Photovoltaic inverter system and automatic positioning method and fault control method of RSD thereof

Abstract

A photovoltaic inverter system and an automatic positioning method and a fault control method of RSDs thereof. The automatic positioning method comprises: S1: providing a plurality of photovoltaic component strings, each photovoltaic component string comprising at least one photovoltaic component and at least one RSD, the input end of the RSD in the same photovoltaic component string being electrically connected to the output end of the photovoltaic component, and the output ends of all the RSDs being connected in series with each other; S2: providing at least one inverter, the photovoltaic component strings being electrically connected to the photovoltaic input end of the inverter; S3: before the inverter works, controlling all the RSDs to be turned off, collecting the current voltage at the output end of each RSD, which is defined as the first voltage; S4: controlling any RSD to be closed, collecting the current voltage at the output end of each RSD again, which is defined as the second voltage, and determining all the RSDs of the photovoltaic component string in which the RSD in the closed state is located according to the corresponding second voltage and the first voltage; and S5: repeating steps S3 and S4 for any RSD outside the photovoltaic component string in which the determined RSD is located until all the RSDs have determined the photovoltaic component string to which they belong.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic power generation, and in particular to a photovoltaic inverter system, an automatic positioning method of a rapid shutdown device of the photovoltaic inverter system, and a fault control method. BACKGROUND

[0002] Photovoltaic power generation technology has developed rapidly and has been widely applied at home and abroad. A traditional photovoltaic power generation system includes photovoltaic modules, junction boxes, inverters and other components. The photovoltaic modules convert received solar energy into direct current power, and the inverters convert the direct current power into alternating current power required by users and deliver the alternating current power to a power grid or directly supply the alternating current power to the users. The photovoltaic modules connected in series, in parallel or in series-parallel have high voltage and energy. In the case of installation, debugging or maintenance of the system or in the case of sudden events such as earthquakes and fires, workers may come into contact with photovoltaic modules or wires with dangerous voltage, which may cause electric shock. Therefore, the photovoltaic power generation system needs to be combined with a rapid shutdown system to quickly cut off the dangerous voltage in the operating area of the workers in the above-mentioned cases, so as to reduce or eliminate the risk of electric shock of the workers.

[0003] The rapid shutdown system generally consists of two parts. One part is a rapid shutdown device (RSD), which is generally installed on the back of a photovoltaic module in a photovoltaic inverter system. The input end of the RSD is connected to the output end of a photovoltaic module, and the output end of the RSD is connected in series with the output ends of other photovoltaic modules and other RSDs to form a photovoltaic module string. The other part is a controller for controlling the RSD. The controller is generally installed in an inverter of the photovoltaic inverter system, can communicate with the RSD in the photovoltaic module string connected to the photovoltaic input end of the inverter, and can change the working state of the inverter and the RSD according to the related data of the inverter and the RSD. Under normal circumstances, the RSD in the photovoltaic inverter system is in a closed state. When a fault occurs, the RSD is in a shutdown state to cut off the circuit.

[0004] However, the photovoltaic inverter system cannot automatically identify the specific installation position of the RSD. Therefore, although the controller can control each RSD, it cannot control the specific circuit and can only use the same control instruction for all RSDs, which greatly reduces the flexibility and controllability of the entire system.

[0005] Therefore, it is of great significance to locate the RSD in the photovoltaic inverter system. The prior art mainly has the following two positioning methods: method one is a manual marking method, which mainly specifies the installation position of each RSD during system installation, and the installation personnel specifically records the installation details, and then enters the controller of the inverter through a tool, which is low in efficiency and low in fault tolerance; method two is a current or power positioning method, which mainly uses the same current characteristics of the same photovoltaic module string to locate the RSD of the same photovoltaic module string, that is, the controller is turned off or bypassed, and the position of the RSD is determined according to the change of the current or power point. However, the RSD generally does not have a current sensor, so this method will increase the production cost of the photovoltaic inverter system. SUMMARY

[0006] In view of the problems existing in the prior art, the purpose of the present application is to provide a photovoltaic inverter system and an automatic positioning method and fault control method of a rapid shutdown device (RSD) thereof, which can effectively solve one or more defects of the prior art.

