Combined type separated photovoltaic framework

Abstract

The present invention relates to a power supply system and a power generation system based on photovoltaic (PV). The present invention proposes a power supply system having two PV-based power generation systems combined together. A first power generation system of the power supply system includes one or more first PV strings and includes a first power conversion system connected to the one or more first PV strings. A second power generation system of the power supply system comprises one or more second PV strings and comprises a second power conversion system, and the second power conversion system is connected to the one or more second PV strings; the power supply system further includes one or more switches for selectively connecting and disconnecting the first power conversion system to and from the second power conversion system, and selectively connecting and disconnecting the first power conversion system and the second power conversion system to and from ground.

Description

Technical Field

[0001] The present invention relates to a photovoltaic-based power supply system and a power generation system. The present invention proposes a power supply system having two photovoltaic-based power generation systems combined together. The two power generation systems of the power supply system can be separated and reassembled. Background Art

[0002] The first exemplary power system uses a single photovoltaic-based power generation system limited to 1500V DC and 1000V AC.

[0003] The second exemplary power supply system uses two photovoltaic-based power generation systems combined together. Compared with the comparable solution of two independent first exemplary power supply systems, the second exemplary power supply system has higher overall efficiency, fewer components, and thus lower CAPEX and OPEX.

[0004] However, since the two combined power generation systems are quasi-floating systems, the second exemplary power system may not comply with the European Low Voltage Directive (EU LVD). Similar compliance issues may arise for the IEC LV standard. Summary of the invention

[0005] In view of this, the present invention aims to provide a different power supply system. The purpose is to obtain the advantages of the second exemplary power supply system while complying with EU LVD and IEC LV standards. Another purpose is to avoid the need for any additional power conversion components (e.g., for voltage reversal) to avoid reducing efficiency and increasing costs.

[0006] These and other objects are achieved by the invention as described in the independent claims. Advantageous implementations are further described in the dependent claims.

[0007] A first aspect of the present invention provides a power supply system, comprising: a first power generation system, comprising one or more first photovoltaic (PV) strings and comprising a first power conversion system, wherein the first power conversion system is connected to the one or more first PV strings; a second power generation system, comprising one or more second PV strings and comprising a second power conversion system, wherein the second power conversion system is connected to the one or more second PV strings; and one or more switches for selectively connecting the first power conversion system to the second power conversion system and disconnecting it from the second power conversion system, and selectively connecting the first power conversion system and the second power conversion system to the ground and disconnecting them from the ground.

[0008] The power supply system of the first aspect combines two power generation systems and therefore has the above-mentioned similar advantages of the second exemplary power supply system, namely, higher overall efficiency, fewer components, and lower CAPEX and OPEX than the first exemplary power supply system. In addition, since one or more switches can be used to connect the first power conversion system and the second power conversion system (and the two power generation systems) to and from the ground, the power supply system of the first aspect can comply with the current EU LVD and IECLV standards. Another advantage is that one or more switches can be used to disconnect the two power conversion systems (and the two power generation systems) from each other and disconnect the two power conversion systems (and the two power generation systems) from the ground. This allows measurements to be performed at the power generation system, such as ground leakage detection measurements.

[0009] In an implementation of the first aspect, the first power conversion system includes a first DC / DC converter and a first DC / AC converter, wherein the first DC / DC converter is connected to the one or more first PV strings, the first output end of the first DC / DC converter is connected to the first input end of the first DC / AC converter, and the second output end of the first DC / DC converter is connected to the second input end of the first DC / AC converter through the one or more switches; the second power conversion system includes a second DC / DC converter and a second DC / AC converter, wherein the second DC / DC converter is connected to the one or more second PV strings, the first output end of the second DC / DC converter is connected to the first input end of the second DC / AC converter through the one or more switches, and the second output end of the second DC / DC converter is connected to the second input end of the second DC / AC converter; the one or more switches are used to selectively connect the second output end of the first DC / DC converter to the first output end of the second DC / DC converter and disconnect from the first output end of the second DC / DC converter, and selectively connect the second input end of the first DC / AC converter to the first input end of the second DC / AC converter and disconnect from the first input end of the second DC / AC converter, and connect to ground and disconnect from ground.

