Electric energy quality optimization control system applied to distributed photovoltaic system

Abstract

The invention provides an electric energy quality optimization control system applied to a distributed photovoltaic system, the system comprises photovoltaic power generation and energy storage units, and each photovoltaic power generation and energy storage unit is composed of a power generation module, an inversion module, an energy storage module, an electric energy evaluation module and a control module. The power generation module converts solar energy into direct current, the inversion module converts the direct current into alternating current, and the energy storage module is used for storing redundant electric energy. The electric energy evaluation module acquires electric energy quality related data through the first acquisition sub-module and the second acquisition sub-module, carries out electric energy quality analysis, and carries out cross validation on electric energy quality results of all units through a decentralized electric energy quality evaluation network. The electric energy quality evaluation network adopts a distributed consensus mechanism to ensure the accuracy of an electric energy evaluation result and further control the authority of the photovoltaic power generation energy storage unit to access the public power grid. In addition, the system has double evaluation processes, and consistency and reliability of evaluation results are ensured.

Description

Technical Field

[0001] The present invention belongs to the field of digital information technology, and in particular, relates to a power quality optimization control system applied to a distributed photovoltaic system. Background Art

[0002] In recent years, distributed photovoltaic systems have been widely used around the world due to their high flexibility and easy installation. Photovoltaic power generation, as a clean and renewable energy source, plays an important role in alleviating the energy crisis and reducing environmental pollution. However, in the process of grid-connected operation of distributed photovoltaic systems, power quality issues have gradually become a key challenge that needs to be addressed. The output power of photovoltaic power generation systems may have problems such as voltage fluctuations, frequency deviations, harmonic pollution and low power factor. These unqualified electric energies not only affect the power generation efficiency of the system, but may also pose potential risks to grid equipment and load facilities.

[0003] Traditional power quality monitoring methods mainly rely on centralized monitoring, which is difficult to meet the needs of real-time detection and optimization of power quality in distributed photovoltaic systems. In addition, centralized monitoring systems often face problems such as monitoring blind spots and data transmission delays, and cannot effectively guarantee the stability of photovoltaic systems and the security of power grids. Therefore, there is an urgent need for an efficient, real-time responsive power quality monitoring and optimization control system that can improve the power quality management level of distributed photovoltaic systems, ensure that they do not have a negative impact when connected to the power grid, and at the same time ensure the safety and stability of power grid operation.

[0004] According to the related public technologies, the technical solution with publication number CN103199557A monitors and controls multiple control parameters of photovoltaic power generation components by using highly integrated chips to achieve optimized management of independent photovoltaic power generation components during operation. The technical solution with publication number WO2012059061A1 proposes a high-voltage power quality detection method, which detects the quality of high-voltage power by using low-voltage current components to detect high-voltage electricity. The technical solution with publication number WO2014089900A1 proposes a method for identifying power quality disturbance types based on PQView data source, which improves the efficiency of identifying power disturbance types by using PQView data source as the source of the evaluation algorithm.

[0005] The above technical solutions all propose several methods and related control systems for evaluating power quality. However, for distributed photovoltaic power generation systems, since there are many points that need to be detected and the points are scattered, it is still necessary to continue to propose more effective optimization control methods.

[0006] The foregoing discussion of the background art is intended only to facilitate an understanding of the present invention. This discussion does not acknowledge or admit that any of the material referred to is part of the common general knowledge. Summary of the invention

[0007] The object of the present invention is to provide a power quality optimization control system applied to a distributed photovoltaic system, wherein the system includes a photovoltaic power generation and energy storage unit, and each photovoltaic power generation and energy storage unit is composed of a power generation module, an inverter module, an energy storage module, a power evaluation module and a control module. The power generation module converts solar energy into direct current, the inverter module converts direct current into alternating current, and the energy storage module is used to store excess electric energy. The power evaluation module collects power quality related data through acquisition submodule A and acquisition submodule B, performs power quality analysis, and cross-validates the power quality results of each unit through a decentralized power quality evaluation network. The power quality evaluation network adopts a distributed consensus mechanism to ensure the accuracy of the power evaluation results and further control the access rights of the photovoltaic power generation and energy storage units to the public power grid. In addition, the system has a dual evaluation process to ensure the consistency and reliability of the evaluation results.

[0008] The present invention adopts the following technical solution: a power quality optimization control system applied to a distributed photovoltaic system, the optimization control system includes at least one photovoltaic power generation and energy storage unit; the photovoltaic power generation and energy storage unit includes:

[0009] A power generation module for converting solar energy into direct current electricity;

[0010] An inverter module, used to convert the direct current generated by the power generation module into alternating current;

[0011] Energy storage module, used to store excess electrical energy;

[0012] An electric energy evaluation module, which collects and analyzes indicators related to the power quality in the photovoltaic power generation and energy storage unit through the first collection submodule and the second collection submodule;

[0013] Among them, the power evaluation module is communicated with the power evaluation modules of other photovoltaic power generation and energy storage units to form a decentralized power quality evaluation network; the power quality evaluation network adopts a distributed consensus mechanism to cross-validate the power quality evaluation results to ensure that the power evaluation results of the power evaluation modules of each photovoltaic power generation and energy storage unit are correct and available, and further control the access rights of the photovoltaic power generation and energy storage units to the public power grid.