[0007] In order to achieve the above-mentioned purpose, according to an embodiment of the present application, an automatic positioning method of a rapid shutdown device (RSD) of a photovoltaic inverter system is provided, and the automatic positioning method comprises:

[0008] Step S1: providing a plurality of photovoltaic module strings, each of which comprises at least one photovoltaic module and at least one RSD, the input end of the RSD in the same photovoltaic module string is electrically connected to the output end of the photovoltaic module, and the output ends of all the RSDs are connected in series with each other;

[0009] Step S2: providing at least one inverter, and the photovoltaic module strings are electrically connected to the photovoltaic input end of the inverter;

[0010] Step S3: before the inverter works, all the RSDs are controlled to be turned off, the current voltage of the output end of each RSD is collected, which is defined as the first voltage;

[0011] Step S4: any RSD of the photovoltaic inverter system is controlled to be closed, the current voltage of the output end of each RSD is collected again, which is defined as the second voltage, and the RSDs of the photovoltaic module string in the closed state are determined according to the second voltage and the first voltage corresponding to the output end of each RSD;

[0012] Step S5: for any RSD other than the photovoltaic module string in which the RSD has been determined, steps S3 and S4 are repeatedly executed until all the RSDs have determined their belonging photovoltaic module strings.

[0013] In an embodiment of the present application, step S4 further comprises: calculating the difference between the second voltage and the first voltage corresponding to the output of each RSD, and comparing the difference with a first preset threshold; if the difference is greater than the first preset threshold, it is determined that the RSD belongs to the same photovoltaic module string as the RSD in the closed state.

[0014] In an embodiment of the present application, after all the RSDs have determined the photovoltaic module string to which they belong, the automatic positioning method further comprises:

[0015] Step S6: turning off all the RSDs, collecting the current voltage of each photovoltaic input of each inverter, defined as a third voltage;

[0016] Step S7: turning on all the RSDs in any photovoltaic module string of the photovoltaic inverter system, collecting the current voltage of each photovoltaic input of each inverter again, defined as a fourth voltage, and determining the inverter and the photovoltaic input of the inverter connected to the photovoltaic module string to which all the RSDs in the closed state belong according to the fourth voltage and the third voltage corresponding to each photovoltaic input of each inverter;

[0017] Step S8: repeating steps S6 and S7 for any photovoltaic module string other than the photovoltaic module string to which the connected inverter and photovoltaic input of the inverter have been determined, until all the photovoltaic module strings have determined the inverter and photovoltaic input of the inverter to which they are connected.

[0018] In an embodiment of the present application, step S7 further comprises: calculating the difference between the fourth voltage and the third voltage corresponding to each photovoltaic input of each inverter, and comparing the difference with a second preset threshold; if the difference is greater than the second preset threshold, it is determined that the photovoltaic input of the inverter is connected to the photovoltaic module string to which all the RSDs in the closed state belong.

[0019] In an embodiment of the present application, each inverter comprises a controller in communication with the RSDs in the photovoltaic module string connected to the inverter and the photovoltaic input of the inverter, for controlling the working state of the inverter and the RSDs in the photovoltaic module string.

[0020] In an embodiment of the present application, each RSD comprises a plurality of resistance elements and a plurality of switch elements.

[0021] In an embodiment of the present application, the photovoltaic module string is electrically connected to the photovoltaic input end of the inverter, comprising: N photovoltaic module strings connected in parallel to the same photovoltaic input end of the inverter, N being an integer greater than 1.

[0022] In an embodiment of the present application, the number of the photovoltaic modules in the photovoltaic module string is greater than the number of the RSDs, wherein the photovoltaic modules not connected to the input end of the RSDs are first photovoltaic modules, and the output ends of the first photovoltaic modules are connected in series with the output ends of all the RSDs.

[0023] In an embodiment of the present application, the photovoltaic input end is an input end with maximum power point tracking function.

[0024] In order to achieve the above-mentioned purpose, the present application further provides a photovoltaic inverter system which can realize the automatic positioning method as described above.

[0025] In order to achieve the above-mentioned purpose, the present application further provides a fault control method of a photovoltaic inverter system, comprising:

[0026] By using the automatic positioning method as described above, the installation position of each RSD in the photovoltaic inverter system is identified, wherein the installation position comprises the corresponding connection relationship between the RSD and the photovoltaic module string and the corresponding connection relationship between the photovoltaic module string and the photovoltaic input end of the inverter.

