Voltage regulation and control method of transformer area voltage regulation and control system

Abstract

The invention discloses a voltage regulation and control method of a transformer area voltage regulation and control system, which belongs to the field of on-line monitoring of power transformation and distribution and comprises a photovoltaic module, a voltage regulator, a reactive compensation capacitor, a collecting device and a platform server. The photovoltaic module comprises a photovoltaic assembly, an inverter and an acquisition device, the photovoltaic assembly and the inverter are connected through a power line, and 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, and the inverter is connected with a user load at a load node through a power line. Low-voltage monitoring terminals are arranged on power lines at the low-voltage side of the voltage regulator and the load node, the inverter is in communication connection with the acquisition device, the low-voltage monitoring terminals, the acquisition device, the reactive compensation capacitor and the low-voltage side of the voltage regulator are in communication connection with the collection device, and the collection device is in communication connection with the platform server. According to the invention, distribution area regulation and control of distributed photovoltaic grid connection are realized, and the reliability of power distribution and energy supply is improved.

Description

Technical Field

[0001] The present invention relates to the field of online monitoring of power transformation and distribution, and in particular to a voltage control method of a transformer area voltage control system. Background Art

[0002] With the deepening of energy conservation and emission reduction, distributed photovoltaic technology has been widely promoted and applied. Photovoltaic grid connection has changed the traditional distribution network architecture, and substation regulation has encountered new difficulties. If not handled properly, it may cause problems such as current reverse, voltage over-limit, energy waste, etc., seriously affecting the reliability of power distribution and energy supply. Summary of the invention

[0003] The present invention provides a voltage control method for a substation voltage control system, which realizes substation control of distributed photovoltaic grid-connected power and improves the reliability of power distribution and energy supply.

[0004] The present invention provides the following technical solutions:

[0005] A voltage control method for a substation voltage control system, the substation voltage control 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 includes a photovoltaic component, an inverter and a collection device. The photovoltaic component and the inverter of the same photovoltaic module are connected through a power line, and the inverter of each photovoltaic module is connected in parallel with the low-voltage side of the voltage regulator through the power line; the low-voltage side of the voltage regulator is connected to the output end of the reactive power compensation capacitor through the power line, and the high-voltage side of the voltage regulator is connected to the external high-voltage power grid. The inverter of each photovoltaic module is connected to the user load at the load node through the power line;

[0007] A low-voltage monitoring terminal is provided on the power line on the low-voltage side of the voltage regulator and the power line at the load node, the inverter and the collection device of the same photovoltaic module are communicatively connected, the low-voltage monitoring terminal, the collection device, the reactive power compensation capacitor and the voltage regulator are communicatively connected with the collection device, and the collection device is communicatively connected with the platform server;

[0008] The voltage control method comprises:

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

[0010] S2: The low voltage monitoring terminal collects data on the low voltage side of the voltage regulator and data on 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 compensation capacitor;

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

[0013] S5: Determine whether the voltage data of each node is undervoltage. If undervoltage occurs, calculate the required compensation capacity and adjust it. After the adjustment is completed, go to S1;

[0014] S6: Determine whether the voltage data of each node is over-voltage. If it is over-voltage, calculate the number and position of the over-voltage nodes and make adjustments. After the adjustment is completed, go to S1;

[0015] S7: When the voltage data of all nodes are neither undervoltage nor overvoltage, calculate the power factor of the substation. If the power factor is greater than or equal to the set power factor threshold, the adjustment is completed; otherwise, perform reactive power overcompensation, and jump to S1 after the compensation is completed.

[0016] Furthermore, the data collected by the collection device include 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 include 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 compensation capacitor received by the collection device include the contact information of the voltage regulator, the number of reactive compensation capacitors put into use and the apparent power.