[0014] Exemplarily, the A acquisition submodule is arranged at the input end of the inverter module, and is specifically used to collect the electrical parameter data of the DC power generated by the photovoltaic power generation module; the B acquisition submodule is arranged at the output end of the inverter module, and is specifically used to collect the electrical parameter data of the AC power output by the inverter module.

[0015] Exemplarily, the electric energy evaluation module includes:

[0016] An evaluation unit is configured to use a preset power quality evaluation algorithm to periodically calculate the power quality state of the system and evaluate whether it meets a set threshold requirement;

[0017] A storage unit, used to store the historical electric energy parameter data collected by the first collection submodule and the second collection submodule, and the evaluation data made by the evaluation unit on the historical electric energy parameter data;

[0018] The communication unit is configured to establish a decentralized data communication network with the power evaluation modules of other photovoltaic power generation and energy storage units.

[0019] Exemplarily, a branch selector is further provided between the inverter module and the energy storage module; the branch selector is used to control the flow direction of the electric energy output by the inverter module and realize dynamic switching between the energy storage module, the grid line or the power load.

[0020] Exemplarily, the optimization control system includes executing a dual evaluation process during operation; the dual evaluation process includes the following steps:

[0021] The electric energy evaluation module serves as a main detection module, and based on the main evaluation period T1, uses the collected sample data as the A collection sample, periodically performs a preliminary evaluation on the electric energy quality of the photovoltaic power generation and energy storage unit, and generates the A evaluation result;

[0022] The main detection module periodically sends the A collection sample to at least two other randomly selected power evaluation modules through the power quality evaluation network based on the secondary evaluation cycle T2; the selected power evaluation module acts as a supervision detection module to evaluate the power quality of the A collection sample and generate a B evaluation sample;

[0023] The main detection module sends the evaluation result A to at least one management node through the power quality assessment network;

[0024] At least two of the supervisory detection modules send the second evaluation sample to at least one management node selected by the main detection module;

[0025] At least one management node calculates the degree of deviation between the evaluation result A and the evaluation result B in response to the evaluation result A and the evaluation result B, and performs consistency verification;

[0026] The management node will feed back the degree of deviation to the main detection module; if the deviation exceeds the threshold, the main detection module will trigger the control of the power transmission path of the photovoltaic power generation and energy storage unit.

[0027] Exemplarily, the secondary evaluation period T2 is greater than the primary evaluation period T1.

[0028] Exemplarily, the inverter module is a bidirectional inverter, and the output end of the energy storage module outputs electric energy to the inverter module according to electric energy demand, and provides electric energy to the power grid or the load through a branch selector.

[0029] The beneficial effects achieved by the present invention are:

[0030] 1. This technical solution distributes the power quality monitoring functions of multiple photovoltaic power generation and energy storage units to each unit by establishing a decentralized power quality assessment network, and cross-validates through a distributed consensus mechanism. This structure avoids the single point failure problem of the traditional centralized monitoring system, improves the reliability and fault tolerance of the system, and ensures the accuracy of the power quality assessment results of each unit.

[0031] 2. Through the dual evaluation process of the main detection module and the inspection detection module, this technical solution enables the system to self-check and review the power quality data to ensure the consistency and accuracy of the evaluation results. If a deviation is detected, the system will automatically trigger the consistency check mechanism to further improve the accuracy of power quality monitoring and ensure that any abnormalities in system operation can be discovered and corrected in a timely manner.

[0032] 3. This technical solution realizes the real-time collection and evaluation of power quality, and can respond quickly and make dynamic adjustments when the power quality of the photovoltaic power generation and energy storage unit is abnormal. For example, the system can automatically control the power transmission path or adjust the working state of the inverter according to the evaluation results to ensure that unqualified power will not be directly input into the power grid or load, thereby ensuring the stable operation of the power grid and the safety of the load equipment.

[0033] 4. The software and hardware parts of the optimization control system of this technical solution adopt a modular design. The various working modules and components of the hardware part of the system, as well as the instructions, parameters, and algorithms of the software part can be conveniently replaced and / or upgraded later, thereby reducing the construction cost and maintenance cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention can be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily drawn to scale, but the emphasis is placed on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0035] Description of the accompanying drawings: 1-photovoltaic power generation and energy storage unit; 10-power generation module; 20-electric energy evaluation module; 22-collection submodule A; 24-collection submodule B; 30-inverter module; 40-energy storage module; 42-energy storage module management system; 44-energy storage unit; 50-power load; 60-grid line; 70-branch selector; 80-control module; 200-main detection module; 210-supervision detection module; 220-management node; 500-computing architecture; 502-bus; 504-processor; 506-main memory; 508-read-only memory; 510-storage device; 512-display; 514-input device; 516-cursor control device; 518-network device;

[0036] Figure 1 It is a schematic diagram of the architecture of the optimization system described in an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of a power quality assessment network described in an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the process of dual evaluation in an embodiment of the present invention;

[0039] Figure 4 is a detailed step diagram of the dual evaluation process in an embodiment of the present invention;

[0040] Figure 5 FIG. 1 is a schematic diagram of the architecture of a computer system used in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with its embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. For those skilled in the art, after reviewing the following detailed description, other systems, methods and / or features of the present embodiment will become apparent. It is intended that all such additional systems, methods, features and advantages are included in this specification. Included within the scope of the present invention and protected by the appended claims. Additional features of the disclosed embodiments are described in the following detailed description, and these features will be apparent from the following detailed description.

