Photovoltaic system control method and device and photovoltaic system

Abstract

The invention discloses a photovoltaic system control method and device and a photovoltaic system, and the method comprises the steps: obtaining a first state parameter of a photovoltaic module in a photovoltaic string, so as to determine the working state of the photovoltaic module; if the target photovoltaic module of which the working state is the abnormal state exists, switching the target photovoltaic module to a bypass state; after a preset duration, switching the target photovoltaic module to an access state, and obtaining a second state parameter of each photovoltaic module in a target photovoltaic group string where the target photovoltaic module is located, so as to determine a working state of the target photovoltaic module; if the working state of the target photovoltaic module is an abnormal state, switching the target photovoltaic module to a bypass state, and recording the number of continuous abnormities of the target photovoltaic module; and if the number of continuous abnormalities is greater than a preset abnormality threshold, keeping the target photovoltaic module in a bypass state. The problem that the maintenance cost is high due to the fact that it is difficult to determine whether the abnormity of the photovoltaic module is caused by environmental factors or faults of the photovoltaic module can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a control method and device for a photovoltaic system and a photovoltaic system. Background Art

[0002] The current photovoltaic system is usually composed of multiple photovoltaic modules connected in series to form a photovoltaic string, and then multiple photovoltaic strings are connected in parallel to the inverter to achieve DC to AC conversion and grid connection. When the photovoltaic system is in operation, the photovoltaic modules usually work abnormally due to factors such as shadow shading, fallen leaves shading, aging and damage of photovoltaic modules, resulting in mismatch loss, that is, the output power of the photovoltaic modules after series and parallel connection is less than the sum of the output power of a single photovoltaic module. Among them, the abnormality of photovoltaic modules caused by environmental factors such as shadow shading and fallen leaves shading can usually recover by itself after a period of time, and generally does not require manual maintenance, while the abnormality of photovoltaic modules caused by fault factors such as aging and damage of photovoltaic modules cannot be automatically recovered, and manual maintenance of photovoltaic modules is required on site. In the current photovoltaic system, since it is difficult to determine whether the abnormality of photovoltaic modules is caused by environmental factors or photovoltaic module failure, when the photovoltaic modules are abnormal, the photovoltaic modules are mainly inspected and maintained by dispatching relevant personnel, resulting in high maintenance costs. Summary of the invention

[0003] In view of this, the present invention provides a control method and device for a photovoltaic system and a photovoltaic system to solve the problem that it is difficult to determine whether the abnormality of a photovoltaic component is caused by environmental factors or photovoltaic component failure, resulting in high maintenance costs.

[0004] In a first aspect, the present invention provides a control method for a photovoltaic system, the method comprising:

[0005] Acquire a first state parameter of each photovoltaic component in the photovoltaic string to determine the working state of each photovoltaic component;

[0006] If there is a target photovoltaic component in an abnormal working state, switching the target photovoltaic component to a bypass state;

[0007] After a preset time, the target photovoltaic component is switched to a connected state, and a second state parameter of each photovoltaic component in a target photovoltaic string where the target photovoltaic component is located is obtained to determine a working state of the target photovoltaic component;

[0008] If the working state of the target photovoltaic assembly is an abnormal state, switching the target photovoltaic assembly to a bypass state, and recording the number of consecutive abnormalities of the target photovoltaic assembly;

[0009] If the number of consecutive abnormalities is greater than a preset abnormality threshold, the target photovoltaic component is kept in a bypass state.

[0010] In this method, when a target photovoltaic component with an abnormal working state is detected according to the first state parameter of each photovoltaic component, it is switched to the bypass state, and then after a preset time, the target photovoltaic component is switched back to the connected state, and then the working state of the target photovoltaic component is re-determined according to the second state parameter of each photovoltaic component in the target photovoltaic string where the target photovoltaic component is located, and this is repeated many times until the number of consecutive abnormalities is greater than the preset abnormal threshold, and then the target photovoltaic component is kept in the bypass state. Therefore, short-term abnormalities caused by environmental factors can be automatically eliminated, and faulty photovoltaic components can be accurately screened out, and the faulty photovoltaic components can be kept in the bypass state, thereby reducing warranty and maintenance costs. At the same time, mismatch losses can also be reduced to a certain extent.

