Photovoltaic power generation system and control method

Abstract

The embodiment of the invention relates to the technical field of photovoltaic power generation, and discloses a photovoltaic power generation system and a control method, and the system comprises a plurality of string type inverters, a DC cable protection groove box, an outdoor cabinet, and a boost box transformer. The plurality of string type inverters and the direct current cable protection groove boxes are mounted at the top of the outdoor cabinet to form a power generation unit module; and the power generation unit module is connected with the boosting box transformer to form the modular integrated inversion boosting equipment. According to the embodiment of the invention, the modular design method is adopted, so that the integration level of the integrated inversion boost equipment is improved, a special AC confluence cabinet of original configuration is canceled, and the basic platform cost of the integrated equipment and the transportation cost of complete equipment are reduced. Meanwhile, the arrangement of the special direct-current cable cabinet can increase the reserved quantity of group string cables, and avoids the work of cable excavation, sorting and backfilling under the ground of the bottom of the equipment caused by the fault of the direct-current cable joint of the inverter due to insufficient cable allowance.

Description

TECHNICAL FIELD

[0001] The embodiment of the present disclosure relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation system and a control method. BACKGROUND

[0002] With the development of photovoltaic technology, the wide application of large-capacity, high AC / DC capacity matching photovoltaic sub-square matrix, and the continuous improvement of the capacity of string inverter, in order to solve the problems of large working surface, large number of construction personnel, difficult control of construction quality and construction progress, improve the efficiency and power generation of photovoltaic power station system, and reduce the construction period and operation and maintenance workload, a plurality of distributed string inverters (1) and their supporting AC bus cabinet and booster box transformer can be designed and manufactured in an integrated manner.

[0003] Figure 1 is a schematic diagram of integrated inverter booster equipment arrangement, Figure 1 (a) is a front view, Figure 1 (b) is a top view, as Figure 1 shown, the prior art integrates a plurality of string inverters (1), DC cable protection groove box, AC bus cabinet, communication control device, power distribution equipment, etc. on a set of steel structure foundation platform, and lays the connecting cables between the equipment inside the platform. The AC bus cabinet is connected with the low-voltage side of the photovoltaic sub-square matrix booster box transformer through cables or closed busbars. In this way, the distributed string inverters (1) are concentrated, the integrated manufacturing of inverters and AC bus cabinets, the electrical connection of AC bus cabinets and booster box transformers are solved, and all manufacturing, installation and testing are completed in the factory. After the equipment is transported to the site, it can be quickly hoisted, installed, wired, debugged and connected to the grid. Only three types of cables, 35kV cables, photovoltaic string cables (6) and communication optical cables, need to be connected on site, which can significantly improve the construction quality and progress. However, the prior art has the problems of large equipment size, low integration, small DC cable installation space, small reserved amount, high cost of steel structure foundation platform, and high transportation cost of complete equipment.

[0004] The capacity of centralized inverters and distributed inverters has developed from 500 kW, 630 kW, 1000 kW, 1250 kW to the current 2500 kW, 3150 kW, 4100 kW, and the feature is that the single machine access photovoltaic capacity is large, and the number of single sub-array device configuration is small. The advantages are that the construction and installation are concentrated, and the operation and inspection are concentrated. The disadvantages are that if a fault occurs or maintenance is required during operation, the whole machine stops, resulting in a large loss of power, and the daily maintenance workload is large. The capacity of group string inverters (1) has developed from 40 kW, 50 kW, 75 kW to the current 175 kW, 225 kW, 320 kW, and the feature is that the single machine access photovoltaic capacity is small, and the number of single sub-array device configuration is large. The advantages are that the number of MPPT paths is large, and the power generation capacity is higher than that of centralized and distributed inverters. If a single machine encounters a fault or maintenance is required during operation, the single machine can be quickly replaced, resulting in a small loss of power. The disadvantage is that the installation work site is dispersed in the sub-array. The integrated inverter and booster device integrates the advantages of centralized inverters, distributed inverters, and group string inverters (1), and the advantages are that the factory is integrated, the site is quickly installed, and the operation and maintenance are concentrated. The capacity is matched flexibly, and is not limited by the terrain and region. The disadvantages are that the overall volume of the device is large, the DC cable has a small reserved margin, and the foundation platform and transportation cost are high. The "small DC cable reserved margin" means that the space of the DC cable protection groove box is small, and the photovoltaic string cable (6) cannot reserve a margin in the protection groove. When the DC plug of the inverter fails and needs to be re-made, the earth at the bottom of the integrated inverter and booster device needs to be dug out (the reserved margin of the DC cable is buried below the ground), and the corresponding cable needs to be pulled out. This method has a large workload, cannot be excavated in winter, and affects fault recovery. SUMMARY

[0005] Embodiments of the present disclosure provide a photovoltaic power generation system and a control method to solve or alleviate one or more of the above technical problems in the prior art.

[0006] Term explanation:

[0007] 1. Integrated inverter and booster device: a set of integrated inverter and booster devices formed by installing a plurality of group string inverters, DC cable protection groove boxes, AC bus cabinets (in which AC bus bars, circuit breakers, surge protectors, and power distribution equipment are arranged), and communication control devices on a set of steel structure platform foundations (in which AC connection cables between devices are laid), and then connecting the cables or closed bus bars with booster box transformers.