[0042] The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right" and the like indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation. The invention is constructed and operated in a specific orientation, so the terms describing the positional relationship in the drawings are only used for exemplary description and cannot be understood as a limitation of this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0043] Embodiment 1: Exemplarily, a power quality optimization control system applied to a distributed photovoltaic system is proposed, wherein the optimization control system includes at least one photovoltaic power generation and energy storage unit; the photovoltaic power generation and energy storage unit includes:

[0044] A power generation module for converting solar energy into direct current electricity;

[0045] An inverter module, used to convert the direct current generated by the power generation module into alternating current;

[0046] Energy storage module, used to store excess electrical energy;

[0047] An electric energy evaluation module, which collects and analyzes indicators related to the power quality in the photovoltaic power generation and energy storage unit through the first collection submodule and the second collection submodule;

[0048] Among them, the power evaluation module is communicated with the power evaluation modules of other photovoltaic power generation and energy storage units to form a decentralized power quality evaluation network; the power quality evaluation network adopts a distributed consensus mechanism to cross-validate the power quality evaluation results to ensure that the power evaluation results of the power evaluation modules of each photovoltaic power generation and energy storage unit are correct and available, and further control the access rights of the photovoltaic power generation and energy storage units to the public power grid.

[0049] Exemplarily, the A acquisition submodule is arranged at the input end of the inverter module, and is specifically used to collect the electrical parameter data of the DC power generated by the photovoltaic power generation module; the B acquisition submodule is arranged at the output end of the inverter module, and is specifically used to collect the electrical parameter data of the AC power output by the inverter module.

[0050] Exemplarily, the electric energy evaluation module includes:

[0051] An evaluation unit is configured to use a preset power quality evaluation algorithm to periodically calculate the power quality state of the system and evaluate whether it meets a set threshold requirement;

[0052] A storage unit, used to store the historical electric energy parameter data collected by the first collection submodule and the second collection submodule, and the evaluation data made by the evaluation unit on the historical electric energy parameter data;

[0053] The communication unit is configured to establish a decentralized data communication network with the power evaluation modules of other photovoltaic power generation and energy storage units.

[0054] Exemplarily, a branch selector is further provided between the inverter module and the energy storage module; the branch selector is used to control the flow direction of the electric energy output by the inverter module and realize dynamic switching between the energy storage module, the grid line or the power load.

[0055] Exemplarily, the optimization control system includes executing a dual evaluation process during operation; the dual evaluation process includes the following steps:

[0056] The electric energy evaluation module serves as a main detection module, and based on the main evaluation period T1, uses the collected sample data as the A collection sample, periodically performs a preliminary evaluation on the electric energy quality of the photovoltaic power generation and energy storage unit, and generates the A evaluation result;

[0057] The main detection module periodically sends the A collection sample to at least two other randomly selected power evaluation modules through the power quality evaluation network based on the secondary evaluation cycle T2; the selected power evaluation module acts as a supervision detection module to evaluate the power quality of the A collection sample and generate a B evaluation sample;

[0058] The main detection module sends the evaluation result A to at least one management node through the power quality assessment network;

[0059] At least two of the supervisory detection modules send the second evaluation sample to at least one management node selected by the main detection module;

[0060] At least one management node calculates the degree of deviation between the evaluation result A and the evaluation result B in response to the evaluation result A and the evaluation result B, and performs consistency verification;

[0061] The management node will feed back the degree of deviation to the main detection module; if the deviation exceeds the threshold, the main detection module will trigger the control of the power transmission path of the photovoltaic power generation and energy storage unit.

[0062] Exemplarily, the secondary evaluation period T2 is greater than the primary evaluation period T1.

[0063] Exemplarily, the inverter module is a bidirectional inverter, and the output end of the energy storage module outputs electric energy to the inverter module according to electric energy demand, and provides electric energy to the power grid or the load through a branch selector.

[0064] As attached Figure 1, an exemplary implementation of the optimization control system is described.

[0065] In an exemplary embodiment, a distributed photovoltaic system includes a plurality of photovoltaic power generation and energy storage units 1; each photovoltaic power generation and energy storage unit can be arranged independently of other photovoltaic power generation and energy storage units geographically or physically separated. For example, a photovoltaic power generation and energy storage unit 1 can refer to an assembly of photovoltaic power generation equipment arranged in a household, or a small micro photovoltaic power station arranged outdoors. The scale of the photovoltaic power generation and energy storage unit is generally less than 10kV grid access capability, or the power generation scale is less than 6MW.

[0066] In a preferred embodiment, each photovoltaic power generation and energy storage unit 1 includes at least a power generation module 10 , an electric energy evaluation module 20 , an inverter module 30 and an energy storage module 40 .

[0067] In a preferred embodiment, the power generation module 10 includes at least one photovoltaic module and an electrical connection line supporting it, which is used to convert solar energy into DC power. The photovoltaic module can be a monocrystalline silicon, polycrystalline silicon or thin-film solar panel, and a fixed, adjustable or automatic tracking installation structure can be selected according to the specific application scenario to improve the utilization rate of light energy. The power generation module 10 preferably also includes a DC converging device for converging the power of multiple photovoltaic modules, and ensuring the safety and stability of power transmission through appropriate protection elements such as anti-reverse diodes and fuses.

