WO2020125270A1 - 电势诱导衰减的补偿电路、方法、功率模块及光伏系统 - Google Patents

电势诱导衰减的补偿电路、方法、功率模块及光伏系统 Download PDF

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Publication number
WO2020125270A1
WO2020125270A1 PCT/CN2019/117314 CN2019117314W WO2020125270A1 WO 2020125270 A1 WO2020125270 A1 WO 2020125270A1 CN 2019117314 W CN2019117314 W CN 2019117314W WO 2020125270 A1 WO2020125270 A1 WO 2020125270A1
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Prior art keywords
converter
compensation circuit
photovoltaic
voltage
photovoltaic module
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PCT/CN2019/117314
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English (en)
French (fr)
Inventor
陈保国
陈潘
黄应培
王凤茹
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP19899612.6A priority Critical patent/EP3886284A4/en
Publication of WO2020125270A1 publication Critical patent/WO2020125270A1/zh
Priority to US17/351,988 priority patent/US20210313929A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • H02S50/10—Testing of PV devices, e.g. of PV modules or single PV cells
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/38—Energy storage means, e.g. batteries, structurally associated with PV modules
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

Definitions

  • the present invention relates to the field of power electronics technology, and in particular to a compensation circuit, method, power module, and photovoltaic system for potential-induced attenuation.
  • PID is related to environmental factors, materials of photovoltaic modules, and grounding methods of inverter arrays. However, even with photovoltaic modules using the most advanced materials, PID effects are inevitable.
  • the present invention provides a compensation circuit, method, power module, and photovoltaic system for potential-induced attenuation, which can compensate PID, improve the power generation efficiency of photovoltaic modules, and increase the benefits of power stations.
  • An embodiment of the present application provides a compensation circuit for potential induced attenuation, which is applied to a photovoltaic system.
  • the photovoltaic system includes: a photovoltaic component, an inverter, a first DC-DC converter, and a battery; the first of the first DC-DC converter The terminal is connected to the battery, and the second end of the first DC-DC converter is connected to the input end of the inverter;
  • the compensation circuit includes: a switch, a first resistor and a controller; the switch and the first resistor are connected in series; the first end of the compensation circuit is connected The positive output terminal PV+ of the photovoltaic module; the second terminal of the compensation circuit is connected to the second terminal of the first DC-DC converter; the controller is used to control the switch to close when the output voltage of the photovoltaic module is less than the preset voltage, so that The first DC-DC converter provides the electric energy of the battery to the second end of the compensation circuit; a second resistor is connected between the positive output end PV+ and the
  • the first resistance and the second resistance and the equivalent resistance (third resistance) between the negative output terminal PV- and the ground PE of the photovoltaic module divide the voltage at the second terminal of the first DC-DC converter, because PE is 0 potential, the voltage of PV- is the voltage on the third resistance, so the voltage of PV- is higher than PE, that is, PV- is a positive voltage relative to PE, this solution is equivalent to raising the voltage of PV-to-ground, so as to achieve PID compensation.
  • the controller is also used to control the switch to open when the output voltage of the photovoltaic module is greater than or equal to the preset voltage.
  • the compensation circuit may further include: a diode; the diode is connected in series with the switch and the first resistor; the anode of the diode is close to the side of the second end of the first DC-DC converter, and the cathode of the diode is close to One side of PV+. That is, when the output voltage of the photovoltaic module is greater than or equal to the preset voltage, the switch malfunctions and the current flows from PV+ to the input terminal of the inverter when the switch is closed, that is, the path of the compensation circuit during the day is disconnected, and no current flows.
  • the compensation circuit may further include: a voltage detection circuit; used to detect the output voltage of the photovoltaic module and send the output voltage to the controller, so that the controller determines when the switch is closed and when it is opened according to the output voltage.
  • a voltage detection circuit used to detect the output voltage of the photovoltaic module and send the output voltage to the controller, so that the controller determines when the switch is closed and when it is opened according to the output voltage.
  • the switch may be selected according to actual needs, for example, it may be one of a relay, a contactor, a circuit breaker, or an insulated gate bipolar transistor IGBT, or a combination of multiple types.
  • an embodiment of the present application also provides a compensation method for potential-induced attenuation, which is applied to the compensation circuit described above.
