Direct current bus connection state monitoring system for solar photovoltaic modules

Abstract

The application belongs to the technical field of power supervision, and specifically relates to a DC bus connection state monitoring system for a solar photovoltaic module, which comprises a monitoring platform, a connection abnormality analysis module, a point-by-point monitoring module, a DC bus state evaluation module and a background terminal; the connection abnormality analysis module is used for analysis to determine an abnormal connection position and assign a corresponding connection judgment symbol, the point-by-point monitoring module is used for point-by-point monitoring and analysis of the DC bus to assign a corresponding bus judgment symbol, the DC bus state evaluation module is used for comprehensive analysis and accurate judgment of the DC bus connection state and operation risk of the solar photovoltaic module based on the connection judgment symbol and the bus judgment symbol, and when a DC bus state abnormality signal is generated, the management personnel are reminded to take improvement measures, so that the system has high intelligent degree and is conducive to ensuring the safe and stable operation of the DC bus.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power supervision, in particular to a DC bus connection state monitoring system of a solar photovoltaic module. BACKGROUND

[0002] The solar photovoltaic module is composed of high-efficiency crystalline silicon solar cell pieces, back plates and frames, and is mainly used for photovoltaic power generation. Photovoltaic power generation has no noise and pollutant emission, and the application technology is mature and safe and reliable. Solar energy is the cleanest, safest and most reliable energy in the future, and the photovoltaic industry is becoming another explosive industry after the IT and microelectronic industries.

[0003] In the photovoltaic power generation system, the connection state of the DC bus directly affects its safety and stability. At present, it is difficult to reasonably analyze and comprehensively evaluate the running connection state of the DC bus of the solar photovoltaic module, and the surface hidden danger state of the DC bus cannot be accurately fed back, the safety hidden danger of the DC bus cannot be timely warned, and the intelligent degree is low, which is not conducive to ensuring the safe and stable operation of the DC bus.

[0004] In view of the above technical defects, a solution is proposed. SUMMARY

[0005] The purpose of the present application is to provide a DC bus connection state monitoring system of a solar photovoltaic module, which solves the problem that the prior art cannot reasonably analyze and comprehensively evaluate the running connection state of the DC bus of the solar photovoltaic module, cannot accurately feed back the surface hidden danger state of the DC bus, cannot timely warn the safety hidden danger of the DC bus, and has a low intelligent degree.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] The DC bus connection state monitoring system of the solar photovoltaic module comprises a monitoring platform, a connection anomaly analysis module, a point-by-point monitoring module, a DC bus state evaluation module and a background terminal.

[0008] The connection anomaly analysis module obtains all bus connection points existing on the DC bus of the solar photovoltaic module, marks the corresponding bus connection point as a target connection point i, and i is a natural number greater than 1; by analyzing to determine the abnormal connection point and give the connection judgment symbol LP-1 or LP-2, and send the connection judgment symbol LP-1 or LP-2 to the DC bus state evaluation module;

[0009] The point-by-point monitoring module carries out point-by-point monitoring analysis on the DC bus, gives the bus judgment symbol GP-1 or GP-2 through analysis, and sends the bus judgment symbol GP-1 or GP-2 to the DC bus state evaluation module;

[0010] The DC bus state evaluation module performs intersection analysis on the connection judgment symbol and the bus judgment symbol, and if LP-2∩GP-2 is obtained, a DC bus state qualified signal is generated, otherwise a DC bus state abnormal signal is generated, and the DC bus state qualified signal or the DC bus state abnormal signal is sent to the background terminal through the monitoring platform. When the background terminal receives the DC bus state abnormal signal, a warning is issued.

[0011] Further, the specific operation process of the connection abnormality analysis module includes:

[0012] The tightening force of the connecting piece of the target connection i on the DC bus is obtained and marked as a connection force measured value, and the deviation of the connection force measured value from the standard connection force measured value is marked as a connection force deviation value. The real-time bus joint contact resistance of the target connection i is collected and marked as a contact resistance measured value, and the contact resistance trend value of the target connection i is obtained through contact resistance trend analysis;

[0013] The connection force deviation value, the contact resistance measured value and the contact resistance trend value are numerically calculated to obtain a connection abnormality analysis value, and the connection abnormality analysis value is compared with a preset connection abnormality analysis threshold value. If the connection abnormality analysis value exceeds the preset connection abnormality analysis threshold value, the target connection i is marked as an abnormal connection. If there is an abnormal connection, the connection judgment symbol LP-1 is given; if there is no abnormal connection, the connection judgment symbol LP-2 is given.

