Main and distribution voltage coordination regulation method suitable for distributed photovoltaic wide access

Abstract

The invention discloses a main and distribution voltage coordinated regulation method suitable for distributed photovoltaic wide access, which comprises the following steps: S1, uniformly planning the gear of a distribution transformer, and reserving a sufficient margin for the uniform regulation of a main network; s2, installing a voltage acquisition terminal in a typical distribution network area, and taking the voltage of the distribution network as the input of an AVC system; and S3, transformer substations are classified, and AVC voltage limit value strategies of all the transformer substations are determined. According to the voltage regulation method, through unified planning of distribution and transformation gears, linkage of main and distribution network voltages and scientific setting of an AVC strategy, the provided main and distribution voltage coordinated regulation method can extend into a distribution network to directly sense the voltage of the distribution network and realize linkage with the main network, the voltage of the distribution network is used as input of an AVC system, and the voltage of the distribution network is reflected and regulated more accurately through distribution and allocation. The problems of AVC adjustment strategy lagging, insufficient adjustment accuracy and the like caused by the bidirectional power flow of the distribution network are effectively solved.

Description

Technical Field

[0001] The present invention relates to a main-distribution voltage coordinated regulation method, and in particular to a main-distribution voltage coordinated regulation method that is adaptable to the wide access of distributed photovoltaics. Background Art

[0002] In recent years, the installed capacity of distributed photovoltaic power generation has increased dramatically. Before the large-scale access of distributed photovoltaic power generation, the power flow of conventional distribution network lines was basically one-way flow, that is, from the substation bus to each load node, and from high voltage to low voltage. The large-scale grid connection of new energy has fundamentally changed the traditional system power flow direction, making the system power flow a two-way flow, and the system structure and operating characteristics of the distribution network have changed greatly. When the output power of the photovoltaic power generation system is greater than the current load, the power flow of some parts of the line or even the entire line may be reversed, that is, the power flow flows from the load node to the substation bus. In addition, since the output of the photovoltaic power generation system is greatly affected by natural factors such as light and clouds, the output capacity of the photovoltaic power generation system has a large volatility, which brings many challenges to the power grid. For example, the fluctuation of the power flow makes it difficult for the traditional voltage regulation strategy to work, and the role of voltage is very extensive in life, including power transmission, electronic equipment operation, communication, light source lighting, etc. Therefore, the existing voltage regulation mode needs to be changed urgently.

[0003] The Automatic Voltage Control (AVC) system has been widely used as an important means to improve voltage quality. The AVC system is a grid voltage reactive power control system that operates in online mode. It collects bus voltage, bus reactive power, high and low voltage reactive power measurement data of each substation and power plant, as well as real-time data such as the status data of each switch through the dispatching automation SCADA system for online analysis and calculation. From the perspective of grid optimization operation, it adjusts the parameters of various reactive power control devices in the entire network, conducts centralized monitoring and analysis and calculation, and realizes coordinated optimization of reactive power devices through automatic closed-loop control.

[0004] Previously, the traditional voltage regulation mode of the AVC system was based on unidirectional power flow and the reverse voltage regulation principle (avoid low voltage and raise voltage when the load is large and the voltage drop is large; avoid high voltage and lower voltage when the load is small and the voltage drop is small). The bus voltage in the substation is used as the input of the AVC system, and the upper and lower limits of the bus voltage in the substation are set uniformly at different times to estimate and adjust the distribution network voltage (special voltage requirements are set separately for substations, and unified limits are used otherwise). That is, the AVC system inputs the main network data (parameters of 10kV and above), and adjusts the main network equipment through the main network data, thereby affecting the main and distribution network voltages, reactive power flows, etc., which is to a certain extent a "blind" adjustment.

[0005] The existing AVC system has the following problems: First, it does not solve the high and low voltage problems caused by the coexistence of high and low gears in the distribution transformer. After the AVC adjustment strategy is issued, it will affect all the substations with outgoing lines. The traditional AVC voltage regulation method does not make scientific suggestions and adjustments for the distribution transformer gear. If the substation with outgoing lines has both high and low gear problems, according to the accumulated data, the natural voltage difference between high and low gears can reach 20V. After the strategy adjustment is issued, all substations will be uniformly boosted or reduced. When boosting to alleviate the low voltage problem, it may cause high voltage problems in other substations. When reducing the voltage to alleviate the high voltage problem, it may cause low voltage problems in other substations.