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

[0018] S41: Establish the following power flow calculation formula:

[0019]

[0020] Among them, S G is the apparent power on the low voltage side of the voltage regulator, S PVi is the apparent power of the ith inverter, i = 1, 2, ..., n, n is the total number of inverters, S Cj is the apparent power of the kth group of reactive power compensation capacitors, k = 1, 2, ..., n1, n1 is the number of reactive power compensation capacitors, S FVi is the apparent power of the ith load node, S Zi is the line loss power consumption of the i-th load node;

[0021] S42: Combine the following equations:

[0022]

[0023] Where P represents active power, Q represents reactive power, j is an imaginary unit, and Z i is the impedance of the ith load node, R i For X i The resistance and reactance of the i-th load node respectively, m is the m-th node to be calculated, m = 0, 1, 2, ..., n;

[0024] S43: Calculate the voltage data U of the mth load node by the following formula: m :

[0025]

[0026] Wherein, U0 is the voltage on the low voltage side of the voltage regulator.

[0027] Further, the S5 includes:

[0028] S51: Judgment m -U set ) / U set Is it less than the set undervoltage threshold? If so, calculate the compensation capacity S by the following formula B ;

[0029]

[0030] in, U set is the set voltage value.

[0031] S52: preferentially regulating the mth node with undervoltage through adjacent photovoltaic modules;

[0032] Among them, the number of photovoltaic modules put into use is The PV modules to be put into operation are selected from the mth node with undervoltage from near to far. When , the adjustment is completed and go to S1;

[0033] P pv is the average apparent power of each inverter, K=0,1,2,…,n, ΔS is the set value;

[0034] S53: When the regulation of the adjacent photovoltaic modules cannot be met, first calculate the adjustment capacity S of the number of reactive compensation capacitors put into use C , is regulated by the reactive power compensation capacitor, and the remaining part is regulated by the adjacent photovoltaic module according to S52;

[0035] in, when When , the adjustment is completed and go to S1;

[0036] S54: When the regulation of the adjacent photovoltaic modules and the reactive power compensation capacitor cannot meet the requirements, the voltage regulator is adjusted by the upshift operation, and the remaining part (S B -S G ) adjusting through the reactive power compensation capacitor and the adjacent photovoltaic module according to S53;

[0037] Among them, when When the adjustment is completed, go to S1.

[0038] Further, the S6 includes:

[0039] S61: Judgment m -U set ) / U set Is it greater than the set overpressure threshold? If so, calculate the number and location of overpressure nodes;

[0040] S62: When the overvoltage node and voltage data are at [U set , 1.1U set ] When the total number of other non-overvoltage nodes in the interval exceeds the first set percentage of all nodes, the voltage regulator is adjusted by step-down operation, and the power flow calculation is repeated after the step-down is completed until the voltage data of the overvoltage node is within the set interval [0.9U set , 1.1U set ]Inside;

[0041] S63: When the overvoltage node and voltage data are at [U set , 1.1U set ] interval is less than the second set percentage of all nodes, the mth node with undervoltage is adjusted through the adjacent photovoltaic modules until the voltage data of the overvoltage node is within the set interval [0.9U set , 1.1U set ]Inside;

[0042] Among them, the number of photovoltaic modules put into use is The photovoltaic modules to be put into use are selected from the mth node with undervoltage from near to far;

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

[0044] Furthermore, when reactive power overcompensation is performed, the reactive capacity S' required to be compensated B Select the number of capacitor groups N to be removed by reactive compensation capacitors C, until the voltage data of all nodes are neither undervoltage nor overvoltage and the power factor is greater than or equal to the set power factor threshold;

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

[0046] Furthermore, the substation voltage control system further includes a micro-meteorological sensor, and the collection device is communicatively connected with the micro-meteorological sensor;

[0047] The method further comprises:

[0048] S7: judging the output power of the photovoltaic module by the data collected by the micro-meteorological sensor, and judging the damage or dirtiness of the photovoltaic module by the difference between the output power calculated by the photovoltaic module and its actual power;

[0049] Among them, if the difference between the calculated output power and the actual power exceeds the set power threshold and the actual power decreases sharply, it is judged that the photovoltaic component or inverter is damaged; if the difference between the calculated output power and the actual power exceeds the set power threshold and the actual power decreases smoothly, it is judged that the photovoltaic component is dirty.

[0050] Furthermore, 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] Furthermore, the platform server is communicatively connected to the collection device via a 4G or 5G network, the micro-meteorological sensor, reactive compensation capacitor and voltage regulator are communicatively connected to the collection device via RS485, the collection device is communicatively connected to the inverter via RS485, and the low-voltage monitoring terminal and collection device are communicatively connected to the collection device via wireless or power carrier.