[0008] 2. Modular integrated inverter and booster device: a plurality of string inverters and cable protection groove boxes are installed on the top of an outdoor cabinet (AC busbar, circuit breaker, surge protector, communication control device, power distribution equipment, AC connection cable and string cable fixing rack are arranged in the cabinet), which constitutes a power generation unit module, and is connected with a booster box through a cable or a closed bus to form a modular integrated inverter and booster device. When energy storage is configured on the photovoltaic power generation side, the modular integrated inverter and booster device and the energy storage system constitute an AC coupled photovoltaic power generation unit.

[0009] According to one aspect of the present disclosure, a photovoltaic power generation system is provided, comprising:

[0010] a plurality of string inverters, DC cable protection groove boxes, an outdoor cabinet and a booster box;

[0011] The plurality of string inverters and DC cable protection groove boxes are installed on the top of the outdoor cabinet to constitute a power generation unit module;

[0012] The power generation unit module is connected with the booster box to form a modular integrated inverter and booster device.

[0013] In one possible implementation, the power generation unit module comprises 6 string inverters and 6 DC cable protection groove boxes;

[0014] Each DC cable protection groove box is installed between each string inverter and the outdoor cabinet;

[0015] The string inverters are installed back-to-back on the top of the outdoor cabinet;

[0016] The outdoor cabinet is provided with an AC busbar, a circuit breaker, a communication control device, a power distribution equipment, an AC connection cable and a string cable fixing rack;

[0017] The power generation unit module is connected with the booster box through a cable or a closed bus.

[0018] In one possible implementation, the outdoor cabinet is provided with a busbar cabin and a cable cabin; the AC busbar, the circuit breaker, the communication control device and the power distribution equipment are installed in the busbar cabin;

[0019] The photovoltaic string cable connected with each string inverter is fixed separately, and the excess photovoltaic string cable after being fixed is reserved in the cable cabin in an "S" shape.

[0020] In one possible implementation, comprising: a photovoltaic power generation device and a photovoltaic power station, the photovoltaic power generation device comprises a photovoltaic sub-square array assembly, the photovoltaic sub-square array assembly is connected to the power generation unit module through a photovoltaic sub-square array assembly cable, and is connected to the photovoltaic power station after being inverted, bused and boosted.

[0021] In a possible implementation, the modular integrated inverter-boosting device is configured with a communication device including a data collector, a switch and a fiber interface box to collect and process information of each inverter, box transformer control, tracking support and energy storage system, and upload the information to a photovoltaic power station monitoring system.

[0022] According to one aspect of the present disclosure, a control method of a photovoltaic power generation system is provided, based on the above photovoltaic power generation system, comprising:

[0023] When the energy storage device is not configured, the data collector is used as a control device to coordinate and manage the output of all inverters.

[0024] In a possible implementation, when the energy storage device is not configured, the data collector is used as a control device to coordinate and manage the output of all inverters, comprising:

[0025] The data collector accepts the station control layer AGC power instruction through the monitoring communication interface; and adjusts the inverters in real time according to the AGC system issued power value Pagc, the maximum power Pmax of the low-voltage side grid connection point of the booster transformer, the real-time power Ppcc of the low-voltage side grid connection point of the booster transformer and the real-time power Ppv of the photovoltaic, comprising:

[0026] Adjusting the inverters in real time according to the AGC system issued power value Pagc, the maximum power Pmax of the low-voltage side grid connection point of the booster transformer, the real-time power Ppcc of the low-voltage side grid connection point of the booster transformer and the real-time power Ppv of the photovoltaic, comprising:

[0027] Taking the minimum value of the AGC system instruction power Pagc and the maximum power Pmax of the low-voltage side grid connection point of the booster transformer as the maximum grid connection point power Pmax of the sub-matrix;

[0028] Collecting the power Ppcc of the low-voltage side grid connection point of the booster transformer in real time to determine the relationship between Ppcc and the maximum grid connection point power Pmax of the sub-matrix;

[0029] If Ppcc>Pmax, then taking Pmax as the target value of the power of the sub-matrix, the instruction is issued to the inverter in real time to reduce the power generation power;

[0030] If Ppcc

[0031] In a possible implementation, when the energy storage device is not configured, the data collector is used as a control device to coordinate and manage the output of all inverters, comprising:

[0032] The data collector accepts the primary frequency regulation power instruction of the station control layer through the communication interface, and performs real-time adjustment on the inverter according to the primary frequency regulation power value Ptp, the maximum power Pmax of the low-voltage side grid connection point of the step-up transformer, the real-time power Ppcc of the low-voltage side grid connection point of the step-up transformer, and the real-time power Ppv of the photovoltaic, including:

[0033] The minimum value of the primary frequency regulation system instruction power Ptp and the maximum power Pmax of the low-voltage side grid connection point of the step-up transformer is taken as the maximum grid connection point power Pmax of the sub-matrix;

[0034] The real-time power Ppcc of the low-voltage side grid connection point of the step-up transformer is collected, and the relationship between Ppcc and the maximum grid connection point power Pmax of the sub-matrix is judged;

[0035] If Ppcc>Pmax, the maximum power Pmax of the sub-matrix is taken as the target value of the power, and the instruction is issued to the inverter in real time to reduce the power generation power;

[0036] If Ppcc<Pmax, the maximum power Pmax of the sub-matrix is taken as the target value of the power, and the instruction is issued to the inverter in real time to increase the power generation power.