[0006] Second, under the current situation of bidirectional power flow in active distribution networks, the traditional voltage regulation mode does not take into account the "source" influence of the distribution network, and does not consider the influence of weather factors on photovoltaic power generation. Before distributed photovoltaics are connected to the distribution network, the flow direction flows from high voltage to low voltage, that is, according to the principle of the power system, the main grid voltage is always higher than the distribution grid voltage; but after distributed photovoltaics are connected, this flow direction will change. When distributed photovoltaics are generated or even returned, the flow will flow from the distribution network to the main grid, and the distribution network voltage will even be higher than the main grid voltage. That is, after distributed photovoltaics are connected, the corresponding relationship between the main and distribution network voltages has changed, and the previous AVC adjustment method based only on the main grid voltage may no longer be applicable.

[0007] Third, the voltage drop is not taken into account, and the real-time linkage with the distribution network voltage is not achieved. The AVC system adjusts the transformer and capacitor according to the bus voltage of the substation far away from the user to meet the user's voltage demand to the greatest extent. However, due to the voltage drop caused by the distance, load size and other reasons, the bus voltage may appear to be qualified and there is no need to adjust it, but the distribution network voltage has reached a low or high value and urgently needs to be adjusted. In addition, the distribution network voltage cannot be fed back to the main grid in real time, and the effect of the distribution network voltage adjustment cannot be understood in time. There are problems such as lagging adjustment strategies and insufficient adjustment accuracy, which cannot fully meet the user's power quality requirements. Summary of the invention

[0008] In order to solve the deficiencies of the above-mentioned technologies, the present invention provides a main-distribution voltage coordinated regulation method that is adaptable to the widespread access of distributed photovoltaics.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a main distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics, comprising the following steps:

[0010] S1, uniformly plan the gear positions of distribution transformers to leave sufficient margin for uniform adjustment of the main grid;

[0011] S2, install voltage acquisition terminals in typical distribution network areas and use the distribution network voltage as input to the AVC system;

[0012] S3, classify the substations and determine the AVC voltage limit strategy for each station.

[0013] Furthermore, the unified planning of the gear positions of distribution transformers in S1 is to compare the bus converted voltage with the distribution transformer voltage derived by using the new generation of electricity consumption information collection system, batch infer the distribution transformer gear positions and give suggestions for upshifting or downshifting, so that the voltages of all substations carried by the same bus are highly concentrated.

[0014] Furthermore, S2 selects to install a voltage collection terminal in a typical distribution network substation close to the end to collect the distribution network voltage, and fits it to the high-voltage side of the distribution transformer to replace the original bus voltage in the station and incorporate it into the AVC adjustment criterion.

[0015] Furthermore, the voltage collection terminal compares the data to detect voltage highs and lows and fluctuations at the terminal photovoltaic station compared to other stations.

[0016] Furthermore, the calculation method of the input voltage of the AVC system is:

[0017]

[0018] Among them, U AVC输入 is the input voltage, U 1 ..U n is the theoretical value of the voltage at the end of each outgoing line, and n is the number of outgoing lines;

[0019] U 1 =U-ΔU 1

[0020] U 2 =U-ΔU 2

[0021] U 3 =U-ΔU 3

[0022]

[0023] U n-1 =U-ΔU n-1

[0024] U n =U-ΔU n ;

[0025] Among them, U is the bus voltage, △U 1 ..△U n The voltage drop of each outlet line.

[0026] Furthermore, S3 is to classify the substations, analyze the load characteristics of each substation, determine the AVC voltage limit strategy for the station and implement it.

[0027] Furthermore, the AVC voltage limit strategy of S3 includes the following steps:

[0028] S31, determine the criteria on which the strategy is based;

[0029] S32, determine the initial strategy range based on the percentage of voltage tolerance at the user receiving end in S31, including: the tolerance of three-phase power supply voltage of 20kV and below is +-7% of the nominal voltage, and the tolerance of 220V single-phase power supply voltage is -10% to +7% of the nominal voltage. ;

[0030] S33, determine and implement the final strategy based on the photovoltaic access capacity and load conditions of each substation.

