DC coupled wind-solar hybrid system and photovoltaic PID repair control method thereof

Abstract

The present invention provides a direct current coupling wind-solar complementary system and a photovoltaic PID repair control method thereof. The system comprises: a wind turbine, a photovoltaic array, a PID repair type DC / DC converter, a transformer, a machine-side converter and a grid-side converter; the input end of the PID repair type DC / DC converter is connected to the output end of the photovoltaic array, and the output end is connected to a wind power direct current bus, and is used for switching from a normal power generation mode to a PID repair mode when the electrical parameters of the photovoltaic array meet the PID repair conditions or the direct current coupling wind-solar complementary system receives a PID repair instruction, and performing PID repair on the photovoltaic array with the voltage on the wind power direct current bus; while realizing photovoltaic complementary power generation between the photovoltaic array and the wind turbine, reducing the influence of the PID effect on the power generation of the photovoltaic array, and avoiding the raising of the neutral point voltage of the wind turbine, thereby improving the power generation and safety of the direct current coupling wind-solar complementary system.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind-solar complementary construction, and more specifically, particularly relates to a direct current coupled wind-solar complementary system and a photovoltaic PID repair control method thereof. Background Art

[0002] Photovoltaic power generation and wind power generation are both green power sources that my country focuses on developing. my country has a vast territory. In view of the regional differences in wind energy and light energy, photovoltaic power stations and wind farms are independently built and operated. However, due to the intermittent characteristics of both wind energy and solar energy, when it is night or cloudy, solar energy does not generate electricity or the power generation is low, and the wind speed may be very high at this time, which is conducive to wind power generation; when the weather is clear, photovoltaic power generation is rapid, but wind power generation is not necessarily strong; therefore, there is a certain degree of complementarity between wind energy and solar energy in terms of power generation, and the complementary application of wind energy and solar energy is valuable for the stability of the power grid. On the other hand, in order to give full play to wind and light resources, my country's photovoltaic power stations and wind farms are mostly built in the northwest region. Large-scale power stations occupy more land resources, and because wind turbines are point-requisitioned land, the gaps between each wind turbine and the surrounding area are idle. If there are wind turbines on the top and photovoltaic arrays on the bottom, the two can be combined in space, so that more power generation units can be built on the same land area, which improves land utilization. In view of this, it is economically valuable to apply wind power and photovoltaic power in a nearby space.

[0003] See also Figure 1 , which shows a schematic diagram of a wind-solar complementary system, which couples photovoltaic and wind power on the DC side, and shares the downstream equipment, which not only improves efficiency but also reduces costs. However, due to the coupling of photovoltaic and wind power systems, some traditional photovoltaic problems cannot be handled by conventional solutions, such as the typical PID (Potential Induced Degradation) repair problem. The conventional PID repair solution is to raise the virtual midpoint on the AC side, or raise the voltage on the DC side. However, because the insulation level of the wind turbine does not match the insulation of the photovoltaic array, if the traditional solution is used in this solution to raise the voltage of the photovoltaic module, it means that the neutral point voltage of the wind turbine must be raised by more than half of the bus voltage; for example, for a 1500V photovoltaic system, the neutral point voltage of the wind turbine must be raised by more than 750V. At present, traditional wind turbines cannot meet such a high withstand voltage value, and the development and use of this wind-solar complementary system is limited. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a DC-coupled wind-solar complementary system and a photovoltaic PID repair control method thereof, so as to realize the PID repair of the photovoltaic array of the DC-coupled wind-solar complementary system, while avoiding the increase of the neutral point voltage of the wind turbine.

[0005] The first aspect of the present invention discloses a DC-coupled wind-solar complementary system, comprising: a wind turbine, a photovoltaic array, a PID-repaired DC / DC converter, a transformer, a machine-side converter and a grid-side converter; wherein:

[0006] The AC side of the machine-side converter is connected to the output end of the wind turbine, and the DC side of the machine-side converter and the DC side of the grid-side converter are both connected to the wind power DC bus;

[0007] The AC side of the grid-side converter is connected to the grid through the transformer;

[0008] The input end of the PID repair type DC / DC converter is connected to the output end of the photovoltaic array, and the output end of the PID repair type DC / DC converter is connected to the wind power DC bus;

[0009] The PID repair DC / DC converter is used to switch from a normal power generation mode to a PID repair mode when the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, and perform PID repair on the photovoltaic array using the voltage on the wind power DC bus.

[0010] Optionally, the PID repair type DC / DC converter comprises: a DC / DC circuit;

[0011] The input end of the DC / DC circuit serves as the input end of the PID repair type DC / DC converter, and the output end of the DC / DC circuit serves as the output end of the PID repair type DC / DC converter;

[0012] The DC / DC circuit is a Buck circuit, a Boost circuit, or a modified circuit based on a Buck circuit or a Boost circuit.

[0013] Optionally, when the DC / DC circuit is a mirror boost circuit, if the electrical parameters of the photovoltaic array meet the PID repair conditions, the mirror boost circuit disconnects itself from the negative pole of the photovoltaic array by reverse cutoff of a diode arranged on its own negative branch, and at the same time clamps the positive pole voltage of the photovoltaic array by the positive pole voltage on the wind power DC bus to achieve PID repair.

[0014] Optionally, when the DC / DC circuit is a mirrored Buck circuit, the PID repair type DC / DC converter further comprises: a switching power supply that draws power from the photovoltaic array;

[0015] If the electrical parameters of the photovoltaic array meet the PID repair conditions, the mirror Buck circuit controls the switch tube arranged on its own negative branch to disconnect by losing power to the switching power supply, so as to disconnect itself from the negative pole of the photovoltaic array; at the same time, the positive voltage of the photovoltaic array is clamped by the positive voltage on the wind power DC bus to achieve PID repair.

[0016] Optionally, if the DC / DC circuit is the Buck circuit, the PID repair type DC / DC converter further includes: a first controllable switch;

[0017] If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the Buck circuit controls the disconnection between itself and the negative pole of the photovoltaic array by disconnecting the first controllable switch, and at the same time closes the switch tube on its own positive branch to clamp the positive pole of the photovoltaic array with the positive voltage on the wind power DC bus to achieve PID repair.