[0014] Further, the specific analysis process of the contact resistance trend analysis is as follows:

[0015] A rectangular coordinate system located in the first quadrant is established with time as the X-axis and bus joint contact resistance as the Y-axis, and a contact resistance curve is drawn in the rectangular coordinate system based on all bus joint contact resistances of the target connection i in a unit time. Mark several coordinate points on the contact resistance curve and define them as verification points, and the X-direction distance between adjacent two verification points is the same.

[0016] And a ray parallel to the X-axis and with its end point on the Y-axis is drawn in the rectangular coordinate system and marked as a resistance verification ray, and the number of verification points above the resistance verification ray in the rectangular coordinate system is counted and marked as a verification number abnormal value.

[0017] The verification point located above the resistance verification ray is marked as an abnormal verification point, a line segment perpendicular to the resistance verification ray is drawn with the abnormal verification point as an end point and marked as a nucleation distance line segment, the length of the nucleation distance line segment is marked as a nucleation distance value, the nucleation distance values of all abnormal verification points are averaged to obtain a verification over-check value, and the X-direction length and value involved in the part in the rising state of the contact resistance curve are obtained and marked as a contact resistance increase time value; the contact resistance trend value is obtained by numerically calculating the verification number abnormal value, the verification over-check value and the contact resistance increase time value.

[0018] Further, the specific operation process of the split-point monitoring module includes:

[0019] A plurality of monitoring points are set on the DC bus of the solar photovoltaic assembly, the real-time voltage and the real-time current of all monitoring points are collected, the real-time voltage of all monitoring points is subjected to variance calculation to obtain a bus voltage value, and the real-time current of all monitoring points is subjected to variance calculation to obtain a bus current value, the bus voltage value and the bus current value are respectively compared with a preset bus voltage threshold value and a preset bus current threshold value, and if the bus voltage value or the bus current value exceeds the corresponding preset threshold value, a bus judgment symbol GP-1 is assigned.

[0020] Further, if the bus voltage value and the bus current value do not exceed the corresponding preset threshold value, the bus point condition value of the corresponding monitoring point is obtained by analysis, the bus point condition values of all monitoring points are averaged to obtain a bus point measurement value, the bus point condition value is compared with a preset bus point condition threshold value, the number of bus point condition values exceeding the preset bus point condition threshold value is marked as a bus abnormal point value, and the bus point condition value with the largest value is marked as a bus point amplitude value.

[0021] The bus abnormal table value is obtained by numerically calculating the bus point measurement value, the bus abnormal point value and the bus point amplitude value, the bus abnormal table value is compared with a preset bus abnormal table threshold value, if the bus abnormal table value exceeds the preset bus abnormal table threshold value, the bus judgment symbol GP-1 is assigned, and if the bus abnormal table value does not exceed the preset bus abnormal table threshold value, the bus judgment symbol GP-2 is assigned.

[0022] Further, the specific analysis process of obtaining the bus point condition value of the corresponding monitoring point is as follows:

[0023] The deviation value of the real-time voltage of the corresponding monitoring point from the median value of the preset appropriate voltage range is marked as a bus point voltage value, the deviation value of the real-time current of the corresponding monitoring point from the median value of the preset appropriate current range is marked as a bus point current value, and the real-time temperature of the corresponding monitoring point is collected and marked as a bus point temperature value; the bus point condition value is obtained by numerically calculating the bus point voltage value, the bus point current value and the bus point temperature value.

[0024] Further, the monitoring platform is connected with a DC bus scanning decision module, the monitoring platform sends a DC bus state qualified signal to the DC bus scanning decision module, the DC bus scanning decision module collects a surface image of the DC bus when receiving the DC bus state qualified signal, analyzes the surface quality of the DC bus based on the surface image of the DC bus, generates a DC bus scanning qualified signal or a DC bus scanning abnormal signal through analysis, and sends the DC bus scanning qualified signal or the DC bus scanning abnormal signal to the background terminal through the monitoring platform, and the background terminal sends a warning when receiving the DC bus scanning abnormal signal.

