Voltage regulation method of transformer area voltage regulation system

Abstract

The application discloses a voltage regulation method of a transformer area voltage regulation system, and belongs to the field of power transformation and distribution online monitoring. The method comprises a photovoltaic module, a voltage regulator, a reactive compensation capacitor, a collection device and a platform server. The photovoltaic module comprises a photovoltaic assembly, an inverter and a collection device. The photovoltaic assembly and the inverter are connected through a power line. The inverter is connected with the low-voltage side of the voltage regulator through a power line. The low-voltage side of the voltage regulator is connected with the output end of the reactive compensation capacitor through a power line. The inverter is connected with user load at a load node through a power line. A low-voltage monitoring terminal is arranged on the power line at the low-voltage side of the voltage regulator and the load node. The inverter is in communication connection with the collection device. The low-voltage monitoring terminal, the collection device, the reactive compensation capacitor and the low-voltage side of the voltage regulator are in communication connection with the collection device. The collection device is in communication connection with the platform server. The application realizes transformer area regulation of distributed photovoltaic grid connection and improves the reliability of power distribution.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power distribution online monitoring, in particular to a voltage regulation method of a transformer area voltage regulation system. BACKGROUND

[0002] With the deepening of energy saving and emission reduction, distributed photovoltaic technology has been widely applied, and photovoltaic grid connection has changed the traditional distribution network architecture, and transformer area regulation has encountered new problems, and improper handling may cause reverse power flow, voltage out-of-limit, energy waste and other problems, which seriously affects the reliability of power distribution. SUMMARY

[0003] The present application provides a voltage regulation method of a transformer area voltage regulation system, which realizes the transformer area regulation of distributed photovoltaic grid connection and improves the reliability of power distribution.

[0004] The technical scheme provided by the present application is as follows:

[0005] A voltage regulation method of a transformer area voltage regulation system, the transformer area voltage regulation system comprising a plurality of distributed photovoltaic modules, a voltage regulator, a reactive power compensation capacitor, a collection device and a platform server, wherein:

[0006] Each photovoltaic module comprises a photovoltaic assembly, an inverter and a collection device, the photovoltaic assembly and the inverter of the same photovoltaic module are connected through a power line, and the inverters of the respective photovoltaic modules are connected in parallel through power lines with the low-voltage side of the voltage regulator; the low-voltage side of the voltage regulator is connected with the output end of the reactive power compensation capacitor through a power line, and the high-voltage side of the voltage regulator is connected with an external high-voltage power grid; the inverter of each photovoltaic module is connected with a user load at a load node through a power line;

[0007] The power line of the low-voltage side of the voltage regulator and the power line at the load node are both provided with a low-voltage monitoring terminal, the inverter and the collection device of the same photovoltaic module are in communication connection, the low-voltage monitoring terminal, the collection device, the reactive power compensation capacitor and the voltage regulator are in communication connection with the collection device, and the collection device is in communication connection with the platform server;

[0008] The voltage regulation method comprises:

[0009] S1: the collection device collects data of each inverter;

[0010] S2: the low-voltage monitoring terminal collects data of the low-voltage side of the voltage regulator and data of the load node;

[0011] S3: the collection device receives the data collected by the collection device, the data collected by the low-voltage monitoring terminal, the data of the voltage regulator and the data of the reactive power compensation capacitor;

[0012] S4: The collecting device performs power flow calculation according to the received data and a set topology to obtain voltage data of each node; wherein the nodes include each load node and a low-voltage side of the voltage regulator;

[0013] S5: It is judged whether the voltage data of each node is under-voltage, when under-voltage, the required compensation capacity is calculated, and adjustment is performed, and after the adjustment is completed, it is switched to S1;

[0014] S6: It is judged whether the voltage data of each node is over-voltage, when over-voltage, the number and position of over-voltage nodes are calculated, and adjustment is performed, and after the adjustment is completed, it is switched to S1;

[0015] S7: When the voltage data of all nodes is neither under-voltage nor over-voltage, the power factor of the transformer area is calculated, if the power factor is greater than or equal to a set power factor threshold, the adjustment is ended; otherwise, over-compensation of reactive power is performed, and after the compensation is completed, it is switched to S1.

[0016] Further, the data collected by the collecting device includes voltage, current, active power, reactive power, apparent power, power factor, DC bus voltage and DC bus current of the inverter; the data collected by the low-voltage monitoring terminal includes voltage, current, active power, reactive power, apparent power, power factor and harmonic content of the low-voltage side of the voltage regulator and the load node; the data of the voltage regulator and the data of the reactive compensation capacitor received by the collecting device include contact information of the voltage regulator, input group number and apparent power of the reactive compensation capacitor.