[0010] In an implementation of the first aspect, the power supply system includes two or more switches, wherein a first switch among the two or more switches is used to selectively connect the first power conversion system to the second power conversion system or disconnect it from the second power conversion system; and a second switch among the two or more switches is used to selectively connect the first power conversion system and the second power conversion system to ground or disconnect them from ground.

[0011] In an implementation of the first aspect, the first switch is used to selectively connect the second output end of the first DC / DC converter to the first output end of the second DC / DC converter and disconnect it from the first output end of the second DC / DC converter, and connect to a common potential or disconnect it from the common potential; the second switch is used to selectively connect the second input end of the first DC / AC converter and the first input end of the second DC / AC converter to the common potential and disconnect it from the common potential, and connect to ground.

[0012] The two switches provide improved control over the connection and disconnection of the two power conversion systems.

[0013] In an implementation of the first aspect, the first DC / DC converter is used for a positive voltage between the first output terminal and the second output terminal of the first DC / DC converter; and the second DC / DC converter is used for a positive voltage between the first output terminal and the second output terminal of the second DC / DC converter.

[0014] The positive voltage of the first DC / DC converter can be provided by a positive potential at the first output terminal of the first DC / DC converter and a zero potential or a potential at least lower than the positive potential at the second output terminal of the first DC / DC converter. The positive voltage of the second DC / DC converter can be provided by a negative potential at the second output terminal of the second DC / DC converter and a zero potential or a potential at least higher than the negative potential at the first output terminal of the second DC / DC converter.

[0015] In an implementation of the first aspect, the first DC / AC converter is used for a positive voltage between the first input terminal and the second input terminal of the first DC / AC converter; and the second DC / AC converter is used for a positive voltage between the first input terminal and the second input terminal of the second DC / AC converter.

[0016] The positive voltage of the first DC / AC converter can be provided by a positive potential at the first input terminal of the first DC / AC converter and a zero potential or a potential at least lower than the positive potential at the second input terminal of the first DC / AC converter. The positive voltage of the second DC / AC converter can be provided by a negative potential at the second input terminal of the second DC / AC converter and a zero potential or a potential at least higher than the negative potential at the first input terminal of the second DC / AC converter.

[0017] In an implementation of the first aspect, the one or more first PV strings include multiple positive PV fields, wherein each positive PV field has a positive potential relative to the ground; and the one or more second PV strings include multiple negative PV fields, wherein each negative PV field has a negative potential relative to the ground.

[0018] In an implementation of the first aspect, the power supply system further includes: a voltage generator for providing a positive voltage; and one or more other switches for selectively connecting the voltage generator to and disconnecting it from the one or more second PV strings.

[0019] For example, this may counteract potential induced degradation (PID) of the second PV string when the second PV string is inactive.

[0020] In an implementation of the first aspect, the power supply system includes two or more other switches, wherein a first other switch among the two or more other switches is used to selectively connect the first input end of the second DC / AC converter to the second output end of the second DC / DC converter and disconnect it from the second output end of the second DC / DC converter, and the second DC / AC converter includes the voltage generator; and a second other switch among the two or more other switches is used to selectively connect the second input end of the second DC / AC converter to ground and disconnect it from ground.

[0021] In an implementation of the first aspect, the first output end of the first DC / DC converter is connected to the first input end of the first DC / AC converter through a first diode; and / or the second output end of the second DC / DC converter is connected to the second input end of the second DC / AC converter through a second diode.

[0022] In an implementation of the first aspect, the first DC / AC converter includes a three-phase AC output terminal that can be connected to a winding of a first substation; and / or the second DC / AC converter includes a three-phase AC output terminal that can be connected to a second winding of the first substation or a winding of a second substation.

[0023] The second aspect of the present invention provides a method for operating a power supply system according to the first aspect or any implementation thereof, wherein the method comprises: if a first condition is met, operating the one or more switches to connect the first power conversion system to the second power conversion system, and to connect the first power conversion system and the second power conversion system to ground; if a second condition is met, operating the one or more switches to disconnect the first power conversion system from the second power conversion system, and to disconnect the first power conversion system and the second power conversion system from ground.