[0025] Further, the specific analysis process of the DC bus scanning decision module is as follows:

[0026] Based on the scanning image of the DC bus to determine whether there is damage on the surface of the DC bus, if there is damage on the surface of the DC bus, a DC bus scanning abnormal signal is generated;

[0027] If there is no damage on the surface of the DC bus, the deviation value of the real-time distance value of the corresponding two positions on the DC bus compared with the corresponding initial distance value is collected and marked as a spacing deviation value, the mean value of all spacing deviation values on the DC bus is marked as a spacing deviation table value, and the number of spacing deviation values exceeding a preset spacing deviation threshold is marked as a spacing abnormal deviation value, the spacing deviation table value and the spacing abnormal deviation value are compared with the preset spacing deviation table threshold and the preset spacing abnormal deviation threshold respectively, if the spacing deviation table value or the spacing abnormal deviation value exceeds the corresponding preset threshold, a DC bus scanning abnormal signal is generated.

[0028] Further, if the spacing deviation table value and the spacing abnormal deviation value do not exceed the corresponding preset threshold, the scanning image of the DC bus is subjected to gray scale processing, the real-time gray scale value of all positions on the DC bus is collected, a plurality of regions are set on the DC bus, the total area of the actual gray scale value of the corresponding region exceeding a preset gray scale threshold is marked as a non-clean surface measurement value, and the mean value of all real-time gray scale values of the corresponding region is calculated to obtain a gray scale detection condition value, the non-clean surface measurement value and the gray scale detection condition value are compared with the preset non-clean surface measurement threshold and the preset gray scale detection condition threshold, if the non-clean surface measurement value or the gray scale detection condition value exceeds the corresponding preset threshold, the corresponding region is marked as a non-clean region;

[0029] If there is a non-clean area on the DC bus, a DC bus scanning abnormal signal is generated; if there is no non-clean area on the DC bus, the non-clean surface values of all areas on the DC bus are summed to obtain a non-clean surface analysis value, the gray level detection values of all areas are averaged to obtain a gray level analysis value, the non-clean surface analysis value and the gray level analysis value are numerically calculated to obtain a bus cleanliness difference value, the bus cleanliness difference value is compared with a preset bus cleanliness difference threshold value, if the bus cleanliness difference value exceeds the preset bus cleanliness difference threshold value, a DC bus scanning abnormal signal is generated; if the bus cleanliness difference value does not exceed the preset bus cleanliness difference threshold value, a DC bus scanning qualified signal is generated.

[0030] Further, each or more solar photovoltaic components are connected to an SMP Unit to form a photovoltaic component group; a plurality of photovoltaic component groups are connected in parallel to the DC bus and are connected to the energy device through the DC bus.

[0031] Compared with the prior art, the beneficial effects of the present application are:

[0032] 1、In the present application, the abnormal connection is determined by the connection difference analysis module and the corresponding connection judgment symbol is given, the DC bus is monitored and analyzed by the point type monitoring module to give the corresponding bus judgment symbol, and the DC bus state evaluation module is based on the connection judgment symbol and the bus judgment symbol to comprehensively analyze and accurately judge the DC bus connection state and operation risk of the solar photovoltaic component, which has high intelligent degree and is beneficial to ensure the safe and stable operation of the DC bus;

[0033] 2、In the present application, the DC bus state qualified signal is sent to the DC bus scanning decision module through the monitoring platform, the surface image of the DC bus is collected by the DC bus scanning decision module, the surface quality condition of the DC bus is analyzed based on the surface image, and the background terminal issues a warning when the DC bus scanning abnormal signal is generated, which can reasonably analyze and accurately judge the surface abnormal condition of the DC bus and timely remind the management personnel to take corresponding improvement measures, thereby further reducing the use risk of the DC bus. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to facilitate those skilled in the art to understand, the present application will be further described below with reference to the drawings;

[0035] Figure 1 The system block diagram of the first embodiment in the present application;

[0036] Figure 2 The system block diagram of the second embodiment in the present application;

[0037] Figure 3 The structure block diagram of the third embodiment in the present application;

[0038] Figure 4 for Figure 3 Enlarged view of part A;

[0039] Figure 5 for Figure 3 Magnified view of part B. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] Example 1: Figure 1 As shown, the DC bus connection status monitoring system of the solar photovoltaic module proposed in the present invention includes a monitoring platform, a connection abnormality analysis module, a point-based monitoring module, a DC bus status assessment module and a background terminal;

[0042] The connection analysis module obtains all busbar connections on the DC busbar of the solar photovoltaic module. It should be noted that the busbar connection is an important part of the DC busbar that connects different mother devices or cables. The busbar connection usually consists of the busbar body and connectors. The corresponding busbar connection is marked as the target connection i, where i is a natural number greater than 1.