[0017] Further, the voltage data of each node is calculated by the following method:

[0018] S41: The following power flow calculation formula is established:

[0019]

[0020] Wherein, S G is the apparent power of the low-voltage side of the voltage regulator, S PVi is the apparent power of the i-th inverter, i=1, 2, …, n, n is the total number of inverters, S Ck is the apparent power of the k-th group of the reactive compensation capacitor, k=1, 2, …, n1, n1 is the input group number of the reactive compensation capacitor, S FVi is the apparent power of the i-th load node, S Zi is the line loss power consumption of the i-th load node;

[0021] S42: The following equations are solved simultaneously:

[0022]

[0023] wherein P represents active power, Q represents reactive power, j is an imaginary unit, P G , Q G represent active power and reactive power of S G , respectively, P PVi , Q PVi represent active power and reactive power of S PVi , respectively, P Ck , Q Ck represent active power and reactive power of S Ck , respectively, P Zi , Q Zi represent active power and reactive power of S Zi , respectively, Z i is impedance of the i-th load node, R i and X i are resistance and reactance of the i-th load node, respectively, m is the m-th node to be calculated, m = 0, 1, 2, …, n, S m is apparent power of the m-th load node, U m is voltage data of the m-th load node.

[0024] S43: calculating voltage data U m of the m-th load node by the following formula:

[0025]

[0026] wherein U0 is voltage of the low-voltage side of the voltage regulator.

[0027] Further, the S5 comprises:

[0028] S51: judging whether (U m -U set ) / U set is less than a set under-voltage threshold, and if yes, calculating the compensation capacity S B by the following formula:

[0029]

[0030] wherein, U set is a set voltage value.

[0031] S52: preferentially adjusting the under-voltage m-th node by adjacent photovoltaic modules;

[0032] wherein the number of the photovoltaic modules to be put in is The photovoltaic modules to be put in are selected from near to far by the under-voltage m-th node, and when , the adjustment is completed, and the process goes to S1.

[0033] P pv is the average apparent power of each inverter, and ΔS is a set value;

[0034] S53: When the adjustment of the adjacent photovoltaic module cannot meet the requirement, first calculate the adjustment capacity S of the input group number of the reactive compensation capacitor C , adjust through the reactive compensation capacitor, and the remaining part is adjusted through the adjacent photovoltaic module according to the S52;

[0035] wherein, When , the adjustment is completed, and the process goes to S1;

[0036] S54: When the adjustment of the adjacent photovoltaic module and the reactive compensation capacitor cannot meet the requirement, adjust through the upshift operation of the voltage regulator, and the remaining part S B -S G is adjusted through the reactive compensation capacitor and the adjacent photovoltaic module according to the S53;

[0037] wherein, when , the adjustment is completed, and the process goes to S1.

[0038] Further, the S6 comprises:

[0039] S61: Determine whether (U m -U set ) / U set is greater than a set overvoltage threshold value, and if yes, calculate the number and position of overvoltage nodes;

[0040] S62: When the overvoltage nodes and the total number of other non-overvoltage nodes whose voltage data are located in the interval [0.9U set , 1.1U set ] exceed a first set percentage of all nodes, adjust through the step-by-step downshift operation of the voltage regulator, and repeat the power flow calculation after the step-by-step downshift is completed until the voltage data of the overvoltage nodes are in the set interval [0.9U set , 1.1U set ];

[0041] S63: When the total number of overvoltage nodes and other non-overvoltage nodes whose voltage data are located in the interval [0.9U set , 1.1U set ] is less than a second set percentage of all nodes, adjust the mth node of the under-voltage through the adjacent photovoltaic module until the voltage data of the overvoltage nodes are in the set interval [0.9U set , 1.1U set ];

[0042] Wherein, the number of input photovoltaic modules is The input photovoltaic modules are selected by the mth node under voltage from near and far;

[0043] S64: Repeat the steps of S62-S63 above, adjust each overvoltage node until the voltage data of all overvoltage nodes is in the interval [0.9U set , 1.1U set ].

[0044] Further, when reactive power is over-compensated, the number of capacitor groups N B is selected according to the required compensation capacity S' C , until the voltage data of all nodes is not under-voltage and over-voltage and the power factor is greater than or equal to the set power factor threshold value;

[0045] Wherein, S' B = Q G -S G sin(arcsos0.98).

[0046] Further, the voltage regulation system of the transformer area further comprises a microclimate sensor, and the collection device is in communication connection with the microclimate sensor;

[0047] The method further comprises:

[0048] S7: Determine the output power of the photovoltaic module through the data collected by the microclimate sensor, and determine the damage or dirt state of the photovoltaic module through the difference between the calculated output power and the actual power.

[0049] Wherein, if the difference between the calculated output power and the actual power exceeds the set power threshold value, and the actual power decreases sharply, it is determined that the photovoltaic module or the inverter is damaged; if the difference between the calculated output power and the actual power exceeds the set power threshold value, and the actual power decreases gently, it is determined that the photovoltaic module is dirty.

[0050] Further, each low-voltage monitoring terminal is equipped with a CT induction coil, and the current terminal of the low-voltage monitoring terminal is clamped on the power line through the CT induction coil.