[0031] Furthermore, S31 is to determine the allowable deviation range of the voltage at the user's receiving end by referring to national or industry standards.

[0032] Furthermore, S32 preliminarily sets the voltage adjustment range of AVC based on the user-side voltage or the allowable deviation range of the low-voltage side of the distribution transformer. If the user-side system standard range is considered, the allowable deviation of the 220V single-phase power supply voltage is -10%-+7% of the nominal voltage, that is, 198V-235.4V; if the distribution transformer low-voltage side system standard range is considered, the allowable deviation of the three-phase power supply voltage of 20kV and below is -7%-7% of the nominal voltage, that is, the three-phase on the low-voltage side of the distribution transformer: 353.4V-406.6V, single-phase: 204.04V-234.75V.

[0033] Furthermore, in S33, it is necessary to further narrow the preset strategy range according to the photovoltaic access capacity and actual load conditions of each substation. The strategy for stations with more photovoltaic access capacity is low, and the strategy for pure load stations is high. Simulation adjustments are performed to determine whether the preset strategy is suitable for the substation situation.

[0034] The present invention discloses a main-distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics, which has the following advantages:

[0035] The distribution network voltage can be directly collected, with more accurate perception. The voltage collection terminal can "reach into" the distribution network to directly perceive the voltage and link with the main network. It can more accurately reflect the real-time operating status of the transformer end of the distribution network and perceive more accurately than before.

[0036] Ignoring the line voltage drop, the fitted converted voltage can better reflect the low and high values ​​of the distribution network than the bus voltage, and the action is more timely. By comparing the fitted converted voltage of the distribution network with the actual bus voltage in the station, it is found that the fitted converted voltage can perceive the high and low values ​​of the distribution network voltage earlier, and can better reflect the impact of distributed photovoltaic access on the voltage: that is, when there is no photovoltaic current downward and the voltage needs to be increased, it will reach a low value first, and when the photovoltaic current is large or even the return current is upward and the voltage needs to be reduced, it will reach a high value first, and send instructions through AVC, so that the reactive resources can act more timely.

[0037] It is only necessary to ensure that the AVC input is within the demand range and adapt to multiple time periods. The traditional mode is based on reverse voltage regulation (avoiding low voltage and raising voltage when the load is large and the voltage drop is large; avoiding high voltage and lowering voltage when the load is small and the voltage drop is small). It is necessary to set limits according to the peak and valley load time periods. The distribution network fitting conversion voltage of this achievement has reflected the dynamic flow of load and bidirectional power flow, so it is only necessary to ensure that the input fitting conversion voltage is within the qualified range, realizing multi-time period matching.

[0038] The regulation effect is excellent. The user voltage exceeds the limit time by 49% compared with before, the voltage fluctuation amplitude is significantly reduced, the power quality and user perception are greatly improved, and the regulation effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a state diagram of the high and low gear distribution transformer voltages of the same outgoing line with a large difference.

[0040] Figure 2 This is a state diagram of the highly concentrated operating voltage in the gear-consistent area.

[0041] Figure 3 This is a comparison chart between the actual bus voltage and the fitted converted voltage.

[0042] Figure 4 This is a comparison chart of the actual area voltage before and after the application of the results. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0044] A method for coordinated regulation of main and distribution voltages that is suitable for widespread access to distributed photovoltaics. Through unified planning of distribution transformer gears, main and distribution network voltage linkage, and scientific setting of AVC strategies, the proposed method for coordinated regulation of main and distribution voltages can "reach into" the distribution network to directly sense the distribution network voltage and achieve linkage with the main network. The distribution network voltage is used as the input of the AVC system, and the "distribution-based regulation" more accurately reflects and adjusts the distribution network voltage, effectively solving the problems of AVC adjustment strategy lag and insufficient adjustment accuracy caused by the bidirectional flow of the distribution network. The results fundamentally solve the problems of periodic adjustment of distribution transformer gears and repeated adjustment of AVC strategies with low results, and at the same time lay the foundation for unified adjustment of the main network AVC. By "amplifying" the regulation efficiency of AVC on the distribution network voltage, the integrated coordinated control of the main and distribution is realized, and the reactive resources of the main network are adjusted more accurately and timely, effectively improving the power quality of users and the safe operation level of the distribution network voltage.