[0043] By analyzing and identifying abnormal connections and assigning them the connection judgment symbol LP-1 or LP-2, and sending these connection judgment symbols LP-1 or LP-2 to the DC bus status assessment module, this module not only reasonably assesses the safety risk status of each bus connection, prompting management personnel to take targeted measures, but also provides information support for the analysis process of the DC bus status assessment module, ensuring the accuracy of its analysis results. The specific operation process of the connection abnormality analysis module is as follows:

[0044] The tightening force applied by the connector at the target connection i on the DC bus is obtained and marked as the measured connection force value. The deviation of the measured connection force value from the standard measured connection force value is also marked as the connection force deviation value. The tightening force of the connector should be moderate. Too tight can easily cause deformation or damage to the busbar, while too loose can easily cause poor contact or looseness.

[0045] The real-time busbar joint contact resistance at the target connection i is collected and marked as the actual contact resistance value. The busbar joint contact resistance refers to the resistance generated at the busbar connection due to poor contact between the conductor and the connected conductor. The larger the value of the busbar joint contact resistance, the greater the safety risk of the corresponding busbar connection.

[0046] and the contact resistance trend value of the target connection i is obtained by contact resistance trend analysis, specifically: a rectangular coordinate system located in the first quadrant is established with time as the X-axis and the bus joint contact resistance as the Y-axis, and the contact resistance curve is drawn in the rectangular coordinate system based on all bus joint contact resistances of the target connection i in a unit time; a plurality of coordinate points are marked on the contact resistance curve and defined as verification points, and the X-direction distance between adjacent two verification points is the same;

[0047] and a ray parallel to the X-axis and with the end point located on the Y-axis is drawn in the rectangular coordinate system and marked as the resistance verification ray, it should be noted that the Y-axis coordinate corresponding to the resistance verification ray is the preset bus joint contact resistance threshold, and the value of the preset bus joint contact resistance threshold is greater than zero; the number of verification points located above the resistance verification ray in the rectangular coordinate system is counted and marked as the verification number anomaly value;

[0048] the verification points located above the resistance verification ray are marked as anomaly verification points, a line segment perpendicular to the resistance verification ray is drawn with the corresponding anomaly verification point as the end point and marked as the nuclear distance line segment, the length of the nuclear distance line segment is marked as the nuclear distance value, and the nuclear distance values of all anomaly verification points are averaged to obtain the verification super detection value, and the X-direction length and value involved in the part in the rising state of the contact resistance curve are obtained and marked as the contact resistance increase time value;

[0049] the contact resistance trend value TXi is obtained by numerical calculation of the verification number anomaly value TPi, the verification super detection value TYi and the contact resistance increase time value TWi through the formula TXi=nk1*TPi+(nk2*TYi+nk3*TWi) / nk1; wherein nk1, nk2 and nk3 are preset proportion coefficients with values greater than zero, and the greater the value of the contact resistance trend value TXi, the more abnormal the performance of the bus joint contact resistance of the target connection i in a unit time, and the greater the safety risk it brings;

[0050] the connection force bias value QLi, the contact resistance measured value QYi and the contact resistance trend value TXi are calculated through the formula the connection anomaly value QKi is obtained; wherein rp1, rp2 and rp3 are preset proportion coefficients, and the values of rp1, rp2 and rp3 are positive numbers; and the greater the value of the connection anomaly value QKi, the greater the comprehensive safety risk of the target connection i;

[0051] The junction anomaly value QKi is compared with a preset junction anomaly threshold value, if the junction anomaly value QKi exceeds the preset junction anomaly threshold value, it indicates that the safety risk of the target junction i is relatively large in general, and the target junction i is marked as an abnormal junction; if there is an abnormal junction, it indicates that there is a safety hazard in the junction of the DC bus, and the connection judgment symbol LP-1 is given; if there is no abnormal junction, it indicates that there is no safety hazard in the junction of the DC bus, and the connection judgment symbol LP-2 is given.

[0052] The point-type monitoring module performs point-type monitoring analysis on the DC bus, and sends the bus judgment symbol GP-1 or GP-2 to the DC bus state evaluation module, which not only can reasonably judge the running risk condition of the DC bus itself, but also can provide information support for the analysis process of the DC bus state evaluation module, further ensuring the accuracy of the analysis result; the specific operation process of the point-type monitoring module is as follows:

[0053] A plurality of monitoring points are set on the DC bus of the solar photovoltaic module, and the real-time voltage and the real-time current of all monitoring points are collected. The real-time voltage of all monitoring points is calculated to obtain a bus voltage value, and the real-time current of all monitoring points is calculated to obtain a bus current value. The larger the bus voltage value and the bus current value, the more unstable the voltage and current on the DC bus. The bus voltage value and the bus current value are compared with the preset bus voltage threshold value and the preset bus current threshold value respectively, if the bus voltage value or the bus current value exceeds the corresponding preset threshold value, it indicates that the running risk of the DC bus is relatively large, and the bus judgment symbol GP-1 is given.

