Method and device for optimizing reactive voltage of high-proportion photovoltaic transformer area

Abstract

The invention discloses a method and a device for optimizing reactive voltage of a high-proportion photovoltaic transformer area, which can coordinate power output among different nodes in the transformer area and design inverter control parameters on the basis of voltage-active and voltage-reactive quantitative relations in a network. The maximum reactive power output and the maximum active power reduction of the inverters of different nodes under the limiting condition are determined, the dispersity of distributed photovoltaic access and the bidirectional reactive power output of the inverters are effectively utilized, and the problems of high voltage of a transformer area and the like caused by a large number of distributed photovoltaic access are successfully solved. And the method has obvious application value in the aspects of improving the power grid operation economy and reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed photovoltaic power generation grid-connected control, and in particular to a method and a device for optimizing reactive voltage in a high-proportion photovoltaic area. Background Art

[0002] As the global energy crisis and environmental protection become increasingly severe, photovoltaic power generation, as one of the clean and renewable energy sources, has occupied an important position in the field of distributed power generation. Due to the intermittent and unpredictable nature of photovoltaic power generation, its grid connection has a significant impact on the voltage quality, harmonic pollution, three-phase imbalance and other issues of the distribution network. Especially at the end of the distribution network with a high proportion of photovoltaic access, the problem of voltage over-limit is particularly prominent.

[0003] At present, the monitoring of low-voltage distributed photovoltaic, charging piles, user-side energy storage and other equipment mainly relies on post-statistical analysis of metering meters, which cannot support real-time control needs.

[0004] To address the voltage over-limit problem of distribution networks caused by distributed photovoltaic grid connection, existing solutions mainly perform reactive power regulation according to local on-site balancing strategies, or based on complex parameter global optimization strategies. The reactive power regulation function of new power electronic equipment such as photovoltaic inverters and energy storage converters has not been fully utilized, nor can the global reactive power optimization of the substation be effectively solved. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of voltage over-limit in the low-voltage distribution network caused by a high proportion of household photovoltaic access, while taking into account the characteristics of the imperfect communication network and low communication reliability of the low-voltage distribution network, a method and device for optimizing reactive voltage in a high-proportion photovoltaic area is proposed, which makes full use of the reactive and active resources of photovoltaic inverters in the area, and optimizes reactive power flow to achieve voltage adjustment and improve the quality of power supply voltage by constructing a hierarchical collaborative system architecture of "intra-group autonomy and inter-group coordination".

[0006] In order to achieve the above technical purpose, the technical solution of the present invention is:

[0007] In a first aspect, the technical solution of the present invention provides a method for optimizing reactive voltage in a high-proportion photovoltaic area, comprising the following steps:

[0008] Step (1): Obtain the node voltage of each node in the station area and obtain the node voltage sequence S = (U 1 , U 2 , ..., U m ), where S represents the node voltage sequence vector, U i (1≤i≤n) represents the i-th node voltage data, and n represents the total number of node voltage data;

[0009] Obtain the reactive power margin of each photovoltaic inverter in the substation area, and obtain the reactive power margin sequence Qr = (Qr 1 , Qr 2 , ..., Qr m ), where Qr represents the reactive power margin sequence vector, Qr i (1≤i≤m) represents the reactive power margin of the i-th photovoltaic inverter, and m represents the number of reactive power margin data of the total photovoltaic inverters;

[0010] The photovoltaic inverter is a photovoltaic inverter with reactive power regulation capability. The photovoltaic inverter has the ability to generate and absorb reactive power. The relationship between the reactive power margin of the photovoltaic inverter and the photovoltaic inverter capacity is: in, is the reactive power margin of the photovoltaic inverter, P PV is the active power of photovoltaic power generation, S INV The capacity of the photovoltaic inverter can be increased by 0% to 10% compared with the rated active capacity.