[0011] In an optional implementation, the acquiring the second state parameter of each photovoltaic component in the target photovoltaic string where the target photovoltaic component is located to determine the working state of the target photovoltaic component includes:

[0012] Before connecting to the target photovoltaic component, obtaining a first output power of the target photovoltaic string;

[0013] Acquiring a second state parameter of each photovoltaic component in the target photovoltaic string to obtain a second output power of the target photovoltaic string;

[0014] Based on the magnitudes of the first output power and the second output power, the working state of the target photovoltaic assembly is determined.

[0015] In this method, the abnormal target photovoltaic module is first bypassed to obtain the first output power of the target photovoltaic string corresponding to it when bypassed, and then the abnormal target photovoltaic module is connected to the photovoltaic system, and the second output power of the corresponding target photovoltaic string after connection is obtained, so as to re-determine the working state of the target photovoltaic module based on the magnitude of the first output power and the second output power. Therefore, it is possible to automatically rule out whether the short-term abnormality caused by environmental factors has been restored, and to promptly connect the restored target photovoltaic module to the photovoltaic system after the short-term abnormality has been restored, so as to ensure the optimal output power of the entire target photovoltaic string, thereby reducing the loss of power generation.

[0016] In an optional implementation, determining the working state of the target photovoltaic component based on the magnitude of the first output power and the second output power includes:

[0017] When the difference between the second output power and the first output power is greater than a preset power threshold, determining that the working state of the target photovoltaic component is a normal state;

[0018] When the difference between the second output power and the first output power is less than or equal to the preset power threshold, it is determined that the working state of the target photovoltaic component is an abnormal state.

[0019] In this manner, by comparing the output power of the target photovoltaic string when the target photovoltaic component is bypassed and when it is connected, it is possible to accurately determine whether the target photovoltaic component has returned to normal when it is connected.

[0020] In an optional implementation, the obtaining of the first state parameter of each photovoltaic component in the photovoltaic string to determine the working state of each photovoltaic component includes:

[0021] Obtaining a first state parameter of each photovoltaic component in a photovoltaic string;

[0022] The first state parameters of the photovoltaic components in the photovoltaic string are compared, and the working state of each photovoltaic component is determined based on the comparison result.

[0023] In this manner, by comparing the first state parameters of the photovoltaic modules in the photovoltaic string, it is possible to determine whether there is an abnormal photovoltaic module in the photovoltaic string based on the difference in the first state parameters between the photovoltaic modules connected in series.

[0024] In an optional implementation, comparing the first state parameters of the photovoltaic components in the photovoltaic string and determining the working state of each photovoltaic component based on the comparison result includes:

[0025] Determine a parameter mean value corresponding to each photovoltaic component based on a mean value of a first state parameter of other photovoltaic components in the photovoltaic string where each photovoltaic component is located;

[0026] When the difference between the first state parameter of any photovoltaic component and the corresponding parameter mean exceeds a preset parameter difference range, determining that the working state of the photovoltaic component is an abnormal state;

[0027] When the difference between the first state parameter of any photovoltaic component and the corresponding parameter mean value does not exceed a preset parameter difference range, it is determined that the working state of the photovoltaic component is a normal state.

[0028] In this method, the parameter mean of the first state parameters of other photovoltaic components in the photovoltaic string where the photovoltaic component is located is first calculated, and then the working state of the photovoltaic component is judged based on the difference between the first state parameter of the photovoltaic component and the corresponding parameter mean. Therefore, the judgment error of the working state of the photovoltaic component can be reduced to improve the accuracy of the judgment result of the working state.

[0029] In an optional implementation, the first state parameter includes an operating current or an operating temperature, and the method further includes the following steps:

[0030] When the operating current of any photovoltaic component in the photovoltaic string is a reverse current, or the operating current is greater than a preset safety current threshold, or the operating temperature is greater than a preset safety temperature threshold, all photovoltaic components in the photovoltaic string are switched to a bypass state.

[0031] In this mode, if the operating current of a photovoltaic module in a photovoltaic string is a reverse current, or the operating current is greater than a preset safety current threshold, or the operating temperature is greater than a preset safety temperature threshold, all photovoltaic modules in the photovoltaic string are switched to bypass state. Therefore, the risk of DC arcing and fire can be avoided to ensure the stable operation of the photovoltaic system.

[0032] In an optional implementation, comparing the first state parameters of the photovoltaic components in the photovoltaic string and determining the working state of each photovoltaic component based on the comparison result includes:

[0033] Obtaining a parameter change amplitude of a first state parameter of each photovoltaic module in the photovoltaic string within a current time period;

[0034] Based on the magnitude of parameter variation between the photovoltaic components in the photovoltaic string, the working state of each photovoltaic component is determined.