[0054] Further, if the bus voltage value and the bus current value do not exceed the corresponding preset threshold value, the bus point condition value of the corresponding monitoring point is obtained by analysis, specifically: the deviation value of the real-time voltage of the corresponding monitoring point compared with the median value of the preset suitable voltage range is marked as the bus point voltage value, the deviation value of the real-time current of the corresponding monitoring point compared with the median value of the preset suitable current range is marked as the bus point current value, and the real-time temperature of the corresponding monitoring point is collected and marked as the bus point temperature value.

[0055] The bus point voltage value PY, the bus point current value PL and the bus point temperature value PW are calculated by the formula PN=(fu1*PY+fu2*PL+fu3*PW) / 3 to obtain the bus point condition value PN; wherein fu1, fu2 and fu3 are preset proportional coefficients with a value greater than zero, and the larger the bus point condition value PN, the greater the running risk of the corresponding monitoring point on the DC bus.

[0056] The bus point condition values ​​of all monitoring points are averaged to obtain the bus point measured value, and the bus point condition value is numerically compared with the preset bus point condition threshold value, and the number of bus point condition values ​​exceeding the preset bus point condition threshold value is marked as the bus outlier value, and the bus point condition value with the largest value is marked as the bus point amplitude;

[0057] The bus point measurement value WF, the bus point value WS, and the bus point amplitude WK are numerically calculated using the formula WY = hy2*WS + (hy1*WF + hy3*WK) / 2 to obtain the bus abnormal value WY. Hy1, hy2, and hy3 are preset proportional coefficients, and hy2>hy1>hy3>0. A larger bus abnormal value WY indicates a worse DC bus condition and a greater operational risk.

[0058] The bus abnormal meter value WY is numerically compared with the preset bus abnormal meter threshold. If the bus abnormal meter value WY exceeds the preset bus abnormal meter threshold, it indicates that the overall operation risk of the DC bus is large, and the bus judgment symbol GP-1 is assigned; if the bus abnormal meter value WY does not exceed the preset bus abnormal meter threshold, it indicates that the overall operation risk of the DC bus itself is small, and the bus judgment symbol GP-2 is assigned.

[0059] The DC bus status assessment module performs an intersection analysis on the connection judgment symbol and the bus judgment symbol. If LP-2∩GP-2 is obtained, it indicates that the operation and connection status of the DC bus are good, and a DC bus status qualified signal is generated. Otherwise (including LP-1∩GP-1, LP-1∩GP-2, and LP-2∩GP-1), it indicates that the operation and connection status of the DC bus are poor, and a DC bus status error signal is generated.

[0060] The DC bus status qualified signal or DC bus status abnormal signal is sent to the background terminal through the monitoring platform. When the background terminal receives the DC bus status abnormal signal, it will issue an early warning. It can comprehensively analyze and accurately judge the DC bus connection status and operation risk of the solar photovoltaic module. It has a high degree of intelligence, which is conducive to management personnel to make improvement measures in time to ensure the safe and stable operation of the DC bus.

[0061] Example 2: Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the monitoring platform is communicatively connected to the DC bus scanning decision module. The monitoring platform sends a DC bus state qualified signal to the DC bus scanning decision module. When the DC bus scanning decision module receives the DC bus state qualified signal, it collects a surface image of the DC bus, analyzes the surface quality of the DC bus based on the surface image, and generates a DC bus scanning qualified signal or a DC bus scanning abnormality signal through analysis.