[0011] Initialize the reactive power adjustment variation of each photovoltaic inverter to obtain the reactive power adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ), where ΔQ represents the reactive power adjustment change sequence vector, ΔQ i (1≤i≤m) represents the reactive power adjustment change of the i-th photovoltaic inverter, and m represents the number of reactive power adjustment change data of the total photovoltaic inverters;

[0012] Step (2): Obtain the maximum voltage value U in the node voltage sequence S max and minimum voltage value U min , and according to U max and U min Find the voltage regulation point that has the greatest impact on the voltage of the node that exceeds the limit; max and U min The reactive adjustment change is calculated by the sensitivity coefficient; the reactive adjustment is obtained according to the reactive adjustment change and the reactive output margin of the voltage regulation point; the reactive adjustment is assigned to the reactive adjustment change sequence ΔQ, and sent to each local control unit to adjust the reactive output.

[0013] Adjustment strategy A:

[0014] When the maximum voltage U max Greater than the node voltage upper limit U up , and the minimum voltage value U min Greater than the node voltage lower limit U low When, find out the most influential factor max The voltage regulation point A of the node voltage ismax The voltage regulation point with the largest node voltage regulation sensitivity coefficient;

[0015] Voltage regulating point A to U min The sensitivity coefficient of the node voltage is kal, and the voltage regulation point A is related to U max The sensitivity coefficient of the node voltage is kau;

[0016] According to the voltage adjustment point A to U max The sensitivity coefficient kau of the node voltage is obtained to make U max The reactive adjustment change Qa1 when the node voltage returns to the normal range, where: Qa1 = (U max -U up ) / kau;

[0017] According to the voltage adjustment point A to U min The sensitivity coefficient kal of the node voltage is obtained to make U min The reactive power adjustment change when the node voltage exceeds the lower limit is Qa2, where: Qa2 = (U min -U low ) / kal;

[0018] According to the reactive power margin sequence Qr, the reactive power margin Qar of the voltage regulation point A is obtained;

[0019] According to Qa1, Qa2, Qar, the reactive adjustment amount δQa of the voltage regulating point A is obtained, where δQa=min(Qa1, Qa2, Qar), and the reactive adjustment amount δQa of the voltage regulating point A is assigned to the reactive adjustment variation sequence ΔQ; the reactive adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ) output, sent to each local control unit to adjust the reactive power output;

[0020] After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

[0021] Adjustment strategy B:

[0022] When the maximum voltage U max Less than the node voltage upper limit U up , and the minimum voltage value U min Less than the node voltage lower limit U low When, find out the most influential factor min The voltage regulation point D of the node voltage is min The voltage regulation point with the largest node voltage regulation sensitivity coefficient;

[0023] Voltage regulating point D to Umin The sensitivity coefficient of the node voltage is kdl, and the voltage regulation point D is related to U max The sensitivity coefficient of the node voltage is kdu;

[0024] According to the voltage adjustment point D to U min The sensitivity coefficient kdl of the node voltage is obtained to make U min The reactive adjustment change Qd1 when the node voltage returns to the normal range, where: Qd1 = (U low -U min ) / kdl;

[0025] According to the voltage adjustment point D to U max The sensitivity coefficient kdu of the node voltage is obtained to make U max The reactive power adjustment change when the node voltage exceeds the upper limit is Qd2, where: Qd2 = (U up -U max ) / kdu;

[0026] According to the reactive power margin sequence Qr, the reactive power margin Qdr of the voltage regulation point D is obtained;

[0027] According to Qd1, Qd2, Qdr, the reactive adjustment amount δQd of the voltage regulating point D is obtained, where: δQd=min(Qd1, Qd2, Qdr), and the reactive adjustment amount δQa of the voltage regulating point D is assigned to the reactive adjustment variation sequence ΔQ; the reactive adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ) output, sent to each local control unit to adjust the reactive power output;

[0028] After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

[0029] Adjustment strategy C:

[0030] When the maximum voltage U max Greater than the node voltage upper limit U up , and the minimum voltage value U min Less than the node voltage lower limit U low When, find out the most influential factor max Node voltage and U min The node voltage has the least impact on the voltage regulation point B, and the node voltage has the greatest impact on U min Node voltage and U max The voltage regulation point C where the node voltage has the least impact;

[0031] Voltage regulating point B to U minThe sensitivity coefficient of the node voltage is kbl, and the voltage regulation point B is max The sensitivity coefficient of the node voltage is kbu, and the voltage regulation point C is min The sensitivity coefficient of the node voltage is kcl, and the voltage regulation point C is max The sensitivity coefficient of the node voltage is kcu;