[0024] In an implementation of the second aspect, the first condition includes: the power generated by the first power generation system and / or the second power generation system is higher than a threshold power; and / or the second condition includes: the power generated by the first power generation system and / or the second power generation system is lower than the threshold power.

[0025] In an implementation of the second aspect, the first condition includes: it is daytime or it is during the active time of the first power generation system and / or the second power generation system; and / or the second condition includes: it is nighttime or it is during the inactive time of the first power generation system and / or the second power generation system.

[0026] In an implementation of the second aspect, if the one or more switches operate according to the first condition being satisfied, the first output terminal of the first DC / DC converter is at a positive potential, the second output terminal of the first DC / DC converter and the first output terminal of the second DC / DC converter are grounded, and the second output terminal of the second DC / DC converter is at a negative potential.

[0027] In an implementation of the second aspect, if the one or more switches are operated according to the satisfied second condition, the first output terminal of the first DC / DC converter is at a first positive potential relative to ground, the second output terminal of the first DC / DC converter is at a first negative potential relative to ground or at a floating potential, the first output terminal of the second DC / DC converter is at a second positive potential relative to ground or at a floating potential, and the second output terminal of the second DC / DC converter is at a second negative potential relative to ground.

[0028] In an implementation of the second aspect, the method further includes: when the one or more switches are operated according to the second condition being satisfied, operating the one or more other switches to connect the voltage generator to the one or more second PV strings; when the one or more switches are operated according to the first condition being satisfied, operating the one or more other switches to disconnect the voltage generator from the one or more second PV strings.

[0029] In an implementation of the second aspect, the method further includes: when the one or more switches operate according to the second condition being satisfied, performing one or more measurements at the first power generation system and / or at the second power generation system.

[0030] In an implementation of the second aspect, the one or more measurements include earth leakage detection measurements.

[0031] The method of the second aspect and its implementation manner achieve the above-mentioned similar advantages of the power supply system of the first aspect.

[0032] The third aspect of the present invention provides a computer program, which includes instructions. When the program is executed by a computer, the instructions enable the computer to control the one or more switches and optionally the one or more other switches of the power supply system according to the first aspect or any implementation thereof to execute the method according to the second aspect or any implementation thereof.

[0033] The concept of the invention is the interconnection of two power generation systems - the two power generation systems can be two low voltage systems, each low voltage system up to 1500V DC and 1000V AC - this is achieved by one or more switches, which can also connect the system to ground at the interface between the two power generation systems. Therefore, the power supply system has the same advantages as two hard-connected and grounded systems, for example, this can make the whole device 100% LVD compliant. The solution of the invention has one or more switches at the ground connection, which can connect (combine) the two power generation systems and can connect the two power generation systems to ground at the same point to maintain grounding and avoid any possible potential deviation, which may cause the voltage to ground to be higher than 1500V DC.

[0034] The two power generation systems can also be connected only when needed by operating one or more switches, which can be done during the phases of power generation of the PV strings, for example, when power is generated during the day.

[0035] The first of the two power generation systems may operate at a positive voltage to ground, and the second of the two power generation systems may operate at the same absolute voltage but at a negative voltage to ground. The first power generation system may not have any problems related to the physical characteristics of the PV cells, but the second power generation system may experience PID on the PV field. PID is a slow process that will weaken the power generation over time. The present invention contemplates reversing this PID by applying a reversed (positive) voltage of the same amplitude to the PV field of the second PV string at the same time using a voltage generator. In the present invention, for example, the two power generation systems can be separated by opening one or more first switches at night and applying a positive voltage to the negative voltage cable end of the second PV string in the second power generation system.