[0018] Optionally, the first controllable switch is arranged between the negative electrode of the input capacitor in the Buck circuit and the negative electrode of the photovoltaic array;

[0019] Alternatively, the first controllable switch is arranged between the cathode of the input capacitor in the Buck circuit and the anode of the diode in the Buck circuit;

[0020] Alternatively, the first controllable switch is arranged between the cathode of the output capacitor in the Buck circuit and the anode of the diode in the Buck circuit.

[0021] Optionally, if the DC / DC circuit is the Boost circuit, the PID repair type DC / DC converter further includes: a second controllable switch and a third controllable switch; wherein:

[0022] If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the Boost circuit controls the disconnection between itself and the negative pole of the photovoltaic array by opening the third controllable switch, and controls itself to be connected to the positive pole of the photovoltaic array by closing the second controllable switch, so that the positive pole voltage on the wind power DC bus clamps the positive pole of the photovoltaic array to achieve PID repair.

[0023] Optionally, the third controllable switch is arranged between the negative electrode of the input capacitor in the Boost circuit and the negative electrode of the photovoltaic array, or, is arranged between the negative electrode of the input capacitor in the Boost circuit and one end of the switch tube in the Boost circuit, or, is arranged between the negative electrode of the output capacitor in the Boost circuit and one end of the switch tube in the Boost circuit;

[0024] The second controllable switch is connected in parallel with the diode in the Boost circuit, or one end of the second controllable switch is connected to the positive electrode of the input capacitor in the Boost circuit, and the other end of the second controllable switch is connected to the positive electrode of the output capacitor in the Boost circuit.

[0025] Optionally, it also includes: a controller and an auxiliary power supply;

[0026] The input end of the controller is connected to the output end of the electrical parameter detection device in the DC-coupled wind-solar complementary system, so as to detect the electrical parameters of the photovoltaic array through the electrical parameter detection device, and the output end of the controller is connected to the control end of the PID repair type DC / DC converter;

[0027] The input end of the auxiliary power supply is connected to the wind power DC bus, and the output end of the auxiliary power supply is connected to the power supply end of the controller.

[0028] Optionally, the first controllable switch, the second controllable switch and the third controllable switch are mechanical switches or electronic switches.

[0029] Optionally, it also includes: PID power supply;

[0030] One end of the PID power supply is connected to the negative pole of the photovoltaic array, and the other end is grounded.

[0031] The second aspect of the present invention discloses a photovoltaic PID repair control method for a DC-coupled wind-solar hybrid system, characterized in that the controller applied to the DC-coupled wind-solar hybrid system corresponding to the first aspect of the present invention comprises:

[0032] Determine whether the electrical parameters of the photovoltaic array meet the PID repair conditions or whether the DC-coupled wind-solar complementary system receives a PID repair instruction;

[0033] If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the negative branch of the PID repair type DC / DC converter in the DC-coupled wind-solar complementary system is controlled to be disconnected, and the positive electrode of the photovoltaic array is controlled by the positive branch of the PID repair type DC / DC converter to be clamped by the positive electrode on the wind power DC bus in the DC-coupled wind-solar complementary system to achieve PID repair;

[0034] If the electrical parameters of the photovoltaic array do not meet the PID repair conditions and the DC-coupled wind-solar complementary system does not receive a PID repair instruction, the PID repair type DC / DC converter is controlled to be in a normal power generation mode.

[0035] Optionally, before determining whether the electrical parameters of the photovoltaic array meet the PID repair condition, the method further includes:

[0036] The electrical parameters of the photovoltaic array are detected.

[0037] Optionally, determining whether the electrical parameters of the photovoltaic array meet the PID repair condition includes:

[0038] Determining whether an electrical parameter of the photovoltaic array is less than a corresponding threshold;

[0039] If the electrical parameter of the photovoltaic array is less than the corresponding threshold, it is determined that the electrical parameter of the photovoltaic array meets the PID repair condition; if the electrical parameter of the photovoltaic array is greater than or equal to the corresponding threshold, it is determined that the electrical parameter of the photovoltaic array does not meet the PID repair condition.

[0040] Optionally, controlling the negative branch of the PID repair type DC / DC converter in the DC-coupled wind-solar complementary system to be disconnected includes: controlling the switch on the negative branch to be disconnected;

[0041] Controlling the positive electrode of the photovoltaic array to be clamped by the positive electrode on the wind power DC bus in the DC-coupled wind-solar complementary system through the positive electrode branch of the PID repair type DC / DC converter, including: controlling the switch on the positive electrode branch to close, so that the positive electrode voltage on the wind power DC bus clamps the positive electrode of the photovoltaic array;

[0042] Among them, when the PID repair type DC / DC converter is a Boost circuit, the switch on the negative branch is a third controllable switch, and the switch on the positive branch is a second controllable switch; when the PID repair type DC / DC converter is a Buck circuit, the switch on the negative branch is a first controllable switch, and the switch on the positive branch is a switch tube in the Buck circuit.

[0043] It can be seen from the above technical scheme that a DC-coupled wind-solar complementary system provided by the present invention includes: a wind turbine, a photovoltaic array, a PID repair type DC / DC converter, a transformer, a machine-side converter and a grid-side converter; wherein: the AC side of the machine-side converter is connected to the output end of the wind turbine, and its DC side and the DC side of the grid-side converter are both connected to the wind power DC bus, the AC side of the grid-side converter is connected to the power grid through a transformer, the input end of the PID repair type DC / DC converter is connected to the output end of the photovoltaic array, and its output end is connected to the wind power DC bus, and is used to switch from a normal power generation mode to a PID repair mode when the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, and perform PID repair on the photovoltaic array with the voltage on the wind power DC bus; while realizing photovoltaic complementary power generation between the photovoltaic array and the wind turbine, reducing the influence of the PID effect on the power generation of the photovoltaic array, and avoiding the increase of the neutral point voltage of the wind turbine, thereby improving the power generation and safety of the DC-coupled wind-solar complementary system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 It is a schematic diagram of a wind-solar complementary system provided by the prior art;

[0046] Figure 2 is a schematic diagram of a DC-coupled wind-solar complementary system provided by an embodiment of the present invention;