[0045] It is divided into three specific steps: the first step is to propose and adjust the gear adjustment suggestions for the distribution transformer according to the control characteristics of the AVC system to prevent the gear difference of the distribution transformer from being too large, which will cause the high limit to be solved but the low limit to be caused, or the low limit to be solved but the high limit to be caused; the second step is to install voltage acquisition terminals in typical distribution network substations to collect the distribution network voltage, and fit it to the high-voltage side of the distribution transformer to replace the original 10kV bus voltage in the station to be included in the AVC adjustment criterion, so as to avoid the problem that the original station bus voltage cannot correctly reflect the distribution network voltage as AVC input due to line voltage drop; the third step is to classify the substations, analyze the load characteristics of each substation, determine the AVC voltage limit strategy of the station and implement it, which is more targeted and can better classify and solve the distribution network voltage problem than the traditional mode.

[0046] In the first step, the distribution transformer in the gear adjustment of the distribution transformer is a static electrical appliance in the distribution system used to transform AC voltage and current to transmit AC power. It usually operates in the distribution network and directly supplies power to end users.

[0047] Distribution transformers generally have 5 gears (rated voltage 10±2×2.5% / 0.4kV); or, 3 gears (rated voltage 10±5% / 0.4kV), of which 10±2×2.5%kV and 10±5%kV are the three-phase voltages on the high-voltage side of the distribution transformer, and 0.4kV is the three-phase voltage on the low-voltage side of the distribution transformer. It can be seen from the rated voltage of the distribution transformer that the voltage change rate on the low-voltage side is generally 2.5% or 5% for each gear adjustment of the distribution transformer. Assuming that the original busbar operating voltage is 10.4kV, by adjusting the distribution transformer gear by 1 gear, the change value of the distribution transformer low-voltage side is 6V or 12V. Without considering the impact of the flow on the voltage of each node of the distribution network, if the same 10kV busbar has both the highest gear and the lowest gear, the voltage difference between the two different gear stations will always differ by 10%, and the difference will exceed 20V. AVC adjusts the reactive equipment in the substation, affecting the voltage of all substations carried by all 10kV outgoing lines of the station.

[0048] Therefore, the coexistence of high and low gears in the distribution transformers in the substations compresses the unified adjustment margin of the main grid. After the unified adjustment of reactive resources, it may happen that solving high voltage problems in some substations may cause low voltage problems in other substations, or solving low voltage problems in some substations may cause high voltage problems in other substations. Therefore, the first step of this method is to uniformly plan the gears of the distribution transformers to leave sufficient margin for the unified adjustment of the main grid.

[0049] like Figure 1 As shown, it is demonstrated that in the traditional technology, the voltage difference between the high and low gear distribution transformers of the same outgoing line is large, and the adjustment margin is reduced by 67.6%.

[0050] like Figure 2 As shown, the operating voltage in the consistent-gear area is highly concentrated. In this state, the main grid has sufficient regulation margin.

[0051] In the second step, the traditional distribution network structure is radial, that is, the busbar in the substation leads to the trunk, and various branches are separated from the trunk. Before the distributed photovoltaic is connected, the current flows in one direction, that is, from high voltage to low voltage. According to the principle of the power system, each segment has a voltage drop from the head end, and the voltage is the lowest at the end. The voltage loss ΔU is calculated according to the following formula:

[0052]

[0053] Where P is the three-phase active power of the load, Q is the three-phase reactive power of the load, R is the line resistance, which is equal to the line resistance per kilometer multiplied by the line length, X is the line reactance, which is equal to the line reactance per kilometer multiplied by the line length, and U is the real-time voltage of the bus.

[0054] After the distributed photovoltaic is connected, during the night without photovoltaic, the current flow direction is the same as the period without photovoltaic connection, and the voltage at the end is the lowest. During the period of photovoltaic power generation or even return, the current flow direction changes and the voltage at the end is the highest. Therefore, this patent selects a typical photovoltaic area close to the end to install a voltage collection device, and through data comparison, the end photovoltaic area is more sensitive to voltage highs and lows and fluctuations than other areas, which can improve the timeliness and accuracy of adjustment.