[0036] It should be noted that all devices, elements, units and devices described in this application can be implemented in software or hardware elements or any type of combination thereof. All steps performed by various entities described in this application and the functions to be performed by various entities described are intended to refer to the corresponding entities for performing the corresponding steps and functions. Although in the description of the following specific embodiments, the specific functions or steps to be performed by the external entity are not reflected in the description of the specific detailed elements of the entity performing the specific steps or functions, it should be clear to the technician that these methods and functions can be implemented by corresponding software or hardware elements or any combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In conjunction with the accompanying drawings, the following description of specific embodiments will illustrate the above aspects and their implementation methods. In the drawings:

[0038] Figure 1 A power supply system according to the invention is shown.

[0039] Figure 2 A first exemplary power supply system according to the present invention is shown.

[0040] Figure 3 A second exemplary power supply system according to the present invention is shown.

[0041] Figure 4 A method according to the invention for operating a power supply system is shown. DETAILED DESCRIPTION

[0042] Figure 1 A power supply system 100 according to the present invention is shown. The power supply system is PV based, may be a low voltage power supply system, and may comply with EU LVD and IEC LV standards.

[0043] The power supply system 100 includes a first power generation system 110 and a second power generation system 120. The first power generation system 110 includes one or more first PV strings 111 and a first power conversion system 112, which is connected to the one or more first PV strings 111. Each first PV string 111 may include one or more PV panels and / or one or more PV fields, and the one or more PV panels and / or one or more PV fields are capable of generating power based on received light. The second power generation system 120 includes one or more second PV strings 121 and a second power conversion system 122, which is connected to one or more second first PV strings 121. Each second PV string 121 may include one or more PV panels and / or one or more PV fields, and the one or more PV panels and / or one or more PV fields are capable of generating power based on received light.

[0044] In addition, the power supply system 100 may include one or more switches, wherein an example having a switch 101 is shown in FIG. Figure 1 . The switch 101 is used to selectively connect the first power conversion system 112 to the second power conversion system 122 and disconnect it from the second power conversion system 122, and to selectively connect the first power conversion system 112 and the second power conversion system 122 to the ground 102 (which may also be the ground) and disconnect it from the ground 102. For example, the switch 101 can be used to connect the first power conversion system 112 (e.g., close the switch 101) to the second power conversion system 122, or disconnect the first power conversion system 112 from the second power conversion system 122 (e.g., open the switch 101). For example, the switch 101 can be used to connect the first power conversion system 112 and the second power conversion system 122 (e.g., close the switch 101) to the ground 102, or disconnect the first power conversion system 112 and the second power conversion system 122 from the ground 102 (e.g., open the switch 101).

[0045] Figure 2 A first exemplary power supply system 100 of the present invention is shown, which further develops Figure 1 A power supply system 100 is shown. Figure 2 The power supply system 100 has some additional, optional features. These optional features will be described below and can be added separately Figure 1 in the power supply system 100, or any possible combination of features.

[0046] and Figure 1 Similar to the power supply system 100, Figure 2 The power supply system 100 also includes a first power generation system 110 and a second power generation system 120. Therefore, Figure 2 The power supply system 100 also includes a first power conversion system 112 and a second power conversion system 122 . Figure 2 The power supply system 100 also includes one or more switches, for example, Figure 2 The power supply system 100 includes two switches 101a and 101b.

[0047] The first power conversion system 112 includes a first DC / DC converter 211, which is connected to one or more first PV strings 111. The first DC / DC converter 211 can be a unipolar smart string controller DC / DC. In addition, the first power conversion system 112 includes a first DC / AC converter 212, which can be a smart PV controller DC / AC. The first output of the first DC / DC converter 211 is connected to the first input of the first DC / AC converter 212 through an optional first diode 218, etc. The second output of the first DC / DC converter 211 is connected to the second input of the first DC / AC converter 212 through switches 101a and 101b. The first DC / DC converter 211 is used for a positive voltage between the first output and the second output of the first DC / DC converter, and accordingly, the first DC / AC converter 212 is used for a positive voltage between the first input and the second input of the first DC / AC converter 212. The first DC / DC converter 211 may include a power electronic switch 221 for switching on and off the positive voltage.

