers and bus tie circuit breakers of the main transformer;

[0033] The conditions for determining whether the unit is controllable are: if the three-measurement circuit breaker is closed, the bus voltage measurement is valid, and the switch remote signal is valid, the unit is determined to be controllable; otherwise, the unit is determined to be uncontrollable;

[0034] Determine whether the voltage exceeds the limit:

[0035] If the unit is controllable, the voltage is judged to be qualified; if the voltage is qualified, the reactive power and power factor are judged; if the voltage is unqualified, the voltage is judged to be out of limit;

[0036] If the voltage on the high-voltage side exceeds the limit, the reactive equipment is adjusted first, and then the main transformer tap is adjusted;

[0037] If the voltage on the medium and low voltage side exceeds the limit, determine whether the voltage regulation direction is consistent with that on the high voltage side: if it is consistent with the voltage regulation direction on the high voltage side, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the voltage regulation direction on the high voltage side is inconsistent, determine the reactive direction on the high voltage side: if the reactive direction on the high voltage side is in the reverse state, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the reactive direction on the high voltage side is in the non-reverse state, determine whether the power factor on the high voltage side exceeds the limit: if the power factor on the high voltage side exceeds the upper limit, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the power factor on the high voltage side exceeds the lower limit, prioritize adjusting the main transformer tap and then adjust the reactive equipment;

[0038] If the reactive power on the high-voltage side is unqualified, the reactive equipment is adjusted; if the reactive power on the high-voltage side is qualified, it is determined whether the voltage on the high-voltage side meets the optimization requirements: if the voltage on the high-voltage side meets the optimization requirements, the control ends; if the voltage on the high-voltage side does not meet the optimization requirements, the reactive equipment is adjusted;

[0039] Set the AVC limit range under different voltage regulation steps:

[0040] For 35 kV stations: the tap is adjusted to 1 level, and the voltage changes by 0.25 kV; the voltage change range of one group of capacitors is 0.15-0.35 kV, so the voltage regulation step is 0.25-0.35 kV; for the voltage regulation step of 0.25 kV, the voltage regulation range is set to 0.35 kV; for the voltage regulation step of 0.25-0.30 kV, the voltage regulation range is set to 0.4 kV; for the voltage regulation step greater than 0.30 kV, adjust the main transformer operation mode, or avoid the small main transformer running alone, or lock the large capacitor to reduce the voltage regulation step;

[0041] For 110 kV station: the tap is adjusted to 1 level, the voltage changes by 0.125 kV; the voltage change range of 1 group of capacitors is 0.10~0.35 kV, so the voltage regulation step is 0.125~0.35 kV; for the voltage regulation step less than 0.15 kV, the voltage regulation range is set to 0.25 kV; for the voltage regulation step of 0.15~0.2 kV, the voltage regulation range is set to 0.3 kV; for the voltage regulation step of 0.2~0.25 kV, the voltage regulation range is set to 0.3 5 kV; for voltage regulation steps greater than 0.25 kV, consider adjusting the main transformer operation mode, or avoid operating the small main transformer alone, or lock the large capacitor to reduce the voltage regulation step; at the same time, in order to take into account the voltage adjustment of the lower 35 kV station, the medium-voltage side of the 110 kV main transformer is uniformly adjusted to level 4, and the voltage ratio of the medium- and low-voltage sides of the main transformer is fixed at 3.575. When the 10 kV voltage fluctuates between 10 and 10.4 kV, the 35 kV voltage fluctuates between 35.75 and 37.18 kV, providing support for the overvoltage adjustment of the lower level;

[0042] For 220 kV power stations: the voltage change of one group of capacitors / reactors is generally about 0.15~0.30 kV, so the voltage regulation step is 0.15~0.30 kV; the 220 kV main transformer does not participate in the gear adjustment, so the voltage regulation range is set to 0.3 kV.