[0052] Furthermore, the collection device includes a core board, which is provided with a first LORA module and a first charging circuit, and the core board is connected to a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an AC three-phase input and a first rechargeable battery / capacitor.

[0053] Furthermore, the acquisition device includes an MCU control board, the MCU control board is provided with a second LORA module, a second power carrier module, a second RS485 communication interface and a second charging circuit, and the MCU control board is connected to a second LORA antenna and a second rechargeable battery / capacitor.

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

[0055] The present invention collects data on the user load node and the low-voltage side of the voltage regulator through a low-voltage monitoring terminal, collects data on the photovoltaic inverter through a collection device, and transmits the collected data to a collection device. At the same time, the collection device collects data on the reactive compensation capacitor and the voltage regulator. The data obtained by the collection device is transmitted to the platform server. The present invention designs a voltage method for self-coordination of the substation voltage through a voltage collection and control strategy. After the distributed photovoltaic power source is connected, the platform server and the collection device can collect data information on the voltage regulator, capacitor, photovoltaic inverter and load node, and perform flow calculation through a preset topological structure. The node global control of the voltage operation status of the distribution station area is carried out, and the voltage over-limit nodes (over-limit and under-voltage) are adjusted and compensated, realizing the substation regulation of distributed photovoltaic grid-connected substations and improving the reliability of power distribution and energy supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the overall structure of the transformer area voltage control system of the present invention;

[0057] Figure 2 It is a schematic diagram of a circuit module of the station area voltage control system of the present invention;

[0058] Figure 3 It is a schematic diagram of the circuit module of the collection device;

[0059] Figure 4 It is a schematic diagram of the circuit module of the acquisition device;

[0060] Figure 5 A schematic diagram of a preset topological structure;

[0061] Figure 6 The figure is a flow chart of a voltage control method for a transformer area voltage control system. DETAILED DESCRIPTION

[0062] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0063] The present invention provides a voltage control method for a transformer area voltage control system, such as Figure 1-2 As shown, the area voltage control system includes a number of distributed photovoltaic modules 1, a voltage regulator 2, a reactive power compensation capacitor 3, a collection device 4 and a platform server 5, wherein:

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

[0065] The voltage range of the high-voltage side of the voltage regulator 2 is 1kV~35kV, which is used to connect to an external high-voltage power grid (for example, a 10kV power grid). There are two situations for the low-voltage side of the voltage regulator 2. If it is three-phase electricity, the low-voltage side is 400V, and if it is single-phase electricity, the low-voltage side is 220V. The low-voltage side of the voltage regulator 2 is connected to 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 lines on the low-voltage side of the voltage regulator 2 and the power lines at the load nodes are both provided with low-voltage monitoring terminals (Low-voltage Terminal Unit, LTU) 9, the inverter 7 of the same photovoltaic module 1 is connected in communication with the collection device 8, and the low-voltage monitoring terminal 9, the collection device 8, the reactive power compensation capacitor 3 and the low-voltage side of the voltage regulator 2 are connected in communication with the collection device 4. The platform server 5 is connected in communication with the collection device 4 for data exchange, and the platform server 5 is deployed on the cloud or at a location designated by the power company.

[0067] After the distributed photovoltaic power source is connected, 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 is collected through the collection device 8, and the collected data is 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 is transmitted to the platform server 5. The platform server 5 and the collection device 4 can perform power flow calculations based on the various collected data through the preset topological structure, and perform global control of the load conditions of each node in the topology, thereby realizing the regional control of distributed photovoltaic grid-connected power and improving the reliability of power distribution and energy supply.

[0068] Each of the aforementioned low-voltage monitoring terminals 9 is equipped with an open-and-closed CT induction coil 10, and the current terminal of the low-voltage monitoring terminal 9 is clamped on the power line through the open-and-closed CT (Current transformer) induction coil 10. The low-voltage monitoring terminal 9 obtains the user's load conditions through the open-and-closed CT induction coil, and the load mainly includes voltage, current, active power, reactive power factor, harmonics, etc.

[0069] The substation voltage control system of the present invention further includes a micro-meteorological sensor 11, which is placed at the collection device 4, 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 aggregation device 4 communicates with the platform server 5 via a 4G or 5G network to receive and feedback corresponding control strategies and operating information.