[0037] According to one aspect of the present disclosure, a control method of a photovoltaic power generation system is provided, based on the above photovoltaic power generation system:

[0038] When the energy storage device is configured on the photovoltaic power generation device side, the light storage coordination controller, the energy storage system communication interface and the energy storage system electrical interface are set to realize the joint operation of the light storage.

[0039] In one possible implementation, when the energy storage device is configured, the light storage coordination controller is taken as a control device to control the output of the photovoltaic power generation unit and the charging and discharging of the energy storage system as a whole.

[0040] In one possible implementation, when the energy storage device is configured, the light storage coordination controller is taken as a control device to control the output of the photovoltaic power generation unit and the charging and discharging of the energy storage system as a whole, including:

[0041] The light storage coordination controller accepts the AGC power instruction of the station control layer through the monitoring communication interface, and performs real-time adjustment on the inverter and the energy storage according to the AGC system power value Pagc, the maximum power Pmax of the low-voltage side grid connection point of the step-up transformer, the real-time power Ppcc of the low-voltage side grid connection point of the step-up transformer, the real-time power Ppv of the photovoltaic, the chargeable power Pcharge of the energy storage, the dischargeable power Pdischarge of the energy storage and the SOC value of the energy storage, including:

[0042] When Ppcc>Pagc and the energy storage has charging conditions, the energy storage is controlled to be charged, and when the battery is charged to the upper limit of the SOC setting, the energy storage is on standby. If the Pagc value does not change, the inverter is controlled to be limited to be output, and the photovoltaic power Ppv' output by the inverter after being controlled is Pagc.

[0043] When Ppcc < Pagc, and the energy storage has discharge conditions, control the energy storage to discharge, and when the battery is discharged to the lower limit of the SOC setting, the energy storage is on standby. If the Pagc value does not change, control the inverter to generate electricity at the current maximum power Ppvmax;

[0044] The maximum power value Ppccmax of the step-up transformer low-voltage side grid point is (the maximum output of the photovoltaic power generation unit Ppvmax + the maximum discharge power of the energy storage Pdischargemax) ≤ Pmax.

[0045] In one possible implementation, when the energy storage device is configured, the light storage coordination controller is used as a control device to control the output of the photovoltaic power generation unit and the charging and discharging of the energy storage system as a whole, including:

[0046] The light storage coordination controller receives the primary frequency modulation power instruction of the station control layer through the communication interface, and adjusts the inverter and the energy storage in real time according to the primary frequency modulation power value Ptp, the maximum power Pmax of the step-up transformer low-voltage side grid point, the real-time power Ppcc of the step-up transformer low-voltage side grid point, the real-time power Ppv of the photovoltaic power generation unit, the chargeable power Pcharge of the energy storage, the dischargeable power Pdischarge of the energy storage, and the SOC value of the energy storage, including:

[0047] When the frequency modulation instruction is up, if Pdischarge > Ptp, control the energy storage to discharge at the difference between the two, so that the discharge power Pdischarge' of the energy storage converter after being controlled is Ptp; if Pdischarge < Ptp, control the energy storage to discharge at the current maximum power Pdischargemax;

[0048] When the frequency modulation instruction is down, if Pcharge > Ptp, control the energy storage to charge at the difference between the two, so that the charge power Pcharge' of the energy storage converter after being controlled is Ptp; if Pcharge < Ptp, control the energy storage to discharge at the current maximum power Pchargemax, and control the inverter to limit the generation, so that Pchargemax + Ppv' = Ptp;

[0049] The maximum power value Ppccmax of the step-up transformer low-voltage side grid point is (the maximum output of the photovoltaic power generation unit Ppvmax + the maximum discharge power of the energy storage Pdischargemax) ≤ Pmax.

[0050] The exemplary embodiments of the present disclosure have the following beneficial effects: the exemplary embodiments of the present disclosure improve the integration of the integrated inverter-boosting device by adopting a modular design method, cancel the original special AC bus cabinet, and reduce the cost of the integrated device base platform and the transportation cost of the complete equipment. At the same time, the special DC cable cabinet can increase the reserved amount of group string cables, and avoid the cable excavation, sorting and backfilling work below the ground of the device due to the insufficient cable reserve of the inverter DC cable joint failure.

[0051] The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features and advantages of the application will be apparent from the description that follows. It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and serve to explain the principles of the present disclosure. It is readily apparent to one skilled in the art that the following description in the drawings is merely exemplary of the present disclosure and that other drawings can be derived from these drawings without departing from the scope of the present disclosure.

[0053] Figure 1 is a schematic diagram of an integrated inverter-boosting device arrangement;

[0054] Figure 2 is a schematic diagram of a modular integrated inverter-boosting device arrangement;

[0055] Figure 3 is an electrical wiring diagram of a modular integrated inverter-boosting device;

[0056] Figure 4 is a communication block diagram of a modular integrated inverter-boosting device sub-matrix;

[0057] Figure 5 is a schematic diagram of a modular integrated inverter-boosting device structure;

[0058] Figure 6 is a schematic diagram of a DC cable reservation in a cable cabin of a modular integrated inverter-boosting device.