[0032] According to the voltage adjustment point B to U min The sensitivity coefficient kbl of the node voltage is obtained to make U max The reactive adjustment change Qb1 when the node voltage returns to the normal range, where: Qb1 = (Ulow-Umin) / kbl;

[0033] According to the voltage adjustment point C to U min The sensitivity coefficient kcl of the node voltage is obtained to make U min The reactive adjustment change Qc1 when the node voltage returns to the normal range, where: Qc1 = (Ulow-Umin) / kcl;

[0034] According to the reactive power margin sequence Qr, the reactive power margin of the voltage regulating point B is Qbr, and the reactive power margin of the voltage regulating point C is Qcr;

[0035] According to Qb1 and Qbr, the reactive adjustment amount δQb of the voltage regulating point B is obtained, where: δQb=min(Qb1, Qbr); according to Qc1 and Qcr, the reactive adjustment amount δQc of the voltage regulating point C is obtained, where: δQc=min(Qc1, Qcr); and the reactive adjustment amount δQb of the voltage regulating point B and the reactive adjustment amount δQc of the voltage regulating point C are assigned to the reactive adjustment variation sequence ΔQ; the reactive adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ) output and sent to each local control unit to adjust the reactive power output.

[0036] After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

[0037] Preferably, adjustment strategy A and adjustment strategy B can be cycled 1 to 3 times.

[0038] When kbu / kbl>10 or kcl / kcu>10, the adjustment is terminated; otherwise, step (2) is continued.

[0039] The initial values ​​of the sensitivity coefficients of the above voltage regulating points to the node voltage are all 1, and the sensitivity coefficients are corrected each time the voltage regulating point changes the voltage of the regulated point.

[0040] Find out the voltage regulation point that has the greatest impact on the voltage of the node that exceeds the limit, which is the node where the voltage of the node exceeds the limit in the substation.

[0041] Furthermore, when the reactive power margin in the substation is sufficient, only the reactive power of the photovoltaic inverter is used to control the node voltage, and the effectiveness of the node voltage control is guaranteed by coordinating the control parameters of the photovoltaic inverter; when the reactive power margin is insufficient, the reactive power regulation of the photovoltaic inverter is preferentially used to control the node voltage. When the reactive power margin reaches the limit, the photovoltaic grid-connected active power is reduced, and the reactive power control capacity of the inverter released by the photovoltaic active power reduction is further used for voltage control.

[0042] In a second aspect, the technical solution of the present invention provides a high-proportion photovoltaic area reactive voltage optimization device, including a master station, an area fusion control terminal, a photovoltaic user control unit (PVTU) and an inverter.

[0043] The main station is responsible for collecting the control data of the photovoltaic area, realizing the comparison of the effects before and after the treatment, and the photovoltaic reactive power management;

[0044] The substation integrated control terminal (APP), as the user interface and control center of the on-site substation, is responsible for collecting data, displaying information, issuing instructions, and interacting with other system modules. It provides users with an intuitive operation platform by collecting key data such as voltage, current, active power, reactive power, etc. of the nodes in real time, and calculates the voltage status and reactive power demand of the grid-connected points based on the collected data, and then formulates corresponding reactive power regulation instructions. The instructions are sent to the photovoltaic user control unit through the photovoltaic protocol conversion APP, and then sent to the corresponding inverter via the photovoltaic adapter.

[0045] Photovoltaic User Control Unit (PVTU) is installed with photovoltaic user grid connection point, communicates with inverter downward and fusion terminal upward, realizes photovoltaic user reactive voltage data collection (including voltage, current, active power, reactive power and other important parameters), photovoltaic control strategy reception and execution, single point on-site control, and serves as the sensing end for reactive voltage optimization data collection of photovoltaic users and the operating end for strategy execution;

[0046] The photovoltaic user control unit includes a photovoltaic protocol converter and a photovoltaic adapter. The photovoltaic protocol converter is a bridge connecting the photovoltaic user control unit and the inverter. Its main function is to convert the power data from the user into a format that the inverter can understand, and at the same time feed back the inverter's status and operating data to the photovoltaic user control unit. The networking method supports HPLC carrier and RS485 communication to ensure the stability and accuracy of data transmission. The photovoltaic adapter is used to expand the communication capabilities of a single inverter, and can realize the plug-and-play function of inverters of different manufacturers and models, so that it can communicate with the main station of the power grid company and the manufacturer's cloud platform at the same time, ensuring the reliability of the system;

[0047] The inverter outputs reactive power to adjust the active power according to the received instructions, thereby adjusting the voltage at the grid connection point to the required level within the allowable range.