[0062] The DC bus scan qualified signal or DC bus scan abnormal signal is sent to the background terminal via the monitoring platform. When the background terminal receives the DC bus scan abnormal signal, it issues an early warning, can reasonably analyze and accurately judge the surface abnormality of the DC bus, and promptly remind the management personnel to take corresponding improvement measures, thereby ensuring the safe operation of the DC bus and reducing the use risk. The degree of intelligence is high. The specific analysis process of the DC bus scan decision module is as follows:

[0063] Based on the scanned image of the DC bus, it is determined whether there is damage on its surface. If there is damage on the surface of the DC bus, it indicates that the use risk of the DC bus is relatively high, and a DC bus scan abnormality signal is generated;

[0064] If there is no damage on the surface of the DC bus, the deviation of the real-time distance value of the corresponding two positions on the DC bus compared to the corresponding initial distance value is collected and marked as the spacing deviation value, wherein the larger the value of the spacing deviation value, the greater the probability of deformation between the corresponding two positions; the average of all spacing deviation values ​​on the DC bus is marked as the spacing deviation value, and the number of spacing deviation values ​​exceeding the preset spacing deviation threshold is marked as the spacing deviation value;

[0065] The spacing deviation value and the spacing deviation value are numerically compared with the preset spacing deviation threshold and the preset spacing deviation threshold respectively. If the spacing deviation value or the spacing deviation value exceeds the corresponding preset threshold, it indicates that the deformation condition of the DC bus is abnormal and the use risk of the DC bus is greater, and a DC bus scanning abnormality signal is generated.

[0066] Furthermore, if both the spacing deviation value and the spacing deviation value do not exceed the corresponding preset threshold value, indicating that the deformation condition of the DC bus is relatively normal, the scanned image of the DC bus is grayscale processed, and the real-time grayscale values ​​of all positions on the DC bus are collected. Several areas are set on the DC bus, and the total area of ​​the corresponding area whose actual grayscale value exceeds the preset grayscale threshold is marked as a non-clean surface measurement value. The average of all real-time grayscale values ​​of the corresponding area is calculated to obtain the grayscale inspection value;

[0067] Compare the non-clean surface measurement value and grayscale inspection value with the preset non-clean surface measurement threshold and preset grayscale inspection threshold. If the non-clean surface measurement value or grayscale inspection value exceeds the corresponding preset threshold, it indicates that the pollution condition of the corresponding area is serious, and the corresponding area is marked as a non-clean area;

[0068] If there is a non-clean area on the DC bus, it indicates that the use risk of the DC bus is relatively high, and a DC bus scanning abnormality signal is generated; if there is no non-clean area on the DC bus, the non-clean surface measurement values ​​of all areas on the DC bus are summed to obtain the non-clean surface analysis value, and the grayscale inspection values ​​of all areas are averaged to obtain the grayscale inspection value;

[0069] The busbar cleanliness value MX is obtained by numerically calculating the unclean surface analysis value MS and the grayscale analysis value MK using the formula MX = a1*MS+a2*MK, where a1 and a2 are preset proportional coefficients with values ​​greater than zero. The larger the busbar cleanliness value MX, the more serious the surface contamination of the DC bus, the greater the risk of using the DC bus, and the more timely inspection and treatment are needed.

[0070] The bus cleanliness value MX is compared with the preset bus cleanliness threshold. If the bus cleanliness value MX exceeds the preset bus cleanliness threshold, it indicates that the surface contamination of the DC bus is serious and the use risk of the DC bus is high, which requires timely inspection and treatment, and a DC bus scan abnormal signal is generated; if the bus cleanliness value MX does not exceed the preset bus cleanliness threshold, a DC bus scan qualified signal is generated.

[0071] Preferably, the monitoring platform is communicated with the execution module. When a DC bus scanning abnormality signal is generated, the execution module directly performs a shutdown operation to turn off the voltage output of the panel, thereby ensuring the safety of the bus, avoiding accidents, and protecting asset safety. In addition, the execution module also has the function of directly shutting down the output remotely.

[0072] Example 3: Figures 3-5 As shown, the difference between this embodiment and embodiment 1 and embodiment 2 is that the present invention further proposes a connection structure of solar photovoltaic modules, including: each or multiple photovoltaic modules are connected to an SMP Unit {function: including but not limited to shutdown, MPPT, communication (one or more of WIFI / BLE / PLC, etc.) and DC-DC conversion) to form a photovoltaic module group;

[0073] Several PV module groups are connected in parallel to the DC bus; these are then connected to energy devices (including but not limited to energy storage devices, hybrid inverter devices, grid-connected inverter devices, etc.) through the DC bus. It should be noted that the SMP is based on RapidShutDown, MPPT, PLC, and DC-DC bus converters. The DC-DC specifications and PLC of all SMPs are the same. The specifications of the PV modules can be the same or different.