[0059] In the drawings: 1, group string inverter; 2, cable cabin; 3, bus cabin; 4, outdoor cabinet; 5, cable fixing member; 6, photovoltaic group string cable; 7, cable protection pipe. DETAILED DESCRIPTION

[0060] Example implementations are now described with reference to the drawings. Example implementations can, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example implementations to those skilled in the art. The described features, structures, or characteristics can be combined in one or more implementations. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, etc., to provide a thorough understanding of the example implementations. One skilled in the relevant art will recognize, however, that the implementations can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. Some features, structures, or characteristics can be described as being part of one or more implementations, but can be combined in other implementations. In other instances, well-known features, structures or characteristics have not been described in order to avoid obscuring the

[0061] Furthermore, the accompanying drawings are merely idealized representations that are not necessarily drawn to scale. Like reference numerals in the drawings denote like features, structures and / or characteristics, and therefore repeated description thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities that do not necessarily have to correspond to physically or logically independent entities. These functional entities can be implemented in the form of software, or in one or more hardware units or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0062] The flowcharts shown in the drawings are merely illustrative and do not necessarily include all the steps. For example, some steps can be further broken down, and some steps can be combined or partially combined, and therefore the actual execution order can be changed according to the actual situation.

[0063] The terms "first", "second", and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a particular order or sequence. It should be understood that the data thus used can be interchanged, where appropriate, so that the embodiments of the present application described herein can be implemented in other than the order depicted or described herein.

[0064] Furthermore, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusions, for example, processes, methods, systems, products, or devices that comprise a list of steps or sub-modules are not necessarily limited to those clearly listed, but can include other steps or sub-modules that are not clearly listed or inherent to such processes, methods, products, or devices.

[0065] Photovoltaic power station equipment quantity, variety, wide area, short construction period, the design stage needs to match the electrical and communication interface of a large number of equipment; Due to the large number of equipment and types, large cable connection, scattered construction points, there are problems such as large construction organization difficulty, complex on-site equipment management, large number of workers, large control detection surface, and difficult to control installation quality and progress; Due to the dispersion of equipment, resulting in large workload and low efficiency of inspection and maintenance.

[0066] With the development of photovoltaic technology, the wide application of large-capacity, high AC / DC capacity ratio photovoltaic sub-array, and the continuous improvement of string inverter capacity, in order to improve the efficiency of on-site construction and reduce the workload of operation and maintenance, multiple scattered string inverters 1 and their supporting AC bus cabinets and step-up box transformers can be designed and manufactured in an integrated manner.

[0067] The main types of photovoltaic inverters are:

[0068] (1) Centralized inverter: The direct current generated by photovoltaic modules is converted into alternating current, and then stepped up and connected to the grid. Generally, the power is large, above megawatt, and is used with a direct current busbar.

[0069] (2) Distributed inverter: The direct current generated by photovoltaic modules is converted into alternating current, and then stepped up and connected to the grid. Generally, the power is large, above megawatt, and is used with an MPPT pre-type direct current busbar.

[0070] (3) String inverter 1: The direct current generated by photovoltaic modules is directly converted into alternating current, and then stepped up and connected to the grid. It has the characteristics of more MPPT circuits, generally small power, about 100-300 kilowatts, and is used with an AC busbar.

[0071] (4) Integrated / distributed medium voltage complete inverter: It is an integrated device of centralized inverter or distributed inverter and step-up box transformer.

[0072] (5) Integrated inverter and step-up device: Taking string inverter 1 as a unit module, all string inverters 1, AC bus cabinets and step-up box transformers and their foundation steel structure platforms are integrated into an inverter and step-up device.

[0073] (6) Modular integrated inverter and step-up device: Taking multiple string inverters 1 and their outdoor cabinets 4 (with busbar components and cable reel racks, etc.) as basic power generation unit modules, one or more power generation unit modules and step-up box transformers are integrated into an inverter and step-up device.

[0074] Figure 2 is a schematic diagram of the arrangement of the modular integrated inverter and step-up device, Figure 2 (a) is a front view, Figure 2 (b) is a side view,Figure 2 As shown, the exemplary embodiment of the present disclosure provides a photovoltaic power generation system, comprising:

[0075] a plurality of group string inverters 1, a DC cable protection groove box, an outdoor cabinet 4, and a booster transformer;

[0076] The plurality of group string inverters 1 and the DC cable protection groove box are installed on the top of the outdoor cabinet 4 to form a power generation unit module;

[0077] The power generation unit module is connected with the booster transformer to form a modular integrated inverter and booster device.

[0078] In this embodiment, the photovoltaic sub-square array power transformation device is taken as a unit for modular and integrated design and manufacturing. Exemplarily, a plurality of group string inverters 1 and their DC cable protection groove boxes are installed on the top of an outdoor cabinet 4 (in which an AC bus, a circuit breaker, a communication control device, a power distribution device, an AC connecting cable, and a group string cable fixing rack are arranged) to form a power generation unit module, which is then connected with a booster transformer through a cable or a closed bus to form a set of modular integrated inverter and booster device.

[0079] Exemplarily, the power generation unit module comprises 6 group string inverters 1 and 6 DC cable protection groove boxes.

[0080] Each DC cable protection groove box is installed between each group string inverter 1 and the outdoor cabinet 4.

[0081] The group string inverters 1 are installed back-to-back on the top of the outdoor cabinet 4.