[0043] Determine whether the reactive power and power factor are reasonable:

[0044] Set the reactive power threshold to 1.5 times the capacitor capacity and the power factor to the upper limit of 1.2.

[0045] According to the data information obtained in step S3, the step S4 provides suggestions for equipment selection based on the voltage regulation sensitivity analysis, including the following steps:

[0046] Provide suggestions for gear shifting;

[0047] Recommendations for main gear shifting;

[0048] Recommendations for reactive equipment configuration.

[0049] The step S4 specifically comprises the following steps:

[0050] Suggestions for gear shifting:

[0051] Adjust all the distribution transformer gears to the lowest gear; during off-peak hours, the AVC setting remains at 10-10.4 kV, and during peak hours it is adjusted to 10.1-10.5 kV;

[0052] Main gear shift recommendations:

[0053] For 220 kV new construction or whole station renovation project, the main transformer should be 230±8×1.25 / 115 / 10.5 kV; for 110 kV new construction or whole station renovation project, the main transformer should be 115±8×1.25 / 38.5 / 10.5 kV; for 35 kV new construction or whole station renovation project, the main transformer should be 35 / 10 kV; for 10 kV new construction or whole station renovation project, the main transformer should be 10 / 0.4 kV;

[0054] Recommendations for reactive power equipment configuration:

[0055] Select reactive equipment and control the voltage regulation step between 0.1 and 0.2 kV.

[0056] The present invention also provides a system for implementing the active distribution network voltage control method, comprising a data acquisition module, a sensitivity analysis module, a strategy optimization module, a suggestion module and a voltage control module; the data acquisition module, the sensitivity analysis module, the strategy optimization module, the suggestion module and the voltage control module are connected in series in sequence; the data acquisition module is used to acquire data information of the target distribution network, and upload the data information to the sensitivity analysis module; the sensitivity analysis module is used to perform sensitivity analysis based on the received data information and the acquired data information to determine the voltage regulation range, and upload the data information to the strategy optimization module; the strategy optimization module is used to optimize the AVC control strategy and operation mode based on the received data information and the acquired data information, and upload the data information to the suggestion module; the suggestion module is used to make equipment selection recommendations based on the received data information and the acquired data information and based on the voltage regulation sensitivity analysis, and upload the data information to the voltage control module; the voltage control module is used to complete the voltage control of the final target active distribution network based on the received data information.

[0057] The active distribution network voltage control method and system provided by the present invention calculates the voltage regulation step under different main transformer operations and voltage regulation modes through multi-angle analysis and calculation of the active distribution network, optimizes the AVC control strategy and operation mode, and puts forward corresponding equipment selection suggestions; therefore, the present invention can not only complete the voltage control of the active distribution network, but also has high reliability and good accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The figure is a schematic diagram of the method flow of the present invention.

[0059] Figure 2 This is a schematic diagram of an example circuit for capacitor / reactor voltage regulation in the method of the present invention.

[0060] Figure 3 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0061] like Figure 1 The method flow chart of the method of the present invention is shown as follows: The active power distribution network voltage control method disclosed in the present invention comprises the following steps:

[0062] S1. Obtain data information of the target distribution network;

[0063] S2. Perform sensitivity analysis based on the data information obtained in step S1 to determine the voltage regulation range; specifically, the steps include:

[0064] The voltage drop formula of the power system is expressed as

[0065]

[0066] Where ΔU is the voltage drop value; U1 is the source voltage; U2 is the terminal voltage; P is the active power; R is the resistance; Q is the reactive power; X is the reactance; U is the rated voltage;

[0067] Assume that the active power supplied by the 10 kV busbar is P, the reactive power is Q, and the capacitor capacity is Q. c , then the reactive power change after the capacitor is put into operation is QQ c ; The voltage difference from the power source to the 10 kV bus changes, expressed as

[0068]

[0069] Where U Δ is the voltage difference change value;