[0051] Further, the platform server is in communication connection with the collection device through a 4G or 5G network, the microclimate sensor, the reactive compensation capacitor and the voltage regulator are respectively in communication connection with the collection device through RS485, the collection device is in communication connection with the inverter through RS485, and the low-voltage monitoring terminal and the collection device are respectively in communication connection with the collection device through wireless or power carrier.

[0052] Further, the collecting device comprises a core board, the core board is provided with a first LORA module and a first charging circuit, the core board is connected with a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an alternating current three-phase input and a first charging battery / capacitor.

[0053] Further, the collecting device comprises a core board, the core board is provided with a first LORA module and a first charging circuit, the core board is connected with a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an alternating current three-phase input and a first charging battery / capacitor.

[0054] The present application has the following beneficial effects:

[0055] The present application has the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 It is a whole structure schematic diagram of the present application's substation voltage regulation system;

[0057] Figure 2 It is a circuit module schematic diagram of the present application's substation voltage regulation system;

[0058] Figure 3 It is a circuit module schematic diagram of the present application's substation voltage regulation system;

[0059] Figure 4 It is a circuit module schematic diagram of the present application's substation voltage regulation system;

[0060] Figure 5 It is a schematic diagram of the preset topological structure;

[0061] Figure 6 It is a flow chart of the voltage regulation method of the present application's substation voltage regulation system. DETAILED DESCRIPTION

[0062] In order to make the technical problems, technical solutions and advantages of the present application clearer, the following will be described in detail in combination with the drawings and specific embodiments.

[0063] The present application provides a voltage regulation method of a transformer area voltage regulation system, as shown in the figure, the transformer area voltage regulation system comprises a plurality of distributed photovoltaic modules 1, a voltage regulator 2, a reactive compensation capacitor 3, a collection device 4 and a platform server 5, wherein: Figures 1-2

[0064] Each photovoltaic module 1 comprises a photovoltaic assembly 6, an inverter 7 and a collection device 8, the photovoltaic assembly 6 is generally placed on the roof of a user, the inverter 7 is placed close to the photovoltaic assembly 6, and the collection device 8 is placed at the side of the inverter 7. The photovoltaic assembly 6 and the inverter 7 of the same photovoltaic module 1 are connected through a power line, the inverters 7 of the respective photovoltaic modules 1 are respectively connected in parallel with the low-voltage side of the voltage regulator 2 through a power line at a load node, and the inverter 7 of each photovoltaic module 1 is connected with a user load through a power line.

[0065] The voltage range of the high-voltage side of the voltage regulator 2 is 1kV-35kV, which is used for connecting with an external high-voltage power grid (for example, a 10kV power grid), the low-voltage side of the voltage regulator 2 has two cases, if it is three-phase power, the low-voltage side is 400V, if it is single-phase power, the low-voltage side is 220V, the low-voltage side of the voltage regulator 2 is connected with the output end of the reactive compensation capacitor 3 through a power line, and the reactive compensation capacitor 3 is arranged close to the voltage regulator 2.

[0066] The power line of the low-voltage side of the voltage regulator 2 and the power line at the load node are both provided with a low-voltage monitoring terminal (Low-voltage Terminal Unit, LTU) 9, the inverter 7 and the collection device 8 of the same photovoltaic module 1 are in communication connection, the low-voltage monitoring terminal 9, the collection device 8, the reactive compensation capacitor 3 and the low-voltage side of the voltage regulator 2 are in communication connection with the collection device 4. The platform server 5 is in communication connection with the collection device 4 for data interaction, and the platform server 5 is deployed on the cloud or at a designated place of a power company.

[0067] After the distributed photovoltaic power supply is accessed, the data of the user load node and the low-voltage side of the voltage regulator 2 are collected through the low-voltage monitoring terminal 9, the data of the inverter 7 are collected through the collection device 8, and the collected data are transmitted to the collection device 4. At the same time, the collection device 4 collects the data of the reactive compensation capacitor 3 and the voltage regulator 2. The data obtained by the collection device are transmitted to the platform server 5. The platform server 5 and the collection device 4 can perform power flow calculation through a preset topological structure according to the collected various data, globally control the load conditions of each node in the topological structure, realize the transformer area regulation of the distributed photovoltaic grid-connected, and improve the reliability of power distribution.

[0068] ​Each of the aforementioned low-voltage monitoring terminals 9 is equipped with an openable CT induction coil 10. The current terminal of the low-voltage monitoring terminal 9 is connected to the power line via the openable CT (Current Transformer) induction coil 10. The low-voltage monitoring terminal 9 obtains the user's load information through the openable CT induction coil. The load mainly includes voltage, current, active power, reactive power, power factor, harmonics, etc.

[0069] The transformer voltage regulation system of the present invention also includes a micro-meteorological sensor 11, which is placed at the collection device 4 and needs to be placed outdoors, and is communicatively connected to the collection device 4. The micro-meteorological sensor 11 collects information such as temperature, humidity, rainfall, and light radiation.