[0082] The outdoor cabinet 4 is provided with an AC bus, a circuit breaker, a communication control device, a power distribution device, an AC connecting cable, and a group string cable fixing rack.

[0083] The power generation unit module is connected with the booster transformer through a cable or a closed bus.

[0084] It is worth noting that the 6 group string inverters 1 can be installed in a centralized manner, or less than 6 or more than 6. The modular integrated inverter device can be connected with the low-voltage side of the booster transformer through a cable or a closed bus. The modular integrated inverter device is provided with an energy storage system interface and has a photovoltaic and storage combined operation function.

[0085] Specifically, the outdoor cabinet 4 is provided with a bus cabin 3 and a cable cabin 2, and the AC bus, the circuit breaker, the communication control device, and the power distribution device are installed in the bus cabin 3.

[0086] Each group string inverter 1 is connected with photovoltaic group string cable 6 which is fixed separately, and the excess length of the fixed photovoltaic group string cable 6 is reserved in the cable cabin 2 in the shape of "S".

[0087] In order to improve the equipment integration, reduce the equipment volume, increase the DC cable maintenance allowance length, reduce the cost of integrated platform, and reduce the transportation cost of equipment, a modular design method is adopted in the embodiment, and a plurality of group string inverters 1 are installed on the top of a set of outdoor cabinet 4 to form a power generation unit module, and then the power generation unit module is connected with the booster box transformer through a cable or a closed bus to form a modular integrated inverter booster device.

[0088] Specifically, it comprises a photovoltaic power generation device and a photovoltaic power station, the photovoltaic power generation device comprises a photovoltaic sub-square matrix assembly, the photovoltaic sub-square matrix assembly is connected to the power generation unit module through a photovoltaic sub-square matrix assembly cable, and after being inverted, converged and boosted, the photovoltaic sub-square matrix assembly is connected to the photovoltaic power station.

[0089] Specifically, the modular integrated inverter booster device is provided with a communication device comprising a data collector, a switch and a fiber interface box, which is used to collect and process information of each inverter, box transformer measurement and control, tracking support and energy storage system, and upload the information to the photovoltaic power station monitoring system.

[0090] Figure 3 It is an electrical wiring diagram of the modular integrated inverter booster device, as shown in Figure 3 The electrical wiring of the embodiment is described as follows.

[0091] The modular integrated inverter booster device mainly comprises one or more power generation unit modules and the booster box transformer matched therewith, the photovoltaic sub-square matrix assembly cable is connected to the DC side of the group string inverter 1 in the power generation unit module, and after being inverted, converged and boosted, the photovoltaic sub-square matrix assembly is connected to the photovoltaic power station.

[0092] One power generation unit module is composed of a plurality of group string inverters 1 and one outdoor cabinet 4, the group string inverters 1 and the cable protection groove box thereof are installed on the top of the outdoor cabinet 4, and the outdoor cabinet 4 is provided with an AC bus, a circuit breaker, a surge protector, a communication control device, a power distribution device, an inverter AC cable, a group string DC cable fixing frame and the like.

[0093] One or more power generation unit modules are connected with the booster box transformer through a cable or a closed bus, and are used as an integrated inverter booster device of a photovoltaic sub-square matrix.

[0094] When the energy storage is configured on the power supply side, an energy storage system electrical interface is added to form a photovoltaic energy storage power generation system.

[0095] Figure 4 It is a communication block diagram of the modular integrated inverter booster device sub-square matrix; as shown in Figure 4 The communication wiring of the embodiment is described as follows.

[0096] Modular integrated inverter booster equipment is equipped with communication devices to collect and process information from various inverters, transformer substations, and other system equipment (such as tracking brackets and energy storage systems), and simultaneously upload the information to the photovoltaic power station monitoring system.

[0097] Communication equipment mainly includes data acquisition devices, switches, fiber optic interface boxes, etc.

[0098] When energy storage is configured on the power supply side, a photovoltaic-energy storage coordination controller is set up, and an energy storage system communication interface is added to achieve joint operation of photovoltaic and energy storage.

[0099] Figure 5 This is a schematic diagram of a modular integrated inverter boost converter structure; such as Figure 5 As shown, the equipment layout in this embodiment is described as follows:

[0100] The modular integrated inverter step-up equipment mainly consists of two parts: the power generation unit module and the step-up transformer.

[0101] A power generation unit module includes multiple string inverters 1 and an outdoor cabinet 4. The outdoor cabinet 4 is equipped with AC busbars, circuit breakers, communication control devices, power distribution equipment, AC connection cables, string cable fixing trays, etc.

[0102] The substation step-up section includes transformers, high and low voltage power distribution equipment, transformer monitoring and protection devices, etc.

[0103] The modular integrated equipment is arranged as follows: power generation unit module, cable or enclosed busbar, and step-up transformer. The inverter is fixed to the top of outdoor cabinet 4 in a back-to-back installation manner, and a cable protection trough is installed between outdoor cabinet 4 and the inverter.