[0068] In a preferred embodiment, the inverter module 30 is configured to convert the direct current generated by the power generation module 10 into alternating current that can be incorporated into the power grid or used by the load. Preferably, the inverter module 30 may include a power conversion circuit, a maximum power point tracking (MPPT) control unit, a power factor correction unit, and a filter circuit.

[0069] Preferably, the inverter module 30 adjusts the voltage, current, power factor, etc. of the input electric energy in real time, and provides functions such as harmonic suppression, overvoltage protection, and undervoltage protection, so as to make certain output parameter controls on the AC power output through the inverter module 30, and ensure that the power quality of the output AC power meets the predetermined standards.

[0070] In a preferred embodiment, each energy storage module 40 includes an energy storage module management system 42, multiple energy storage units 44, and a circuit electrically connecting the multiple energy storage units 44 to the energy storage block management system 42; the energy storage module 40 can be optimized and designed by the manufacturer, and internally includes a minimum single structural system assembled by connecting two or more energy storage units 44 in series / parallel; the energy storage unit 44 can refer to a single battery or other independent individual with energy storage function, such as a supercapacitor; the energy storage module 40 can be monitored and controlled by the energy storage module management system 42; each energy storage module 40 may include multiple energy storage units 44 and corresponding protection units or any other protection devices.

[0071] Preferably, the energy storage module management system 42 is configured to monitor the working status of each energy storage unit 44 and the energy storage module 40 .

[0072] Preferably, the energy storage unit 44 is a battery pack or a supercapacitor, each of which is independently packaged and electrically connected through a circuit; the battery pack can use a lithium-ion battery, a lithium iron phosphate battery, a lead-acid battery or other energy storage technology suitable for the application scenario.

[0073] Preferably, the energy storage module management system 42 performs real-time monitoring of parameters such as voltage, current, and temperature of the energy storage module 40 , and implements balancing management, overcharge / overdischarge protection, and health status assessment.

[0074] In a preferred embodiment, the input end of the inverter module 30 is electrically connected to the power generation module 10. The output end of the inverter module 30 is connected to the branch selector 70. The branch selector 70 includes a first branch, a second branch and a third branch. The first branch is connected to the energy storage module 40, the second branch is connected to the grid line 60, and the third branch is connected to the power load 50.

[0075] Specifically, the branch selector 70 is used to control the flow direction of the power output by the photovoltaic power generation and energy storage unit 1 to achieve on-demand distribution of photovoltaic power. The branch selector 70 may include multiple power switches, relays or semiconductor switch circuits, which can dynamically switch between the photovoltaic system, energy storage module, power grid and power load.

[0076] The first branch is an energy storage path; the first branch is connected to the energy storage module 40. When the photovoltaic system has sufficient power generation capacity and the grid demand is low, the branch selector 70 can turn on the first branch to store excess power in the energy storage module 40. When the energy storage module 40 is fully charged or the battery charge level reaches a preset threshold, the branch selector 70 can cut off the first branch to prevent overcharging.

[0077] The second branch is a grid-connected path; the second branch is connected to the grid line 60. When the photovoltaic system's power generation capacity meets the grid's power supply needs, the branch selector 70 can conduct the second branch to transmit the electricity generated by the photovoltaic system to the grid. When the grid line fails or the power quality does not meet the standards, the branch selector 70 can automatically disconnect the second branch to prevent affecting the safe operation of the grid.

[0078] The third branch is a load path; the third branch is connected to the power load 50. When the power generated by the photovoltaic system can directly meet the user's load demand, the branch selector 70 can conduct the third branch so that the photovoltaic power generation is preferentially supplied to the local load. When the load power demand is low or the energy storage module 40 needs to be charged preferentially, the branch selector 70 can adjust the load power supply mode according to the system demand.

[0079] In other embodiments, the inverter module 30 is a bidirectional inverter. The output end of the energy storage module 40 outputs current to the inverter module 30 to provide electric energy when the power demand is at a peak, and optionally provides electric energy to the grid or load through the branch selector 70.

[0080] In some embodiments, the user can manually select the power switching direction of the branch selector 70 through an operation interface, such as a switch, a touch screen, or a mobile application, to meet specific application scenarios, such as user-controlled power usage strategies.

[0081] Furthermore, in a preferred embodiment, the power evaluation module 20 cooperates with the A acquisition submodule 22 and the B acquisition submodule 24 to evaluate the power quality of each circuit segment in the photovoltaic power generation and energy storage unit 1. The A acquisition submodule 22 and the B acquisition submodule 24 are used to collect power parameters on the photovoltaic DC side and AC side, respectively, and the power evaluation module 20 is used to analyze and evaluate the collected data to ensure the stability of the system and the compliance of the power output. The A acquisition submodule 22 and the B acquisition submodule 24 are both configured with multiple sensors to achieve continuous measurement of the power characteristics of the configured sampling points.