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

[0072] The collection device 8 is connected to the inverter 7 through RS485 communication to collect the output of the photovoltaic module, mainly including the DC bus voltage, current, power, etc.

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

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

[0075] The collection device 3 is installed on the low-voltage side of the substation transformer, generally in the stand or substation room. It can collect the voltage and current information on the low-voltage side in real time, calculate the power quality of the current node, and send control instructions to the collection device according to the power quality conditions. The instructions include voltage regulation control of the on-load transformer, reactive power compensation control of the capacitor, or reactive power and power factor control of the inverter.

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

[0077] As another improvement of the embodiment of the present invention, Figure 4As shown, the acquisition device 8 includes an MCU (Microcontroller Unit, microcontroller, single chip microcomputer) control board 21, the MCU control board 21 is provided with a second LORA module 22, a second power carrier module 23 and a second charging circuit 24, and the MCU control board 21 is connected to a second LORA antenna 25 and a second rechargeable battery / super capacitor 26. The MCU control board 21 has a second RS485 communication interface for communicating with the inverter 7.

[0078] The MCU control board 21 can be connected to the photovoltaic 220V AC input. In places where it is inconvenient to connect to the power supply, a 12V photovoltaic module can also be used for power supply. The control board has a charging circuit that can charge the second rechargeable battery / supercapacitor. The collected inverter data is sent to the collection device 4 via LORA / HPLC.

[0079] The platform server 5 mainly includes five parts: data visualization display module, data management module, time alarm statistics module, statistical report module, system setting module and the like.

[0080] Data visualization display module: It can display maps and display the distribution of substations. Click on the substation on the map to enter the topology map of the substation. The map can be realized in the form of online maps. Display the statistics of the total number of equipment, including inverters, voltage regulators, LTUs, micro-meteorological sensors, etc. Display statistical charts of various indicators. In the substation topology map, photovoltaic components, LTUs, voltage regulators and other equipment are displayed through different icons. The topology map supports the flashing of power-off equipment. 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. Click the LTU icon to display the ABC three-phase current curve, ABC three-phase voltage curve, active power curve, and power factor curve. Click the photovoltaic icon to display daily power generation, equipment details, equipment power, power curve, display equipment fault records and other information.

[0081] Data management module: can query the equipment installed in the substation (inverter, LTU, voltage regulator, compensation capacitor, micro-meteorological sensor and other equipment), and mark and manage the equipment.

[0082] Time alarm statistics module: voltage over-limit alarm information at load nodes and voltage regulator ends, voltage over-limit includes overvoltage and undervoltage types, compensation capacitors, and gear adjustment alarm information of voltage regulators.

[0083] Statistical report module: summary statistics of inverter power generation data, daily / monthly statistics of power generation in the entire area, and alarm data statistics.

[0084] System setting module: can perform user management, authority management, organizational structure management, station area management, and can set the collection device, aggregation device, LTU, micro-meteorological sensor and other related equipment information.

[0085] The voltage control method of the aforementioned transformer area voltage control system is as follows: Figure 6 As shown, including:

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

[0087] Exemplarily, each acquisition device acquires data of each inverter via RS485, and the inverter data includes voltage, current, active power, reactive power, apparent power, power factor, DC bus voltage, DC bus current and other data.

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

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

[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 data collected by the collection module and the low-voltage monitoring terminal through LORA or power carrier, communicates with the voltage regulator and reactive power compensation capacitor through RS485, and obtains the contact information of the voltage regulator, the number of reactive power compensation capacitors put into use, and the apparent power.

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

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

[0094] The preset topology is as follows Figure 5 As shown, based on the topological structure, a specific implementation of this step is as follows:

[0095] S41: Establish the following power flow calculation formula.

[0096]

[0097] Among them, SG is the apparent power of the low voltage side of the voltage regulator, that is, the apparent power of the grid input, S G Obtained through the LTU installed on the low-pressure side of the voltage regulator.

[0098] S PVi is the apparent power of the ith inverter, that is, the apparent power of the ith photovoltaic input, i = 1, 2, ..., n, n is the total number of inverters, S PVi Obtained through the collection device.