[0070] Set the voltage regulation sensitivity k to Then the voltage difference after the capacitor is put into operation changes to -kQ c; The voltage at the first end remains unchanged, and the voltage difference decreases kQ c , indicating that the tail voltage changes to kQ c ;

[0071] System-side voltage regulation includes power plant voltage regulation, main transformer tap-changer voltage regulation and capacitor / reactor voltage regulation:

[0072] Voltage regulation: The power system sets the power plant voltage control assessment curve, requiring the power plant to adjust its own reactive power output to ensure that the grid-connected voltage does not exceed the limit and absorb reactive power as much as possible; since the reactance of the grid-connected line is about 3 times that of the resistance, according to the voltage drop calculation formula, it is recommended that the reactive power absorbed is about 1 / 3 of the active power, that is, the power factor is -0.95;

[0073] Main transformer tap changer voltage regulation: For transformers of 110 kV and above, set the voltage regulation of each gear on the high-voltage side to 1.25% to 1.5%, corresponding to a 10 kV voltage fluctuation of 0.125 to 0.15 kV; for 35 kV transformers, set the voltage regulation of each gear on the high-voltage side to 2.5%, corresponding to a 10 kV voltage fluctuation of 0.25 kV; considering the dead zone system of the AVC system, set the 10 kV voltage limit range of 110 kV and above substations to not less than 0.25 kV, and the 10 kV voltage limit range of 35 kV substations to not less than 0.35 kV;

[0074] Capacitor / reactor voltage regulation: Set the voltage regulation scheme for capacitors / reactors; the specific implementation is explained with the following examples:

[0075] Circuit structure as Figure 2 As shown;

[0076] Assuming that the maximum short-circuit current of the 110 kV busbar at station A is 10 kA (refer to the annual data), according to the formula The per-unit value of the system impedance is 0.005;

[0077] Assuming that the 110 line L1 is 13 kilometers long, the impedance per unit value is approximately 0.04.

[0078] Assuming that the capacity of main transformer T1 is 50 MVA, the short-circuit impedance percentage of high and medium voltage is 18%, and the short-circuit impedance percentage of high and low voltage is 10.5%. According to the formula The short-circuit impedance per unit value of the high and low voltage sides is 0.36. According to the formula It can be obtained that the per-unit value of the short-circuit impedance on the high and medium voltage side is 0.21.

[0079] 35 Line L2 is assumed to be 13 km, so the impedance per unit value is approximately 0.4.

[0080] Assuming that the capacity of main transformer T2 is 10 MVA, the high and low voltage short-circuit impedance percentage is 7.5%. According to the formula The per-unit value of the short-circuit impedance on the high and low voltage sides is 0.75.

[0081] Existence formula The 10 kV voltage regulation sensitivity of the 110 kV B station is about 0.04, the voltage fluctuation caused by the switching of a single group of 5 Mvar capacitors is 0.2 kV, and the voltage fluctuation caused by the switching of a single group of 3.6 Mvar capacitors is 0.144 kV. The 10 kV voltage regulation sensitivity of the 35 kV C station is about 0.14, and the voltage fluctuation caused by the switching of a single group of 2 Mvar capacitors is 0.28 kV; expressed as

[0082]

[0083] Through the above reactive voltage regulation analysis, the reactive voltage regulation sensitivity of 110 kV substation mainly depends on the main transformer. According to the size of the capacitor, the recommended AVC voltage limit range is 0.25-0.3 kV; the reactive voltage regulation sensitivity of 35 kV substation is affected by many factors. Under the above method, when the line length is about 8 km, the voltage fluctuation caused by 2 MW reactive power is about 0.25 kV, which is consistent with the main transformer 1 gear; therefore, for some 35 kV substations with longer lines, the reactive voltage regulation sensitivity needs to be calculated and analyzed one by one to determine the AVC limit range;

[0084] S3. According to the data information obtained in step S2, the AVC control strategy and operation mode are optimized; comprising the following steps:

[0085] Determine whether the unit is controllable based on the circuit breaker status, bus voltage measurement value and switch telemetering value;