[0082] Specifically, a sampling port is provided at the input end of the inverter module 30, and the electric energy data is sampled by the A acquisition submodule 22, and the sampled data comes from the direct current generated by the photovoltaic module. The collected electrical parameter data include but are not limited to direct current voltage, current, power, power factor, ripple voltage, short-term / long-term voltage fluctuation, direct current harmonic component, temperature, ambient illumination and other indicators. Preferably, the A acquisition submodule 22 collects the output power state of the power generation module 10 in real time, and sends the collected data to the power evaluation module 20 for subsequent power quality analysis.

[0083] On the other hand, a sampling port is provided at the output end of the inverter module 30, and the electric energy data is sampled by the second acquisition submodule 24, and the output end of the inverter module 30 is connected to the branch selector 70 at the same time. The second acquisition submodule 24 acquires parameters related to the AC electric energy output by the inverter. Preferably, the electric parameter data acquired by the second acquisition submodule 24 include but are not limited to indicators such as AC voltage, current, power, power factor, total harmonic distortion (THD), voltage distortion rate, current distortion rate, frequency deviation, three-phase voltage imbalance, transient voltage, instantaneous voltage drop, temporary rise, flicker, overvoltage, and undervoltage. The second acquisition submodule 24 monitors the output power quality of the inverter module 30 in real time, and sends the acquired data to the electric energy evaluation module 20, so as to comprehensively analyze the output quality of the inverter.

[0084] Preferably, the electric energy evaluation module 20 serves as a core evaluation unit, receives the electric parameter data from the A acquisition submodule 22 and the B acquisition submodule 24, and performs data analysis according to a preset power quality evaluation algorithm. The evaluation content of the electric energy evaluation module 20 includes but is not limited to comparative analysis of the power quality on the DC side and the AC side, judgment of the power quality qualification, data anomaly detection, load characteristic analysis, energy storage strategy optimization, etc. Based on the evaluation results, the electric energy evaluation module 20 provides adjustment suggestions or protection measures to the control module 80 to ensure the stability and safety of each circuit part of the photovoltaic power generation energy storage unit. When abnormal power quality is detected, the early warning mechanism is triggered by the electric energy evaluation module 20, and the branch selector 70 is instructed to make adaptive adjustments, such as directing electric energy to the energy storage module 40 to avoid direct transmission of unqualified electric energy to the grid line 60 or the power load 50.

[0085] Preferably, the power evaluation module 20 includes evaluating the total harmonic distortion of the AC power output by the inverter module 30 to ensure that the harmonic content is within a specified range to avoid interference with the power grid or load equipment. Harmonic analysis is to decompose the voltage or current waveform provided by the acquisition submodule 24 through Fourier transform (FFT), calculate the amplitude of each harmonic, and determine the THD value according to the following calculation formula:

[0086]

[0087] Among them, V n represents the effective value of the voltage of the nth harmonic; V1 represents the effective value of the fundamental voltage. The power evaluation module 20 is provided with an FFT calculation module in the data processing unit, which can calculate THD in real time and compare the result with the preset threshold. If THD exceeds the set range, the power evaluation module 20 will send an instruction to the control module 80 to adjust the inverter output waveform, or instruct the branch selector 70 to switch to the energy storage mode to prevent unqualified power from entering the power grid.

[0088] Preferably, the electric energy evaluation module 20 includes an evaluation of whether the output voltage of the photovoltaic power generation system meets the rated value to prevent voltage deviation from affecting the normal operation of the equipment. The calculation of the voltage deviation is based on the voltage data collected by the B acquisition submodule 24. The electric energy evaluation module 20 will calculate the voltage deviation in a short time (for example, a 1-second cycle) and a long time (for example, a 15-minute cycle), and compare it with the national standard to determine whether adjustment measures need to be taken. If the voltage deviation exceeds the allowable range, such as ±3%, an adjustment instruction is sent to the control module 80 to optimize the output parameters of the inverter, or trigger the energy storage unit to provide electric energy compensation to maintain voltage stability.

[0089] Preferably, the power evaluation module 20 uses the voltage and current data provided by the A acquisition submodule 22 and the B acquisition submodule 24 to calculate the power factor of the system to ensure the high efficiency of power utilization. The power factor is a measure of the ratio between the active power provided by the photovoltaic power generation system and the total power. The power evaluation module 20 will periodically evaluate the power factor and compare it with the specified minimum power factor threshold (for example, 0.9 or 0.95). If the power factor is lower than the set threshold, the power evaluation module 20 will trigger the inverter to adjust the reactive power output, or start the energy storage module 40 to provide reactive power compensation to improve the power factor of the system, reduce power loss and meet the grid connection requirements.

[0090] The evaluation indicators listed above are not proposed as restrictive options. In the specific implementation of the present technical solution, calculation of more evaluation indicators can be performed as needed.

[0091] Embodiment 2: This embodiment should be understood to include at least all the features of any of the above embodiments, and further improve upon them;

[0092] Furthermore, in a preferred embodiment, the power evaluation modules 20 of the plurality of photovoltaic power generation and energy storage units 1 in the distributed photovoltaic system are connected by a communication network to form a decentralized power quality evaluation network, which is used to enhance the overall power quality monitoring capability of the distributed photovoltaic system, and ensure the operating stability of each photovoltaic power generation and energy storage unit and the safety of the power grid through a decentralized collaboration mechanism.