[0027] When any one of the RSDs fails, according to the installation position of the RSD that fails, the controller of the inverter selects to disconnect other RSDs in the same photovoltaic module string as the RSD that fails, so as to make them in standby state, and makes the remaining RSDs in the photovoltaic inverter system in normal working state.

[0028] The present application can automatically identify the specific installation position of the RSD in the photovoltaic inverter system, and does not need to increase current sensors, so the cost is lower, and the accuracy and efficiency are higher.

[0029] The present application can control any one photovoltaic module string in the case of identifying different photovoltaic module strings, so the controllability is stronger.

[0030] The unique fault control method of the present application can not affect the power generation work of the photovoltaic modules in other photovoltaic module strings when the RSD in a certain photovoltaic module string fails, so the system robustness and economic benefit are enhanced.

[0031] Additional features and advantages of the present application will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0032] The above and other features and advantages of the present invention will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0033] Figure 1 This is a schematic diagram of the automatic positioning method for the RSD of the photovoltaic inverter system of the present invention;

[0034] Figure 2 This is a schematic diagram of the photovoltaic inverter system of the present invention;

[0035] Figure 3 This is a schematic diagram of the internal voltage sampling circuit of the RSD of the present invention;

[0036] Figure 4 This is a schematic diagram of the circuit connection structure of a photovoltaic module string in the photovoltaic inverter system of the present invention, with one RSD disconnected and the other RSD closed.

[0037] Figure 5 for Figure 4 A schematic diagram of the circuit connection structure of a photovoltaic module string when another RSD switches from closed to open;

[0038] Figure 6 This is a schematic diagram of another automatic positioning method for the RSD of the photovoltaic inverter system of the present invention;

[0039] Figure 7 This is a schematic diagram of a fault control method for a traditional photovoltaic inverter system when a certain RSD (Resistance Detector) fails.

[0040] Figure 8 This is a schematic diagram of the fault control method of the photovoltaic inverter system of the present invention when a certain RSD fails. Detailed Implementation

[0041] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed descriptions will be omitted.

[0042] The use of the terms "one," "a," "an," "the" and "at least one" are used herein to mean one or more than one, depending on the context. The use of the term "at least one" followed by a list of one or more items should be interpreted as including only those items in the list that specifically identify each individual item as an alternative. For example, the phrase "at least one of A and B" should be interpreted to mean "A or B or both A and B." The use of the terms "first," "second," and the like can merely be intended to label various elements without necessarily requiring or implying any actual such relationship or order. The use of the term "or" in the context of a list of items prefaced by "at least one of' should be interpreted as meaning any one of the items in the list, or any combination of two or more of the items in the list.

[0043] Referring now to the drawings Figure 1 FIG. 1 shows a flow chart of an automatic positioning method of a rapid shutdown device (RSD) of a photovoltaic inverter system according to an embodiment of the present application, the automatic positioning method comprising:

[0044] Step S1 : providing a plurality of photovoltaic module strings, each photovoltaic module string comprising at least one photovoltaic module and at least one RSD, the input end of the RSD in the same photovoltaic module string being electrically connected to the output end of the photovoltaic module, and the output ends of all the RSDs being connected in series with each other;

[0045] Step S2: providing at least one inverter, the photovoltaic module strings being electrically connected to the photovoltaic input end of the inverter;

[0046] Step S3: before the inverter is in operation, controlling all the RSDs to be turned off, collecting the current voltage at the output end of each RSD, defined as the first voltage;

[0047] Step S4: controlling any RSD of the photovoltaic inverter system to be closed, collecting the current voltage at the output end of each RSD again, defined as the second voltage, and determining all the RSDs of the photovoltaic module string in which the RSD in the closed state is located according to the corresponding second voltage and the first voltage at the output end of each RSD;

[0048] Step S5: repeating the execution of Step S3 and Step S4 for any RSD outside the photovoltaic module string in which the determined RSD is located, until all the RSDs have determined the photovoltaic module string to which they belong.

[0049] Through the above steps S1-S5, the automatic positioning of all the RSDs in the photovoltaic inverter system can be achieved, i.e., the photovoltaic module string to which all the RSDs belong is determined.