[0086] Determine whether the voltage exceeds the limit;

[0087] Determine whether the reactive power and power factor are reasonable;

[0088] According to the above judgment results, the AVC control strategy is optimized;

[0089] When implementing it, you can take the following steps:

[0090] According to the circuit breaker status, bus voltage measurement value and switch remote signal value, determine whether the unit is controllable:

[0091] A single main transformer or two main transformers running in parallel form a unit; the topological relationship is determined according to the positions of the three-measurement circuit breakers and bus tie circuit breakers of the main transformer;

[0092] The conditions for determining whether the unit is controllable are: if the three-measurement circuit breaker is closed, the bus voltage measurement is valid, and the switch remote signal is valid, the unit is determined to be controllable; otherwise, the unit is determined to be uncontrollable;

[0093] Determine whether the voltage exceeds the limit:

[0094] If the unit is controllable, the voltage is judged to be qualified; if the voltage is qualified, the reactive power and power factor are judged; if the voltage is unqualified, the voltage is judged to be out of limit;

[0095] If the voltage on the high-voltage side exceeds the limit, the reactive equipment is adjusted first, and then the main transformer tap is adjusted;

[0096] If the voltage on the medium and low voltage side exceeds the limit, determine whether the voltage regulation direction is consistent with that on the high voltage side: if it is consistent with the voltage regulation direction on the high voltage side, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the voltage regulation direction on the high voltage side is inconsistent, determine the reactive direction on the high voltage side: if the reactive direction on the high voltage side is in the reverse state, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the reactive direction on the high voltage side is in the non-reverse state, determine whether the power factor on the high voltage side exceeds the limit: if the power factor on the high voltage side exceeds the upper limit, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the power factor on the high voltage side exceeds the lower limit, prioritize adjusting the main transformer tap and then adjust the reactive equipment;

[0097] If the reactive power on the high-voltage side is unqualified, the reactive equipment is adjusted; if the reactive power on the high-voltage side is qualified, it is determined whether the voltage on the high-voltage side meets the optimization requirements: if the voltage on the high-voltage side meets the optimization requirements, the control ends; if the voltage on the high-voltage side does not meet the optimization requirements, the reactive equipment is adjusted;

[0098] Set the AVC limit range under different voltage regulation steps:

[0099] Every 5 minutes is a calculation cycle. The bus voltage, reactive power, and power factor are sampled and recorded once in the 25th to 35th seconds of the 1st, 2nd, and 3rd minutes, and calculations are performed in the 4th and 5th minutes. If any of the three samplings exceed the limit, the effect of adjusting the main transformer tap or switching capacitors / reactors is evaluated, and an optimal solution is selected and implemented. The principle of mainly anchoring the 10 kV bus voltage and giving priority to switching capacitors / reactors is followed;

[0100] The bus voltage cannot be adjusted steplessly. The voltage regulation step is equal to the maximum value of the voltage change value of the tap changer 1 level and the voltage change value of the capacitor / reactor group. According to the voltage regulation sensitivity analysis in the previous section, the voltage regulation sensitivity of the whole network is analyzed, and the AVC limit range under different voltage regulation step sizes is considered as follows:

[0101] For 35 kV stations: the tap is adjusted to 1 level, and the voltage changes by 0.25 kV; the voltage change range of one group of capacitors is 0.15-0.35 kV, so the voltage regulation step is 0.25-0.35 kV; for the voltage regulation step of 0.25 kV, the voltage regulation range is set to 0.35 kV; for the voltage regulation step of 0.25-0.30 kV, the voltage regulation range is set to 0.4 kV; for the voltage regulation step greater than 0.30 kV, adjust the main transformer operation mode, or avoid the small main transformer running alone, or lock the large capacitor to reduce the voltage regulation step;