[0074] The present invention connects a single or several photovoltaic modules in series and then connects SMPs in series to form a photovoltaic module group, which is then connected in parallel to the DC bus. Each photovoltaic module or a photovoltaic string composed of multiple photovoltaic modules is connected to an SMP, and all SMPs are then connected in parallel. This can completely solve the "wooden barrel effect" of conventional string connections, while solving the power optimization of each independent photovoltaic module and string, transmitting energy and data in a DC bus manner, and has the advantages of reliable performance and strong scalability.

[0075] The working principle of the application is: when in use, all bus connections existing on the DC bus of the solar photovoltaic module are obtained through the connection abnormality analysis module, abnormal connections are determined through analysis and corresponding connection judgment symbols are assigned, the safety risk conditions of each bus connection can be reasonably evaluated, the DC bus is monitored and analyzed by the point type monitoring module, corresponding bus judgment symbols are assigned through analysis, the operation risk condition of the DC bus can be reasonably judged, the DC bus state evaluation module comprehensively analyzes and accurately judges the DC bus connection state and operation risk of the solar photovoltaic module based on the connection judgment symbol and the bus judgment symbol, and when the DC bus state abnormality signal is generated, the management personnel are reminded to take improvement treatment measures, the degree of intelligence is high, and the safe and stable operation of the DC bus is beneficial to be ensured.

[0076] The above formulas are dimensionless values, and the formulas are obtained by software simulation of a large amount of data to obtain a formula of the most recent real situation, and the preset parameters in the formula are set by a person skilled in the art according to the actual situation. The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments. Obviously, according to the content of the specification, many modifications and changes can be made. The embodiments are selected and specifically described in the specification in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited by the claims and their entire scope and equivalents.

Claims

1. A system for monitoring the state of connection of a DC bus of a solar photovoltaic assembly, characterized in that, The monitoring platform, the connection anomaly analysis module, the point-by-point monitoring module, the DC bus state evaluation module and the background terminal are included. The connection anomaly analysis module obtains all bus connections existing on the DC bus of the solar photovoltaic module, marks the corresponding bus connection as a target connection i, and i is a natural number greater than 1; the abnormal connection is determined by analysis, and the connection judgment symbol LP-1 or LP-2 is given, and the connection judgment symbol LP-1 or LP-2 is sent to the DC bus state evaluation module; The point-by-point monitoring module carries out point-by-point monitoring analysis on the DC bus, gives the bus judgment symbol GP-1 or GP-2 through analysis, and sends the bus judgment symbol GP-1 or GP-2 to the DC bus state evaluation module; The DC bus state evaluation module carries out intersection analysis on the connection judgment symbol and the bus judgment symbol, if LP-2∩GP-2 is obtained, the DC bus state qualified signal is generated, otherwise the DC bus state abnormal signal is generated, and the DC bus state qualified signal or the DC bus state abnormal signal is sent to the background terminal through the monitoring platform, and the background terminal sends a warning when receiving the DC bus state abnormal signal; The specific operation process of the connection anomaly analysis module includes: The connection force bias value of the target connection i is obtained, the real-time bus joint contact resistance of the target connection i is collected and marked as the contact resistance measured value, and the contact resistance trend value of the target connection i is obtained through contact resistance trend analysis; The connection anomaly value is obtained by numerical calculation of the connection force bias value, the contact resistance measured value and the contact resistance trend value, if the connection anomaly value exceeds the preset connection anomaly threshold, the target connection i is marked as an abnormal connection; if there is an abnormal connection, the connection judgment symbol LP-1 is given; if there is no abnormal connection, the connection judgment symbol LP-2 is given; The specific analysis process of the contact resistance trend analysis is as follows: A rectangular coordinate system located in the first quadrant is established with time as the X-axis and bus joint contact resistance as the Y-axis, and a contact resistance curve is drawn in the rectangular coordinate system based on all bus joint contact resistances of the target connection i in unit time; mark several coordinate points on the contact resistance curve and define them as verification points, and the X-direction distance between adjacent two verification points is the same; And draw a ray parallel to the X-axis and with its end point on the Y-axis in the rectangular coordinate system and mark it as the resistance verification ray, count the number of verification points above the resistance verification ray in the rectangular coordinate system and mark it as the verification number anomaly value; Mark the verification points above the resistance verification ray as abnormal verification points, draw a line segment perpendicular to the resistance verification ray with the corresponding abnormal verification point as the end point and mark it as the distance line segment, mark the length of the distance line segment as the distance value, and calculate the mean value of the distance values of all abnormal verification points to obtain the verification super detection value, and obtain the X-direction length and value involved in the rising part of the contact resistance curve and mark it as the contact resistance increase time value; the contact resistance trend value is obtained by numerical calculation of the verification number anomaly value, the verification super detection value and the contact resistance increase time value; The specific operation process of the point-by-point monitoring module includes: A plurality of monitoring points are set on a DC bus of a solar photovoltaic module, real-time voltages and real-time currents of all monitoring points are collected, a bus voltage value is obtained by performing variance calculation on the real-time voltages of all monitoring points, and a bus current value is obtained by performing variance calculation on the real-time currents of all monitoring points, if the bus voltage value or the bus current value exceeds a corresponding preset threshold, a bus judgment symbol GP-1 is assigned; If the bus voltage value and the bus current value do not exceed the corresponding preset threshold, a bus point condition value of the corresponding monitoring point is obtained by analysis, a bus abnormal value is obtained by performing numerical calculation on the bus point measurement value, the bus abnormal point value and the bus point amplitude value, if the bus abnormal value exceeds a preset bus abnormal value threshold, the bus judgment symbol GP-1 is assigned, and if the bus abnormal value does not exceed the preset bus abnormal value threshold, the bus judgment symbol GP-2 is assigned; The specific analysis process of obtaining the bus point condition value of the corresponding monitoring point by analysis is as follows: The deviation value of the real-time voltage of the corresponding monitoring point compared with the median value of the preset suitable voltage range is marked as a bus point voltage value, the deviation value of the real-time current of the corresponding monitoring point compared with the median value of the preset suitable current range is marked as a bus point current value, and the real-time temperature of the corresponding monitoring point is collected and marked as a bus point temperature value; the bus point condition value is obtained by performing numerical calculation on the bus point voltage value, the bus point current value and the bus point temperature value.