[0055] After the voltage acquisition terminal is installed on the low-voltage side of the n photovoltaic areas selected above, the collected voltage is the single-phase voltage on the low-voltage side of the area. If the voltage values ​​are U1, U2, U3, U4...Un, and the AVC system needs to input a 10kV voltage, the collected voltage value is converted to the U on the high-voltage side of the distribution transformer. 高 (When the gear position of the unified planning distribution is the middle rated gear position in the first step):

[0056]

[0057] The above U 高 This is the AVC input criterion, that is, the AVC input source is the distribution network voltage.

[0058] In order to prevent a line from tripping and losing power, causing the voltage collected by the voltage collection device in the upper section of the line to be 0, it is set here that when one or several voltage items U≥260 or U≤200, the item or items are discarded, and the denominator n changes according to the number of discarded items.

[0059] Among them, U 高 The calculation formula is implemented in the automation system as follows:

[0060] Taking the installation of 6 acquisition devices as an example, set the SCADA other telemetry table operands @2, @3, @4, @5, @6, @7 to collect the voltages of the 6 acquisition devices respectively. Depending on whether @2, @3, @4, @5, @6, @7 are within the specified range, they are assigned to @14, @15, @16, @17, @18, @19 in the calculation table for calculation. Depending on whether @2, @3, @4, @5, @6, @7 are within the specified range, @8, @9, @10, @11, @12, @13 are 1 or 0 respectively. @1 is the final AVC system input voltage.

[0061] If(200<@2<260)@8=1; else@8=0;

[0062] If(200<@2<260)@14=@2; else@14=0;

[0063] If(200<@3<260)@9=1; else@9=0;

[0064] If(200<@3<260)@15=@3; else@15=0;

[0065] If(200<@4<260)@10=1; else@10=0;

[0066] If(200<@4<260)@16=@4; else@16=0;

[0067] If(200<@5<260)@11=1; else@11=0;

[0068] If(200<@5<260)@17=@5; else@17=0;

[0069] If(200<@6<260)@12=1; else@12=0;

[0070] If(200<@6<260)@18=@6; else@18=0;

[0071] If(200<@7<260)@13=1; else@13=0;

[0072] If(200<@7<260)@19=@7; else@19=0;

[0073] @1=(sum(@14:@19)*1.732*25) / sum((@8:@13)*1000).

[0074] In the actual operation system, P, Q, and U are real-time changing and known, and R and X are line parameters that are also known. Therefore, the following calculation method for AVC system input is proposed:

[0075] If a substation has 1, 2, 3, ..., n-1, n, ... outgoing lines, and n outgoing lines are available (the new generation of power consumption information collection system is used to derive the distribution network area voltage, the outgoing line terminal voltage is converted to the low-voltage side of the area and compared with the system derived voltage, the outgoing line with a large difference in trend and value is not available; if an outgoing line i trips and loses power, that is, the outgoing line P i , Q i is 0, then ΔU i =0, the item U i Ignoring the denominator n, the output line is unavailable. If the load and voltage drop of an output line j are small, the item U j If it is basically coincident with the bus voltage U, then this item is also treated in the same way as the i tripping power failure, that is, the data of this outgoing line is ignored and the outgoing line is unavailable). The active, reactive, resistance and reactance of each available outgoing line are: P 1 , P 2 , P 3 ......P n-1 , P n , Q 1 , Q 2 , Q 3 ......Q n-1 , Q n , R 1 , R 2 , R 3 ......R n-1 , R n , X 1 , X 2 , X 3 ......X n-1 , X n ;

[0076] The bus voltage U is known and changes in real time, then the voltage drop of each outgoing line is:

[0077]

[0078] The theoretical value of the voltage at each available outgoing line end is:

[0079] U 1 =U-ΔU 1

[0080] U 2 =U-ΔU 2

[0081] U 3 =U-ΔU3

[0082]

[0083] U n-1 =U-ΔU n-1

[0084] U n =U-ΔU n

[0085] Then the AVC system input data can be:

[0086]

[0087] In the third step, the AVC voltage limit strategy is determined and optimized as follows:

[0088] 1) Determine the basis of the standard;

[0089] According to the regulations such as "Supply Voltage Deviation", "Power Quality, Supply Voltage Deviation", and "Technical Guidelines for Power System Voltage and Reactive Power", the voltage deviation at the user's receiving end is allowed to be:

[0090] The sum of the absolute values ​​of positive and negative deviations of the user power supply voltage of 35kV and above should not exceed 10% of the nominal voltage.