[0048] The voltage over-limit management strategy of the adjustable capacity of the photovoltaic inverter is based on the substation, which can coordinate the power output between different nodes in the substation, design the inverter control parameters based on the voltage-active power and voltage-reactive power quantitative relationship in the network, and determine the maximum reactive power output and maximum active power reduction of the inverters at different nodes under extreme conditions to ensure the effectiveness of network voltage control; on this basis, the optimization model is optimized with the goal of reducing network loss and photovoltaic power reduction, and the control parameters of photovoltaic inverters at different nodes are optimized to minimize unnecessary reactive power flow and photovoltaic power reduction in the line, thereby improving the economic efficiency of network operation.

[0049] Based on HPLC / HRF communication technology, photovoltaic user control units are installed at the grid connection point to collect and monitor user operation data, including important parameters such as voltage, current, active power, reactive power, etc., and summarize and analyze them through intelligent fusion terminals to adjust the reactive and active power output of photovoltaic inverters, effectively solving the voltage over-limit problem caused by distributed photovoltaic power generation. Especially during peak hours, when the photovoltaic output exceeds the rated capacity of the access line or distribution transformer, the system can avoid the risk of overvoltage by adjusting the reactive power output, ensuring the stable operation of power equipment and personal safety. In addition, by implementing this strategy, the stability and economy of the power grid are also improved, unnecessary reactive flow and photovoltaic power reduction are reduced, and an efficient and economical reactive voltage management solution is provided for the distribution network.

[0050] The present invention constructs a hierarchical collaborative system architecture of "intra-group autonomy and inter-group coordination", effectively utilizes the decentralization of distributed photovoltaic access and the bidirectional reactive output of the inverter, can coordinate the power output between different nodes in the substation, and designs inverter control parameters based on the voltage-active power and voltage-reactive power quantitative relationship in the network, determines the maximum reactive output and maximum active power reduction of inverters at different nodes under extreme conditions, effectively utilizes the decentralization of distributed photovoltaic access and the bidirectional reactive output of the inverter, successfully solves the problems of high voltage in the substation caused by a large number of distributed photovoltaic access, and has significant application value in improving the economy and reliability of power grid operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0052] Figure 1 It is a technical framework for optimizing reactive power and voltage in areas with a high proportion of photovoltaic power stations.

[0053] Figure 2 This is the reactive power voltage optimization flow chart for high-proportion photovoltaic areas.

[0054] Figure 3 This is a schematic diagram of the installation of the photovoltaic user control unit.

[0055] Figure 4 This is a line graph of the active power of a new village in a certain place on October 29.

[0056] Figure 5 This is a line graph of the three-phase voltage on the 10.29 distribution voltage side of a new village in a certain place.

[0057] Figure 6 This is a line graph of the maximum, minimum and average values ​​of low-voltage users in a new village on October 29. DETAILED DESCRIPTION

[0058] The inverter is a photovoltaic inverter with reactive power regulation capability. The relationship between the reactive power margin of the photovoltaic inverter and the capacity of the photovoltaic inverter is: in, is the reactive power margin of the photovoltaic inverter, P PV is the active power of photovoltaic power generation, S INV The capacity of the photovoltaic inverter can be increased by 0% to 10% compared with the rated active capacity.