[0102] For 110 kV station: the tap is adjusted to 1 level, the voltage changes by 0.125 kV; the voltage change range of 1 group of capacitors is 0.10~0.35 kV, so the voltage regulation step is 0.125~0.35 kV; for the voltage regulation step less than 0.15 kV, the voltage regulation range is set to 0.25 kV; for the voltage regulation step of 0.15~0.2 kV, the voltage regulation range is set to 0.3 kV; for the voltage regulation step of 0.2~0.25 kV, the voltage regulation range is set to 0.3 5 kV; for voltage regulation steps greater than 0.25 kV, consider adjusting the main transformer operation mode, or avoid operating the small main transformer alone, or lock the large capacitor to reduce the voltage regulation step; at the same time, in order to take into account the voltage adjustment of the lower 35 kV station, the medium-voltage side of the 110 kV main transformer is uniformly adjusted to level 4, and the voltage ratio of the medium- and low-voltage sides of the main transformer is fixed at 3.575. When the 10 kV voltage fluctuates between 10 and 10.4 kV, the 35 kV voltage fluctuates between 35.75 and 37.18 kV, providing support for the overvoltage adjustment of the lower level;

[0103] For 220 kV power stations: the voltage change of one group of capacitors / reactors is generally about 0.15~0.30 kV, so the voltage regulation step is 0.15~0.30 kV; 220 kV main transformers generally do not participate in gear adjustment, so the voltage regulation range is set to 0.3 kV.

[0104] Determine whether the reactive power and power factor are reasonable:

[0105] To highlight the voltage control target and avoid ineffective AVC action, the reactive power threshold is set to 1.5 times the capacitor capacity and the power factor is set to the upper limit of 1.2;

[0106] S4. According to the data information obtained in step S3, based on the voltage regulation sensitivity analysis, make recommendations on equipment selection; including the following steps:

[0107] Provide suggestions for gear shifting;

[0108] Recommendations for main gear shifting;

[0109] Provide suggestions for reactive equipment configuration;

[0110] When implementing it, you can take the following steps:

[0111] Suggestions for gear shifting:

[0112] The voltage ratio of the distribution transformer is generally 10.0±5% / 0.4 kV or 10.0±2×2.5% / 0.4 kV; when the distribution transformer is in gear 1 (lowest gear, +5%), the rated voltage is 10.5 / 0.4. If the transformer voltage drop is not considered, when the high-voltage side voltage is 10.5 kV and the low-voltage side is 0.4 kV, the single-phase user voltage is During load valleys, the distribution transformer is almost unloaded. If the system (bus) voltage does not exceed 10.5 kV, the distribution transformer is in gear 1, and the user voltage does not exceed 105%, it is within the qualified range. If the distribution transformer is in gear +2.5% or 0%, the user voltage may reach 7.5% or 10%, exceeding the upper limit. When managing low voltage, a large number of distribution transformers are adjusted to -2.5% or even -5%. During load valleys, if the system voltage is 10.5 kV, the user voltage reaches 115%, seriously exceeding the upper limit. One of the tasks to improve the user voltage qualification rate is to adjust all distribution transformer gears to the lowest gear; during valley periods, the AVC setting remains at 10-10.4 kV, and is adjusted to 10.1-10.5 kV during peak periods;

[0113] Main gear shift recommendations:

[0114] At present, the system voltage is generally high. In the early morning hours, the gear positions of the main transformers of 110 kV and below have been adjusted to gear 1 or close to gear 1, and there are no measures to continue voltage adjustment. The main reason is the unreasonable selection of transformation ratio. Taking the transformer with a voltage ratio of 230±8×1.5% / 121 / 10.5 as an example, the gear position is adjusted on the high-voltage side, and the medium- and low-voltage sides cannot be adjusted. If the internal voltage loss of the transformer is not considered, the voltage fluctuation range of the medium and low voltages is very narrow, 115 to 117.7 kV on the medium-voltage side and 10 to 10.23 kV on the low-voltage side. The actual operating voltage value on the medium-voltage side is close to the upper limit voltage, and the actual operating voltage on the low-voltage side is close to the lower limit voltage. The rated voltages of the medium and low-voltage sides of the transformer do not match, resulting in difficulty in adjusting the voltage on the medium and low-voltage sides. For example, mode changes, load fluctuations, gear adjustments on the high-voltage side, and capacitor withdrawals on the low-voltage side will all cause voltage fluctuations, which can easily lead to the medium-voltage side voltage exceeding the upper limit and the low-voltage side voltage exceeding the lower limit. After theoretical verification, it is recommended that: for 220 kV new construction or whole station renovation projects, the main transformer should be 230±8×1.25 / 115 / 10.5 kV; for 110 kV new construction or whole station renovation projects, the main transformer should be 115±8×1.25 / 38.5 / 10.5 kV; for 35 kV new construction or whole station renovation projects, the main transformer should be 35 / 10 kV; for 10 kV new construction or whole station renovation projects, the main transformer should be 10 / 0.4 kV;

[0115] Recommendations for reactive power equipment configuration:

[0116] Since the voltage regulation step of the standard large capacitor is too large, AVC is frequently switched on or off or has ineffective action. It is advisable to select the appropriate capacity of reactive equipment based on the voltage regulation sensitivity analysis and control the voltage regulation step between 0.1 and 0.2 kV.

[0117] S5. Complete the voltage control of the final target active distribution network.

[0118] like Figure 3 The figure shows a schematic diagram of the functional modules of the system of the present invention: the system for realizing the active distribution network voltage control method disclosed in the present invention comprises a data acquisition module, a sensitivity analysis module, a strategy optimization module, a suggestion module and a voltage control module; the data acquisition module, the sensitivity analysis module, the strategy optimization module, the suggestion module and the voltage control module are connected in series in sequence; the data acquisition module is used to acquire data information of the target distribution network, and upload the data information to the sensitivity analysis module; the sensitivity analysis module is used to perform sensitivity analysis according to the received data information and the acquired data information to determine the voltage regulation range, and upload the data information to the strategy optimization module; the strategy optimization module is used to optimize the AVC control strategy and operation mode according to the received data information and the acquired data information, and upload the data information to the suggestion module; the suggestion module is used to make recommendations on equipment selection according to the received data information and the acquired data information based on the voltage regulation sensitivity analysis, and upload the data information to the voltage control module; the voltage control module is used to complete the voltage control of the final target active distribution network according to the received data information.

Claims

1. A method for controlling voltage of an active power distribution network, comprising the following steps: S1. Obtain data information of the target distribution network; S2. Perform sensitivity analysis based on the data information obtained in step S1 to determine the voltage regulation range; S3. Optimize the AVC control strategy and operation mode according to the data information obtained in step S2; S4. According to the data information obtained in step S3, based on the voltage regulation sensitivity analysis, make recommendations on equipment selection; S5. Complete the voltage control of the final target active distribution network.

2. The active power distribution network voltage control method according to claim 1, characterized in that Step S2, based on the data information obtained in step S1, performs sensitivity analysis to determine the voltage regulation range, specifically including the following steps: The voltage drop formula of the power system is expressed as Where ΔU is the voltage drop value; U1 is the source voltage; U2 is the terminal voltage; P is the active power; R is the resistance; Q is the reactive power; X is the reactance; U is the rated voltage; Assume that the active power supplied by the 10 kV busbar is P, the reactive power is Q, and the capacitor capacity is Q. c , then the reactive power change after the capacitor is put into operation is QQ c ; The voltage difference from the power source to the 10 kV bus changes, expressed as Where U Δ is the voltage difference change value; Set the voltage regulation sensitivity k to Then the voltage difference after the capacitor is put into operation changes to -kQ c ; The voltage at the first end remains unchanged, and the voltage difference decreases kQ c , indicating that the tail voltage changes to kQ c ; System-side voltage regulation includes power plant voltage regulation, main transformer tap-changer voltage regulation and capacitor / reactor voltage regulation: Voltage regulation: The power system sets the voltage control assessment curve for the power plant, requiring the power plant to adjust its own reactive power output to ensure that the grid voltage does not exceed the limit and absorb reactive power as much as possible; Main transformer tap changer voltage regulation: For transformers of 110 kV and above, set the voltage regulation of each gear on the high-voltage side to 1.25% to 1.5%, corresponding to a 10 kV voltage fluctuation of 0.125 to 0.15 kV; for 35 kV transformers, set the voltage regulation of each gear on the high-voltage side to 2.5%, corresponding to a 10 kV voltage fluctuation of 0.25 kV; considering the dead zone system of the AVC system, set the 10 kV voltage limit range of 110 kV and above substations to not less than 0.25 kV, and the 10 kV voltage limit range of 35 kV substations to not less than 0.35 kV; Capacitor / reactor voltage regulation: Set the voltage regulation scheme for capacitors / reactors.