[0047] Figure 3 is a schematic diagram of another DC-coupled wind-solar complementary system provided by an embodiment of the present invention;

[0048] Figure 4 is a schematic diagram of another DC-coupled wind-solar complementary system provided by an embodiment of the present invention;

[0049] Figure 5 is a schematic diagram of another DC-coupled wind-solar complementary system provided by an embodiment of the present invention;

[0050] Figure 6 is a schematic diagram of another DC-coupled wind-solar complementary system provided by an embodiment of the present invention;

[0051] Figure 7 is a schematic diagram of another DC-coupled wind-solar complementary system provided by an embodiment of the present invention;

[0052] Figure 8 It is a schematic diagram of a photovoltaic PID repair control method for a DC-coupled wind-solar complementary system provided by 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0055] The embodiment of the present invention provides a DC-coupled wind-solar complementary system to solve the problem in a traditional wind-solar complementary system that the development and use of the wind-solar complementary system is limited due to the inability to perform PID repair on the photovoltaic array.

[0056] The DC-coupled wind-solar hybrid system, see Figure 2 , including: wind turbines, photovoltaic arrays, PID repair type DC / DC converters, transformers, machine-side converters (such as Figure 2 AC / DC) and grid-side converter (as shown Figure 2 DC / AC as shown); where:

[0057] The AC side of the machine-side converter is connected to the output end of the wind turbine, and the DC side of the machine-side converter and the DC side of the grid-side converter are both connected to the wind power DC bus; the AC side of the grid-side converter is connected to the grid through a transformer.

[0058] Specifically, the machine-side converter includes at least one rectifier module, which is used to rectify the AC power output by the wind turbine into DC power, and output the rectified DC power to the wind power DC bus. The grid-side converter includes at least one inverter module, which is used to convert the DC power on the wind power DC bus into AC power, that is, to convert the generated power of the wind turbine, and output the converted AC power to the transformer for the transformer to step up / down the voltage and then output to the grid.

[0059] The input end of the PID repair type DC / DC converter is connected to the output end of the photovoltaic array, and the output end of the PID repair type DC / DC converter is connected to the wind power DC bus. Specifically, the PID repair type DC / DC converter may include multiple DC / DC conversion circuits, whose input ends are respectively connected to the corresponding photovoltaic strings in the photovoltaic array, and whose output ends are connected in parallel.

[0060] The PID repair DC / DC converter works in two modes: normal power generation mode and PID repair mode. The PID repair DC / DC converter is used to switch from normal power generation mode to PID repair mode when the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar hybrid system receives a PID repair instruction, and perform PID repair on the photovoltaic array with the voltage on the wind power DC bus.

[0061] It should be noted that at night / on cloudy days, the photovoltaic array cannot generate electricity or its power generation is low, while the wind turbine will continue to generate electricity as long as there is wind. Therefore, under normal circumstances, at night / on cloudy days, when the photovoltaic power generation requirements are not met but the wind power generation requirements are met, the wind turbine will continue to generate electricity and the photovoltaic array will stop generating electricity. In other words, the wind power DC busbar remains powered at night / on cloudy days. Under normal circumstances, the voltage of the wind power DC busbar is about 1050V, and its positive pole to ground voltage is about +500V.

[0062] Specifically, when the PID-repaired DC / DC converter is in normal power generation mode, the PID-repaired DC / DC converter converts the DC power of the photovoltaic array into DC power with the same voltage as the wind power DC bus, and outputs the converted DC power to the wind power DC bus, so that the grid-side converter also converts the generated electric energy of the photovoltaic array, and outputs the converted AC power to the transformer for the transformer to perform voltage conversion and then output to the power grid.

[0063] When the PID repair DC / DC converter is in the PID repair mode, such as at night / on cloudy days, the PID repair DC / DC converter does not perform DC conversion, that is, does not output DC to the wind power DC bus, and its negative branch is disconnected, and its positive branch is connected to the wind power DC bus. At this time, the common-mode voltage of the positive pole of the photovoltaic module in the photovoltaic array to the ground will be automatically clamped by the wind power DC bus to the positive pole voltage of the wind power DC bus, that is, the common-mode voltage of the positive pole of the photovoltaic module to the ground is greater than 0, and then the voltage on the wind power DC bus is used to perform PID repair on the photovoltaic array to reduce the PID effect of the photovoltaic array.

[0064] That is to say, in normal power generation mode, the power generated by the wind turbine and the photovoltaic array are both output to the grid to achieve economic benefits; in PID repair mode, only the power generated by the wind turbine is output to the grid, and part of the power generated by the wind turbine is used to perform PID repair on the photovoltaic array.

[0065] In this embodiment, while realizing photovoltaic complementary power generation between the photovoltaic array and the wind turbine, the influence of the PID effect on the power generation of the photovoltaic array can be reduced by the electric energy on the wind power DC bus, avoiding the increase of the neutral point voltage of the wind turbine, thereby improving the power generation and safety of the DC-coupled wind-solar complementary system.

[0066] It is also worth noting that a photovoltaic array repair method suitable for photovoltaic systems is proposed in the prior art. Specifically, a switch is added to the negative pole of the DC side of the inverter, and the switch is disconnected when repair is required. However, in this solution, the inverter needs to provide additional DC voltage in reverse during repair, and the additional DC voltage is generally obtained by AC rectification, the voltage is low, and the repair effect is poor.

[0067] In this embodiment, a PID repair type DC / DC converter is set between the grid-side converter and the photovoltaic array, so that in the PID repair mode, the voltage on the wind power DC bus is used to perform PID repair. The voltage on the wind power DC bus is higher and the repair effect is better.

[0068] Optionally, in an embodiment of the present invention, the above-mentioned PID repair type DC / DC converter includes a DC / DC circuit.

[0069] The input end of the DC / DC circuit serves as the input end of the PID repair DC / DC converter and is connected to the output end of the photovoltaic array. The output end of the DC / DC circuit serves as the output end of the PID repair DC / DC converter and is connected to the wind power DC bus.