[0035] In this method, by comparing the parameter change amplitudes of the first state parameters between the photovoltaic components in the photovoltaic string, it is possible to determine whether there is an abnormal photovoltaic component in the photovoltaic string based on the difference in the parameter change amplitudes between the photovoltaic components in series.

[0036] In an optional implementation, the determining the working state of each photovoltaic component based on the magnitude of the parameter variation between each photovoltaic component in the photovoltaic string includes:

[0037] Determine the amplitude mean corresponding to each photovoltaic component based on the average of the parameter change amplitudes of other photovoltaic components in the photovoltaic string where each photovoltaic component is located;

[0038] When the difference between the parameter change amplitude of any photovoltaic assembly and the corresponding amplitude mean is within a preset amplitude difference range, determining that the working state of the photovoltaic assembly is a normal state;

[0039] When the difference between the parameter variation amplitude of any photovoltaic assembly and the corresponding amplitude mean exceeds the preset amplitude difference range, it is determined that the working state of the photovoltaic assembly is an abnormal state.

[0040] In this method, the mean amplitude of the parameter change amplitudes of other photovoltaic modules in the photovoltaic string where the photovoltaic module is located is first calculated, and then the working state of the photovoltaic module is judged based on the difference between the parameter change amplitude of the photovoltaic module and the corresponding mean amplitude. Therefore, the judgment error of the working state of the photovoltaic module can be reduced to improve the accuracy of the judgment result of the working state.

[0041] In a second aspect, the present invention provides a control device for a photovoltaic system, comprising:

[0042] A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the control method of the photovoltaic system of the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0043] In a third aspect, the present invention provides a photovoltaic system, characterized in that it includes:

[0044] At least one photovoltaic string, wherein the photovoltaic string is provided with one or more photovoltaic modules connected in series;

[0045] A component control device connected to each of the photovoltaic components in a one-to-one correspondence, the component control device is used to control the corresponding photovoltaic component to switch to a bypass state or a connection state;

[0046] The control device of the photovoltaic system of the second aspect is communicatively connected with each of the component control devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 is a flow chart of a first photovoltaic system control method according to an embodiment of the present invention;

[0049] Figure 2 is a flow chart of a second photovoltaic system control method according to an embodiment of the present invention;

[0050] Figure 3 is a schematic diagram of a curve of operating current and operating voltage of a photovoltaic string according to an embodiment of the present invention;

[0051] Figure 4is a schematic structural diagram of a control device for a photovoltaic system according to an embodiment of the present invention;

[0052] Figure 5 is a schematic structural diagram of a photovoltaic system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0054] In current photovoltaic systems, it is difficult to determine whether the abnormality of a photovoltaic module is caused by environmental factors or a failure of the photovoltaic module. Therefore, when an abnormality occurs in a photovoltaic module, the photovoltaic module is mainly inspected and maintained by dispatching relevant personnel, resulting in high maintenance costs.

[0055] In view of this, according to an embodiment of the present invention, a control method embodiment of a photovoltaic system is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0056] In this embodiment, a first photovoltaic system control method is provided, which can be used for the above-mentioned photovoltaic system. The photovoltaic system includes one or more photovoltaic strings connected in parallel, and each photovoltaic string includes one or more photovoltaic modules connected in series. Figure 1 is a flow chart of a control method for a photovoltaic system according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0057] Step S101, obtaining a first state parameter of each photovoltaic module in a photovoltaic string to determine a working state of each photovoltaic module.

[0058] Specifically, the first state parameter includes at least one of an operating current, an operating voltage, an output power, and an operating temperature. In addition, the first state parameter may also include other state parameters of the photovoltaic component, which are not limited here.

[0059] It can be understood that since the photovoltaic modules in the photovoltaic string are connected in series, the working current of the same photovoltaic string is the same. Moreover, in order to ensure the stable operation of the photovoltaic system, the performance parameters of the photovoltaic modules in the same photovoltaic string are also theoretically the same, that is, the working voltage and output power of the photovoltaic modules in the same photovoltaic string are essentially the same. Therefore, the working state of each photovoltaic module can be determined by the difference in the first state parameters of each photovoltaic module in the photovoltaic string.

[0060] Step S102: If there is a target photovoltaic component whose working state is abnormal, the target photovoltaic component is switched to a bypass state.

[0061] It should be noted that when the target PV module in an abnormal state is bypassed, other PV modules in a normal state remain in a connected state and operate normally.