[0048] Likewise, the second power conversion system 122 includes a second DC / DC converter 213, which is connected to one or more second PV strings 121. The second DC / DC converter 213 can be a unipolar intelligent string controller DC / DC. In addition, the second power conversion system 122 includes a second DC / AC converter 214, which can be an intelligent PV controller DC / AC. The first output of the second DC / DC converter 213 is connected to the first input of the second DC / AC converter 214 through switches 101a and 101b. The second output of the second DC / DC converter 213 is connected to the second input of the second DC / AC converter 214 through an optional second diode 219, etc. The second DC / DC converter 213 is used for a positive voltage between the first output and the second output of the second DC / DC converter 213, and accordingly, the second DC / AC converter 214 is used for a positive voltage between the first input and the second input of the second DC / AC converter 214. The second DC / DC converter 213 may include a power electronic switch 221 for disconnecting the positive voltage.

[0049] It can also be seen that in this example, the first switch 101a of the two switches 101a and 101b is used to selectively connect the second output terminal of the first DC / DC converter 211 to the first output terminal of the second DC / DC converter 213 and disconnect it from the first output terminal of the second DC / DC converter 213, and to connect to or disconnect it from the common potential 215. The second switch 101b of the two switches 101a and 101b is used to selectively connect the second input terminal of the first DC / AC converter 212 and the first input terminal of the second DC / AC converter 214 to or disconnect it from the common potential 215, and to the ground 102. In this way, the first switch 101a is used to selectively connect the first power conversion system 112 to or disconnect it from the second power conversion system 122, and the second switch 101b is used to selectively connect the first power conversion system 112 and the second power conversion system 122 to or disconnect it from the ground 102 through the common potential 215.

[0050] if Figure 2 When the first switch 101a is closed, the first power generation system 110 is connected to the second power generation system 120, and when the first switch 101a is opened, these power generation systems 110, 120 are separated. Figure 2 When the second switch 101 b is closed, the first power generation system 110 and the second power generation system 120 are connected to the ground 102 , and when the second switch 101 b is opened, these power generation systems 110 and 120 are disconnected from the ground 101 .

[0051] Optionally, the power system 100 may include two identical power generation systems 110 and 120. The first power generation system 110 may be configured to operate at a positive potential relative to ground, and the second power generation system may be configured to operate at a negative voltage relative to ground 102. That is, the one or more first PV strings 111 may include multiple positive PV fields, such as Figure 2 As shown, each positive PV field has a positive potential to ground 102, for example, a positive DC voltage up to +1500 V. One or more second PV strings 121 may include a plurality of negative PV fields, each negative PV field having a negative potential to ground 102, for example, a negative DC voltage up to -1500 V.

[0052] The switches 101a and 101b can be used to be closed only during an active period of the power system 100, which can be when power is generated in the PV fields 111 and 121 of multiple PV strings (for example, a PV field of multiple PV panels). The active period can be a time with daylight. During an inactive period of the power system 100, such as when there is no daylight, such as at night, the two switches 101a and 101b can be used to be in an open state, so that the two power generation systems 110 and 120 are disconnected from each other. Since the PV field does not generate power during the inactive period, there is no voltage on one or more lines of the first PV string 111 (for example, the +1500V line) and one or more lines of the second PV string 121 (for example, the -1500V line).

[0053] During the inactive period, when the first PV string 111 and the second PV string 121 do not generate power, the positive voltage to ground can be fed back to the (negative) second PV string 121. Therefore, an opposite electric field can be generated compared to the active (sunlight) period, which can reverse the PID in the PV field of the second PV string 121. To this end, the power supply system 100 can also include a voltage generator 217, which is used to provide the positive voltage.

[0054] exist Figure 2 In the embodiment, the voltage generator 217 may be included in the second DC / AC converter 214. The power supply system 100 may include one or more other switches for selectively connecting the voltage generator 217 to and disconnecting it from the one or more second PV strings 121. For example, Figure 2 The power supply system 100 is shown as having a first further switch 216a for selectively connecting and disconnecting a first input of a second DC / AC converter 214 (the second DC / AC converter 214 includes a voltage generator 217) to and from a second output of the second DC / DC converter 213. The power supply system 100 is also shown as having a second further switch 216b for selectively connecting and disconnecting a second input of the second DC / AC converter 214 to and from ground 102. In this way, a positive voltage can be provided to the second PV string 112.