[0091] The allowable deviation of three-phase power supply voltage of 20kV and below should be +-7% of the nominal voltage.

[0092] The allowable deviation of 220V single-phase power supply voltage should be -10% to +7% of the nominal voltage.

[0093] 2) Determine the initial strategic scope;

[0094] If the user-side system standard range is considered, the allowable deviation of the 220V single-phase power supply voltage should be -10%-+7% of the nominal voltage, that is, 198V-235.4V (user side). The preliminary strategy determination process is as follows, see Table 1:

[0095] Table 1

[0096]

[0097] If the standard range of the low-voltage side of the distribution transformer is taken into consideration, the allowable deviation of the three-phase power supply voltage of 20kV and below should be -7%-7% of the nominal voltage, that is, the three-phase of the low-voltage side of the distribution transformer: 353.4V-406.6V, single-phase: 204.04V-234.75V. The preliminary strategy determination process is as follows, see Table 2:

[0098] Table 2

[0099]

[0100]

[0101] 3) Confirm the final strategy;

[0102] Determine that the initial strategy range is set too wide. If the strategy range is set too wide, and the AVC input is difficult to reach the upper and lower limits of the strategy in actual operation, it is equivalent to not setting the strategy range, that is, the AVC system cannot function. Therefore, it is necessary to preset a suitable strategy range according to the actual situation of each substation and simulate and adjust it in combination with the AVC adjustment characteristics. The strategy of the station with more photovoltaic access capacity is low (such as 9.95-10.35), and the strategy of the pure load station is high (such as 10.05-10.45). Simulate and adjust to determine whether the preset strategy is in line with the situation of the substation.

[0103] Traditional AVC voltage regulation is based on the "blind" adjustment of the bus voltage of the substation far away from the user to meet the user's voltage demand to the greatest extent. However, due to the change in the corresponding relationship between the main and distribution network voltages after the distribution network is activated and the fact that the distribution network voltage has not been linked to the AVC system in real time, the adjustment results in some areas may be unsatisfactory. The main and distribution voltage coordinated regulation method proposed in this patent has the following effects:

[0104] 1. The distribution network voltage can be directly collected, and the perception is more accurate. Relying on the voltage collection terminal to "reach into" the distribution network to directly perceive the voltage and realize linkage with the main network, it can more accurately reflect the real-time operating status of the transformer end of the distribution network and perceive it more accurately than before.

[0105] 2. Ignoring the line voltage drop, the fitted converted voltage can better reflect the low and high values ​​of the distribution network than the bus voltage, and the action is more timely. By comparing the fitted converted voltage of the distribution network with the actual bus voltage in the station, it is found that the fitted converted voltage can perceive the high and low values ​​of the distribution network voltage earlier, and can better reflect the impact of distributed photovoltaic access on the voltage: that is, when there is no photovoltaic current downward and the voltage needs to be increased, it will reach a low value first; when the photovoltaic current is large or even the return current is upward and the voltage needs to be reduced, it will reach a high value first, and send instructions through AVC, so that the reactive resources can act more timely. Figure 3 The comparison diagram between the actual bus voltage and the fitted converted voltage is shown in the figure. In the figure, the converted voltage represents the fitted converted voltage, and the actual voltage represents the actual bus voltage in the station.

[0106] 3. It is only necessary to ensure that the AVC input is within the demand range and adapt to multiple time periods. The traditional mode is based on reverse voltage regulation (avoiding low voltage and raising voltage when the load is large and the voltage drop is large; avoiding high voltage and lowering voltage when the load is small and the voltage drop is small), and it is necessary to set limits according to the peak and valley of load. The distribution network fitting conversion voltage of this achievement has reflected the dynamic flow of load and bidirectional power flow, so it is only necessary to ensure that the input fitting conversion voltage is within the qualified range, and multi-time period matching is achieved.