[0070] The DC / DC circuit is a Buck circuit, a Boost circuit, or a deformed circuit based on a Buck circuit or a Boost circuit, such as a mirror Buck circuit and a mirror Boost circuit. The Buck circuit refers to a conventional Buck circuit with an inductor arranged on the positive branch, the Boost circuit refers to a conventional Boost circuit with an inductor arranged on the positive branch, the mirror Buck circuit refers to a circuit with an inductor arranged on the negative branch and a mirror structure with a conventional Buck circuit, and the mirror Boost circuit refers to a circuit with an inductor arranged on the negative branch and a mirror structure with a conventional Boost circuit. Here, the DC / DC circuit is described as a Buck circuit, a Boost circuit, a mirror Buck circuit, and a mirror Boost circuit.

[0071] (1) See Figure 3 , the DC / DC circuit is a mirror boost circuit, which includes: a first input capacitor Cin1, a first output capacitor Cout1, a first inductor L1, a first diode D1 and a first switch tube Q1, wherein:

[0072] The positive and negative electrodes of the first input capacitor Cin1 serve as the positive and negative electrodes of the input end of the mirror Boost circuit respectively; the positive and negative electrodes of the first output capacitor Cout1 serve as the positive and negative electrodes of the output end of the mirror Boost circuit respectively; one end of the first inductor L1 is connected to the positive electrode of the first input capacitor Cin1, and the other end is connected to the cathode of the first diode D1 and one end of the first switch tube Q1 respectively; the anode of the first diode D1 is connected to the negative electrode of the first output capacitor Cout1; the other end of the first switch tube Q1 is connected to the positive electrode of the first input capacitor Cin1 and the positive electrode of the first output capacitor Cout1 respectively.

[0073] If the electrical parameters of the photovoltaic array meet the PID repair conditions, the mirror Boost circuit disconnects itself from the negative electrode of the photovoltaic array by reversely cutting off the first diode D1 set on its own negative branch, and clamps the positive voltage of the photovoltaic array by the positive voltage on the wind power DC bus to achieve PID repair; if the electrical parameters of the photovoltaic array do not meet the PID repair conditions, the mirror Boost circuit connects the negative electrode of the wind power DC bus with the negative electrode of the photovoltaic array by forward conducting the first diode D1 set on its own negative branch, so as to output the generated electric energy of the photovoltaic array to the wind power DC bus.

[0074] That is to say, the photovoltaic array automatically generates electricity during the day, and when the photovoltaic array cannot generate electricity at night, that is, when there is no electricity at its output end or the output voltage is very low, the mirror Boost circuit stops working due to the reverse cutoff of the first diode D1. At this time, since the positive electrode of the photovoltaic array is still connected to the wind power DC bus, the positive electrode voltage on the wind power DC bus is automatically clamped to a level greater than 0.

[0075] In this embodiment, the characteristics of the mirror Boost circuit are utilized to realize the automatic PID repair function, and the circuit cost is relatively low.

[0076] (2) See Figure 4 ( Figure 4 The wind turbine, transformer, machine-side converter and grid-side converter are not shown in the figure). When the DC / DC circuit is a mirror Buck circuit, the PID repair DC / DC converter also includes: a switching power supply that draws power from the photovoltaic array, and the mirror Buck circuit includes: a second input capacitor Cin2, a second output capacitor Cout2, a second inductor L2, a second diode D2 and a second switch tube Q2, wherein:

[0077] The positive and negative electrodes of the second input capacitor Cin2 serve as the positive and negative electrodes of the input end of the mirror Buck circuit; the positive and negative electrodes of the second output capacitor Cout2 serve as the positive and negative electrodes of the output end of the mirror Buck circuit; one end of the second inductor L2 is connected to the negative electrode of the second output capacitor Cout2, and the other end is respectively connected to one end of the second switch tube Q2 and the anode of the second diode D2; the other end of the second switch tube Q2 is connected to the negative electrode of the second input capacitor Cin2; the cathode of the second diode D2 is respectively connected to the positive electrode of the second input capacitor Cin2 and the positive electrode of the second output capacitor Cout2.

[0078] One end of the switching power supply is connected to the output end of the photovoltaic array to obtain power from the photovoltaic array; the other end of the switching power supply is connected to the control end of the second switch tube Q2 to provide power to the second switch tube Q2 to keep it in a closed state.

[0079] If the electrical parameters of the photovoltaic array meet the PID repair conditions, the mirror Buck circuit controls the second switch tube Q2 set on its own negative branch to be disconnected by powering off the switching power supply, so that the connection between itself and the negative pole of the photovoltaic array is disconnected; at the same time, the positive voltage of the photovoltaic array is clamped by the positive voltage on the wind power DC bus to achieve PID repair; if the electrical parameters of the photovoltaic array do not meet the PID repair conditions, the mirror Buck circuit controls the second switch tube Q2 set on its own negative branch to be closed by powering on the switching power supply, so that itself is connected to the negative pole of the photovoltaic array, so as to output the generated electric energy of the photovoltaic array to the wind power DC bus.

[0080] That is to say, when the photovoltaic array can generate electricity during the day, the switching power supply draws power from the photovoltaic array and drives the second switch tube Q2 to turn on, and the mirror Buck circuit maintains the normal power generation mode. In the evening to night, when the output voltage of the photovoltaic array is very low, the switching power supply will automatically cut off the power, and the second switch tube Q2 will automatically disconnect when it loses power, so that the mirror Buck circuit can also automatically enter the PID repair mode. In this embodiment, the output voltage of the photovoltaic array is used as a driving signal to drive the second switch tube Q2, reducing the circuit cost.

[0081] (3) See Figure 5 ( Figure 5 The fan, transformer, machine-side converter and grid-side converter are not shown in the figure). If the DC / DC circuit is a Buck circuit, the PID repair type DC / DC converter further includes: a first controllable switch K1; the Buck circuit includes: a fourth input capacitor Cin4, a fourth output capacitor Cout4, a fourth inductor L4, a fourth diode D4 and a fourth switch tube Q4, wherein:

[0082] The positive and negative electrodes of the fourth input capacitor Cin4 serve as the positive and negative electrodes of the input end of the Buck circuit; the positive and negative electrodes of the fourth output capacitor Cout4 serve as the positive and negative electrodes of the output end of the Buck circuit; one end of the fourth inductor L4 is connected to the positive electrode of the fourth output capacitor Cout4, and the other end is respectively connected to one end of the fourth switch tube Q4 and the cathode of the fourth diode D4; the other end of the fourth switch tube Q4 is connected to the negative electrode of the fourth input capacitor Cin4; the anode of the fourth diode D4 is respectively connected to the negative electrode of the fourth input capacitor Cin4 and the negative electrode of the fourth output capacitor Cout4.