[0055] Figure 3 Another power supply system 100 of the present invention is shown. The other power supply system 100 is similar to Figure 2The power supply system 100 of FIG. 2 is shown in FIG. 2 . However, the voltage generator 217 is an additional voltage source, and the positive voltage is obtained from the additional, independent voltage source. In this case, a further switch 216 is provided, which is used to selectively connect the voltage generator 217 to the second output terminal of the second DC / DC converter 213 and disconnect it from the second output terminal of the second DC / DC converter 213.

[0056] Figure 3 and Figure 4 It is also shown that the first DC / AC converter 212 includes a three-phase AC output that can be connected to the winding of the first substation 220. In addition, the second DC / AC converter 214 includes a three-phase AC output that can be connected to the second winding of the first substation 220. Alternatively, the three-phase AC output of the second DC / AC converter 214 can be connected to the winding of the second substation.

[0057] The power system 100 may include a processor or processing circuit (not shown) for executing, implementing or starting various operations of the power system 100 herein, specifically, for controlling one or more switches 101, 101a, 101b and optionally one or more other switches 216a, 216b of the power system 100. The processing circuit may include hardware and / or the processing circuit may be controlled by software. The hardware may include analog circuits or digital circuits, or both. The digital circuit may include components such as an application-specific integrated circuit (ASIC), a field-programmable array (FPGA), a digital signal processor (DSP) or a multi-purpose processor. The power system 100 may also include a memory circuit that stores one or more instructions that can be executed by a processor or processing circuit, especially under software control. For example, the memory circuit may include a non-transitory storage medium that stores executable software code, which, when executed by a processor or processing circuit, can perform various operations of the switch of the power system 100. In one embodiment, the processing circuit includes one or more processors and non-transitory memory connected to the one or more processors. The non-transitory memory can carry executable program code that, when executed by the one or more processors, can cause the power system 100 to perform, implement, or initiate the operations or methods described herein.

[0058] Figure 4 Shown is the operation Figure 1 , Figure 2 or Figure 3Method 400 of a power supply system 100. Method 400 may include step 401: if a first condition is met, one or more switches 101, 101a, 101b are operated to connect the first power conversion system 110 to the second power conversion system 120, and to connect the first power conversion system 110 and the second power conversion system 120 to the ground 102. Method 400 may also include step 402: if a second condition is met, one or more switches 101, 101a, 101b are operated to disconnect the first power conversion system 110 from the second power conversion system 120, and to disconnect the first power conversion system 110 and the second power conversion system 120 from the ground 102.

[0059] The first condition may include at least one of the following: the power generated by the first power generation system 110 and / or the second power generation system 120 is higher than the threshold power; it is during the day; it is during the activity time of the first power generation system 110 and / or the second power generation system 120.

[0060] The second condition may include at least one of the following: the power generated by the first power generation system 110 and / or the second power generation system 120 is lower than the threshold power; it is at night; it is in the inactive time of the first power generation system 110 and / or the second power generation system 120.

[0061] The invention has been described in conjunction with various embodiments as examples and in conjunction with implementations. However, a person skilled in the art will be able to understand and implement other variations when implementing the claimed subject matter, based on a study of the drawings, the invention and the independent claims. In the claims as well as in the specification, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfil the functions of several entities or items described in the claims. The fact that certain measures are recited in mutually different dependent claims does not in itself mean that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. A power supply system (100), characterized in that: include: A first power generation system (110) comprising one or more first photovoltaic (PV) strings (111) and comprising a first power conversion system (112), the first power conversion system (112) being connected to the one or more first PV strings (111); A second power generation system (120) comprising one or more second PV strings (121) and comprising a second power conversion system (122), the second power conversion system (122) being connected to the one or more second PV strings (121); One or more switches (101, 101a, 101b) are used to selectively connect the first power conversion system (112) to the second power conversion system (122) and disconnect it from the second power conversion system (122), and selectively connect the first power conversion system (112) and the second power conversion system (122) to the ground (102) and disconnect them from the ground (102).