[0050] As Figure 2As shown in FIG. 1, a structure diagram of a specific embodiment of a photovoltaic inverter system provided by the present application is shown, which comprises a plurality of photovoltaic component strings and at least one inverter, each photovoltaic component string comprises at least one photovoltaic component M and at least one rapid shutdown device (RSD), the input end of the RSD in the same photovoltaic component string is electrically connected to the output end of a photovoltaic component, the output ends of all RSDs are connected in series with each other, and the photovoltaic component string is electrically connected to a photovoltaic input end of an inverter. For example, Figure 2 As shown in FIG. 2, the photovoltaic inverter system comprises m photovoltaic component strings (S1-S m ) and 1 inverter, the photovoltaic component strings S1-S m may but are not limited to consist of 5 photovoltaic components and 2 RSDs. Taking S1 as an example in the same photovoltaic component string, the RSD comprises R1 and R2, the input end of R1 is connected to the output end of a photovoltaic component, the input end of R2 is connected to the output end of another photovoltaic component, and the output ends of the photovoltaic components in the photovoltaic component string S1 other than the above two photovoltaic components are connected in series with each other. The inverter has n photovoltaic input ends PV1-PVn, and the photovoltaic component strings are electrically connected to the photovoltaic input ends of the inverter, for example, the photovoltaic input end PV1 is electrically connected to the photovoltaic component string S1, the photovoltaic input end PV2 is electrically connected to the photovoltaic component string S2, and the photovoltaic input end PVn is electrically connected to the parallelly connected photovoltaic component strings S m-1 and S m . However, it can be understood that in other embodiments, the photovoltaic inverter system of the present application can also comprise more inverters, and the number of photovoltaic components and RSDs comprised by each photovoltaic component string can also be other numbers, which are not regarded as limitations to the present application. In other embodiments, N photovoltaic component strings can be connected in parallel to the same photovoltaic input end of an inverter, and N is an integer greater than 1.

[0051] In an embodiment of the present application, the photovoltaic inverter system can also comprise one or more photovoltaic component strings consisting only of photovoltaic components, which consist of one photovoltaic component or a plurality of photovoltaic components connected in series with each other, and the photovoltaic component string can be directly electrically connected to a photovoltaic input end of an inverter, or can be connected to the same photovoltaic input end of an inverter after being connected in parallel with other photovoltaic component strings.

[0052] In an embodiment of the present application, each inverter can comprise a controller, for example, which can communicate with the inverter and the RSD in the photovoltaic component string connected to the photovoltaic input end of the inverter, so as to control the working state of the inverter and the above-mentioned RSD. Moreover, the photovoltaic input ends PV1-PVn can be input ends with a maximum power point tracking (MPPT) function, for example.

[0053] In an embodiment of the present application, the number of photovoltaic modules in the same photovoltaic module string can be greater than or equal to the number of RSDs, wherein, when the number of photovoltaic modules is equal to the number of RSDs, the input end of each RSD is electrically connected to the output end of a photovoltaic module, and the output ends of all RSDs are connected in series with each other; when the number of photovoltaic modules is greater than the number of RSDs, the input end of each RSD is electrically connected to the output end of a photovoltaic module, the photovoltaic module not connected to the input end of an RSD is a first photovoltaic module, and the output end of the first photovoltaic module and the output ends of all RSDs are connected in series with each other.

[0054] In an embodiment of the present application, each RSD can include a plurality of resistance elements and a plurality of switch elements, for example. As shown in FIG. 3, which shows the internal circuit characteristics of an RSD, the RSD includes three sampling resistors Ra, Rb and Rc and two switches K1 and K2. Figure 3 The three sampling resistors Ra, Rb and Rc can be used to sample the voltage at the output end PV+ of a photovoltaic module (relative to PV-), the voltage at the output end Out- of an RSD (relative to PV-), and the voltage at the output end Out+ of an RSD (relative to PV-), respectively, as shown in FIG. 4. Figure 3 As shown in FIG. 4, point G is connected to PV-, point A is connected to PV+, point B is connected to Out-, and point C is connected to Out+. Points A, B and C are all voltage sampling points, the sampling voltage at point A is defined as the absolute value (without considering positive or negative) of the relative voltage between point A and point G, and the sampling voltages at points B and C are defined as the absolute values (without considering positive or negative) of the relative voltages between point B and point G and between point C and point G, respectively. Since the resistance values of the sampling resistors Ra, Rb and Rc are generally large, Rb = Rc > 1 Mom can be set for convenience of analysis. The voltage at the output end of the RSD in the automatic positioning method of the RSD of the photovoltaic inverter system described above can be understood as the sampling voltage at point B or point C.