[0062] Understandably, in actual operating environments, photovoltaic modules may be in a reverse bias state due to factors such as shadow shading, fallen leaves shading, aging and damage of photovoltaic modules, etc., which may cause the working current of the photovoltaic module to be greater than the current generated by the entire photovoltaic system, causing the photovoltaic module to heat up, and even cause fires, leakage, etc. Therefore, in order to ensure the safe and stable operation of the photovoltaic system, when a target photovoltaic module in an abnormal state is detected, the target photovoltaic module needs to be switched to a bypass state to prevent the target photovoltaic module in an abnormal state from affecting the operation of other photovoltaic modules.

[0063] Step S103, after a preset time, switching the target photovoltaic component to a connected state, and obtaining a second state parameter of each photovoltaic component in a target photovoltaic string where the target photovoltaic component is located, to determine a working state of the target photovoltaic component.

[0064] It is understandable that the abnormality of the target photovoltaic module may be a short-term abnormality caused by environmental factors such as shadow occlusion and fallen leaves occlusion. This type of short-term abnormality generally does not require manual maintenance and will automatically return to normal after a period of time. Therefore, after a preset period of time, the target photovoltaic module can be switched back to the connected state, and the working state of the target photovoltaic module can be re-determined based on the second state parameters of each photovoltaic module in the target photovoltaic string corresponding to the target photovoltaic module after the target photovoltaic module is reconnected, so that when the target photovoltaic string returns to normal, it can be connected to the target photovoltaic string, thereby reducing the power generation loss to a certain extent.

[0065] Step S104: if the working state of the target photovoltaic assembly is an abnormal state, the target photovoltaic assembly is switched to a bypass state, and the number of consecutive abnormalities of the target photovoltaic assembly is recorded.

[0066] Step S105: if the number of consecutive abnormalities is greater than a preset abnormality threshold, the target photovoltaic component is kept in a bypass state.

[0067] It should be noted that the preset duration and the number of consecutive exceptions can be determined based on the historical recovery time of short-term exceptions caused by environmental factors in actual situations. The specific duration of the preset duration and the specific number of consecutive exceptions are not limited here.

[0068] Understandably, if the number of consecutive abnormalities of the target photovoltaic module is greater than the preset abnormal threshold, it indicates that the target photovoltaic module may have aging, damage and other faults. Such abnormalities caused by fault factors often require manual maintenance. Therefore, it is necessary to keep the target photovoltaic module in bypass state to reduce the impact of the target photovoltaic module on other photovoltaic modules. At the same time, the maintenance information is reported so that relevant personnel can perform maintenance and repair on the target photovoltaic module.

[0069] The control method of the photovoltaic system provided in this embodiment switches the target photovoltaic component to the bypass state when the target photovoltaic component with abnormal working state is detected according to the first state parameter of each photovoltaic component, and then switches the target photovoltaic component back to the access state after a preset time, and then re-determines the working state of the target photovoltaic component according to the second state parameter of each photovoltaic component in the target photovoltaic string where the target photovoltaic component is located, and repeats this process many times until the number of consecutive abnormalities is greater than the preset abnormal threshold, and then the target photovoltaic component is kept in the bypass state. Therefore, short-term abnormalities caused by environmental factors can be automatically eliminated, and faulty photovoltaic components can be accurately screened out, and the faulty photovoltaic components can be kept in the bypass state, thereby reducing warranty and maintenance costs. At the same time, mismatch losses can also be reduced to a certain extent.

[0070] Figure 2 is a flow chart of a second photovoltaic system control method according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0071] Step S201, obtaining a first state parameter of each photovoltaic module in a photovoltaic string to determine a working state of each photovoltaic module.

[0072] Specifically, the above step S201 includes:

[0073] Step S2011, obtaining a first state parameter of each photovoltaic module in a photovoltaic string.

[0074] Step S2012: comparing the first state parameters of the photovoltaic modules in the photovoltaic string, and determining the working state of each photovoltaic module based on the comparison result.

[0075] The control method of the photovoltaic system provided in this embodiment compares the first state parameters between the photovoltaic components in the photovoltaic string. Therefore, it is possible to determine whether there is an abnormal photovoltaic component in the photovoltaic string based on the difference in the first state parameters between the photovoltaic components connected in series.

[0076] It can be understood that the first state parameters of each photovoltaic component in the same photovoltaic string are theoretically the same. If any photovoltaic component is abnormal, its first state parameter will be significantly changed compared with other normal photovoltaic components in the same photovoltaic string. Therefore, the working state of each photovoltaic component can be determined by comparing the first state parameters of each photovoltaic component in the photovoltaic string.