2. The power supply system (100) according to claim 1, characterized in that: The first power conversion system (112) comprises a first DC / DC converter (211) and a first DC / AC converter (212), wherein the first DC / DC converter (211) is connected to the one or more first PV strings (111), a first output end of the first DC / DC converter (211) is connected to a first input end of the first DC / AC converter (212), and a second output end of the first DC / DC converter (211) is connected to a second input end of the first DC / AC converter (212) via the one or more switches (101, 101a, 101b); The second power conversion system (122) comprises a second DC / DC converter (213) and a second DC / AC converter (214), wherein the second DC / DC converter (213) is connected to the one or more second PV strings (121), a first output terminal of the second DC / DC converter (213) is connected to a first input terminal of the second DC / AC converter (214) through the one or more switches (101, 101a, 101b), and a second output terminal of the second DC / DC converter (213) is connected to a second input terminal of the second DC / AC converter (214); The one or more switches (101, 101a, 101b) are used to selectively connect the second output end of the first DC / DC converter (211) to the first output end of the second DC / DC converter (213) and disconnect it from the first output end of the second DC / DC converter (213), and selectively connect the second input end of the first DC / AC converter (212) to the first input end of the second DC / AC converter (214) and disconnect it from the first input end of the second DC / AC converter (214), and connect to the ground (102) and disconnect it from the ground (102).

3. The power supply system (100) according to claim 1 or 2, characterized in that: It includes two or more switches (101a, 101b), wherein: A first switch (101a) of the two or more switches is used to selectively connect the first power conversion system (112) to the second power conversion system (122) or disconnect the first power conversion system (122); The second switch (101b) of the two or more switches is used to selectively connect the first power conversion system (112) and the second power conversion system (122) to the ground (102) or disconnect them from the ground (102).

4. The power supply system (100) according to claim 2 and 3, characterized in that: The first switch (101a) is used to selectively connect the second output end of the first DC / DC converter (211) to the first output end of the second DC / DC converter (213) and disconnect it from the first output end of the second DC / DC converter (213), and connect it to a common potential (215) or disconnect it from the common potential (215); The second switch (101b) is used to selectively connect the second input terminal of the first DC / AC converter (212) and the first input terminal of the second DC / AC converter (214) to and disconnect from the common potential (215), and to connect to the ground (102).

5. The power supply system (100) according to any one of claims 2 to 4, characterized in that: The first DC / DC converter (211) is used for a positive voltage between the first output terminal and the second output terminal of the first DC / DC converter (211); The second DC / DC converter (213) is used for a positive voltage between the first output terminal and the second output terminal of the second DC / DC converter (213).

6. The power supply system (100) according to any one of claims 2 to 5, characterized in that: The first DC / AC converter (212) is used for a positive voltage between the first input terminal and the second input terminal of the first DC / AC converter (212); The second DC / AC converter (214) is used for a positive voltage between the first input terminal and the second input terminal of the second DC / AC converter (214).

7. The power supply system (100) according to any one of claims 1 to 6, characterized in that: The one or more first PV strings (111) include a plurality of positive PV fields, wherein each positive PV field has a positive potential relative to ground (102); The one or more second PV strings (121) include a plurality of negative PV fields, wherein each negative PV field has a negative potential with respect to the ground (102).

8. The power supply system (100) according to claim 7, characterized in that: Also includes: A voltage generator (217) for providing a positive voltage; One or more other switches (216, 216a, 216b) for selectively connecting the voltage generator (217) to and disconnecting the voltage generator (217) from the one or more second PV strings (121).

9. The power supply system (100) according to claim 8, characterized in that: Two or more other switches (216a, 216b) are included, wherein: a first other switch (216a) of the two or more other switches for selectively connecting the first input terminal of the second DC / AC converter (214) to the second output terminal of the second DC / DC converter (213) and disconnecting the first input terminal of the second DC / AC converter (214) from the second output terminal of the second DC / DC converter (213), the second DC / AC converter (214) comprising the voltage generator (217); A second other switch (216b) of the two or more other switches is used to selectively connect the second input terminal of the second DC / AC converter (214) to and disconnect from the ground (102).