[0099] S Cj is the apparent power of the kth group of reactive compensation capacitors (here only reactive power), k = 1, 2, ..., n1, n1 is the number of reactive compensation capacitors, S Cj and n1 are read from the reactive compensation capacitor through the collection device.

[0100] S FVi is the apparent power of the i-th load node, that is, the load consumption power, obtained through the LTU installed at the load node.

[0101] S Zi is the line loss power consumption of the ith load node, obtained by dividing the sum of the squares of the voltages in the branch by the impedance.

[0102] S42: Simulate the following equations.

[0103]

[0104] Among them, P represents active power, Q represents reactive power, and the subscripts of P and Q represent the specific active power and reactive power, for example, P G ,jQ G Respectively represent the active power and reactive power on the low voltage side of the voltage regulator (i.e. S G Similarly, the subscript P PVi , Q PVi , P Ck , Q Ck , P Zi , Q Zi Respectively represent S PVi , S Cj , S Zi of active power and reactive power.

[0105] Z i is the impedance of the ith load node, R i For X i are the resistance and reactance of the ith load node respectively, and j is an 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 on the low voltage side of the voltage regulator.

[0110] S5: Determine whether the voltage data of each node is undervoltage. If undervoltage occurs, calculate the required compensation capacity and make adjustments. After the adjustment is completed, go to S1.

[0111] When the node is undervoltage, the required compensation capacity is calculated and adjusted through the photovoltaic module first; when the photovoltaic module adjustment cannot meet the requirements, capacitor compensation is performed, and the remaining part is adjusted through the photovoltaic module; when both the capacitor and the photovoltaic module cannot meet the requirements, the voltage regulator is used for adjustment, and the remaining part is adjusted through the photovoltaic module and the capacitor. After the adjustment is completed, jump to S1.

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

[0113] S51: Judgment m -U set ) / U set Is it less than the set undervoltage threshold? If so, calculate the compensation capacity S by the following formula B .

[0114]

[0115] in, The undervoltage threshold can be set to -0.1, U set The voltage value can be set to 400V.

[0116] S52: Prioritize the adjacent photovoltaic modules to regulate the undervoltage mth node.

[0117] Among them, according to the undervoltage node number, the photovoltaic modules put into operation are selected from near to far for adjustment. The number of photovoltaic modules put into operation is when When the adjustment is completed, go to S1.

[0118] P pv is the average apparent power of each inverter, K=0,1,2,…,n, ΔS is the set value.

[0119] S53: When the regulation of the adjacent photovoltaic modules cannot be met, first calculate the adjustment capacity S of the number of reactive compensation capacitors put into use C , is regulated by the reactive power compensation capacitor, and the remaining part (S B -S C ) is adjusted by adjacent photovoltaic modules according to S52.

[0120] in, when When the adjustment is completed, go to S1.

[0121] S54: When the adjustment of the adjacent photovoltaic modules and the reactive power compensation capacitor cannot meet the requirements, the voltage regulator is adjusted as the main adjustment method, and the adjustment is performed through the upshift operation of the voltage regulator, and the photovoltaic and capacitor are used as secondary compensation. The remaining part (S B -S G ) According to S53, regulation is performed through the reactive compensation capacitor and the adjacent photovoltaic module.

[0122] Among them, when When the adjustment is completed, go to S1.

[0123] S6: Determine whether the voltage data of each node is overvoltage. If overvoltage occurs, calculate the number and location of overvoltage nodes and make adjustments. After the adjustment is completed, go to S1.

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

[0125] S61: Judgment m -U set ) / U set Is it greater than the set overpressure threshold (for example, 0.1)? If so, calculate the number and location of overpressure nodes.

[0126] S62: When the overvoltage node and voltage data are at [U set , 1.1U set ]When the total number of other non-overpressure nodes in the interval exceeds the first set percentage (for example, 70%) of all nodes, the voltage regulator is adjusted by step-by-step downshifting operation, and the flow calculation is repeated after the step-by-step downshifting is completed.