[0077] As a first optional implementation, the above step S2012 includes:

[0078] Step a1: determining a parameter mean value corresponding to each photovoltaic component based on the mean value of the first state parameters of other photovoltaic components in the photovoltaic string where each photovoltaic component is located.

[0079] Step a2: when the difference between the first state parameter of any photovoltaic component and the corresponding parameter mean exceeds a preset parameter difference range, it is determined that the working state of the photovoltaic component is an abnormal state.

[0080] It should be noted that the preset parameter difference range can be set to a fixed range according to actual conditions, or can be set to a first preset ratio of the parameter mean.

[0081] Step a3: when the difference between the first state parameter of any photovoltaic component and the corresponding parameter mean value does not exceed a preset parameter difference range, it is determined that the working state of the photovoltaic component is a normal state.

[0082] For example, taking the first state parameter as the operating voltage as an example, assuming that the operating voltage of any photovoltaic component A is V i , the average working voltage of other photovoltaic modules in the photovoltaic string where photovoltaic module A is located is V0, then calculate V0 and V i If the voltage difference exceeds the preset difference range, the working state of the photovoltaic component A is determined to be an abnormal state; if the voltage difference does not exceed the preset difference range, the working state of the photovoltaic component A is determined to be a normal state.

[0083] For example, taking the first state parameter as the operating temperature as an example, assuming that the operating temperature of any photovoltaic component A is T i , the average operating temperature of other PV modules in the PV string where PV module A is located is T0, then calculate T0 and T iIf the temperature difference exceeds the preset difference range, the working state of the photovoltaic component A is determined to be abnormal; if the temperature difference does not exceed the preset difference range, the working state of the photovoltaic component A is determined to be normal.

[0084] As a second optional implementation, the above step S2012 includes:

[0085] Step b1, obtaining the parameter variation range of the first state parameter of each photovoltaic module in the photovoltaic string within the current time period.

[0086] Step b2, determining the working state of each photovoltaic module based on the magnitude of the parameter variation between each photovoltaic module in the photovoltaic string.

[0087] It can be understood that the parameter change amplitude of the first state parameter between each photovoltaic component in the same photovoltaic string is theoretically the same. If any photovoltaic component is abnormal, its parameter change amplitude will be significantly different from other normal photovoltaic components in the same photovoltaic string. Therefore, the working status of each photovoltaic component can be determined by comparing the parameter change amplitudes between each photovoltaic component in the photovoltaic string.

[0088] Furthermore, the above step b2 also includes:

[0089] Step b21, determining the amplitude mean corresponding to each photovoltaic component based on the average of the parameter variation amplitudes of other photovoltaic components in the photovoltaic string where each photovoltaic component is located.

[0090] Step b22: when the difference between the parameter variation amplitude of any photovoltaic module and the corresponding amplitude mean value is within a preset amplitude difference range, it is determined that the working state of the photovoltaic module is normal.

[0091] Step b23: when the difference between the parameter variation amplitude of any photovoltaic module and the corresponding amplitude mean exceeds a preset amplitude difference range, it is determined that the working state of the photovoltaic module is an abnormal state.

[0092] Exemplarily, taking the working current as the first state parameter, if the working current change amplitude of any photovoltaic component A is significantly greater than the working current change amplitude of other photovoltaic components in the same photovoltaic string, it indicates that the working state of photovoltaic component A is abnormal; if the working current change amplitude of any photovoltaic component A is similar to or the same as the working current change amplitude of other photovoltaic components in the same photovoltaic string, it indicates that the working state of photovoltaic component A is normal.

[0093] Similarly, when the first state parameter is the operating voltage, if the operating voltage change amplitude of any photovoltaic module A obviously exceeds the operating voltage change amplitude of other photovoltaic modules in the same photovoltaic string, it indicates that the operating state of photovoltaic module A is abnormal; if the operating voltage change amplitude of any photovoltaic module A is similar to or the same as the operating voltage change amplitude of other photovoltaic modules in the same photovoltaic string, it indicates that the working state of photovoltaic module A is normal.

[0094] Also, when the first state parameter is output power, if the output power change amplitude of any photovoltaic component A obviously exceeds the output power change amplitude of other photovoltaic components in the same photovoltaic string, it indicates that the working state of photovoltaic component A is abnormal; if the output power change amplitude of any photovoltaic component A is similar to or the same as the output power change amplitude of other photovoltaic components in the same photovoltaic string, it indicates that the working state of photovoltaic component A is normal.