[0104] Figure 6 This is a schematic diagram showing the reserved DC cables inside the cable compartment of a modular integrated inverter booster unit. (For example...) Figure 6 As shown, the structure of this embodiment is described as follows: A combiner compartment 3 (inner side) and a cable compartment 2 (outer side) are set in the outdoor cabinet 4 of the power generation unit module. Except for the inverter, all components (combiner bus, circuit breaker, data acquisition device, communication control device, power distribution equipment, etc.) are installed in the combiner compartment 3. The string DC cables are fixed according to the inverters connected to them. The excess cable is reserved in the cable compartment 2 of the outdoor cabinet 4 below the inverter in an "S-shape" by the cable fixing piece 5. The ends of the photovoltaic string cables 6 are covered with cable protection pipes 7 to protect the photovoltaic string cables 6. It is worth noting that each string inverter can be connected to 20 to 30 cables. In order to prevent the cables from being placed in the wrong position and to fix them in an orderly manner, the cables corresponding to the inverter are arranged on its lower side.

[0105] The plurality of power generation unit modules are connected in parallel through cables or bus bridges and connected with a booster box transformer; each power generation unit module is reserved with two grounding terminals connected with a power station main grounding network; when a tracking support system is configured, the power generation unit module is reserved with a communication cabinet and a wind speed instrument installation position of the tracking support system; when an oil-immersed transformer is used, an oil blocking facility and an accident oil pool are arranged; the power generation unit module is reserved with an energy storage device interface to form a "light storage alternating current coupling power generation system".

[0106] In summary, the embodiment groups a plurality of stringed inverters 1 and an outdoor cabinet 4 into a power generation unit module; integrates stringed DC cable connection and fixation, inverter AC bus connection components and communication control equipment in the outdoor cabinet 4; the inverter can be a stringed inverter 1 or a centralized / distributed inverter with a matched DC bus connection box; when a tracking support system is configured, the outdoor cabinet 4 can fix a communication cabinet and a wind speed instrument stand of the tracking support system and provide working power supply and a communication interface.

[0107] The exemplary embodiment of the disclosure provides a control method of a photovoltaic power generation system, based on the above photovoltaic power generation system, comprising:

[0108] The modular integrated inverter booster device is configured with a control device, when only a photovoltaic system is used, a data collector is used as the control device to coordinate and manage the output of all inverters; when the photovoltaic system is matched with energy storage, a photovoltaic energy storage coordination controller is configured as the control device to control the photovoltaic output and the charging and discharging of the energy storage. At the same time, the control device receives and executes instructions of a photovoltaic power station monitoring system, an AGC / AVC system and a primary frequency modulation system.

[0109] (1) Photovoltaic power generation: the data collector receives the station control layer AGC power instruction through the monitoring communication interface, and adjusts the inverter in real time according to the AGC system issued power value Pagc, the maximum power Pmax of the low voltage side grid connection point of the booster transformer (1.1 times the rated capacity of the booster transformer), the real-time power Ppcc of the low voltage side grid connection point of the booster transformer and the real-time power Ppv of the photovoltaic.

[0110] 1) Take the minimum value of the AGC system instruction power Pagc and the maximum power Pmax of the low voltage side grid connection point of the booster transformer as the maximum grid connection point power Pmax of the subarray;

[0111] 2) Collect the real-time power Ppcc of the low voltage side grid connection point of the booster transformer, and judge the relationship between Ppcc and the maximum grid connection point power Pmax of the subarray;

[0112] 3) If Ppcc>Pmax, take Pmax as the target value of the power of the subarray, and real-time issue instructions to the inverter to reduce the power generation power;

[0113] 4) If Ppcc < Pmax, take Pmax as the target value of the sub-matrix power, real-time issue instructions to the inverter to increase the power generation;

[0114] 5) Repeat the above steps.

[0115] (2) Photovoltaic primary frequency modulation: the data collector accepts the primary frequency modulation power instruction of the station control layer through the fast control communication interface, and adjusts the inverter in real time according to the primary frequency modulation issued power value Ptp, the maximum power Pmax of the low-voltage side grid connection point of the booster transformer (taking 1.1 times the rated capacity of the booster transformer), the real-time power Ppcc of the low-voltage side grid connection point of the booster transformer, and the real-time power Ppv of the photovoltaic.

[0116] 1) Take the minimum value of the primary frequency modulation system instruction power Ptp and the maximum power Pmax of the low-voltage side grid connection point of the booster transformer as the maximum grid connection point power Pmax of the sub-matrix;

[0117] 2) Real-time collection of the low-voltage side grid connection point power Ppcc of the booster transformer to determine the relationship between Ppcc and the maximum grid connection point power Pmax of the sub-matrix;

[0118] 3) If Ppcc > Pmax, take Pmax as the target value of the sub-matrix power, real-time issue instructions to the inverter to reduce the power generation;

[0119] 4) If Ppcc < Pmax, take Pmax as the target value of the sub-matrix power, real-time issue instructions to the inverter to increase the power generation;

[0120] 5) Repeat the above steps.

[0121] (3) Photovoltaic and energy storage combined power generation: the photovoltaic and energy storage coordinated controller accepts the AGC power instruction of the station control layer through the monitoring communication interface, and adjusts the inverter and the energy storage in real time according to the AGC system issued power value Pagc, the maximum power Pmax of the low-voltage side grid connection point of the booster transformer (taking 1.1 times the rated capacity of the booster transformer), the real-time power Ppcc of the low-voltage side grid connection point of the booster transformer, the real-time power Ppv of the photovoltaic, the chargeable power Pcharge of the energy storage, the dischargeable power Pdischarge of the energy storage, and the SOC value of the energy storage.