[0055] Before the inverter is in operation, and when the switches K1 and K2 are both closed, i.e., the RSD is in a closed state, point B is connected to point G, and the sampling resistor Rb is bypassed, so the sampling voltage at point B is 0; when the switches K1 and K2 are both open, i.e., the RSD is in an off state, point B is connected to point G through the sampling resistor Rb, and point C is connected to point G through the sampling resistor Rc, so the sampling resistors Rb and Rc are not bypassed, and the sampling voltages at points B and C are not 0, and the actual voltage values depend on the number of photovoltaic modules connected in the photovoltaic module string and the number of voltage dividing resistors. As shown in FIG. 5 and FIG. 6, a photovoltaic module string S1 including five photovoltaic modules and two RSDs (R1 and R2) is taken as an example to illustrate the influence of changing the working state of one RSD (R2) on other RSDs in the same photovoltaic module string. Figure 4 Figure 5 As shown in FIG. 5 and FIG. 6, a photovoltaic module string S1 including five photovoltaic modules and two RSDs (R1 and R2) is taken as an example to illustrate the influence of changing the working state of one RSD (R2) on other RSDs in the same photovoltaic module string.​Figure 4 The circuit connection is shown when R1 is in the off state and the switch in R2 is in the closed state, the number of photovoltaic components connected to the photovoltaic input end PV1 is 4, the photovoltaic components connected to the input end of R1 are not connected to the photovoltaic input end PV1 due to the off state of R1, the total voltage of photovoltaic component string S1 is 4Vo, the number of voltage division resistors connected to the photovoltaic input end PV1 is 2, and the sampling voltage at point B (or point C) of R1 is:

[0056] U B2 = 4Vo / 2 = 2Vo

[0057] In the automatic positioning method of the RSD point of the photovoltaic inversion system, U B2 It can be understood as the second voltage of the output end of R1. R2 is switched from the closed state to the off state, Figure 5 The circuit connection is shown at this time, the number of photovoltaic components connected to the photovoltaic input end PV1 is 3, and the two photovoltaic components connected to the input ends of R1 and R2 are not connected to the photovoltaic input end PV1 due to the off state of R1 and R2, the total voltage of photovoltaic component string S1 is 3Vo, the number of voltage division resistors connected to the photovoltaic input end PV1 is 4, and the sampling voltage at point B (or point C) of R1 is:

[0058] U B1 = 3Vo / 4

[0059] In the automatic positioning method of the RSD point of the photovoltaic inversion system, U B1 It can be understood as the first voltage of the output end of R1. Therefore, after R2 is switched from the closed state to the off state, the B point voltage of other RSDs of the same photovoltaic component string changes obviously, and this change can be used to distinguish the connection of the RSD and the photovoltaic component string.

[0060] Generally, it is assumed that the photovoltaic component string has x photovoltaic components and y RSDs, and the voltage of each photovoltaic component is Vo. Before the operation of the inverter, all RSDs of the photovoltaic component string are in the off state, and the sampling voltage at the B point (or the C point) of any RSD, i.e. the first voltage of the output end of the RSD, is:

[0061] U B1 = (x-y)*Vo / 2y

[0062] Close any RSD in the photovoltaic component string, the sampling voltages at the B point and the C point of other RSDs of the photovoltaic component string change, at this time, the number of photovoltaic components connected to the photovoltaic input end is x-y+1, the number of RSDs in the off state in the photovoltaic component string is y-1, and the sampling voltage at the B point (or the C point) of the RSD in the off state, i.e. the second voltage of the output end of the RSD, is:

[0063] U B2 = (x - y + 1) * Vo / 2 (y - 1)

[0064] Therefore, after switching any one RSD of the same photovoltaic module string from the off state to the closed state, the B point (or C point) voltage of any RSD in the off state in the photovoltaic module string changes to:

[0065] ΔU B = U B2 - U B1 = x * Vo / 2 y (y - 1)

[0066] Therefore, the B point (or C point) voltage change of the RSD in the off state in the same photovoltaic module string can identify the connection of the RSD and the photovoltaic module string, that is, according to the second voltage and the first voltage corresponding to the output end of each RSD, all RSDs in the photovoltaic module string in the closed state can be determined.