[0095] Step S202: If there is a target photovoltaic module in an abnormal working state, the target photovoltaic module is switched to a bypass state. Please refer to the above step S102 for details, which will not be repeated here.

[0096] Step S203, after a preset time, switching the target photovoltaic component to a connected state, and obtaining a second state parameter of each photovoltaic component in a target photovoltaic string where the target photovoltaic component is located, to determine a working state of the target photovoltaic component.

[0097] In some optional implementations, the step S203 of obtaining the second state parameter of each photovoltaic component in the target photovoltaic string where the target photovoltaic component is located to determine the working state of the target photovoltaic component includes:

[0098] Step S2031, before connecting to the target photovoltaic module, obtaining the first output power of the target photovoltaic string.

[0099] Specifically, before connecting to the target photovoltaic component, that is, when the target photovoltaic component is switched to the bypass state, since the target photovoltaic component is just switched to the bypass state, each photovoltaic component of the target photovoltaic string is affected by the bypass of the target photovoltaic component, and the second state parameter of each photovoltaic component will fluctuate briefly. Therefore, when the target photovoltaic component is switched to the bypass state, a preset bypass time can be passed to stabilize the second state parameter of each photovoltaic component, and then the first output power of the target photovoltaic string at this time can be recorded.

[0100] Step S2032, obtaining a second state parameter of each photovoltaic module in the target photovoltaic string to obtain a second output power of the target photovoltaic string.

[0101] Specifically, after a preset time, when the target photovoltaic component is switched to the access state, since when the target photovoltaic component is just switched to the access state, each photovoltaic component of the target photovoltaic string is affected by the access of the target photovoltaic component, the second state parameters of each photovoltaic component will fluctuate briefly. Therefore, when the target photovoltaic component is switched to the access state, the preset access time can be passed to allow the second state parameters of each photovoltaic component to stabilize, and then the second state parameters of each photovoltaic component in the target photovoltaic string at this time can be detected to obtain the second output power of the target photovoltaic string.

[0102] Step S2033: determining the working state of the target photovoltaic assembly based on the magnitude of the first output power and the second output power.

[0103] The control method of the photovoltaic system provided in this embodiment first bypasses the abnormal target photovoltaic component, obtains the first output power of the target photovoltaic string corresponding to it when bypassed, then connects the abnormal target photovoltaic component to the photovoltaic system, and obtains the second output power of the corresponding target photovoltaic string after connection, so as to re-determine the working state of the target photovoltaic component based on the magnitude of the first output power and the second output power. Therefore, it is possible to automatically exclude whether the short-term abnormality caused by environmental factors is restored, and connect the restored target photovoltaic component to the photovoltaic system in time after the short-term abnormality is restored, so as to ensure that the output power of the entire target photovoltaic string is optimal, thereby reducing the loss of power generation.

[0104] It can be understood that if the target photovoltaic component has returned to normal when connected, based on the optimization algorithm of the current maximum power point tracking of the photovoltaic system, compared with the first output power of the target photovoltaic string when the target photovoltaic component is bypassed, after the target photovoltaic component that has returned to normal is reconnected, the second output power of the target photovoltaic string will also increase with the connection of the target photovoltaic component. Therefore, the working state of the target photovoltaic component can be re-determined based on the size of the first output power and the second output power.

[0105] Specifically, the above step S2033 includes:

[0106] Step c1: when the difference between the second output power and the first output power is greater than a preset power threshold, determining that the working state of the target photovoltaic component is a normal state.

[0107] Step c2: when the difference between the second output power and the first output power is less than or equal to a preset power threshold, determining that the working state of the target photovoltaic component is an abnormal state.

[0108] For example, see Figure 3 , Figure 3 Curve ① is the IV curve when all photovoltaic modules of the photovoltaic string are in normal state. Figure 3Curve ② is the IV curve when there are PV modules in the PV string in an abnormal state. Figure 3 Curve ③ is the IV curve when the abnormal PV modules in the PV string are switched to the bypass state. Figure 3 As shown in FIG. 1 , when all PV modules of the PV string are in normal state, the PV string operates at the maximum power point of curve ①.