[0070] Specifically, the collection device 4 communicates with the platform server 5 via a 4G or 5G network to receive and feedback the corresponding control strategies and operating information.

[0071] The micro-weather sensor 11, the reactive power compensation capacitor 3, and the voltage regulator 2 are respectively connected to the collection device 4 via RS485 (serial communication).

[0072] The data acquisition device 8 is connected to the inverter 7 via RS485 to collect the output of the photovoltaic modules, mainly including DC bus voltage, current, power, etc.

[0073] The low-pressure monitoring terminal 9 and the acquisition device 8 are connected to the collection device 4 via wireless or power line carrier (High Power Line Communication, HPLC) respectively.

[0074] As an improvement to an embodiment of the present invention, such as Figure 3 As shown, the aggregation device 4 includes a core board 12, which is equipped with a first LORA (Long Range Radio) module 13. The core board 12 is connected to a first LORA antenna 14, a 4G / 5G antenna 15, a first power line carrier module 16, and a first RS485 communication interface 17.

[0075] The collection device 4 is installed on the low-voltage side of the transformer in the distribution area, usually on a platform or in the substation. It can collect low-voltage side voltage and current information in real time, calculate the power quality of the current node, and send control commands to the collection device according to the power quality. The commands include voltage regulation control of on-load transformers, reactive power compensation control of capacitors, or reactive power and power factor control of inverters.

[0076] Furthermore, the core board 12 is provided with a first charging circuit 18, and the core board 12 is connected to the AC three-phase input 20 and the first rechargeable battery / supercapacitor 19.

[0077] As another improvement of the embodiments of the present application, as shown in Figure 4 The collection device 8 includes an MCU (Microcontroller Unit) control board 21, which is provided with a second LORA module 22, a second power carrier module 23 and a second charging circuit 24. The MCU control board 21 is connected with a second LORA antenna 25 and a second charging battery / super capacitor 26. The MCU control board 21 has a second RS485 communication interface, which communicates with the inverter 7.

[0078] The MCU control board 21 can access photovoltaic 220V alternating current input. In places where it is inconvenient to access electricity, 12V photovoltaic modules can also be used for power supply. The control board has a charging circuit, which can charge the second charging battery / super capacitor. The collected inverter data is sent to the collection device 4 through LORA / HPLC.

[0079] The platform server 5 mainly includes five parts of data image display module, data management module, time alarm statistical module, statistical report module and system setting module.

[0080] The data image display module can display a map to show the distribution of the transformer area. By clicking the transformer area on the map, the topology map of the transformer area can be entered. The map can be realized in the form of an online map. The total number of display devices, including inverters, voltage regulators, LTUs and micro-weather sensors, is displayed. The statistical chart of each index is displayed. The devices such as photovoltaic modules, LTUs and voltage regulators in the topology map are displayed by different icons. The topology map supports the flashing of power-off devices. The blank area of the topology map displays the user voltage qualification rate curve, the user voltage qualification rate proportion curve, the transformer gear change curve and the capacitor switching record. Clicking the LTU icon displays the ABC three-phase current curve, the ABC three-phase voltage curve, the active power curve and the power factor curve. Clicking the photovoltaic icon displays the daily power generation, device detailed information, device power, power curve and device fault record.

[0081] The data management module can query the installed devices (inverters, LTUs, voltage regulators, compensation capacitors and micro-weather sensors) in the transformer area and mark and manage the devices.

[0082] The time alarm statistical module includes the voltage out-of-limit alarm information of the load node and the voltage regulator, including overvoltage and low voltage types, as well as the gear adjustment alarm information of the compensation capacitor and the voltage regulator.

[0083] The statistical report module includes the inverter power generation data summary statistics, the daily / monthly statistics of the total power generation of the transformer area and the alarm data statistics.

[0084] System setting module: user management can be carried out, permission management can be carried out, organization structure management, area management, can set up collection device, collection device, LTU, microclimate sensor and other related equipment information.

[0085] The voltage regulation method of the foregoing distribution area voltage regulation system is as shown in Figure 6 , and includes:

[0086] S1: The collection device collects data of each inverter.

[0087] Exemplarily, each collection device collects inverter data through RS485, and the inverter data includes voltage, current, active power, reactive power, apparent power, power factor, DC bus voltage, DC bus current and the like.

[0088] S2: The low-voltage monitoring terminal collects data of the low-voltage side of the voltage regulator and data of the load node.

[0089] Exemplarily, the data collected by the low-voltage monitoring terminal includes voltage, current, active power, reactive power, apparent power, power factor and harmonic content and the like.

[0090] S3: The collection device receives the data collected by the collection device, the data collected by the low-voltage monitoring terminal, the data of the voltage regulator and the data of the reactive compensation capacitor.

[0091] Exemplarily, the collection device receives the data collected by the collection module and the low-voltage monitoring terminal through LORA or power carrier, and communicates with the voltage regulator and the reactive compensation capacitor through RS485 to obtain the voltage regulator contact information, the number of groups of the reactive compensation capacitor to be put into and the apparent power.