  • the method includes: when the output voltage of the photovoltaic module is less than a preset voltage, the control switch is closed so that the first A DC-DC converter works to provide battery power to the second end of the compensation circuit; a second resistor is connected between the positive output terminal PV+ and the negative output terminal PV- of the photovoltaic module. It can effectively compensate the PID generated by the photovoltaic module, thereby improving the power generation efficiency.
  • the embodiments of the present application also provide a power module applied to a photovoltaic system.
  • the compensation circuit described above is integrated into the power module.
  • the power module is applied to a photovoltaic system.
  • the photovoltaic system includes: a photovoltaic component and an inverter 1.
  • the first DC-DC converter and the battery The first DC-DC converter and the battery; the first end of the first DC-DC converter is connected to the battery, and the second end of the first DC-DC converter is connected to the input end of the inverter; the power module further includes a second DC-DC converter; the input end of the second DC-DC converter is connected to the output end of the photovoltaic module, the output end of the second DC-DC converter is connected to the input end of the inverter; the second DC-DC converter connects the photovoltaic The output voltage of the component is boosted and provided to the input end of the inverter.
  • the power module can not only boost the output voltage of the photovoltaic module, but also compensate for the PID generated by the photovoltaic module and improve the power generation efficiency of the photovoltaic module.
  • an embodiment of the present application further provides a photovoltaic system, including the compensation circuit described above; further including: a photovoltaic module, an inverter, a first DC-DC converter, and a battery; and a first DC-DC converter The first end is connected to the battery, the second end of the first DC-DC converter is connected to the input end of the inverter; the compensation circuit is used to induce the potential attenuation of the photovoltaic module when the output voltage of the photovoltaic module is less than the preset voltage make up.
  • the photovoltaic system can compensate the PID of the photovoltaic component through a compensation circuit, thereby improving the power generation efficiency of the photovoltaic system.
  • the photovoltaic system further includes: a second DC-DC converter, the input end of the second DC-DC converter is connected to the output end of the photovoltaic module, and the output end of the second DC-DC converter is connected to the input end of the inverter
  • the second DC-DC converter is used to boost the output voltage of the photovoltaic module and provide it to the input end of the inverter.
  • the first DC-DC converter is a bidirectional DC-DC converter; the controller is also used to use the photovoltaic module when the output voltage of the photovoltaic module is greater than or equal to the preset voltage and the battery power is lower than the preset power
  • the battery is charged in sequence through the second DC-DC converter and the first DC-DC converter.
  • the first DC-DC converter can use the electrical energy output by the photovoltaic module to charge the battery, and can also compensate for the PID generated by the photovoltaic module when the photovoltaic module does not output electrical energy or the output electrical energy is low.
  • the present invention has at least the following advantages:
  • This application adds a compensation circuit between the positive input terminal of the inverter and the positive output terminal PV+ of the photovoltaic module, and a second resistor is connected between the positive output terminal PV+ and the negative output terminal PV- of the photovoltaic module.
  • the photovoltaic modules rely on sunlight to generate electricity, when there is no sun at night, the photovoltaic modules output almost no electrical energy, that is, the output voltage of the photovoltaic modules is less than the preset voltage.
  • the battery provides electrical energy for the compensation circuit and controls the switches in the compensation circuit Closed, the first resistance and the second resistance and the equivalent resistance (third resistance) between the negative output terminal PV- and the ground PE of the photovoltaic module divide the voltage at the second terminal of the first DC-DC converter, because PE is 0 potential, the voltage of PV- is the voltage on the third resistance, so the voltage of PV- is higher than PE, that is, PV- is a positive voltage relative to PE, this scheme is equivalent to raising the voltage of PV-to ground, so , When the output voltage of the photovoltaic module is less than the preset voltage, the PID effect of the photovoltaic module can be reversely compensated to improve the power generation efficiency of the photovoltaic module, thereby improving the efficiency of the power station.
  • FIG. 1 is a schematic diagram of a compensation circuit for potential-induced attenuation provided by an embodiment of the present application
  • FIG. 2 is a schematic diagram of another compensation circuit for potential-induced attenuation provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of another compensation circuit for potential-induced attenuation provided by an embodiment of the present application.
  • FIG. 4 is a flowchart of a method for compensating for potential induced attenuation provided by an embodiment of the present application
  • FIG. 5 is a schematic diagram of a photovoltaic system provided by an embodiment of the present application.
  • the negative potential of the photovoltaic module when the negative potential of the photovoltaic module is negative to ground, the PID effect is likely to occur.