[0127] That is to say, when the voltage of the overvoltage node and the voltage of other non-overvoltage nodes are generally high, that is, the voltage of most nodes is in [U set , 1.1U set ] interval (the percentage of nodes that have not exceeded the limit and whose voltage is high can be set to 70% of all nodes), the voltage regulator acts as the main regulator and performs a downshift operation. The downshift is gradually reduced by the current contact. After the downshift is completed, the power flow calculation is performed and the above process is repeated until the node voltage is within the set interval [0.9U set, 1.1U set ]middle.

[0128] S63: When the overvoltage node and voltage data are at [U set , 1.1U set ]When the total number of other non-overvoltage nodes in the interval is less than a second set percentage (for example, 10%) of all nodes, the mth undervoltage node is regulated through the adjacent photovoltaic module.

[0129] Among them, the number of photovoltaic modules put into use is The photovoltaic modules to be put into use are selected from the mth node with undervoltage from near to far.

[0130] That is to say, when the number of overvoltage nodes is small (for example, less than 10% of the total number of nodes), photovoltaic adjustment is carried out according to the principle of proximity to adjust the photovoltaic power of the adjacent nodes. The number of photovoltaic adjustment groups is The adjustment sequence starts from the overvoltage node, from near to far, and repeats the above process until the node voltage is within the set range [0.9U set , 1.1U set ]middle.,

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

[0132] S7: When the voltage data of all nodes are neither undervoltage nor overvoltage, calculate the power factor of the substation. 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 reactive power overcompensation, and jump to S1 after the compensation is completed.

[0133] When reactive power overcompensation is performed, the reactive capacity S' required to be compensated B Select the number of capacitor groups N to be removed by reactive compensation capacitors C , until the voltage data of all nodes are neither undervoltage nor overvoltage and the power factor is greater than or equal to the set power factor threshold.

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

[0135] The reactive capacity compensation method is photovoltaic, capacitor, photovoltaic + capacitor. After the compensation is completed, jump to step 1 until the node voltage does not exceed the limit and the power factor reaches the set target, and the regulation is completed.

[0136] The present invention designs a voltage method for self-coordination of substation voltage through voltage collection and control strategy. After the distributed photovoltaic power source is connected, the data information of the voltage regulator, capacitor, photovoltaic inverter and load node is collected to perform power flow calculation, the node control of the voltage operation status of the distribution station area is performed, and the voltage exceeding the limit node (over-limit and under-voltage) is adjusted and compensated.

[0137] As an implementation method, when the voltage exceeds the limit, the node adopts the nearest node voltage compensation method, optimizes the output algorithm of the voltage regulator, reactive compensation capacitor and photovoltaic inverter, photovoltaic is given priority, capacitor is second, and the voltage regulator participates in the adjustment last, quickly reduces the node voltage exceeding the limit time, reduces the number of times the voltage regulator is operated, and increases the service life of the voltage regulator. When the voltage meets the requirements, the power factor of the substation is adjusted to improve the power factor of the distribution station area, which has great practical value.

[0138] As an improvement of the embodiment of the present invention, when a micro-meteorological sensor is included, the method of the present invention further includes:

[0139] S7: judging the output power of the photovoltaic module by the data collected by the micro-meteorological sensor, and judging the damage or dirtiness of the photovoltaic component by the difference between the output power calculated by the photovoltaic module and its actual power.

[0140] Among them, if the difference between the calculated output power and the actual power exceeds the set power threshold and the actual power decreases sharply, it is judged that the photovoltaic component or inverter is damaged; if the difference between the calculated output power and the actual power exceeds the set power threshold and the actual power decreases smoothly, it is judged that the photovoltaic component is dirty.

[0141] The power generation of photovoltaic modules can be predicted through the relevant information of micro-meteorological sensors, S = kW, S is the output power of photovoltaic modules, k is the conversion efficiency, and W is the light intensity. In daily operation, the difference between the photovoltaic output power that should be generated by the light radiation intensity and the actual photovoltaic module output power is determined. When the difference exceeds the set power threshold, the photovoltaic module is judged to be damaged or dirty. If a sudden change in output power is detected, it can be judged that the photovoltaic module or inverter is damaged. If the reduction in power generation is relatively gentle, it is determined that the photovoltaic module is dirty. The collection device sends an alarm message to the collection device, and the collection device sends the alarm message to the platform server. The platform service notifies the relevant personnel to perform maintenance and cleaning, that is, dust cleaning or repair.