[0083] In practical applications, the first controllable switch K1 has multiple connection relationships. One connection relationship is: the first controllable switch K1 is set between the negative electrode of the fourth input capacitor Cin4 in the Buck circuit and the negative electrode of the photovoltaic array, that is, one end of the first controllable switch K1 is connected to the negative electrode of the fourth input capacitor Cin4, and the other end of the first controllable switch K1 is connected to the negative electrode of the photovoltaic array (such as Figure 5 As shown). Another connection relationship is: the first controllable switch K1 is arranged between the cathode of the fourth input capacitor Cin4 in the Buck circuit and the anode of the fourth diode D4 in the Buck circuit, that is, one end of the first controllable switch K1 is connected to the cathode of the fourth input capacitor Cin4, and the other end of the first controllable switch K1 is connected to the anode of the fourth diode D4 (not shown). Another connection relationship is: the first controllable switch K1 is arranged between the cathode of the fourth output capacitor Cout4 in the Buck circuit and the anode of the fourth diode D4 in the Buck circuit, that is, one end of the first controllable switch K1 is connected to the cathode of the fourth output capacitor Cout4, and the other end of the first controllable switch K1 is connected to the anode of the fourth diode D4 (not shown).

[0084] If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the Buck circuit controls the disconnection between itself and the negative pole of the photovoltaic array by disconnecting the first controllable switch K1, and at the same time closes the fourth switch tube Q4 on its own positive branch, so that the positive voltage on the wind power DC bus clamps the positive pole of the photovoltaic array to achieve PID repair. However, if the electrical parameters of the photovoltaic array do not meet the PID repair conditions and the DC-coupled photovoltaic complementary system does not receive a PID repair instruction, the Buck circuit controls itself to be connected to the negative pole of the photovoltaic array by closing the first controllable switch K1, and at the same time performs corresponding actions through the fourth switch tube Q4 on its own positive branch to achieve the output of the generated electricity of the photovoltaic array to the wind power DC bus.

[0085] In practical applications, the PID repair type DC / DC converter may also include a fourth controllable switch (not shown); one end of the fourth controllable switch is connected to the positive electrode of the fourth input capacitor Cin4, and the other end is connected to the positive electrode of the fourth output capacitor Cout4. When the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the fourth controllable switch is controlled to close so that the positive voltage on the wind power DC bus clamps the positive electrode of the photovoltaic array, while reducing (when the fourth switch tube Q4 is also closed) or avoiding (when the fourth switch tube Q4 is disconnected) the loss on the fourth inductor L4; when the electrical parameters of the photovoltaic array meet the PID repair conditions and the DC-coupled wind-solar complementary system receives a PID repair instruction, the fourth controllable switch is controlled to open.

[0086] (4) See Figure 6 ( Figure 6 The fan, transformer, machine-side converter and grid-side converter are not shown in the figure). If the DC / DC circuit is a Boost circuit, the PID repair type DC / DC converter further includes: a second controllable switch K2 and a third controllable switch K3; the Boost circuit includes: a third input capacitor Cin3, a third output capacitor Cout3, a third inductor L3, a third diode D3 and a third switch tube Q3; wherein:

[0087] The two ends of the third input capacitor Cin3 serve as the positive and negative electrodes of the input end of the Boost circuit respectively; the positive and negative electrodes of the third output capacitor Cout3 serve as the positive and negative electrodes of the output end of the Boost circuit; one end of the third inductor L3 is connected to the positive electrode of the third input capacitor Cin3, and the other end is connected to the anode of the third diode D3 and one end of the third switch tube Q3 respectively; the cathode of the third diode D3 is connected to the positive electrode of the third output capacitor Cout3; the other end of the third switch tube Q3 is connected to the negative electrode of the third input capacitor Cin3 and the negative electrode of the third output capacitor Cout3 respectively.

[0088] In practical applications, the third controllable switch K3 has a variety of connection relationships. Specifically, one connection relationship is: the third controllable switch K3 is set between the negative electrode of the third input capacitor Cin3 in the Boost circuit and the negative electrode of the photovoltaic array, that is, one end of the third controllable switch K3 is connected to the negative electrode of the third input capacitor Cin3, and the other end of the third controllable switch K3 is connected to the negative electrode of the photovoltaic array (such as Figure 6As shown). Another connection relationship is: the third controllable switch K3 is arranged between the negative electrode of the third input capacitor Cin3 in the Boost circuit and one end of the third switch tube Q3 in the Boost circuit, that is, one end of the third controllable switch K3 is connected to the negative electrode of the third input capacitor Cin3, and the other end of the third controllable switch K3 is connected to one end of the third switch tube Q3 (not shown). Another connection relationship is: the third controllable switch K3 is arranged between the negative electrode of the third output capacitor Cout3 in the Boost circuit and one end of the third switch tube Q3 in the Boost circuit, that is, one end of the third controllable switch K3 is connected to the negative electrode of the third output capacitor Cout3, and the other end of the third controllable switch K3 is connected to one end of the third switch tube Q3 (not shown).

[0089] The second controllable switch K2 also has a variety of connection relationships, such as the second controllable switch K2 is connected in parallel with the third diode D3 in the Boost circuit (not shown); or, one end of the second controllable switch K2 is connected to the positive electrode of the third input capacitor Cin3 in the Boost circuit, and the other end of the second controllable switch K2 is connected to the positive electrode of the third output capacitor Cout3 in the Boost circuit (such as Figure 6 shown).