10. The power supply system (100) according to any one of claims 2 to 9, characterized in that: The first output terminal of the first DC / DC converter (211) is connected to the first input terminal of the first DC / AC converter (212) via a first diode (218); and / or The second output terminal of the second DC / DC converter (213) is connected to the second input terminal of the second DC / AC converter (214) via a second diode (219).

11. The power supply system (100) according to any one of claims 2 to 10, characterized in that: The first DC / AC converter (212) comprises a three-phase AC output connectable to a winding of a first substation (220); and / or The second DC / AC converter (214) comprises a three-phase AC output connectable to a second winding of the first substation (220) or to a winding of a second substation.

12. A method (400) for operating a power supply system (100) according to any one of claims 1 to 11, characterized in that: The method (400) comprises: If a first condition is met, operating (401) the one or more switches (101, 101a, 101b) to connect the first power conversion system (112) to the second power conversion system (122), and to connect the first power conversion system (112) and the second power conversion system (122) to ground (102); If a second condition is met, the one or more switches (101a, 101b) are operated (402) to disconnect the first power conversion system (110) from the second power conversion system (120), and to disconnect the first power conversion system (110) and the second power conversion system (120) from the ground (102).

13. The method (400) according to claim 12, characterized in that: The first condition includes: the power generated by the first power generation system (110) and / or the second power generation system (120) is higher than a threshold power; and / or The second condition includes: the power generated by the first power generation system (110) and / or the second power generation system (120) is lower than the threshold power.

14. The method (400) according to claim 12 or 13, characterized in that: The first condition includes: it is daytime or it is during the activity time of the first power generation system (110) and / or the second power generation system (120); and / or The second condition includes: it is night time or it is in an inactive time of the first power generation system (110) and / or the second power generation system (120).

15. The method (400) according to any one of claims 12 to 14, characterized in that: If the one or more switches (101, 101a, 101b) operate according to the first condition being satisfied, the first output terminal of the first DC / DC converter (211) is at a positive potential, the second output terminal of the first DC / DC converter (211) and the first output terminal of the second DC / DC converter (213) are grounded (102), and the second output terminal of the second DC / DC converter (213) is at a negative potential.

16. The method (400) according to any one of claims 12 to 15, characterized in that: If the one or more switches (101, 101a, 101b) are operated according to the second condition being satisfied, Then the first output terminal of the first DC / DC converter (211) is at a first positive potential relative to the ground (102), The second output end of the first DC / DC converter (211) is at a first negative potential relative to the ground (102) or at a floating potential, the first output end of the second DC / DC converter (213) is at a second positive potential relative to the ground (102) or at a floating potential, and the second output end of the second DC / DC converter (213) is at a second negative potential relative to the ground (102).

17. The method (400) according to any one of claims 12 to 16, characterized in that: Also includes: When the one or more switches (101, 101a, 101b) are operated according to the second condition being satisfied, operating the one or more other switches (216, 216a, 26b) to connect the voltage generator (217) to the one or more second PV strings (121); When the one or more switches (101, 101a, 101b) are operated according to the first condition being satisfied, the one or more other switches (216, 216a, 216b) are operated to disconnect the voltage generator (217) from the one or more second PV strings (211).

18. The method (400) according to any one of claims 12 to 15, characterized in that: Also includes: When the one or more switches (101, 101a, 101b) are operated according to the second condition being satisfied, one or more measurements are performed at the first power generation system (110) and / or at the second power generation system (120).

19. The method (400) according to claim 18, characterized in that: The one or more measurements include an earth leakage detection measurement.

20. A computer program, characterized in that Comprising instructions which, when the program is executed by a computer, cause the computer to control the one or more switches (101, 101a, 101b) and optionally the one or more other switches (216, 216a, 216b) of the power supply system (100) according to any one of claims 1 to 11, so as to perform the method (400) according to any one of claims 12 to 19.

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