[0059] like Figure 1-3 As shown, the high-proportion photovoltaic area reactive voltage optimization device includes a master station, an area fusion control terminal APP, a photovoltaic user control unit (PVTU) and an inverter;

[0060] The main station is responsible for collecting the control data of the photovoltaic area, realizing the comparison of the effects before and after the treatment, and the photovoltaic reactive power management;

[0061] The substation integrated control terminal APP, as the user interface and control center of the on-site substation, provides users with an intuitive operation platform by collecting key data such as voltage, current, active power, reactive power, etc. of the nodes in real time, and calculates the voltage status and reactive power demand of the grid-connected points based on the collected data, and then formulates corresponding reactive power regulation instructions; the instructions are sent to the photovoltaic user control unit through the photovoltaic protocol conversion APP, and then sent to the corresponding inverter via the photovoltaic adapter;

[0062] The photovoltaic user control unit (PVTU) is equipped with a photovoltaic user grid connection point, which communicates with the inverter downward and the fusion terminal upward, so as to realize the reactive voltage data collection of photovoltaic users, the reception and execution of photovoltaic control strategies, and the single-point on-site control, and is the sensing end for the reactive voltage optimization data collection of photovoltaic users and the operation end for the strategy execution. Specifically, the photovoltaic user control unit includes a photovoltaic protocol converter and a photovoltaic adapter. The photovoltaic protocol converter is a bridge connecting the photovoltaic user control unit and the inverter. Its main function is to convert the power data from the user (including important parameters such as voltage, current, active power, reactive power, etc.) into a format that the inverter can understand, and at the same time, feedback the status and operation data of the inverter to the photovoltaic user control unit. The networking mode supports HPLC carrier and RS485 communication to ensure the stability and accuracy of data transmission. The photovoltaic adapter is used to expand the communication capability of a single inverter, which can realize the plug-and-play function of inverters of different manufacturers and models, so that it can communicate with the main station of the power grid company and the manufacturer's cloud platform at the same time.

[0063] The inverter outputs reactive power to adjust the active power according to the received instructions, thereby adjusting the voltage at the grid connection point to the required level within the allowable range.

[0064] The optimization method of the reactive voltage optimization device in a high-proportion photovoltaic area includes the following steps:

[0065] Step (1): Obtain the node voltage of each node in the station area and obtain the node voltage sequence S = (U 1 , U 2 , ..., U n ), where S represents the node voltage sequence vector, U i (1≤i≤n) represents the i-th node voltage data, and n represents the total number of node voltage data;

[0066] Obtain the reactive power margin of each photovoltaic inverter in the substation area, and obtain the reactive power margin sequence Qr = (Qr 1 , Qr 2 , ..., Qr m ), where Qr represents the reactive power margin sequence vector, Qr i (1≤i≤m) represents the reactive power margin of the i-th photovoltaic inverter, and m represents the number of reactive power margin data of the total photovoltaic inverters;

[0067] Initialize the reactive power adjustment variation of each photovoltaic inverter to obtain the reactive power adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ), where ΔQ represents the reactive power adjustment change sequence vector, ΔQ i(1≤i≤m) represents the reactive power adjustment change of the i-th photovoltaic inverter, and m represents the number of reactive power adjustment change data of the total photovoltaic inverters;

[0068] Step (2): Obtain the maximum voltage value U in the node voltage sequence S max and minimum voltage value U min , and according to the maximum voltage value U max and minimum voltage value U min If the limit is exceeded, adjust the reactive power output;

[0069] Adjustment strategy A:

[0070] When the maximum voltage U max Greater than the node voltage upper limit U up , and the minimum voltage value U min Greater than the node voltage lower limit U low When, find out the most influential factor max The voltage regulation point A of the node voltage is the maximum voltage value U max Nodes;

[0071] According to the voltage adjustment point A to U max The sensitivity coefficient kau of the node voltage is obtained to make U max The reactive adjustment change Qal when the node voltage returns to the normal range, where: Qa1 = (U max -U up ) / kau; According to the voltage adjustment point A to U min The sensitivity coefficient kal of the node voltage is obtained to make U min The reactive power adjustment change when the node voltage exceeds the lower limit is Qa2, where: Qa2 = (U min -U low ) / kal; obtain the reactive power margin Qar of the voltage regulation point A according to the reactive power margin sequence Qr;

[0072] According to Qa1, Qa2, Qar, the reactive adjustment amount δQa of the voltage regulating point A is obtained, where δQa=mmin(Qa1, Qa2, Qar), and the reactive adjustment amount δQa of the voltage regulating point A is assigned to the reactive adjustment variation sequence ΔQ; the reactive adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ) output and sent to each local control unit to adjust the reactive power output.