[0092] Before adjustment, the initial working state default value of the distribution area is that the voltage regulator is at the middle contact position, the high-voltage side contact is 10kV, the distributed photovoltaic power factor is defaulted to 1, and can be set to the required preset value when participating in adjustment, and the compensation capacitor is defaulted to be cut off.

[0093] S4: The collection device performs power flow calculation according to the received data and according to the set topological structure to obtain voltage data of each node; wherein the nodes include each load node and the low-voltage side of the voltage regulator.

[0094] The preset topological structure is as shown in Figure 5 , and one specific implementation manner of the present step based on the topological structure is as follows:

[0095] S41: The following power flow calculation formula is established.

[0096]

[0097] Wherein, SG S is the apparent power of the low voltage side of the voltage regulator, i.e. the apparent power of the grid input G S is acquired by the LTU installed at the low voltage side of the voltage regulator.

[0098] S PVi S is the apparent power of the i-th inverter, i.e. the apparent power of the i-th photovoltaic input, i = 1, 2, …, n, n is the total number of inverters, S PVi S is acquired by the acquisition device.

[0099] S Ck S is the apparent power of the k-th group of the reactive compensation capacitor (here only the reactive power), k = 1, 2, …, n1, n1 is the number of groups of reactive compensation capacitors, S Ck S and n1 are read from the reactive compensation capacitors by the collection device.

[0100] S FVi S is the apparent power of the i-th load node, i.e. the power consumed by the load, acquired by the LTU installed at the load node.

[0101] S Zi S is the power loss of the i-th load node branch, obtained by dividing the sum of the squares of the voltages in the branch by the impedance.

[0102] S42: Simultaneously solve the following equations.

[0103]

[0104] Wherein, P represents the active power, Q represents the reactive power, the subscripts of P and Q represent which kind of active power and reactive power, for example, P G , Q G respectively represent the active power and the reactive power of the low voltage side of the voltage regulator (i.e. the active power and the reactive power of S G ). Similarly, the subscripts P PVi , Q PVi , P Ck , Q Ck , P Zi , Q Zi respectively represent the active power and the reactive power of S PVi , S Ck , S Zi .

[0105] Z i is the impedance of the i-th load node, R i and X i are respectively the resistance and the reactance of the i-th load node, and j is the imaginary unit.

[0106] m is the mth node to be calculated, m = 0, 1, 2, …, n, S m is the apparent power of the mth node, U m is the voltage data of the mth load node.

[0107] S43: Calculate the voltage data U of the mth load node by the following formula m .

[0108]

[0109] Wherein, U0 is the voltage of the low voltage side of the voltage regulator.

[0110] S5: Determine whether the voltage data of each node is under-voltage, when under-voltage, calculate the required compensation capacity, and adjust, after adjustment, jump to S1.

[0111] When the node is under-voltage, calculate the required compensation capacity, and adjust preferentially through the photovoltaic module; when the photovoltaic module adjustment cannot meet the requirement, carry out capacitor compensation, the remaining part is adjusted through the photovoltaic module; when the capacitor and the photovoltaic module cannot meet the requirement, adjust through the voltage regulator, the remaining part is adjusted through the photovoltaic module and the capacitor, and jump to S1 after adjustment.

[0112] The specific adjustment process can include the following steps:

[0113] S51: Determine whether (U m -U set ) / U set is less than the set under-voltage threshold, if yes, calculate the compensation capacity S B .

[0114]

[0115] Wherein, The under-voltage threshold can be set to -0.1, U set is the set voltage value, which can be set to 400V.

[0116] S52: Adjust the mth node under-voltage preferentially through the adjacent photovoltaic module.

[0117] Wherein, according to the under-voltage node number, the selected photovoltaic module is adjusted from near to far, and the number of the selected photovoltaic module is When , the adjustment is completed, and jump to S1.

[0118] P pv is the average apparent power of each inverter, and ΔS is a set value.

[0119] S53: When the adjustment of adjacent photovoltaic modules cannot meet the requirements, first calculate the adjustment capacity S of the number of reactive power compensation capacitor banks connected. C The remaining portion S is adjusted through the aforementioned reactive power compensation capacitor. B -S C According to S52, adjustment is performed via a nearby photovoltaic module.

[0120] in, when When the adjustment is complete, switch to S1.

[0121] S54: When the adjustment of the adjacent photovoltaic module and the reactive power compensation capacitor cannot meet the requirements, the voltage regulator adjustment is used as the primary adjustment method, and adjustment is performed through the voltage regulator's upshift operation. The photovoltaic module and capacitor serve as secondary compensations, and the remaining part S B -S G According to S53, the adjustment is made through the reactive power compensation capacitor and the adjacent photovoltaic module.

[0122] Among them, when When the adjustment is complete, switch to S1.