2. The direct current bus connection status monitoring system of a solar photovoltaic assembly according to claim 1, characterized in that, The monitoring platform is in communication connection with the DC bus scanning decision module, the monitoring platform sends a DC bus state qualified signal to the DC bus scanning decision module, the DC bus scanning decision module collects the surface image of the DC bus when receiving the DC bus state qualified signal, analyzes the surface quality condition of the DC bus based on the surface image of the DC bus, generates a DC bus scanning qualified signal or a DC bus scanning abnormal signal through analysis, and sends the DC bus scanning qualified signal or the DC bus scanning abnormal signal to the background terminal through the monitoring platform, and the background terminal sends a warning when receiving the DC bus scanning abnormal signal.

3. The direct current bus connection status monitoring system of a solar photovoltaic assembly according to claim 2, wherein, The specific analysis process of the DC bus scanning decision module is as follows: Based on the scanning image of the DC bus, whether the surface of the DC bus is damaged is judged, if the surface of the DC bus is damaged, a DC bus scanning abnormal signal is generated; If the surface of the DC bus is not damaged, the deviation value of the real-time distance value of the corresponding two positions on the DC bus compared with the corresponding initial distance value is collected and marked as a spacing deviation condition value, the mean value of all spacing deviation condition values on the DC bus is marked as a spacing deviation table value, and the number of spacing deviation condition values exceeding a preset spacing deviation condition threshold is marked as a spacing abnormal deviation value, if the spacing deviation table value or the spacing abnormal deviation value exceeds a corresponding preset threshold, a DC bus scanning abnormal signal is generated.

4. The direct current bus connection status monitoring system of a solar photovoltaic assembly according to claim 3, characterized in that, If the spacing deviation table value and the spacing abnormal deviation value do not exceed the corresponding preset threshold, the scanning image of the DC bus is subjected to grayscale processing, real-time grayscale values of all positions on the DC bus are collected, a plurality of regions are set on the DC bus, and if the non-clean surface measurement value or the grayscale detection condition value exceeds a corresponding preset threshold, the corresponding region is marked as a non-clean region; If there is a non-clean area on the DC bus, a DC bus scanning abnormal signal is generated; if there is no non-clean area on the DC bus, a bus clean difference value is obtained by numerically calculating the non-clean surface value and the gray scale analysis value, if the bus clean difference value exceeds the preset bus clean difference threshold, a DC bus scanning abnormal signal is generated; if the bus clean difference value does not exceed the preset bus clean difference threshold, a DC bus scanning qualified signal is generated.

5. The direct current bus connection status monitoring system of a solar photovoltaic assembly according to claim 1, wherein, Each or multiple solar photovoltaic components are connected to an SMP Unit to form a photovoltaic component group; a plurality of photovoltaic component groups are connected in parallel to a DC bus, and are further connected to an energy device through the DC bus.

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