[0073] After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

[0074] Adjustment strategy B:

[0075] When the maximum voltage U max Less than the node voltage upper limit U up , and the minimum voltage value U min Less than the node voltage lower limit U low When, find out the most influential factor min The voltage regulation point D of the node voltage is the minimum voltage value U min Nodes;

[0076] According to the voltage adjustment point D to U min The sensitivity coefficient kdl of the node voltage is obtained to make U min The reactive adjustment change Qd1 when the node voltage returns to the normal range, where: Qd1 = (U low -U min ) / kdl; According to the voltage adjustment point D to U max The sensitivity coefficient kdu of the node voltage is obtained to make U max The reactive power adjustment change when the node voltage exceeds the upper limit is Qd2, where: Qd2 = (U up -U max ) / kdu; according to the reactive power margin sequence Qr, the reactive power margin Qdr of the voltage regulation point D is obtained;

[0077] According to Qd1, Qd2, Qdr, the reactive adjustment amount δQd of the voltage regulating point D is obtained, where: δQd=mmin(Qd1, Qd2, Qdr), and the reactive adjustment amount δQa of the voltage regulating point D is assigned to the reactive adjustment variation sequence ΔQ; the reactive adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ) output and sent to each local control unit to adjust the reactive power output.

[0078] After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

[0079] Adjustment strategy C:

[0080] When the maximum voltage U max Greater than the node voltage upper limit U up , and the minimum voltage value U min Less than the node voltage lower limit U low When, find out the most influential factor max Node voltage and U min The node voltage has the least impact on the voltage regulation point B, and the node voltage has the greatest impact on U min Node voltage and U maxThe voltage regulation point C has the least influence on the node voltage, and the voltage regulation point B is the maximum voltage value U max The voltage regulating point C is the minimum voltage value U min Node.

[0081] According to the voltage adjustment point B to U min The sensitivity coefficient kbl of the node voltage is obtained to make U max The reactive power adjustment change Qb1 when the node voltage returns to the normal range, where: Qb1 = (Ulow-Umin) / kbl; according to the voltage regulation point C to U min The sensitivity coefficient kcl of the node voltage is obtained to make U min The reactive power adjustment change Qc1 when the node voltage returns to the normal range, where: Qc1 = (Ulow-Umin) / kcl; according to the reactive power margin sequence Qr, the reactive power margin of the voltage regulation point B is Qbr, and the reactive power margin of the voltage regulation point C is Qcr;

[0082] According to Qb1 and Qbr, the reactive adjustment amount δQb of the voltage regulating point B is obtained, where: δQb=min(Qb1, Qbr); according to Qc1 and Qcr, the reactive adjustment amount δQc of the voltage regulating point C is obtained, where: δQc=min(Qc1, Qcr); and the reactive adjustment amount δQb of the voltage regulating point B and the reactive adjustment amount δQc of the voltage regulating point C are assigned to the reactive adjustment variation sequence ΔQ; the reactive adjustment variation sequence ΔQ=(ΔQ 1 , ΔQ 2 , ..., ΔQ m ) output and sent to each local control unit to adjust the reactive power output.

[0083] After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

[0084] When kbu / kbl>10 or kcl / kcu>10, the adjustment is terminated; otherwise, step (2) is continued.

[0085] Depending on the adjustment situation, adjustment strategy A and adjustment strategy B can be cycled 1 to 3 times to stabilize the over-limit situation.

[0086] Furthermore, when the reactive power margin in the substation is sufficient, only the reactive power of the photovoltaic inverter is used to control the node voltage, and the effectiveness of the node voltage control is guaranteed by coordinating the control parameters of the photovoltaic inverter; when the reactive power margin is insufficient, the reactive power regulation of the photovoltaic inverter is preferentially used to control the node voltage. When the reactive power margin reaches the limit, the photovoltaic grid-connected active power is reduced, and the reactive power control capacity of the inverter released by the photovoltaic active power reduction is further used for voltage control.

[0087] Test example:

[0088] like Figure 4-6 As shown, the capacity of a new village distribution transformer is 400kVA, with two outgoing lines, 1 loop length is 640M, 2 loop length is 480M, and both lines are LGJ-50. There are 151 ordinary electricity users, including 131 single-phase users and 20 three-phase users. The grid structure is a single power supply double-injection structure. There are 15 photovoltaic users, with an installed capacity of 87.96kW and a photovoltaic penetration rate of 22%, and all are single-phase grid-connected. The photovoltaic power generation in this area cannot be absorbed, and the high voltage problem of the low-voltage users at the end is prominent, which affects the safe and orderly use of electricity by customers.