[0142] The above-mentioned control method of the present invention can be performed on the platform server, or the platform server can issue autonomous instructions to the collection device, and the collection device performs autonomous control operation according to the preset control scheme, and 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, through neural network training and learning, to obtain the user's electricity usage habits-time load data, and combine the historical data of micro-meteorological sensors to predict photovoltaic output, pre-deduce the energy supply and load of the substation, and perform over-limit control of node voltage in advance to reduce the probability of over-limit voltage.

[0143] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A voltage control method for a transformer area voltage control system, characterized in that: The area voltage control system includes a number of distributed photovoltaic modules, voltage regulators, reactive power compensation capacitors, collection devices and platform servers, wherein: Each photovoltaic module includes a photovoltaic component, an inverter and a collection device. The photovoltaic component and the inverter of the same photovoltaic module are connected through a power line, and the inverter of each photovoltaic module is connected in parallel with the low-voltage side of the voltage regulator through the power line; the low-voltage side of the voltage regulator is connected to the output end of the reactive power compensation capacitor through the power line, and the high-voltage side of the voltage regulator is connected to the external high-voltage power grid. The inverter of each photovoltaic module is connected to the user load at the load node through the power line; A low-voltage monitoring terminal is provided on the power line on the low-voltage side of the voltage regulator and the power line at the load node, the inverter and the collection device of the same photovoltaic module are communicatively connected, the low-voltage monitoring terminal, the collection device, the reactive power compensation capacitor and the voltage regulator are communicatively connected with the collection device, and the collection device is communicatively connected with the platform server; The voltage control method comprises: S1: the collection device collects data of each inverter; S2: The low voltage monitoring terminal collects data on the low voltage side of the voltage regulator and data on 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 compensation capacitor; S4: The collection device performs power flow calculation according to the received data and the set topology 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: Determine whether the voltage data of each node is undervoltage. If undervoltage occurs, calculate the required compensation capacity and adjust it. After the adjustment is completed, go to S1; S6: Determine whether the voltage data of each node is over-voltage. If it is over-voltage, calculate the number and position of the over-voltage nodes and make adjustments. After the adjustment is completed, go to S1; S7: When the voltage data of all nodes are neither undervoltage nor overvoltage, calculate the power factor of the substation. If the power factor is greater than or equal to the set power factor threshold, the adjustment is completed; otherwise, perform reactive power overcompensation, and jump to S1 after the compensation is completed.

2. The voltage control method of the substation voltage control system according to claim 1, characterized in that: The data collected by the collection device include 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 include 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 compensation capacitor received by the collection device include the contact information of the voltage regulator, the number of reactive compensation capacitor groups put into use and the apparent power.

3. The voltage control method of the substation voltage control system according to claim 2, characterized in that: The voltage data of each node is calculated by the following method: S41: Establish the following power flow calculation formula: Among them, S G is the apparent power on the low voltage side of the voltage regulator, S PVi is the apparent power of the ith inverter, i = 1, 2, ..., n, n is the total number of inverters, S Cj is the apparent power of the kth group of reactive power compensation capacitors, k = 1, 2, ..., n1, n1 is the number of reactive power compensation capacitors, S FVi is the apparent power of the ith load node, S Zi is the line loss power consumption of the i-th load node; S42: Combine the following equations: Where P represents active power, Q represents reactive power, j is an imaginary unit, and Z i is the impedance of the i-th load node, R i For X i The resistance and reactance of the i-th load node respectively, m is the m-th node to be calculated, m = 0, 1, 2, ..., n; S43: Calculate the voltage data U of the mth load node by the following formula: m : Wherein, U0 is the voltage on the low voltage side of the voltage regulator.