[0123] S6: Determine whether the voltage data of each node is over-voltage. If over-voltage occurs, calculate the number and location of over-voltage nodes and adjust them. After adjustment, return to S1.

[0124] The specific adjustment process may include the following steps:

[0125] S61: Judgment (U m -U set ) / U set If the pressure exceeds the set overpressure threshold (e.g., 0.1), calculate the number and location of overpressure nodes.

[0126] S62: When the overvoltage node and voltage data are located in [U set 1.1U set When the total number of other non-overpressured nodes within the interval exceeds a first set percentage (e.g., 70%) of all nodes, the voltage regulator is adjusted by step-down operation. After step-down is completed, the power flow calculation is repeated.

[0127] In other words, when the voltage at overvoltage nodes and the voltage at other non-overvoltage nodes are generally high, i.e., most node voltages are within the range [U... set 1.1U set When the voltage is within the set range (the percentage of nodes that are not exceeding the limit and have high voltage can be set to 70% of all nodes), the voltage regulator, as the main regulator, performs a downgrading operation. The downgrading is performed step by step from the current contact. After the downgrading is completed, power flow calculation is performed, and the above process is repeated until the node voltage is within the set range [0.9U]. set,1.1U set ] interval.

[0128] S63: When the number of overvoltage nodes and the voltage data of other nodes in the [0.9U set ,1.1U set ] interval is less than the second set percentage (for example, 10%) of all nodes, adjust the mth node of the under-voltage by the adjacent photovoltaic module.

[0129] Wherein, the number of photovoltaic modules put in is The photovoltaic modules put in are selected from the mth node of the under-voltage by the principle of proximity.

[0130] That is, when the number of overvoltage nodes is small (for example, less than 10% of the total nodes), photovoltaic adjustment is performed by the principle of proximity, and the number of photovoltaic adjustment groups is The adjustment sequence starts from the overvoltage node and proceeds from near to far, and the above process is repeated until the node voltage is in the set interval [0.9U set ,1.1U set ] interval.

[0131] S64: Repeat the steps of S62-S63 above to adjust each overvoltage node until the voltage data of all overvoltage nodes is in the [0.9U set ,1.1U set ] interval.

[0132] S7: When the voltage data of all nodes is not under-voltage and over-voltage, calculate the power factor of the transformer area, and if the power factor is greater than or equal to the set power factor threshold (for example, 0.98), the adjustment is completed; otherwise, perform over-compensation of reactive power, and jump to S1 after the compensation is completed.

[0133] When over-compensation of reactive power is performed, the required compensation of reactive power S' B The number of capacitor groups N C is selected according to the required compensation of reactive power, until the voltage data of all nodes is not under-voltage and over-voltage and the power factor is greater than or equal to the set power factor threshold.

[0134] Wherein, S' B = Q G -S G sin(arcsos0.98).

[0135] The compensation mode of the compensation capacity is photovoltaic, capacitor, photovoltaic+capacitor, and after the compensation is completed, jump to step 1 until the node voltage is not out of limit and the power factor reaches the set target, and the control is completed.

[0136] The application designs a voltage self-coordination method of the distribution area through a voltage collection and control strategy, collects data information of the voltage regulator, capacitor, photovoltaic inverter and load node after the distributed photovoltaic power supply is connected, performs power flow calculation, controls the nodes of the voltage operation state of the distribution area, and adjusts and compensates the voltage out-of-limit nodes (over-limit and under-voltage).

[0137] As an implementation manner, the voltage out-of-limit node adopts a nearby node voltage compensation manner, optimizes the output algorithm of the voltage regulator, reactive power compensation capacitor and photovoltaic inverter, the photovoltaic is prior, the capacitor is second, and the voltage regulator is last to participate in adjustment, quickly reduces the node voltage out-of-limit time, reduces the action times of the voltage regulator, improves the service life of the voltage regulator, adjusts the power factor of the distribution area under the condition that the voltage meets the requirements, improves the power factor of the distribution area, and has great practical value.

[0138] As an improvement of the embodiment of the application, when the micro-weather sensor is included, the method of the application further includes:

[0139] S7: judging the output power of the photovoltaic module through the data collected by the micro-weather sensor, and judging the damage or dirt state of the photovoltaic module through the difference between the calculated output power and the actual power of the photovoltaic module.

[0140] Wherein, if the difference between the calculated output power and the actual power exceeds the set power threshold value, and the actual power is sharply reduced, it is judged that the photovoltaic module or the inverter is damaged; if the difference between the calculated output power and the actual power exceeds the set power threshold value, and the actual power is gently reduced, it is judged that the photovoltaic module is dirty.