[0090] If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the Boost circuit controls the disconnection between itself and the negative pole of the photovoltaic array by disconnecting the third controllable switch K3, and controls itself to be connected to the positive pole of the photovoltaic array by closing the second controllable switch K2, so that the positive pole voltage on the wind power DC bus clamps the positive pole of the photovoltaic array to achieve PID repair. However, if the electrical parameters of the photovoltaic array do not meet the PID repair conditions and the DC-coupled photovoltaic complementary system does not receive a PID repair instruction, the Boost circuit controls itself to be connected to the negative pole of the photovoltaic array by closing the third controllable switch K3, and disconnects the second controllable switch K2 on its own positive branch to achieve the output of the generated electricity of the photovoltaic array to the wind power DC bus.

[0091] It is also worth mentioning that in the existing technical solution of adding a switch to the negative pole of the DC side of the inverter, this solution is only applicable to traditional single-stage inverters. For inverters with DC / DC links, due to the presence of devices such as diodes, the common-mode voltage cannot be effectively established, there are limitations, it cannot work reliably, and the safety of the circuit is reduced.

[0092] In this embodiment, on the basis of a conventional DC / DC circuit, a parallel controllable switch is additionally provided for the diode branch on the positive branch of the DC / DC circuit, and the controllable switch is controlled to be closed to short-circuit the diode; or, the diode is placed on its own negative branch to make the diode reverse cutoff and automatically disconnected, thereby avoiding the problem that the above scheme cannot effectively establish a common-mode voltage and has limitations, and the circuit can operate safely and reliably.

[0093] In practical applications, the first controllable switch K1, the second controllable switch K2, the third controllable switch K3 and the fourth controllable switch are mechanical switches or electronic switches. Specifically, the first to fourth controllable switches can be IGBTs (Insulated Gate Bipolar Transistor) or relays. Mechanical switches are preferred because they have a smaller on-resistance and a larger off-resistance.

[0094] Optional, see also Figure 5 , the DC-coupled wind-solar complementary system also includes: a controller and an auxiliary power supply.

[0095] The input end of the controller is connected to the output end of the electrical parameter detection device in the DC-coupled wind-solar hybrid system to detect the electrical parameters of the photovoltaic array through the electrical parameter detection device. The output end of the controller is connected to the control end of the PID repair type DC / DC converter, that is, the output end of the controller is respectively connected to the control end of the first controllable switch K1 and the fourth switch tube Q4; in addition, the controller can also be provided with a communication end for receiving PID repair instructions. The input end of the auxiliary power supply is connected to the wind power DC bus, and the output end of the auxiliary power supply is connected to the power supply end of the controller, that is, the auxiliary power supply is powered from the wind power DC bus, so that there will be no power outage at night / on cloudy days, and the power supply of the controller will not be affected, that is, control can be performed at night.

[0096] It should be noted that the controller can be a controller in a PID repair type DC / DC converter or a system controller, which is not specifically limited here and can be determined according to the actual situation, all of which are within the protection scope of this application. The above electrical parameters can be parameters such as the output voltage, output power and output current of the photovoltaic array, which are not specifically limited here and are within the protection scope of this application.

[0097] Of course, in Figure 6 On the basis of, the DC-coupled wind-solar hybrid system can also include: a controller and an auxiliary power supply, and the specific connection relationship is the same as Figure 5 The connection relationships shown are similar and will not be described in detail here.

[0098] by Figure 6 The working principle is described as follows:

[0099] When the controller detects an electrical parameter less than a corresponding threshold value through the electrical parameter detection device or receives an external PID repair instruction, the controller controls the third controllable switch K3 (or Figure 5 The first controllable switch K1 in the circuit is disconnected, and the second controllable switch K2 (or Figure 5 The fourth switch tube Q4 in the power supply is closed, so that the positive electrode of the photovoltaic array is connected to the positive electrode of the wind power DC bus, thereby realizing PID repair.

[0100] If in Figure 5 On the basis of, it also includes a fourth controllable switch. When the electrical parameter detected by the controller through the electrical parameter detection device is less than the corresponding threshold or receives an external PID repair instruction, the first controllable switch K1 is controlled to be disconnected and the fourth controllable switch is closed.

[0101] It should be noted that repair through external PID repair instructions is active repair, that is, actively switching between two modes, and repair through electrical parameters is automatic repair. Active repair and / or self-repair methods can be selected according to actual conditions. No specific limitations are made here, and all are within the scope of protection of this application.

[0102] Optionally, in the above-mentioned embodiment of the present invention Figure 2-Figure 6 On the basis of Figure 7 (exist Figure 6 The DC-coupled wind-solar complementary system also includes: PID power supply.

[0103] One end of the PID power supply is connected to the negative pole of the photovoltaic array, and the other end is grounded.

[0104] In this embodiment, by setting a PID power supply at the negative pole of the photovoltaic array, the common mode voltage of the system can be further raised within a safe range to improve the PID repair effect of the photovoltaic array; wherein, the voltage of the PID power supply can be determined according to actual conditions and is not specifically limited here, and all are within the protection scope of this application.

[0105] In the implementation of the present invention, a variety of PID repair DC / DC converters are provided. Compared with isolated DC / DC circuits, they have lower costs, or even no hardware cost increase, and have reduced impact on the conversion efficiency of the grid-side converter. They solve the PID repair problem of photovoltaic arrays in DC-coupled wind-solar complementary systems and are suitable for various types of DC / DC circuits with wide adaptability.

[0106] The embodiment of the present invention provides a photovoltaic PID repair control method for a DC-coupled wind-solar complementary system, which is applied to the above embodiment. Figure 2, 5-7 any of the controllers of the DC-coupled wind-solar complementary system, the controller can be a system controller, or a controller in a PID repair type DC / DC converter. The specific structure of the DC-coupled wind-solar complementary system can be referred to the above embodiment, which will not be described here one by one.

[0107] The photovoltaic PID repair control method of the DC-coupled wind-solar hybrid system is shown in Figure 8 ,include:

[0108] S101, judging whether the electrical parameters of the photovoltaic array meet the PID repair conditions or whether the DC-coupled wind-solar complementary system receives a PID repair instruction.

[0109] Before determining whether the electrical parameters of the photovoltaic array meet the PID repair condition in step S101, the method further includes: detecting the electrical parameters of the photovoltaic array. The electrical parameters may be parameters such as the output voltage, output power and output current of the photovoltaic array, and the electrical parameters include at least one of the output voltage, output power and output current.