[0109] When any PV module is in an abnormal state, the IV curve of the PV string changes to curve ②, and the operating point drops to point M1. In this case, although the actual maximum power operating point of the PV string should be the M2 power point of curve ②, if the abnormal PV module is not bypassed at this time, according to the currently common maximum power tracking algorithm, the PV string may seek optimization downward and fail to find the optimal point M2, so that the PV string cannot work at the actual maximum power point, resulting in power loss.

[0110] Therefore, this solution first bypasses the abnormal PV modules, so that the IV curve of the PV string becomes curve ③, so that the PV string will normally find the optimal point M2 along curve ③. After finding the optimal point M2, the abnormal PV modules are connected back to the PV string. Although the IV curve of the PV string changes back to curve ②, the working point of the entire PV string will remain at the M2 power point corresponding to curve ③. Therefore, this solution can ensure the optimal output power of the PV string to reduce the loss of power generation.

[0111] Step S204: if the working state of the target photovoltaic module is abnormal, switch the target photovoltaic module to the bypass state, and record the number of consecutive abnormalities of the target photovoltaic module. Please refer to the above step S104 for details, which will not be repeated here.

[0112] Step S205: If the number of consecutive abnormalities is greater than the preset abnormality threshold, the target photovoltaic module is kept in the bypass state. Please refer to the above step S105 for details, which will not be repeated here.

[0113] In some optional implementations, the first state parameter includes an operating current or an operating temperature, and the method further includes the following steps:

[0114] When the operating current of any photovoltaic component in the photovoltaic string is a reverse current, or the operating current is greater than a preset safety current threshold, or the operating temperature is greater than a preset safety temperature threshold, all photovoltaic components in the photovoltaic string are switched to a bypass state.

[0115] The control method of the photovoltaic system provided in the present embodiment switches all photovoltaic components in the photovoltaic string to the bypass state when the operating current of the photovoltaic components in the photovoltaic string is a reverse current, or the operating current is greater than a preset safety current threshold, or the operating temperature is greater than a preset safety temperature threshold. Therefore, the risk of DC arcing and fire can be avoided to ensure the stable operation of the photovoltaic system.

[0116] It is understandable that when the working current of the photovoltaic module is a reverse current or greater than the preset safety current threshold, it means that the photovoltaic module may have a DC arc at this time, which poses a fire risk, so all photovoltaic modules in the photovoltaic string need to be switched to the bypass state. Similarly, when the working temperature of the photovoltaic module is greater than the preset safety temperature threshold, it also means that DC arc may occur at this time, which poses a fire risk, so all photovoltaic modules in the photovoltaic string need to be switched to the bypass state.

[0117] In this embodiment, a control device for a photovoltaic system is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0118] This embodiment provides a control device for a photovoltaic system, such as Figure 4 As shown, the control device 4 includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. The various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the control device 4, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple control devices 4 can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 4 A processor 10 is taken as an example.

[0119] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0120] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0121] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required by at least one function; the data storage area may store data created according to the use of the control device 4, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the control device 4 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0122] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0123] The control device 4 further includes a communication interface 30 for the control device 4 to communicate with other devices or a communication network.

[0124] like Figure 5 As shown, an embodiment of the present invention further provides a photovoltaic system, including:

[0125] At least one photovoltaic string 1, wherein the photovoltaic string 1 is provided with one or more photovoltaic modules 2 connected in series;

[0126] A component control device 3 connected to each photovoltaic component 2 in a one-to-one correspondence, and the component control device 3 is used to control the corresponding photovoltaic component 2 to switch to a bypass state or a connection state;

[0127] The control device 4 of the photovoltaic system is communicatively connected with each component control device 3 and is used to execute the control method of the photovoltaic system of any of the above-mentioned embodiments.

[0128] In practical applications, the control device 4 communicates with each component control device 3 via PLC (Power Line Communication). The control device 4 includes a plurality of magnetic rings 401, which are mounted on the power lines of the photovoltaic string. The control device 4 can communicate with all component control devices in the photovoltaic string by PLC. The component control device 3 may be a component-level control or power electronic device such as a component switch or a component optimizer.

[0129] Specifically, the photovoltaic system also includes:

[0130] At least one inverter 5 is connected in series with the photovoltaic strings 1 and corresponds one to one.