[0067] In an embodiment of the present application, step S4 can further include: calculating the difference between the second voltage and the first voltage corresponding to the output end (B point or C point) of each RSD, and comparing the difference with a first preset threshold; when the difference is greater than the first preset threshold, it is determined that the RSD belongs to the same photovoltaic module string as the RSD in the closed state.

[0068] In an embodiment of the present application, as shown in Figure 6 After all RSDs have determined their belonging photovoltaic module string, the above automatic positioning method can further include:

[0069] Step S6: control all RSDs to be off, collect the current voltage of each photovoltaic input end of each inverter, defined as the third voltage;

[0070] Step S7: control all RSDs in any photovoltaic module string of the photovoltaic inverter system to be closed, collect the current voltage of each photovoltaic input end of each inverter again, defined as the fourth voltage, and determine the inverter and photovoltaic input end of the inverter connected to the photovoltaic module string of all RSDs in the closed state according to the fourth voltage and the third voltage corresponding to each photovoltaic input end of each inverter.

[0071] Step S8: for any photovoltaic module string other than the photovoltaic module string of the inverter and the photovoltaic input end of the inverter that has been determined, repeat steps S6 and S7 until all photovoltaic module strings have determined their connected inverters and photovoltaic input ends of the inverter.

[0072] Through the steps S6-S8, the automatic positioning of all photovoltaic module strings in the photovoltaic inverter system can be realized, i.e., the connection of all photovoltaic module strings with the inverter and the photovoltaic input end of the inverter is determined.

[0073] Referring again to Figure 5 Before the inverter works, and R1 and R2 of the photovoltaic module string S1 are in the off state, the number of photovoltaic modules connected to the photovoltaic input end PV1 is 3, but due to the existence of the voltage dividing resistor in R1 and R2, the current voltage of the photovoltaic input end PV1 is 0, i.e., the third voltage is 0. When R1 and R2 of the photovoltaic module string S1 are controlled to be in the closed state, the number of photovoltaic modules connected to the photovoltaic input end PV1 is 5, and the voltage dividing resistor in R1 and R2 is bypassed, so the current voltage of the photovoltaic input end PV1 is 5Vo, i.e., the fourth voltage is 5Vo, so after all RSDs of the photovoltaic module string S1 are switched from the off state to the closed state, the voltage of the photovoltaic input end connected by the photovoltaic module string S1 changes to 5Vo. Therefore, when all RSDs of a photovoltaic module string in the photovoltaic inverter system are switched from the off state to the closed state, the voltage of the photovoltaic input end connected by the photovoltaic module string changes obviously, and this change can be used to distinguish the connection of the photovoltaic module string with the inverter and the photovoltaic input end of the inverter.

[0074] In an embodiment of the present application, step S7 can further include: calculating the difference between the fourth voltage and the third voltage corresponding to each photovoltaic input end of each inverter, and comparing the difference with a second preset threshold value; if the difference is greater than the second preset threshold value, it is judged that the photovoltaic input end of the inverter is connected with the photovoltaic module string whose all RSDs are in the closed state.

[0075] In an embodiment of the present application, the voltage of each photovoltaic input end of each inverter can be the maximum power tracking point voltage of the photovoltaic input end of the inverter, i.e., the MPPT voltage.

[0076] The photovoltaic inverter system of the present application comprises a general controller which is electrically connected to the controllers of all inverters, each of which can control the opening and closing of the RSDs of the photovoltaic module string connected to the photovoltaic input end of the inverter, and record the voltage change data of all RSDs before and after the action, according to which the connection of the RSDs and the photovoltaic module string can be determined and uploaded to the general controller of the photovoltaic inverter system. The general controller of the photovoltaic inverter system controls the opening and closing of all RSDs of a certain photovoltaic module string through the controllers of the inverters, and records the voltage change data of each photovoltaic input end of each inverter before and after the action, according to which the connection of a certain photovoltaic module string and the inverter and the photovoltaic input end of the inverter, i.e. which photovoltaic input end of which inverter the photovoltaic module string is connected to, can be determined.