[0110] In practical applications, the specific process of judging whether the electrical parameters of the photovoltaic array meet the PID repair conditions is: judging whether the electrical parameters of the photovoltaic array are less than the corresponding threshold value.

[0111] Specifically, if the electrical parameters include output voltage, then determine whether the output voltage of the photovoltaic array is less than a voltage threshold value such as 100V. If the electrical parameters include output voltage, output power and output current, then determine whether the output voltage of the photovoltaic array is less than the voltage threshold, whether the output power is less than the power threshold and whether the output current is less than the current threshold. Of course, when the electrical parameters include other parameters, the process of determining whether the electrical parameters of the photovoltaic array are less than the corresponding threshold is similar to the above, and will not be repeated here one by one, all within the scope of protection of this application. The electrical parameters are not specifically limited here, and can be determined according to the actual situation, all within the scope of protection of this application.

[0112] If the electrical parameters of the photovoltaic array are less than the corresponding threshold value, it is determined that the electrical parameters of the photovoltaic array meet the PID repair conditions, that is, step S102 is executed; if the electrical parameters of the photovoltaic array are greater than or equal to the corresponding threshold value, it is determined that the electrical parameters of the photovoltaic array do not meet the PID repair conditions, that is, step S103 is executed.

[0113] S102, controlling the negative branch of the PID repair type DC / DC converter in the DC-coupled wind-solar hybrid system to be disconnected, and controlling the positive pole of the photovoltaic array to be clamped to the positive pole on the wind power DC bus in the DC-coupled wind-solar hybrid system through the positive branch of the PID repair type DC / DC converter, so as to achieve PID repair.

[0114] In practical applications, the specific process of controlling the disconnection of the negative branch of the PID repair type DC / DC converter in the DC-coupled wind-solar hybrid system involved in step S102 is: controlling the switch on the negative branch to be disconnected. The specific process of controlling the positive electrode of the photovoltaic array to be clamped by the positive electrode of the wind power DC busbar in the DC-coupled wind-solar hybrid system through the positive branch of the PID repair type DC / DC converter involved in step S102 is: controlling the switch on the positive branch to be closed, so that the positive voltage on the wind power DC busbar clamps the positive electrode of the photovoltaic array.

[0115] Among them, see Figure 6 When the PID repair type DC / DC converter is a Boost circuit, the switch on the negative branch is the third controllable switch K3, and the switch on the positive branch is the second controllable switch K2. Figure 5 When the PID repair type DC / DC converter is a Buck circuit, the switch on the negative branch is the first controllable switch K1, and the switch on the positive branch is the fourth switch tube Q4 in the Buck circuit. Alternatively, when the PID repair type DC / DC converter includes a Buck circuit and a fourth controllable switch, the switch on the negative branch is the first controllable switch K1, and the switch on the positive branch is the fourth controllable switch.

[0116] S103 , controlling the PID repair type DC / DC converter to be in a normal power generation mode.

[0117] When the PID-repaired DC / DC converter is in normal power generation mode, the PID-repaired DC / DC converter converts the DC power of the photovoltaic array into high-voltage / low-voltage DC power, and outputs the converted DC power to the wind power DC bus in the DC-coupled wind-solar complementary system, so that the grid-side converter in the DC-coupled wind-solar complementary system converts the generated electric energy of the photovoltaic array and the wind turbine, and the converted AC power is output to the transformer in the DC-coupled wind-solar complementary system for the transformer to step up / down the voltage and then output to the power grid.

[0118] In this embodiment, whether the PID repair type DC / DC converter needs to enter the PID repair mode is determined by the electrical parameters of the photovoltaic array and the PID repair instruction. It is simple to control the PID repair type DC / DC converter to enter the PID repair mode, which is conducive to popularization and use.

[0119] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0120] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0121] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A DC-coupled wind-solar hybrid system, characterized in that: include: Wind turbines, photovoltaic arrays, potential induced decay PID repair type DC / DC converters, transformers, machine-side converters and grid-side converters; among them: The AC side of the machine-side converter is connected to the output end of the wind turbine, and the DC side of the machine-side converter and the DC side of the grid-side converter are both connected to the wind power DC bus; The AC side of the grid-side converter is connected to the grid through the transformer; The input end of the PID repair type DC / DC converter is connected to the output end of the photovoltaic array, and the output end of the PID repair type DC / DC converter is connected to the wind power DC bus; The PID repair type DC / DC converter is used to switch from the normal power generation mode to the PID repair mode when the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, and perform PID repair on the photovoltaic array with the voltage on the wind power DC bus; Wherein, the PID repair type DC / DC converter comprises: a DC / DC circuit; the DC / DC circuit is a Buck circuit or a Boost circuit; If the DC / DC circuit is the Buck circuit, the PID repair type DC / DC converter further includes: a first controllable switch; the first controllable switch controls the connection between the Buck circuit and the negative pole of the photovoltaic array; If the DC / DC circuit is the Boost circuit, the PID repair DC / DC converter also includes: a second controllable switch and a third controllable switch; the second controllable switch controls the connection between the Boost circuit and the positive pole of the photovoltaic array; the third controllable switch controls the connection between the Boost circuit and the negative pole of the photovoltaic array.

2. The DC-coupled wind-solar hybrid system according to claim 1, characterized in that: The input end of the DC / DC circuit serves as the input end of the PID repair type DC / DC converter, and the output end of the DC / DC circuit serves as the output end of the PID repair type DC / DC converter.

3. The DC-coupled wind-solar hybrid system according to claim 2, characterized in that: When the DC / DC circuit is a mirror boost circuit, if the electrical parameters of the photovoltaic array meet the PID repair conditions, the mirror boost circuit disconnects itself from the negative electrode of the photovoltaic array by reverse cutoff of the diode arranged on its own negative branch, and at the same time clamps the positive voltage of the photovoltaic array by the positive voltage on the wind power DC bus to achieve PID repair.