[0093] Specifically, each of the power evaluation modules 20 is configured with a communication submodule. Through the communication submodule, the power evaluation module 20 is allowed to communicate data with other power evaluation modules 20, and the power evaluation module 20 becomes a network node of the power quality evaluation network. In a decentralized network, each power evaluation module 20 forms a distributed topology. The power quality evaluation network does not rely on a single central server, but cross-validates the power quality evaluation results through a distributed consensus mechanism.

[0094] In a preferred embodiment, the electric energy evaluation module 20 includes the following working units:

[0095] Evaluation unit: The evaluation unit adopts a preset power quality evaluation algorithm, such as based on root mean square error analysis, voltage deviation calculation, FFT harmonic analysis, etc., to periodically calculate the power quality status of the system and evaluate whether it meets the set threshold requirements.

[0096] Storage unit: used to store the historical power parameter data collected by the A collection submodule 22 and the B collection submodule 24, and the evaluation data of the historical power parameter data made by the evaluation unit, so as to perform trend analysis, predictive maintenance and compliance audit. The storage unit preferably adopts a ring buffer storage mechanism to store recent data and periodically upload it to the cloud or local management node.

[0097] Communication unit: The communication unit establishes a decentralized data sharing network with the power evaluation module 20 of other photovoltaic power generation and energy storage units through wired communication methods, such as RS485, CAN, Ethernet, etc., or wireless communication methods, such as LoRa, Wi-Fi, 5G, etc.

[0098] In some embodiments, the photovoltaic power generation and energy storage unit 1 performs a dual evaluation process. The dual evaluation process first uses the power evaluation module 20 configured by the photovoltaic power generation and energy storage unit 1 itself as the main detection module 200, and the main detection module 200 performs a self-evaluation of the power quality based on a main evaluation cycle T1. At the same time, each main detection module 200 randomly selects at least two power evaluation modules 20 in the power quality evaluation network other than itself and in an active working state as the inspection detection module 210 based on a secondary evaluation cycle T2 to perform a secondary evaluation.

[0099] Moreover, the secondary evaluation period T2 is greater than the primary evaluation period T1. In a preferred embodiment, T2 can be calculated according to T1 by using the review multiple p, that is, T2=p·T1. The optional value of p can be 100 or more, such as 120, 150, 180 or other values.

[0100] More specifically, the dual assessment process involves performing the following steps:

[0101] S100: The main detection module 200 prepares the electric energy parameter data collected by the photovoltaic power generation and energy storage unit 1 in the previous main evaluation cycle T1, which is referred to as the A collection sample; and prepares the electric energy quality evaluation result for the A collection sample, which is referred to as the A evaluation result.

[0102] S200: The main detection module 200 sends the evaluation result of A to at least one management node 220 in the power quality assessment network; further, sends the A collection sample and the identification information of the selected management node 220 to at least two of the inspection and detection modules 210.

[0103] S300: The two power evaluation modules 20 selected as the inspection and detection modules 210 respond to the received A collection samples, recalculate the power quality represented by the A collection samples according to the same evaluation algorithm, and generate B evaluation results.

[0104] S400: At least two of the inspection and detection modules 210 send the B evaluation result to the management node 220 selected in step S200.

[0105] S500: The management node 220 calculates the degree of deviation between the evaluation result A and the evaluation result B in response to the received evaluation result A and evaluation result B.

[0106] S600: The management node 220 reflects the calculation result of the deviation degree of the sample collected by A to the main detection module 200.

[0107] In a preferred embodiment, when the deviation between evaluation result A and evaluation result B exceeds a preset threshold, the system will trigger a consistency check mechanism. Under this mechanism, it can include again requiring the main detection module 200 to shorten the cycle duration of the main evaluation cycle T1 to increase the frequency of executing the dual evaluation process; or requiring the main detection module 200 to immediately execute the dual evaluation process again, and requesting to select at least two additional inspection and detection modules 210 to execute the dual evaluation process to ensure the accuracy and consistency of the evaluation results. The management node 220 is responsible for coordinating these evaluation processes and ultimately confirming the validity of the results. Once it is confirmed that a photovoltaic power generation and energy storage unit has an abnormality, its electric energy evaluation module 20 will trigger the corresponding protection mechanism, such as notifying the control module 80 to take necessary adjustment measures, such as limiting the grid-connected output, switching to the energy storage mode or shutting down for self-inspection, to prevent unqualified electric energy from affecting the stable operation of the entire photovoltaic system.

[0108] In a preferred embodiment, the deviation degree σ between the evaluation result A and the evaluation result B is calculated by the following formula: 甲 :

[0109]

[0110] In the above formula, N is the total number of power quality indicators, m is the number of selected inspection and detection modules 210; X 甲,i is the value of the ith indicator in the evaluation result of A; X 乙,m,iis the value of the ith indicator in the evaluation result of the mth inspection and detection module 210.

[0111] Preferably, when three or more inspection and detection modules 210 are selected, the deviation value σ of the evaluation result A can be calculated in the execution 甲 Before, we first calculate whether there is an abnormally deviated B evaluation result among the m B evaluation results, that is, we first exclude the abnormal inspection detection module 210. The following calculation formula can be used to calculate the deviation degree σ of each B evaluation result: 乙 :

[0112]

[0113] σ 乙,j Indicates the degree of deviation of the jth B evaluation result, X 乙,j,i represents the value of the ith indicator in the evaluation result of the jth inspection module, μ 乙，i is the mean of the ith indicator in the m evaluation results of B.