[0141] The related information of the micro-weather sensor can predict the power generation of the photovoltaic module, S=kW, S is the output power of the photovoltaic module, k is the conversion efficiency, and W is the light intensity. In daily operation, the difference between the photovoltaic output power generated by judging the light radiation intensity and the actual photovoltaic module output power is judged, when the difference exceeds the set power threshold value, it is judged that the photovoltaic module is damaged or dirty. If the output power is detected to be suddenly changed, it can be judged that the photovoltaic module or the inverter is damaged, and if the power generation is reduced relatively gently, it is determined that the photovoltaic module is dirty. The collection device sends an alarm information to the collection device, the collection device sends the alarm information to the platform server, and the platform service notifies the relevant personnel to maintain and clean, that is, to clean the dust or to repair.

[0142] The above-described control method of the present invention can be performed on a platform server, or the platform server can issue autonomous commands to the collection device, which then performs autonomous control operation according to a preset control scheme. The corresponding process and results of the control operation are uploaded to the platform server. When the platform server performs control, it can combine the user's historical load data with neural network training to obtain the user's electricity consumption habits—time load data. Combined with historical data from micro-meteorological sensors, it can predict photovoltaic output, pre-simulate the power supply and load of the distribution area, and perform over-limit control of node voltage in advance to reduce the probability of over-limit voltage occurrence.

[0143] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A voltage regulation method of a substation voltage regulation system, characterized by, The transformer area voltage regulation system comprises a plurality of distributed photovoltaic modules, a voltage regulator, a reactive power compensation capacitor, a collection device and a platform server, wherein: Each photovoltaic module comprises a photovoltaic assembly, an inverter and a collection device, the photovoltaic assembly and the inverter of the same photovoltaic module are connected through a power line, the inverters of the respective photovoltaic modules are connected in parallel through power lines to the low-voltage side of the voltage regulator; the low-voltage side of the voltage regulator is connected through a power line to the output end of the reactive power compensation capacitor, and the high-voltage side of the voltage regulator is connected to an external high-voltage power grid; the inverter of each photovoltaic module is connected through a power line to a user load at a load node; The power line of the low-voltage side of the voltage regulator and the power line at the load node are each provided with a low-voltage monitoring terminal, the inverter and the collection device of the same photovoltaic module are in communication connection, the low-voltage monitoring terminal, the collection device, the reactive power compensation capacitor and the voltage regulator are in communication connection with the collection device, and the collection device is in communication connection with the platform server; The voltage regulation method comprises: S1: the collection device collects data of each inverter; S2: the low-voltage monitoring terminal collects data of the low-voltage side of the voltage regulator and data of the load node; S3: the collection device receives the data collected by the collection device, the data collected by the low-voltage monitoring terminal, the data of the voltage regulator and the data of the reactive power compensation capacitor; S4: the collection device performs power flow calculation according to the received data and according to a set topological structure to obtain voltage data of each node; wherein the nodes include each load node and the low-voltage side of the voltage regulator; S5: it is judged whether the voltage data of each node is under-voltage, when under-voltage, the required compensation capacity is calculated, and adjustment is made, and after the adjustment is completed, it is turned to S1; S6: it is judged whether the voltage data of each node is over-voltage, when over-voltage, the number and position of the over-voltage nodes are calculated, and adjustment is made, and after the adjustment is completed, it is turned to S1; S7: when the voltage data of all nodes is neither under-voltage nor over-voltage, the transformer area power factor is calculated, if the power factor is greater than or equal to a set power factor threshold, the adjustment is ended; otherwise, the reactive power is over-compensated, and after the compensation is completed, it is jumped to S1; The data collected by the collection device includes the voltage, current, active power, reactive power, apparent power, power factor, DC bus voltage and DC bus current of the inverter; the data collected by the low-voltage monitoring terminal includes the voltage, current, active power, reactive power, apparent power, power factor and harmonic content of the low-voltage side of the voltage regulator and the load node; the data of the voltage regulator and the data of the reactive power compensation capacitor received by the collection device include the contact information of the voltage regulator, the number of groups of the reactive power compensation capacitor and the apparent power; The voltage data of each node is calculated by the following method: S41: the following power flow calculation formula is established: wherein S G is the apparent power of the low voltage side of the voltage regulator, S PVi is the apparent power of the i-th inverter, i = 1, 2, …, n, n being the total number of inverters, S Ck is the apparent power of the k-th group of the reactive compensation capacitor put in, k = 1, 2, …, n1, n1 being the number of groups of the reactive compensation capacitor put in, S FVi is the apparent power of the i-th load node, S Zi is the line loss power consumption of the i-th load node; S42: the following equations are solved simultaneously: wherein P represents active power, Q represents reactive power, j is an imaginary unit, P G , Q G represent active power and reactive power of S G , respectively, P PVi , Q PVi represent active power and reactive power of S PVi , respectively, P Ck , Q Ck represent active power and reactive power of S Ck , respectively, P Zi , Q Zi represent active power and reactive power of S Zi , respectively, Z i is impedance of the i-th load node, R i and X i are resistance and reactance of the i-th load node, respectively, m is the m-th node to be calculated, m = 0, 1, 2, …, n, S m is apparent power of the m-th load node, U m is voltage data of the m-th load node; S43: Calculate the voltage data U of the mth load node by the following formula m : wherein U0 is the voltage of the low-voltage side of the voltage regulator; The S5 comprises: S51: judging (U m -U set ) / U set whether it is less than a set under-voltage threshold, if yes, calculating the compensation capacity S B ; wherein U set is a set voltage value; S52: the under-voltage mth node is preferentially adjusted by the adjacent photovoltaic module; Wherein, the number of the input photovoltaic modules is The input photovoltaic modules are selected by the mth node under voltage from near to far, when the adjustment is completed, and the process goes to S1. P pv for the average apparent power of the individual inverters, AS is a set value; S53: When the adjustment of the adjacent photovoltaic module cannot be satisfied, first calculate the adjustment capacity S of the input group number of the reactive compensation capacitor C , adjust through the reactive compensation capacitor, and the remaining part is adjusted through the adjacent photovoltaic module according to S52; wherein When adjustment is complete, go to S1. S54: When the adjustment of the adjacent photovoltaic module and the reactive compensation capacitor cannot be satisfied, the adjustment is made by upshift operation of the voltage regulator, and the remaining portion S B -S G adjustment is made by the reactive compensation capacitor and the adjacent photovoltaic module according to the S53; wherein, when adjustment is complete, proceeding to S1.