4. The DC-coupled wind-solar hybrid system according to claim 2, characterized in that: When the DC / DC circuit is a mirrored Buck circuit, the PID repair type DC / DC converter further comprises: a switching power supply that draws power from the photovoltaic array; If the electrical parameters of the photovoltaic array meet the PID repair conditions, the mirror Buck circuit controls the switch tube arranged on its own negative branch to disconnect by losing power to the switching power supply, so as to disconnect itself from the negative pole of the photovoltaic array; at the same time, the positive voltage of the photovoltaic array is clamped by the positive voltage on the wind power DC bus to achieve PID repair.

5. The DC-coupled wind-solar hybrid system according to claim 2, characterized in that: If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the Buck circuit controls the disconnection between itself and the negative pole of the photovoltaic array by disconnecting the first controllable switch, and at the same time closes the switch tube on its own positive branch to clamp the positive pole of the photovoltaic array with the positive voltage on the wind power DC bus to achieve PID repair.

6. The DC-coupled wind-solar hybrid system according to claim 5, characterized in that: The first controllable switch is arranged between the negative electrode of the input capacitor in the Buck circuit and the negative electrode of the photovoltaic array; Alternatively, the first controllable switch is arranged between the cathode of the input capacitor in the Buck circuit and the anode of the diode in the Buck circuit; Alternatively, the first controllable switch is arranged between the cathode of the output capacitor in the Buck circuit and the anode of the diode in the Buck circuit.

7. The DC-coupled wind-solar hybrid system according to claim 2, characterized in that: If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the Boost circuit controls the disconnection between itself and the negative pole of the photovoltaic array by opening the third controllable switch, and controls itself to be connected to the positive pole of the photovoltaic array by closing the second controllable switch, so that the positive pole voltage on the wind power DC bus clamps the positive pole of the photovoltaic array to achieve PID repair.

8. The DC-coupled wind-solar hybrid system according to claim 7, characterized in that: The third controllable switch is arranged between the negative electrode of the input capacitor in the Boost circuit and the negative electrode of the photovoltaic array, or between the negative electrode of the input capacitor in the Boost circuit and one end of the switch tube in the Boost circuit, or between the negative electrode of the output capacitor in the Boost circuit and one end of the switch tube in the Boost circuit; The second controllable switch is connected in parallel with the diode in the Boost circuit, or one end of the second controllable switch is connected to the positive electrode of the input capacitor in the Boost circuit, and the other end of the second controllable switch is connected to the positive electrode of the output capacitor in the Boost circuit.

9. The DC-coupled wind-solar hybrid system according to any one of claims 5 to 8, characterized in that: Also includes: Controller and auxiliary power supply; The input end of the controller is connected to the output end of the electrical parameter detection device in the DC-coupled wind-solar complementary system, so as to detect the electrical parameters of the photovoltaic array through the electrical parameter detection device, and the output end of the controller is connected to the control end of the PID repair type DC / DC converter; The input end of the auxiliary power supply is connected to the wind power DC bus, and the output end of the auxiliary power supply is connected to the power supply end of the controller.

10. The DC-coupled wind-solar hybrid system according to any one of claims 6 to 8, characterized in that: The first controllable switch, the second controllable switch and the third controllable switch are mechanical switches or electronic switches.

11. The DC-coupled wind-solar hybrid system according to any one of claims 1 to 8, characterized in that: Also includes: PID power supply; One end of the PID power supply is connected to the negative pole of the photovoltaic array, and the other end is grounded.

12. A photovoltaic PID repair control method for a DC-coupled wind-solar hybrid system, characterized in that: The DC-coupled wind-solar hybrid system according to any one of claims 1 to 11 comprises: Determine whether the electrical parameters of the photovoltaic array meet the PID repair conditions or whether the DC-coupled wind-solar complementary system receives a PID repair instruction; If the electrical parameters of the photovoltaic array meet the PID repair conditions or the DC-coupled wind-solar complementary system receives a PID repair instruction, the negative branch of the PID repair type DC / DC converter in the DC-coupled wind-solar complementary system is controlled to be disconnected, and the positive electrode of the photovoltaic array is controlled by the positive branch of the PID repair type DC / DC converter to be clamped by the positive electrode on the wind power DC bus in the DC-coupled wind-solar complementary system to achieve PID repair; If the electrical parameters of the photovoltaic array do not meet the PID repair conditions and the DC-coupled wind-solar complementary system does not receive a PID repair instruction, the PID repair type DC / DC converter is controlled to be in a normal power generation mode.

13. The photovoltaic PID repair control method of the DC-coupled wind-solar hybrid system according to claim 12, characterized in that: Before judging whether the electrical parameters of the photovoltaic array meet the PID repair condition, the method further includes: The electrical parameters of the photovoltaic array are detected.

14. The photovoltaic PID repair control method of the DC-coupled wind-solar hybrid system according to claim 12, characterized in that: Determining whether the electrical parameters of the photovoltaic array meet the PID repair conditions includes: Determining whether an electrical parameter of the photovoltaic array is less than a corresponding threshold; If the electrical parameter of the photovoltaic array is less than the corresponding threshold, it is determined that the electrical parameter of the photovoltaic array meets the PID repair condition; if the electrical parameter of the photovoltaic array is greater than or equal to the corresponding threshold, it is determined that the electrical parameter of the photovoltaic array does not meet the PID repair condition.

15. The photovoltaic PID repair control method of the DC-coupled wind-solar hybrid system according to any one of claims 12 to 14, characterized in that: Controlling the negative branch of the PID repair type DC / DC converter in the DC-coupled wind-solar complementary system to be disconnected includes: controlling the switch on the negative branch to be disconnected; Controlling the positive electrode of the photovoltaic array to be clamped by the positive electrode on the wind power DC bus in the DC-coupled wind-solar complementary system through the positive electrode branch of the PID repair type DC / DC converter, including: controlling the switch on the positive electrode branch to close, so that the positive electrode voltage on the wind power DC bus clamps the positive electrode of the photovoltaic array; Among them, when the PID repair type DC / DC converter is a Boost circuit, the switch on the negative branch is a third controllable switch, and the switch on the positive branch is a second controllable switch; when the PID repair type DC / DC converter is a Buck circuit, the switch on the negative branch is a first controllable switch, and the switch on the positive branch is a switch tube in the Buck circuit.

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