3. The active power distribution network voltage control method according to claim 2, characterized in that The step S3 described in which the AVC control strategy and operation mode are optimized according to the data information obtained in the step S2 includes the following steps: Determine whether the unit is controllable based on the circuit breaker status, bus voltage measurement value and switch telemetering value; Determine whether the voltage exceeds the limit; Determine whether the reactive power and power factor are reasonable; According to the above judgment results, the AVC control strategy is optimized.

4. The active power distribution network voltage control method according to claim 3, characterized in that The step S3 specifically includes the following steps: According to the circuit breaker status, bus voltage measurement value and switch remote signal value, determine whether the unit is controllable: A single main transformer or two main transformers running in parallel form a unit; the topological relationship is determined according to the positions of the three-measurement circuit breakers and bus tie circuit breakers of the main transformer; The conditions for determining whether the unit is controllable are: if the three-measurement circuit breaker is closed, the bus voltage measurement is valid, and the switch remote signal is valid, the unit is determined to be controllable; otherwise, the unit is determined to be uncontrollable; Determine whether the voltage exceeds the limit: If the unit is controllable, the voltage is judged to be qualified; if the voltage is qualified, the reactive power and power factor are judged; if the voltage is unqualified, the voltage is judged to be out of limit; If the voltage on the high-voltage side exceeds the limit, the reactive equipment is adjusted first, and then the main transformer tap is adjusted; If the voltage on the medium and low voltage side exceeds the limit, determine whether the voltage regulation direction is consistent with that on the high voltage side: if it is consistent with the voltage regulation direction on the high voltage side, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the voltage regulation direction on the high voltage side is inconsistent, determine the reactive direction on the high voltage side: if the reactive direction on the high voltage side is in the reverse state, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the reactive direction on the high voltage side is in the non-reverse state, determine whether the power factor on the high voltage side exceeds the limit: if the power factor on the high voltage side exceeds the upper limit, prioritize adjusting the reactive equipment and then adjust the main transformer tap; if the power factor on the high voltage side exceeds the lower limit, prioritize adjusting the main transformer tap and then adjust the reactive equipment; If the reactive power on the high-voltage side is unqualified, the reactive equipment is adjusted; if the reactive power on the high-voltage side is qualified, it is determined whether the voltage on the high-voltage side meets the optimization requirements: if the voltage on the high-voltage side meets the optimization requirements, the control ends; if the voltage on the high-voltage side does not meet the optimization requirements, the reactive equipment is adjusted; Set the AVC limit range under different voltage regulation steps: For 35 kV stations: the tap is adjusted to 1 level, and the voltage changes by 0.25 kV; the voltage change range of one group of capacitors is 0.15-0.35 kV, so the voltage regulation step is 0.25-0.35 kV; for the voltage regulation step of 0.25 kV, the voltage regulation range is set to 0.35 kV; for the voltage regulation step of 0.25-0.30 kV, the voltage regulation range is set to 0.4 kV; for the voltage regulation step greater than 0.30 kV, adjust the main transformer operation mode, or avoid the small main transformer running alone, or lock the large capacitor to reduce the voltage regulation step; For 110 kV station: the tap is adjusted to 1 level, the voltage changes by 0.125 kV; the voltage change range of 1 group of capacitors is 0.10~0.35 kV, so the voltage regulation step is 0.125~0.35 kV; for the voltage regulation step less than 0.15 kV, the voltage regulation range is set to 0.25 kV; for the voltage regulation step of 0.15~0.2 kV, the voltage regulation range is set to 0.3 kV; for the voltage regulation step of 0.2~0.25 kV, the voltage regulation range is set to 0.3 5 kV; for voltage regulation steps greater than 0.25 kV, consider adjusting the main transformer operation mode, or avoid operating the small main transformer alone, or lock the large capacitor to reduce the voltage regulation step; at the same time, in order to take into account the voltage adjustment of the lower 35 kV station, the medium-voltage side of the 110 kV main transformer is uniformly adjusted to level 4, and the voltage ratio of the medium- and low-voltage sides of the main transformer is fixed at 3.