[0089] Taking October 29, 2023 as an example, the maximum load rate of the area on that day was 20.8%. During the period from 9:00 to 14:00, photovoltaic power generation could not be absorbed, and there was power reverse transmission. The voltage on the low-voltage side of the distribution transformer fluctuated between 230 and 234V, the maximum voltage of low-voltage users fluctuated between 233 and 252.7V, and the minimum voltage fluctuated between 223 and 237.9V, with a voltage fluctuation difference of about 20V.

[0090] By adopting the optimization method of reactive voltage optimization device in high-proportion photovoltaic area, the optimization control of reactive voltage was successfully achieved.

[0091] The above embodiments do not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for optimizing reactive voltage in a high-proportion photovoltaic area, characterized in that: The steps include: Step (1): Obtain the node voltage sequence S = (U1, U2, ..., U m ) and the reactive power margin sequence Qr=(Qr1,Qr2,...,Qr m ); Initialize the reactive power adjustment variation of each photovoltaic inverter to obtain the reactive power adjustment variation sequence ΔQ=(ΔQ1,ΔQ2,...,ΔQ m ); Step (2): Obtain the maximum voltage value U in the node voltage sequence S max and minimum voltage value U min , and according to U max and U min Find the voltage regulation point that has the greatest impact on the voltage of the node that exceeds the limit; max and U min The reactive adjustment change is calculated by the sensitivity coefficient; the reactive adjustment is obtained according to the reactive adjustment change and the reactive output margin of the voltage regulation point; the reactive adjustment is assigned to the reactive adjustment change sequence ΔQ, and sent to each local control unit to adjust the reactive output.

2. A method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: When the maximum voltage U max Greater than the node voltage upper limit U up , and the minimum voltage value U min Greater than the node voltage lower limit U low When, find out the most influential factor U max The node voltage is regulated at point A; according to the voltage regulation point A, U max The sensitivity coefficient kau of the node voltage is obtained to make U max The reactive adjustment change Qa1 when the node voltage returns to the normal range, where: Qa1 = (U max -U up ) / kau; According to the voltage adjustment point A to U min The sensitivity coefficient kal of the node voltage is obtained to make U min The reactive power adjustment change when the node voltage exceeds the lower limit is Qa2, where: Qa2 = (U min -U low ) / kal; obtain the reactive power margin Qar of the voltage regulating point A according to the reactive power margin sequence Qr; obtain the reactive power adjustment amount δQa of the voltage regulating point A according to Qa1, Qa2, Qar, where δQa=min(Qa1, Qa2, Qar), and assign the reactive power adjustment amount δQa of the voltage regulating point A to the reactive power adjustment variation sequence ΔQ; When the maximum voltage U max Less than the node voltage upper limit U up , and the minimum voltage value U min Less than the node voltage lower limit U low When, find out the most influential factor U min The voltage regulation point D of the node voltage; according to the voltage regulation point D, U min The sensitivity coefficient kdl of the node voltage is obtained to make U min The reactive adjustment change Qd1 when the node voltage returns to the normal range, where: Qd1 = (U low -U min ) / kdl; According to the voltage adjustment point D to U max The sensitivity coefficient kdu of the node voltage is obtained to make U max The reactive power adjustment change when the node voltage exceeds the upper limit is Qd2, where: Qd2 = (U up -U max ) / kdu; obtain the reactive power margin Qdr of the voltage regulating point D according to the reactive power margin sequence Qr; obtain the reactive power adjustment δQd of the voltage regulating point D according to Qd1, Qd2, Qdr, where: δQd=min(Qd1, Qd2, Qdr), and assign the reactive power adjustment δQa of the voltage regulating point D to the reactive power adjustment variation sequence ΔQ; When the maximum voltage U max Greater than the node voltage upper limit U up , and the minimum voltage value U min Less than the node voltage lower limit U low When, find out the most influential factor U max Node voltage and U min The node voltage has the least impact on the voltage regulation point B, and the node voltage has the greatest impact on U min Node voltage and U max The voltage regulation point C has the smallest impact on the node voltage; according to the voltage regulation point B, U min The sensitivity coefficient kbl of the node voltage is obtained to make U max The reactive power adjustment change Qb1 when the node voltage returns to the normal range, where: Qb1 = (Ulow-Umin) / kbl; according to the voltage regulation point C to U min The sensitivity coefficient kcl of the node voltage is obtained to make U min The reactive adjustment change Qc1 when the node voltage returns to the normal range, where: Qc1 = (Ulow-Umin) / kcl; according to the reactive output margin sequence Qr, the reactive output margin Qbr of the voltage regulating point B and the reactive output margin Qcr of the voltage regulating point C are obtained; according to Qb1 and Qbr, the reactive adjustment δQb of the voltage regulating point B is obtained, where: δQb = min(Qb1, Qbr); according to Qc1 and Qcr, the reactive adjustment δQc of the voltage regulating point C is obtained, where: δQc = min(Qc1, Qcr); and the reactive adjustment δQb of the voltage regulating point B and the reactive adjustment δQc of the voltage regulating point C are assigned to the reactive adjustment change sequence ΔQ.