4. The voltage control method of the substation voltage control system according to claim 3, characterized in that: The S5 includes: S51: Judgment m -U set ) / U set Is it less than the set undervoltage threshold? If so, calculate the compensation capacity S by the following formula B ; in, U set is the set voltage value. S52: preferentially regulating the mth node with undervoltage through adjacent photovoltaic modules; Among them, the number of photovoltaic modules put into use is The PV modules to be put into operation are selected from the mth node with undervoltage from near to far. When , the adjustment is completed and go to S1; P pv is the average apparent power of each inverter, K=0,1,2,…,n, ΔS is the set value; S53: When the regulation of the adjacent photovoltaic modules cannot be met, first calculate the adjustment capacity S of the number of reactive compensation capacitors put into use C , is regulated by the reactive power compensation capacitor, and the remaining part is regulated by the adjacent photovoltaic module according to S52; in, when When , the adjustment is completed and go to S1; S54: When the regulation of the adjacent photovoltaic modules and the reactive power compensation capacitor cannot meet the requirements, the voltage regulator is adjusted by the upshift operation, and the remaining part (S B -S G ) adjusting through the reactive power compensation capacitor and the adjacent photovoltaic module according to S53; Among them, when When the adjustment is completed, go to S1.

5. The voltage control method of the substation voltage control system according to claim 4, characterized in that: The S6 includes: S61: Judgment m -U set ) / U set Is it greater than the set overpressure threshold? If so, calculate the number and location of overpressure nodes; S62: When the overvoltage node and voltage data are at [U set , 1.1U set ] When the total number of other non-overvoltage nodes in the interval exceeds the first set percentage of all nodes, the voltage regulator is adjusted by step-down operation, and the power flow calculation is repeated after the step-down is completed until the voltage data of the overvoltage node is within the set interval [0.9U set , 1.1U set ]Inside; S63: When the overvoltage node and voltage data are at [U set , 1.1U set ] interval is less than the second set percentage of all nodes, the mth node with undervoltage is adjusted through the adjacent photovoltaic modules until the voltage data of the overvoltage node is within the set interval [0.9U set , 1.1U set ]Inside; Among them, the number of photovoltaic modules put into use is The photovoltaic modules to be put into use are selected from the mth node with undervoltage from near to far; S64: Repeat the above steps S62 to S63 to adjust each overvoltage node until the voltage data of all overvoltage nodes are within [0.9U set , 1.1U set ] interval.

6. The voltage control method of the substation voltage control system according to claim 5, characterized in that: When reactive power overcompensation is performed, the reactive capacity S' required to be compensated B Select the number of capacitor groups N to be removed by reactive compensation capacitors C , until the voltage data of all nodes are neither undervoltage nor overvoltage and the power factor is greater than or equal to the set power factor threshold; in, S' B =Q G -S G sin(arcsos0.98).

7. The voltage control method of the substation voltage control system according to any one of claims 1 to 6, characterized in that: The substation voltage control system further includes a micro-meteorological sensor, and the collection device is communicatively connected with the micro-meteorological sensor; The method further comprises: S8: judging the output power of the photovoltaic module by the data collected by the micro-meteorological sensor, and judging the damage or dirtiness of the photovoltaic module by the difference between the output power calculated by the photovoltaic module and its actual power; Among them, if the difference between the calculated output power and the actual power exceeds the set power threshold and the actual power decreases sharply, it is judged that the photovoltaic component or inverter is damaged; if the difference between the calculated output power and the actual power exceeds the set power threshold and the actual power decreases smoothly, it is judged that the photovoltaic component is dirty.

8. The voltage control method of the substation voltage control system according to claim 7, characterized in that: 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.

9. The voltage control method of the substation voltage control system according to claim 8, characterized in that: The platform server is communicatively connected to the collection device via a 4G or 5G network, the micro-meteorological sensor, reactive compensation capacitor and voltage regulator are communicatively connected to the collection device via RS485, the collection device is communicatively connected to the inverter via RS485, and the low-voltage monitoring terminal and collection device are communicatively connected to the collection device via wireless or power carrier.

10. The voltage control method of the substation voltage control system according to claim 9, characterized in that: The collection device includes a core board, which is provided with a first LORA module and a first charging circuit. The core board is connected to a first LORA antenna, a 4G / 5G antenna, a first power carrier module, a first RS485 communication interface, an AC three-phase input and a first rechargeable battery / capacitor.

11. The voltage control method of the substation voltage control system according to claim 10, characterized in that: The acquisition device includes an MCU control board, the MCU control board is provided with a second LORA module, a second power carrier module, a second RS485 communication interface and a second charging circuit, and the MCU control board is connected to a second LORA antenna and a second rechargeable battery / capacitor.

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