575. When the 10 kV voltage fluctuates between 10 and 10.4 kV, the 35 kV voltage fluctuates between 35.75 and 37.18 kV, providing support for the overvoltage adjustment of the lower level; For 220 kV power stations: the voltage change of one group of capacitors / reactors is generally about 0.15~0.30 kV, so the voltage regulation step is 0.15~0.30 kV; the 220 kV main transformer does not participate in the gear adjustment, so the voltage regulation range is set to 0.3 kV. Determine whether the reactive power and power factor are reasonable: Set the reactive power threshold to 1.5 times the capacitor capacity and the power factor to the upper limit of 1.

2.

5. The active power distribution network voltage control method according to claim 3, characterized in that According to the data information obtained in step S3, the step S4 provides suggestions for equipment selection based on the voltage regulation sensitivity analysis, including the following steps: Provide suggestions for gear shifting; Recommendations for main gear shifting; Recommendations for reactive equipment configuration.

6. The active power distribution network voltage control method according to claim 5, characterized in that The step S4 specifically comprises the following steps: Suggestions for gear shifting: Adjust all the distribution transformer gears to the lowest gear; during off-peak hours, the AVC setting remains at 10-10.4 kV, and during peak hours it is adjusted to 10.1-10.5 kV; Main gear shift recommendations: For 220 kV new construction or whole station renovation project, the main transformer should be 230±8×1.25 / 115 / 10.5 kV; for 110 kV new construction or whole station renovation project, the main transformer should be 115±8×1.25 / 38.5 / 10.5 kV; for 35 kV new construction or whole station renovation project, the main transformer should be 35 / 10 kV; for 10 kV new construction or whole station renovation project, the main transformer should be 10 / 0.4 kV; Recommendations for reactive power equipment configuration: Select reactive equipment and control the voltage regulation step between 0.1 and 0.2 kV.

7. A system for implementing the active distribution network voltage control method according to any one of claims 1 to 6, characterized in that It includes a data acquisition module, a sensitivity analysis module, a strategy optimization module, a suggestion module and a voltage control module; the data acquisition module, the sensitivity analysis module, the strategy optimization module, the suggestion module and the voltage control module are connected in series in sequence; the data acquisition module is used to acquire the data information of the target distribution network and upload the data information to the sensitivity analysis module; The sensitivity analysis module is used to perform sensitivity analysis based on the received data information to determine the voltage regulation range, and upload the data information to the strategy optimization module; The strategy optimization module is used to optimize the AVC control strategy and operation mode according to the received data information, and upload the data information to the suggestion module; The suggestion module is used to make suggestions for equipment selection based on the received data information and voltage regulation sensitivity analysis, and upload the data information to the voltage control module; The voltage control module is used to complete the voltage control of the final target active distribution network according to the received data information.

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