[0077] The present application can also provide a photovoltaic inverter system which can realize the above-mentioned automatic positioning method.

[0078] The present application can also provide a fault control method for a photovoltaic inverter system, which can comprise:

[0079] Using the above-mentioned automatic positioning method, the installation position of each RSD in the photovoltaic inverter system can be identified, wherein the installation position comprises the corresponding connection relationship between the RSD and the photovoltaic module string and the corresponding connection relationship between the photovoltaic module string and the photovoltaic input end of the inverter.

[0080] When any RSD of the photovoltaic module string fails, according to the installation position of the failed RSD, the controller of the inverter can select to open the other RSDs of the same photovoltaic module string as the failed RSD, so as to make them in standby state, and make the remaining RSDs in the photovoltaic inverter system in normal working state. It can be understood that the general controller of the photovoltaic inverter system can also select to open the other RSDs of the same photovoltaic module string as the failed RSD through the controller of the inverter, so as to make them in standby state.

[0081] As Figure 7As shown, it is a fault control method of traditional photovoltaic inverter system when a certain RSD fails, which shows the working mode of inverter when a single RSD fails, wherein the dark gray RSD represents a fault state, and the light gray RSD represents a standby state. Only when all RSDs of a certain photovoltaic module string are in normal operation state, the photovoltaic module string can provide power to the inverter. Then, when a certain RSD (such as dark gray R1) fails, the inverter can only choose to put all other RSDs (such as light gray R2-R8) in standby state, so that all photovoltaic inputs PV1-PVn cannot deliver power to the inverter, resulting in a certain loss of power generation.

[0082] However, if the specific installation position of each RSD can be identified, then at this time, the RSD of the photovoltaic module string can be selected to be turned off, and the RSD of the other photovoltaic module string connected to the photovoltaic input of the inverter in the system can be in normal working state, so that the other photovoltaic module string can normally deliver power to the inverter. As shown, Figure 8 wherein the dark gray RSD represents a fault state, the medium gray RSD represents a normal operation state, and the light gray RSD represents a standby state. Although the controller in the inverter detects the failure of the RSD, as shown, Figure 8 R1 in the dark gray has a fault, and the traditional photovoltaic inverter system will choose to turn off all RSDs. However, through the automatic positioning method of RSD of the photovoltaic inverter system of the present application, the controller knows that R1 and R2 belong to the same photovoltaic module string S1 and are connected to the photovoltaic input PV1 of the inverter, and other RSDs (such as R3-R8) are located in different photovoltaic module strings S2-S m Therefore, the damage of R1 actually does not affect R3-R8, and only all other RSDs (R2) in the photovoltaic module string S1 need to be turned off.

[0083] As shown, Figure 8 In the case of failure of the dark gray R1, the controller of the inverter can make the light gray R2 in standby state, and the medium gray R3-R8 continue to be in normal working state, which is superior to Figure 7 the fault processing method of the traditional inverter system as shown.

[0084] The present application can automatically identify the specific installation position of the rapid shutdown device (RSD), without the need to increase the current sensor, with lower cost, higher accuracy and efficiency.

[0085] The present application can control the photovoltaic module of any photovoltaic module string in the case of identifying different photovoltaic module strings, with stronger controllability.

[0086] The unique fault control method of the application can not affect the power generation of photovoltaic modules of other photovoltaic module strings when RSD in a certain photovoltaic module string fails, thereby enhancing system robustness and economic benefits.