[0122] 1) When Ppcc > Pagc and the energy storage has charging conditions, control the energy storage to charge. When the battery is charged to the set upper limit of SOC, the energy storage is on standby. If the Pagc value does not change, control the inverter to limit the output, so that the output photovoltaic power Ppv' of the inverter is equal to Pagc;

[0123] 2) When Ppcc < Pagc and the energy storage has discharging conditions, control the energy storage to discharge. When the battery is discharged to the set lower limit of SOC, the energy storage is on standby. If the Pagc value does not change, control the inverter to generate power at the current maximum power Ppvmax;

[0124] 3) Ppccmax(Ppvmax+Pdischargemax)≤Pmax.

[0125] (4) Light storage primary frequency modulation: The light storage coordination controller accepts the station control layer primary frequency modulation power instruction through the fast control communication interface, and adjusts the inverter and the energy storage in real time according to the primary frequency modulation power value Ptp, the maximum power Pmax of the step-up transformer low-voltage side grid-connected point (taking 1.1 times the rated capacity of the step-up transformer), the real-time power Ppcc of the step-up transformer low-voltage side grid-connected point, the real-time power Ppv of the photovoltaic, the energy storage chargeable power Pcharge, the energy storage dischargeable power Pdischarge, and the energy storage SOC value.

[0126] 1) When the frequency modulation instruction is up, if Pdischarge>Ptp, control the energy storage to discharge by the difference between the two, so that the discharge power Pdischarge' of the energy storage converter after being controlled is Ptp; if Pdischarge

[0127] 2) When the frequency modulation instruction is down, if Pcharge>Ptp, control the energy storage to charge by the difference between the two, so that the charge power Pcharge' of the energy storage converter after being controlled is Ptp; if Pcharge

[0128] 3) Ppccmax(Ppvmax+Pdischargemax)≤Pmax. Wherein, Ppccmax refers to the maximum power of the step-up transformer low-voltage side grid-connected point, which is the maximum output of the photovoltaic Ppvmax+the maximum discharge power of the energy storage dischargemax.

[0129] The above is only the preferred embodiment of the present disclosure, and the protection scope of the present disclosure is not limited to the above-mentioned embodiments only. Any technical solution that belongs to the technical solution of the present disclosure should be considered as the protection scope of the present disclosure. It should be noted that for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present disclosure should be considered as the protection scope of the present disclosure.

Claims

1. A photovoltaic power system, characterized by, The utility model relates to a kind of modular integrated inverter and booster equipment, including: multiple group string inverters (1), DC cable protection groove box, outdoor cabinet (4) and booster box transformer; The multiple group string inverters (1) and DC cable protection groove box are installed on the top of outdoor cabinet (4), to form power generation unit module; The power generation unit module is connected with booster box transformer, to form modular integrated inverter and booster equipment. The power generation unit module includes: 6 group string inverters (1) and 6 DC cable protection groove boxes; 2. The photovoltaic power system of claim 1, wherein, Each DC cable protection groove box is installed between each group string inverter (1) and outdoor cabinet (4); Group string inverters (1) are installed back-to-back on the top of outdoor cabinet (4); The outdoor cabinet (4) is provided with AC busbar, circuit breaker, communication control device, distribution equipment, AC connection cable and group string cable fixing rack in it; The power generation unit module is connected with booster box transformer through cable or enclosed busbar. The outdoor cabinet (4) is provided with bus chamber (3) and cable chamber (2) in it;The AC busbar, circuit breaker, communication control device and distribution equipment are installed in bus chamber (3); 3. The photovoltaic power system of claim 2, wherein, Each group string inverter (1) is connected with photovoltaic group string cable (6) fixed separately, and the excess of the fixed photovoltaic group string cable (6) is reserved in cable chamber (2) in "S" shape. The utility model relates to a kind of modular integrated inverter and booster equipment, including: multiple group string inverters (1), DC cable protection groove box, outdoor cabinet (4) and booster box transformer; 4. The photovoltaic power system of claim 1, wherein, The power generation unit module is connected with booster box transformer through cable or enclosed busbar. The utility model relates to a kind of modular integrated inverter and booster equipment, including: multiple group string inverters (1), DC cable protection groove box, outdoor cabinet (4) and booster box transformer; 5. The photovoltaic power system of claim 1, wherein, The power generation unit module is connected with booster box transformer through cable or enclosed busbar.

6. A control method of a photovoltaic power generation system based on the photovoltaic power generation system according to any one of claims 1 to 5, characterized by, The utility model relates to a kind of modular integrated inverter and booster equipment, including: multiple group string inverters (1), DC cable protection groove box, outdoor cabinet (4) and booster box transformer; When no energy storage equipment is configured, the data collector is used as control equipment to coordinate and manage the output of all inverters.