2. The voltage regulation method of the voltage regulation system of a district according to claim 1, characterized by, The S6 comprises: S61: judge (U m -U set ) / U set whether it is greater than a set overpressure threshold, if yes, calculate the number and position of overpressure nodes; S62: When the total number of other non-overvoltage nodes whose voltage data are located in the interval [0.9U set , 1.1U set ] exceeds the first set percentage of all nodes, the step-down operation of the voltage regulator is adjusted, and the power flow calculation is repeated until the voltage data of the overvoltage node are located in the set interval [0.9U set , 1.1U set ]. S63: when the overvoltage node and the voltage data of other non-overvoltage nodes in the interval [0.9U set , 1.1U set ] are less than the second set percentage of all nodes, adjust the mth node of the under-voltage by the adjacent photovoltaic module until the voltage data of the over-voltage node is in the set interval [0.9U set , 1.1U set ]; Wherein, the number of photovoltaic modules put in is The photovoltaic modules put in are selected from the mth node with under-voltage from near to far; S64: repeat the steps of S62-S63 above to adjust each overvoltage node until the voltage data of all overvoltage nodes are within the interval [0.9U set , 1.1U set ].

3. The voltage regulation method of the transformer district voltage regulation system according to claim 2, characterized by, When over-compensating the reactive power, according to the required compensation capacity S' B Selecting the number N of capacitor banks for reactive compensation capacitor removal C , until the voltage data of all nodes are neither under-voltage nor over-voltage and the power factor is greater than or equal to the set power factor threshold. wherein S′ B = Q G -S G sin(arcsos0.98).

4. The voltage regulation method of the transformer district voltage regulation system according to any one of claims 1 to 3, characterized by, The transformer area voltage regulation system further comprises a micro-weather sensor, and the collecting device is in communication connection with the micro-weather sensor. The method further comprises: S8: judging the output power of the photovoltaic module through the data collected by the micro-weather sensor, and judging the damage or dirt state of the photovoltaic module through the difference between the calculated output power and the actual power of the photovoltaic module; If the difference between the calculated output power and the actual power exceeds the set power threshold value, and the actual power decreases sharply, it is judged that the photovoltaic module or the inverter is damaged; if the difference between the calculated output power and the actual power exceeds the set power threshold value, and the actual power decreases gently, it is judged that the photovoltaic module is dirty.

5. The voltage regulation method of the voltage regulation system of a district according to claim 4, characterized by, Each low-voltage monitoring terminal is equipped with a CT induction coil, and the current terminal of the low-voltage monitoring terminal is clamped on the power line through the CT induction coil.

6. The voltage regulation method of the voltage regulation system of a district according to claim 5, characterized by, The platform server is in communication connection with the collecting device through a 4G or 5G network, the micro-weather sensor, the reactive compensation capacitor and the voltage regulator are respectively in communication connection with the collecting device through RS485, the collecting device is in communication connection with the inverter through RS485, and the low-voltage monitoring terminal and the collecting device are respectively in communication connection with the collecting device through wireless or power carrier.

7. The voltage regulation method of the voltage regulation system of a district according to claim 6, characterized by, The collecting device comprises a core board, the core board is provided with a first LORA module and a first charging circuit, the core board is connected with a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an alternating current three-phase input and a first charging battery / capacitor.

8. The voltage regulation method of the voltage regulation system of a district according to claim 7, characterized by, The collecting device comprises a core board, the core board is provided with a first LORA module and a first charging circuit, the core board is connected with a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an alternating current three-phase input and a first charging battery / capacitor. The collecting device comprises a core board, the core board is provided with a first LORA module and a first charging circuit, the core board is connected with a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an alternating current three-phase input and a first charging battery / capacitor.

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