[0087] The exemplary embodiments of this application are specifically shown and described above. It is understood that this application is not limited to the disclosed embodiments, rather, this application is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. An automatic positioning method for a fast shutdown device (RSD) in a photovoltaic inverter system, characterized in that, The automatic positioning method includes: Step S1: Provide multiple photovoltaic module strings, each photovoltaic module string including at least one photovoltaic module and at least one RSD, the input terminal of the RSD in the same photovoltaic module string is electrically connected to the output terminal of the photovoltaic module, and the output terminals of all the RSDs are connected in series. Step S2: Provide at least one inverter, wherein the photovoltaic modules are connected in series to the photovoltaic input terminal of the inverter; Step S3: Before the inverter starts working, control all RSDs to turn off, and collect the current voltage at the output terminal of each RSD, which is defined as the first voltage; Step S4: Control any of the RSDs of the photovoltaic inverter system to close, and collect the current voltage of the output terminal of each RSD again, which is defined as the second voltage. Based on the second voltage corresponding to the output terminal of each RSD and the first voltage, determine all RSDs in the photovoltaic module string where the RSD in the closed state is located. Step S5: For any RSD that is outside the photovoltaic module string to which the RSD is located, repeat steps S3 and S4 until all RSDs have been identified as belonging to the photovoltaic module string.

2. The automatic positioning method according to claim 1, characterized in that, Step S4 also includes: Calculate the difference between the second voltage and the first voltage corresponding to the output terminal of each RSD, and compare the difference with a first preset threshold. If the difference is greater than the first preset threshold, then it is determined that the RSD and the RSD in the closed state belong to the same photovoltaic module string.

3. The automatic positioning method according to claim 1, characterized in that, After all the RSDs have been identified as belonging to the photovoltaic module string, the automatic positioning method further includes: Step S6: Control all RSDs to turn off, and collect the current voltage of each photovoltaic input terminal of each inverter, defining it as the third voltage; Step S7: Control all RSDs in any photovoltaic module string of the photovoltaic inverter system to close, and collect the current voltage of each photovoltaic input terminal of each inverter again, which is defined as the fourth voltage. Based on the fourth voltage and the third voltage corresponding to each photovoltaic input terminal of each inverter, determine the inverter connected to the photovoltaic module string in which all RSDs are closed and the photovoltaic input terminal of the inverter. Step S8: For any photovoltaic module string other than the photovoltaic module string of the inverter and the photovoltaic input terminal of the inverter that has been determined to be connected, repeat steps S6 and S7 until all photovoltaic module strings have been determined to be connected to the inverter and the photovoltaic input terminal of the inverter.

4. The automatic positioning method according to claim 3, characterized in that, Step S7 also includes: Calculate the difference between the fourth voltage and the third voltage corresponding to each photovoltaic input terminal of each inverter, and compare the difference with a second preset threshold. If the difference is greater than the second preset threshold, it is determined that the photovoltaic input terminal of the inverter is connected to the photovoltaic module string where all the RSDs are in the closed state.

5. The automatic positioning method according to claim 1, characterized in that, Each inverter includes a controller that is communicatively connected to the inverter and the RSD in the photovoltaic module string connected to the photovoltaic input terminal of the inverter, for controlling the operating state of the inverter and the RSD in the photovoltaic module string.

6. The automatic positioning method according to claim 1, characterized in that, Each of the RSDs includes multiple resistive elements and multiple switching elements.

7. The automatic positioning method according to claim 1, characterized in that, The photovoltaic module is connected in series to the photovoltaic input terminal of the inverter, including: N photovoltaic modules are connected in series and parallel to the same photovoltaic input terminal of the inverter, where N is an integer greater than 1.

8. The automatic positioning method according to claim 1, characterized in that, The number of photovoltaic modules in the photovoltaic module string is greater than the number of RSDs. The photovoltaic module that is not connected to the input terminal of the RSD is the first photovoltaic module, and the output terminal of the first photovoltaic module is connected in series with the output terminals of all the RSDs.

9. The automatic positioning method according to claim 1, characterized in that, The photovoltaic input terminal is an input terminal with maximum power point tracking function.

10. A photovoltaic inverter system, characterized in that, The photovoltaic inverter system can realize the automatic positioning method as described in any one of claims 1-9.

11. A fault control method for a photovoltaic inverter system, characterized in that, include: Using the automatic positioning method as described in claim 3, the installation position of each RSD in the photovoltaic inverter system is identified, wherein the installation position includes the corresponding connection relationship between the RSD and the photovoltaic module string and the corresponding connection relationship between the photovoltaic module string and the photovoltaic input terminal of the inverter; When any one of the RSDs fails, the controller in the inverter selects to disconnect other RSDs in the same photovoltaic module string as the failed RSD, based on the installation location of the failed RSD, so that they are put into standby mode, and put the remaining RSDs in the photovoltaic inverter system into normal working mode.

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