7. The control method of a photovoltaic power generation system according to claim 6, characterized by: When no energy storage equipment is configured, the data collector is used as control equipment to coordinate and manage the output of all inverters, including: The data collector accepts AGC power instruction of station control layer through monitoring communication interface;According to the power value Pagc issued by AGC system, the maximum power Pmax of low-voltage side grid connection point of booster transformer, real-time power Ppcc of low-voltage side grid connection point of booster transformer and real-time power Ppv of photovoltaic, the inverter is adjusted in real time, including: According to the power value Pagc issued by AGC system, the maximum power Pmax of low-voltage side grid connection point of booster transformer, real-time power Ppcc of low-voltage side grid connection point of booster transformer and real-time power Ppv of photovoltaic, the inverter is adjusted in real time, including: The minimum value of AGC system instruction power Pagc and the maximum power Pmax of low-voltage side grid connection point of booster transformer is taken as the maximum grid connection point power Pmax of sub-array; Real-time acquisition of the power Ppcc of low-voltage side grid connection point of booster transformer judges the relationship between Ppcc and the maximum grid connection point power Pmax of sub-array; If Ppcc>Pmax, then Pmax is used as the target value of sub-array power, and the instruction is issued to the inverter in real time to reduce power generation. If Ppcc < Pmax, the Pmax is taken as the target value of the sub-matrix power, and the real-time command is issued to the inverter to increase the power generation.

8. The control method of a photovoltaic power generation system according to claim 6, characterized by: When the energy storage device is not configured, the data collector is used as the control device to coordinate and manage the output of all inverters, including: The data collector accepts the primary frequency regulation power command through the communication interface, and adjusts the inverter in real time according to the primary frequency regulation power value Ptp, the maximum power Pmax of the low-voltage side of the step-up transformer, the real-time power Ppcc of the low-voltage side of the step-up transformer, and the real-time power Ppv of the photovoltaic, including: The minimum value of the primary frequency regulation system command power Ptp and the maximum power Pmax of the low-voltage side of the step-up transformer is taken as the maximum grid point power Pmax of the sub-matrix. The real-time power Ppcc of the low-voltage side of the step-up transformer is collected to determine the relationship between Ppcc and the maximum grid point power Pmax of the sub-matrix. If Ppcc > Pmax, the Pmax is taken as the target value of the sub-matrix power, and the real-time command is issued to the inverter to reduce the power generation. If Ppcc < Pmax, the Pmax is taken as the target value of the sub-matrix power, and the real-time command is issued to the inverter to increase the power generation.

9. A control method for a photovoltaic power generation system, based on any one of claims 1-5, characterized in that: When the energy storage device is configured on the photovoltaic power generation device side, the light storage coordination controller, the energy storage system communication interface and the energy storage system electrical interface are set to realize joint operation of light storage.

10. The control method of a photovoltaic power generation system according to claim 9, characterized by: When the energy storage device is configured, the light storage coordination controller is used as the control device to control the output of the photovoltaic power generation unit and the charging and discharging of the energy storage system.

11. The control method of a photovoltaic power generation system according to claim 10, characterized by, When the energy storage device is configured, the light storage coordination controller is used as the control device to control the output of the photovoltaic power generation unit and the charging and discharging of the energy storage system, including: The light storage coordination controller accepts the AGC power command through the monitoring communication interface, and adjusts the inverter and the energy storage in real time according to the AGC system power value Pagc, the maximum power Pmax of the low-voltage side of the step-up transformer, the real-time power Ppcc of the low-voltage side of the step-up transformer, the real-time power Ppv of the photovoltaic, the chargeable power Pcharge of the energy storage, the dischargeable power Pdischarge of the energy storage, and the SOC value of the energy storage, including: When Ppcc > Pagc and the energy storage has charging conditions, the energy storage is controlled to charge, and when the battery is charged to the upper limit of the SOC setting, the energy storage is on standby. If the Pagc value does not change, the inverter is controlled to limit the output, and the output of the inverter after being controlled is Ppv' = Pagc. When Ppcc < Pagc and the energy storage has discharging conditions, the energy storage is controlled to discharge, and when the battery is discharged to the lower limit of the SOC setting, the energy storage is on standby. If the Pagc value does not change, the inverter is controlled to generate power at the current maximum power Ppvmax. The maximum power value Ppccmax of the low-voltage side of the step-up transformer × (the maximum output of the photovoltaic Ppvmax + the maximum discharge power of the energy storage Pdischargemax) ≤ Pmax.

12. The control method of a photovoltaic power generation system according to claim 10, characterized by, When the energy storage device is configured, the light storage coordination controller is used as the control device to control the output of the photovoltaic power generation unit and the charging and discharging of the energy storage system, including: The light storage coordination controller accepts the station control layer primary frequency modulation power instruction through the communication interface, and adjusts the inverter and the energy storage in real time according to the primary frequency modulation issued power value Ptp, the maximum power Pmax of the low-voltage side grid-connected point of the step-up transformer, the real-time power Ppcc of the low-voltage side grid-connected point of the step-up transformer, the real-time power Ppv of the photovoltaic, the chargeable power Pcharge of the energy storage, the dischargeable power Pdischarge of the energy storage and the SOC value of the energy storage, including: When the frequency modulation instruction is up-regulation, if Pdischarge>Ptp, the energy storage is controlled to discharge by the difference between the two, so that the discharge power Pdischarge' of the energy storage converter after being controlled is Ptp; if Pdischarge When the frequency modulation instruction is down-regulation, if Pcharge>Ptp, the energy storage is controlled to charge by the difference between the two, so that the charge power Pcharge' of the energy storage converter after being controlled is Ptp; if Pcharge The maximum power value Ppccmax of the low-voltage side grid-connected point of the step-up transformer is multiplied by (the maximum output Ppvmax of the photovoltaic + the maximum discharge power Pdischargemax of the energy storage) to be less than or equal to Pmax.

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