3. The method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: After adjusting the reactive power output, the node voltage of each node in the substation is re-acquired, and the node voltage sequence S is updated; the reactive power margin of each photovoltaic inverter in the substation is re-acquired, and the reactive power margin sequence Qr is updated.

4. The method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: The voltage regulation point is the node in the substation where the voltage exceeds the limit.

5. The method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: The initial value of the sensitivity coefficient of the voltage regulating point to the node voltage is 1, and the sensitivity coefficient is corrected each time the voltage regulating point changes the voltage of the regulated point.

6. The method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: The relationship between the reactive power margin of the photovoltaic inverter and the capacity of the photovoltaic inverter is: in, is the reactive power margin of the photovoltaic inverter, P PV is the active power of photovoltaic power generation, S INV The capacity of the photovoltaic inverter can be increased by 0% to 10% compared with the rated active capacity.

7. The method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: When kbu / kbl>10 or kcl / kcu>10, the adjustment is terminated; otherwise, the adjustment is continued to step (2).

8. The method for optimizing reactive voltage in a high-ratio photovoltaic area according to claim 1, characterized in that: When the reactive power margin in the substation is sufficient, only the reactive power of the photovoltaic inverter is used for node voltage control, and the effectiveness of the node voltage control is guaranteed by coordinating the control parameters of the photovoltaic inverter. When the reactive power margin is insufficient, the reactive power regulation of the photovoltaic inverter is preferentially used to control the node voltage. When the reactive power margin reaches the limit, the photovoltaic grid-connected active power is reduced, and the reactive power control capacity of the inverter released by the photovoltaic active power reduction is further used for voltage control.

9. A reactive voltage optimization device for high-proportion photovoltaic areas, characterized in that: Including master station, area fusion control terminal, photovoltaic user control unit and inverter; The main station is responsible for collecting the control data of the photovoltaic area, realizing the effect comparison before and after the control, and the photovoltaic reactive power management; The integrated control terminal of the substation is responsible for collecting data, displaying information, issuing instructions, and interacting with other system modules; The photovoltaic user control unit is equipped with a photovoltaic user grid connection point, which communicates with the inverter downward and with the integrated control terminal of the substation upward, so as to realize the reactive voltage data collection of photovoltaic users, the reception and execution of photovoltaic control strategies, and single-point on-site control, and is the sensing end for the reactive voltage optimization data collection of photovoltaic users and the operating end for the strategy execution; The inverter outputs reactive power to adjust the active power according to the received instructions, thereby adjusting the voltage at the grid connection point to the required level within the allowable range.

10. A high-ratio photovoltaic area reactive power voltage optimization device according to claim 9, characterized in that: The photovoltaic user control unit includes a photovoltaic protocol converter and a photovoltaic adapter. The photovoltaic protocol converter converts the power data from the user into a format that the inverter can understand, and feeds back the inverter's status and operating data to the photovoltaic user control unit; the photovoltaic adapter is used to expand the communication capabilities of a single inverter.

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