[0114] Furthermore, relevant technical personnel set σ 甲 and σ 乙 The threshold value.

[0115] In a preferred embodiment, if the degree of deviation of an evaluation result B is also significantly higher than that of an evaluation result A and at least two evaluation results B, the management node 220 sends a message to the main detection module 200 to re-execute steps S100 to S600, and re-selects at least two electric energy evaluation modules 20 that are different from the previous inspection and detection modules 210 as the inspection and detection modules 210 to perform a double evaluation process.

[0116] The advantages of decentralized networks are high reliability, fault tolerance, and data consistency. Since the evaluation process is distributed across multiple independent units, the overall system can still operate normally even if some units fail. In addition, the network can be dynamically expanded. When adding a new photovoltaic power generation and energy storage unit, it is only necessary to add its power evaluation module 20 to the existing network architecture without making large-scale changes to the overall system.

[0117] Embodiment 3: This embodiment should be understood to include at least all the features of any of the above embodiments, and further improve upon them;

[0118] For example, as shown in the attached Figure 5 As shown, the implementation method of the computer system 500 used in the optimization control system, such as the power evaluation module 20 or the control module 80, or other working modules is described; the computer system 500 can be used to identify and judge the data storage, calculation and result output process of each working module in the system.

[0119] Illustratively, computer system 500 includes a bus 502 or other communication mechanism for communicating information, one or more processors 504 coupled to bus 502 for processing information; processor 504 may be, for example, one or more general-purpose microprocessors;

[0120] The computer system 500 also includes a main memory 506, such as a random access memory (RAM), a cache, and / or other dynamic storage device, coupled to the bus 502 for storing information and instructions to be executed by the processor 504; the main memory 506 may also be used to store temporary variables or other intermediate information during the execution of instructions to be executed by the processor 504; these instructions, when stored in a storage medium accessible to the processor 504, present the computer system 500 as a special-purpose machine customized to perform the operations specified in the instructions;

[0121] The computer system 500 may also include a read-only memory (ROM) 508 or other static storage device coupled to the bus 502 for storing static information and instructions for the processor 504; a storage device 510 such as a disk, an optical disk, or a USB drive (flash drive) will be coupled to the bus 502 for storing information and instructions;

[0122] And further, coupled to the bus 502 may also include a display 122 for displaying various information, data, media, etc., an input device 514 for allowing a user of the computer system 500 to control, manipulate, and / or interact with the computer system 500;

[0123] A preferred way to interact with the management system may be through a cursor control device 516, such as a computer mouse or similar control / navigation mechanism;

[0124] Furthermore, the computer system 500 may also include a network device 518 coupled to the bus 502; wherein the network device 518 may include, for example, a wired network card, a wireless network card, a switching chip, a router, a switch, and other components;

[0125] In general, the terms "engine", "component", "system", "database", etc., as used herein, may refer to logic embodied in hardware or firmware, or to a collection of software instructions, possibly with entry and exit points, written in a programming language such as Java, C, or C++; software components may be compiled and linked into executable programs, installed in a dynamic link library, or may be written in an interpreted programming language (e.g., BASIC, Perl, or Python); it should be understood that software components may be called from other components or from themselves, and / or may be called in response to detected events or interrupts;

[0126] Software components configured to execute on a computing device may be provided on a computer-readable medium, such as a compact disc, digital video disc, flash drive, diskette, or any other tangible medium, or as a digital download (and may be initially stored in a compressed or installable format that requires installation, decompression, or decryption prior to execution); such software code may be stored in part or in whole on a memory device of the executing computing device for execution by the computing device; software instructions may be embedded in firmware, such as an EPROM; it is also understood that hardware components may be composed of connected logic units (such as gates and flip-flops), and / or may be composed of programmable units (such as programmable gate arrays or processors);

[0127] Computer system 500 includes the techniques described herein that may be implemented using custom hardwired logic, one or more ASICs or FPGAs, firmware, and / or program logic that, in combination with the computer system, renders computer system 500 a special-purpose computing device;

[0128] According to one or more embodiments, the techniques herein may be performed by computer system 500 in response to processor 504 executing one or more sequences of one or more instructions contained in main memory 506; such instructions may be read into main memory 506 from another storage medium, such as storage device 510; execution of the sequences of instructions contained in main memory 506 causes processor 504 to perform the process steps described herein; in alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions;

[0129] As used herein, the term "non-transitory media" and similar terms refer to any media that store data and / or instructions that cause a machine to operate in a specific manner; such non-transitory media may include non-volatile media and / or volatile media; non-volatile media include, for example, optical or magnetic disks, such as storage device 510; volatile media include dynamic memory, such as main memory 506;

[0130] Among them, common forms of non-transitory media include, for example, floppy disks, diskettes, hard disks, solid-state drives, magnetic tapes or any other magnetic data storage medium, CD-ROMs, any other optical data storage medium, any physical medium having a pattern of holes, RAM, PROM and EPROM, FLASH-EPROM, NVRAM, any other memory chip or cartridge, and network versions thereof;

[0131] Non-transient media are distinct from transmission media but may be used in conjunction with transmission media; transmission media participate in the transmission of information between non-transient media; for example, transmission media include coaxial cables, copper wires, and optical fibers, including the wires that make up bus 502; transmission media may also take the form of sound waves or light waves, such as radio waves and infrared data communications.