[0131] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A control method for a photovoltaic system, characterized in that: The method comprises: Acquire a first state parameter of each photovoltaic component in the photovoltaic string to determine the working state of each photovoltaic component; If there is a target photovoltaic component in an abnormal working state, switching the target photovoltaic component to a bypass state; After a preset time, the target photovoltaic component is switched to a connected state, and a second state parameter of each photovoltaic component in a target photovoltaic string where the target photovoltaic component is located is obtained to determine a working state of the target photovoltaic component; If the working state of the target photovoltaic assembly is an abnormal state, switching the target photovoltaic assembly to a bypass state, and recording the number of consecutive abnormalities of the target photovoltaic assembly; If the number of consecutive abnormalities is greater than a preset abnormality threshold, the target photovoltaic component is kept in a bypass state.

2. The method according to claim 1, characterized in that The step of obtaining the second state parameter of each photovoltaic component in the target photovoltaic string where the target photovoltaic component is located to determine the working state of the target photovoltaic component includes: Before connecting to the target photovoltaic component, obtaining a first output power of the target photovoltaic string; Acquire a second state parameter of each photovoltaic component in the target photovoltaic string to obtain a second output power of the target photovoltaic string; Based on the magnitudes of the first output power and the second output power, the working state of the target photovoltaic assembly is determined.

3. The method according to claim 2, characterized in that The determining the working state of the target photovoltaic component based on the magnitude of the first output power and the second output power includes: When the difference between the second output power and the first output power is greater than a preset power threshold, determining that the working state of the target photovoltaic component is a normal state; When the difference between the second output power and the first output power is less than or equal to the preset power threshold, it is determined that the working state of the target photovoltaic component is an abnormal state.

4. The method according to claim 1, characterized in that The obtaining of the first state parameter of each photovoltaic component in the photovoltaic string to determine the working state of each photovoltaic component includes: Obtaining a first state parameter of each photovoltaic component in a photovoltaic string; The first state parameters of the photovoltaic components in the photovoltaic string are compared, and the working state of each photovoltaic component is determined based on the comparison result.

5. The method according to claim 4, characterized in that The comparing the first state parameters of the photovoltaic components in the photovoltaic string and determining the working state of each photovoltaic component based on the comparison result includes: Determine a parameter mean value corresponding to each photovoltaic component based on a mean value of a first state parameter of other photovoltaic components in the photovoltaic string where each photovoltaic component is located; When the difference between the first state parameter of any photovoltaic component and the corresponding parameter mean exceeds a preset parameter difference range, determining that the working state of the photovoltaic component is an abnormal state; When the difference between the first state parameter of any photovoltaic component and the corresponding parameter mean value does not exceed a preset parameter difference range, it is determined that the working state of the photovoltaic component is a normal state.

6. The method according to claim 1, characterized in that The first state parameter includes an operating current or an operating temperature, and the method further includes the following steps: When the operating current of any photovoltaic component in the photovoltaic string is a reverse current, or the operating current is greater than a preset safety current threshold, or the operating temperature is greater than a preset safety temperature threshold, all photovoltaic components in the photovoltaic string are switched to a bypass state.

7. The method according to claim 4, characterized in that The comparing the first state parameters of the photovoltaic components in the photovoltaic string and determining the working state of each photovoltaic component based on the comparison result includes: Obtaining a parameter change amplitude of a first state parameter of each photovoltaic module in the photovoltaic string within a current time period; Based on the magnitude of parameter variation between the photovoltaic components in the photovoltaic string, the working state of each photovoltaic component is determined.

8. The method according to claim 7, characterized in that The determining the working state of each photovoltaic component based on the magnitude of the parameter variation between each photovoltaic component in the photovoltaic string includes: Determine the amplitude mean corresponding to each photovoltaic component based on the average of the parameter change amplitudes of other photovoltaic components in the photovoltaic string where each photovoltaic component is located; When the difference between the parameter change amplitude of any photovoltaic assembly and the corresponding amplitude mean is within a preset amplitude difference range, determining that the working state of the photovoltaic assembly is a normal state; When the difference between the parameter variation amplitude of any photovoltaic assembly and the corresponding amplitude mean exceeds the preset amplitude difference range, it is determined that the working state of the photovoltaic assembly is an abnormal state.

9. A control device for a photovoltaic system, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the control method of the photovoltaic system according to any one of claims 1 to 8 by executing the computer instructions.

10. A photovoltaic system, characterized in that: include: At least one photovoltaic string, wherein the photovoltaic string is provided with one or more photovoltaic modules connected in series; A component control device connected to each of the photovoltaic components in a one-to-one correspondence, the component control device is used to control the corresponding photovoltaic component to switch to a bypass state or a connection state; The control device for the photovoltaic system according to claim 9, wherein the control device is communicatively connected to each of the component control devices.

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