[0107] 4. The regulation effect is excellent. The results have been put into trial operation in stations such as Qingyuan Zhangdeng (plain area) and Laiyuan Mazhuang (mountainous area), and have been promoted in Xiong'an. The duration of user voltage exceeding the limit has been greatly reduced by 49% compared with before, the voltage fluctuation amplitude has been significantly reduced, the power quality and user perception have been greatly improved, and the regulation effect is good. The regulation effect can be seen in the following table. Figure 4 The actual area voltage comparison diagram before and after the application of the results shown in the figure, as well as the distribution network over-limit time comparison table before and after the adjustment of Mazhuang Station, are shown in Table 3:

[0108] Table 3

[0109] Substation name Time limit before adjustment (minutes) Adjusted over-limit duration (minutes) The time of exceeding the limit has decreased compared with 35kV Mazhuang Substation 4323015 1499670 65.3％

[0110] The above implementation modes are not limitations of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also belong to the protection scope of the present invention.

Claims

1. A method for coordinated regulation of main and distribution voltages adapted to widespread access to distributed photovoltaics, characterized in that: The following steps are involved: S1, uniformly plan the gear positions of distribution transformers to leave sufficient margin for uniform adjustment of the main grid; S2, install voltage acquisition terminals in typical distribution network areas and use the distribution network voltage as input to the AVC system; S3, classify the substations and determine the AVC voltage limit strategy for each station.

2. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 1 is characterized in that: The unified planning of the distribution transformer gears in S1 is to compare the bus converted voltage with the distribution transformer voltage derived by the new generation of electricity consumption information collection system, batch infer the distribution transformer gears and give suggestions for upshifting or downshifting, so that the voltages of all substations carried by the same bus are highly concentrated.

3. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 1 is characterized in that: The S2 is to select a voltage collection terminal installed in a typical distribution network area close to the end to collect the distribution network voltage, and fit it to the high-voltage side of the distribution transformer to replace the original bus voltage in the station and incorporate it into the AVC adjustment criterion.

4. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 3 is characterized in that: The voltage acquisition terminal compares the terminal photovoltaic station's sensitivity to voltage highs and lows and fluctuations compared to other stations through data comparison.

5. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 3 is characterized in that: The calculation method of the AVC system input voltage is: Among them, U AVC输入 is the input voltage, U1..U n is the theoretical value of the voltage at the end of each outgoing line, and n is the number of outgoing lines; Among them, U is the bus voltage, △U1..△U n The voltage drop of each outlet line.

6. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 1 is characterized in that: The S3 classifies the substations, analyzes the load characteristics of each substation, determines the AVC voltage limit strategy for the substation and implements it.

7. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 6 is characterized in that: The AVC voltage limit strategy of S3 includes the following steps: S31, determine the criteria on which the strategy is based; S32, determine the initial strategy range based on the percentage of voltage tolerance at the user receiving end in S31, including: the tolerance of three-phase power supply voltage of 20kV and below is +-7% of the nominal voltage, and the tolerance of 220V single-phase power supply voltage is -10% to +7% of the nominal voltage. ; S33, determine and implement the final strategy based on the photovoltaic access capacity and load conditions of each substation.

8. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 7 is characterized in that: The S31 is to determine the allowable deviation range of the voltage at the user's receiving end by referring to national or industry standards.

9. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 7 is characterized in that: The S32 preliminarily sets the voltage adjustment range of AVC according to the user-side voltage or the allowable deviation range of the low-voltage side of the distribution transformer. If the user-side system standard range is considered, the allowable deviation of the 220V single-phase power supply voltage is -10%-+7% of the nominal voltage, that is, 198V-235.4V; if the distribution transformer low-voltage side system standard range is considered, the allowable deviation of the three-phase power supply voltage of 20kV and below is -7%-7% of the nominal voltage, that is, the three-phase of the distribution transformer low-voltage side: 353.4V-406.6V, single-phase: 204.04V-234.75V.

10. The main and distribution voltage coordinated regulation method adapted to the widespread access of distributed photovoltaics according to claim 7 is characterized in that: In the above S33, it is necessary to further narrow the preset strategy range according to the actual situation of each substation. The strategy of the station with more photovoltaic access capacity is low, and the strategy of the pure load station is high. Simulation adjustment is performed to determine whether the preset strategy is suitable for the substation situation.

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