[0132] Although the present invention has been described above with reference to various embodiments, it should be understood that many changes and modifications may be made without departing from the scope of the present invention. That is, the methods, systems and devices discussed above are examples. Various configurations may appropriately omit, replace or add various processes or components. For example, in alternative configurations, the method may be performed in an order different from the order described, and / or various components may be added, omitted and / or combined. Moreover, the features described with respect to certain configurations may be combined in various other configurations, such as different aspects and elements of the configurations may be combined in a similar manner. In addition, the elements therein may be updated as the technology develops, i.e., many elements are examples and do not limit the scope of the present disclosure or claims.

[0133] Specific details are given in the specification to provide a thorough understanding of the exemplary configurations including implementations. However, the configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary details to avoid obscuring the configurations. This description provides only example configurations and does not limit the scope, applicability, or configurations of the claims. On the contrary, the foregoing description of the configurations will provide those skilled in the art with an enabling description for implementing the described techniques. Various changes may be made to the functions and arrangements of the elements without departing from the spirit or scope of the present disclosure.

[0134] In summary, it is intended that the above detailed description is considered to be illustrative rather than restrictive, and it should be understood that the above embodiments should be understood to be only used to illustrate the present invention and not to limit the scope of protection of the present invention. After reading the contents of the present invention, the technician can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A power quality optimization control system applied to a distributed photovoltaic system, characterized in that: The optimization control system includes at least one photovoltaic power generation and energy storage unit; the photovoltaic power generation and energy storage unit includes: A power generation module for converting solar energy into direct current electricity; An inverter module, used to convert the direct current generated by the power generation module into alternating current; Energy storage module, used to store excess electrical energy; An electric energy evaluation module, which collects and analyzes indicators related to the power quality in the photovoltaic power generation and energy storage unit through the first collection submodule and the second collection submodule; Among them, the power evaluation module is communicated with the power evaluation modules of other photovoltaic power generation and energy storage units to form a decentralized power quality evaluation network; the power quality evaluation network adopts a distributed consensus mechanism to cross-validate the power quality evaluation results to ensure that the power evaluation results of the power evaluation modules of each photovoltaic power generation and energy storage unit are correct and available, and further control the access rights of the photovoltaic power generation and energy storage units to the public power grid.

2. The optimization control system according to claim 1, characterized in that: The A acquisition submodule is arranged at the input end of the inverter module, and is specifically used to collect the electrical parameter data of the DC power generated by the photovoltaic power generation module; the B acquisition submodule is arranged at the output end of the inverter module, and is specifically used to collect the electrical parameter data of the AC power output by the inverter module.

3. The optimization control system according to claim 2, characterized in that: The electric energy evaluation module comprises: An evaluation unit is configured to use a preset power quality evaluation algorithm to periodically calculate the power quality state of the system and evaluate whether it meets a set threshold requirement; A storage unit, used to store the historical electric energy parameter data collected by the first collection submodule and the second collection submodule, and the evaluation data made by the evaluation unit on the historical electric energy parameter data; The communication unit is configured to establish a decentralized data communication network with the power evaluation modules of other photovoltaic power generation and energy storage units.

4. The optimization control system according to claim 3, characterized in that: A branch selector is also provided between the inverter module and the energy storage module; the branch selector is used to control the flow direction of the electric energy output by the inverter module and realize dynamic switching between the energy storage module, the power grid line or the power load.

5. The optimization control system according to claim 4, characterized in that: The optimization control system includes executing a dual evaluation process during operation; the dual evaluation process includes the following steps: The electric energy evaluation module serves as a main detection module, and based on the main evaluation period T1, uses the collected sample data as the A collection sample, periodically performs a preliminary evaluation on the electric energy quality of the photovoltaic power generation and energy storage unit, and generates the A evaluation result; The main detection module periodically sends the A collection sample to at least two other randomly selected power evaluation modules through the power quality evaluation network based on the secondary evaluation cycle T2; the selected power evaluation module acts as a supervision detection module to evaluate the power quality of the A collection sample and generate a B evaluation sample; The main detection module sends the evaluation result A to at least one management node through the power quality assessment network; At least two of the supervisory detection modules send the second evaluation sample to at least one management node selected by the main detection module; At least one management node calculates the degree of deviation between the evaluation result A and the evaluation result B in response to the evaluation result A and the evaluation result B, and performs consistency verification; The management node will feed back the degree of deviation to the main detection module; if the deviation exceeds the threshold, the main detection module will trigger the control of the power transmission path of the photovoltaic power generation and energy storage unit.

6. The optimization control system according to claim 5, characterized in that: The secondary evaluation period T2 is greater than the primary evaluation period T1.

7. The optimization control system according to claim 6, characterized in that: The inverter module is a bidirectional inverter. The output end of the energy storage module outputs electric energy to the inverter module according to electric energy demand, and provides electric energy to the power grid or load through the branch selector.

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