  • the negative potential of the photovoltaic module can be set to 0 potential or positive potential, thereby alleviating the PID effect.
  • grounding the negative electrode PV- of the photovoltaic module increases the high voltage between PV+ and ground PE, thereby increasing the DC cable's requirement for the working voltage of the ground, increasing safety risks and costs.
  • grounding PV- will not protect the centralized inverter from residual current devices. Touching PV+ will cause electric shock accidents and personal injury.
  • PV-grounding if the cable between PV+ or photovoltaic module produces a ground fault, it will generate a fault current or arc discharge through the ground wire, which is likely to cause fire.
  • the PID phenomenon is due to the high voltage existing between the output terminal of the photovoltaic module and the ground, and the output terminal of the photovoltaic module outputs the voltage during the daytime, the PID effect is generated during the daytime. At night, there is no PID effect because the output terminal of the photovoltaic module does not output voltage.
  • the technical solution provided by the embodiment of the present application is to compensate the PID effect when the output voltage of the photovoltaic module is less than a preset voltage.
  • the bus voltage is led to PV-, so that PV-to PE forms a positive voltage, and the PID of the photovoltaic module is reversely compensated, thereby improving the power generation of the photovoltaic module effectiveness.
  • FIG. 1 is a schematic diagram of a compensation circuit for potential-induced attenuation provided by an embodiment of the present application.
  • the compensation circuit for the induced potential attenuation of the photovoltaic module is applied to a photovoltaic system.
  • the photovoltaic system includes: a photovoltaic module PV, an inverter 100, a first DC-DC converter 200, and a battery 300; the first The first end of the DC-DC converter 200 is connected to the battery 300, and the second end of the first DC-DC converter 200 is connected to the input end of the inverter 100;
  • the compensation circuit 400 includes: a switch S, a first resistor R1 and a controller (not shown); the switch S and the first resistor R1 are connected in series;
  • the first end of the compensation circuit 400 is connected to the positive output terminal PV+ of the photovoltaic module; the second end of the compensation circuit 400 is connected to the second end of the first DC-DC (direct current-direct current) converter 200;
  • R1 and S in the compensation circuit 400 may be connected in series, and S may be connected to the input terminal of the inverter 100, or R1 may be connected to the input terminal of the inverter 100, which is not specifically limited in this embodiment.
  • the function of the switch S is to control the connection state of the compensation circuit 400 and the second end of the first DC-DC converter 200.
  • S When S is closed, the compensation circuit 400 is connected to the second end of the first DC-DC converter 200;
  • S When S is off, the compensation circuit 400 is disconnected from the second end of the first DC-DC converter 200.
  • an inverter Since the output of the photovoltaic module is direct current, an inverter is required to convert the direct current into alternating current and feed it back to the power grid or alternating current equipment.
  • the controller is configured to control the switch S to close when the output voltage of the photovoltaic module is less than a preset voltage, so that the first DC-DC converter 200 supplies the power of the battery to the compensation circuit 400
  • the second end; a second resistor R2 is connected between the positive output end PV+ and the negative output end PV- of the photovoltaic module. R2 is the discharge resistance of the circuit port and needs to meet the safety requirements.
  • the third resistance R3, R3 is not the actual resistance connected, but for the analysis of the working principle of the circuit, the schematic equivalent resistance, generally R3 The resistance is larger.
  • the controller is used to control the switching state of the switch S, that is, to control whether S is opened or closed.
  • S is a controllable switch.
  • the specific type of S is not specifically limited in the embodiments of this application.
  • the switch may be a relay, a contactor, a circuit breaker, an insulated gate bipolar transistor (IGBT, Insulated Gate Bipolar Transistor), or a metal oxide semiconductor (MOS, Metal, Oxide, Semiconductor) One or more combinations in the tube.
  • IGBT Insulated Gate Bipolar Transistor
  • MOS Metal oxide semiconductor
  • photovoltaic modules rely on sunlight to generate electricity, when there is no sun at night, that is, the output voltage of the corresponding photovoltaic module is less than the preset voltage, the battery supplies power to the inverter input bus at this time, and the bus voltage is established.
  • the switch in the control compensation circuit is closed, R1, R2 and R3 divide the bus voltage, PV- is connected to PE through R3, because PE is 0 potential, the voltage of PV- is the voltage on R3, so the voltage of PV- is higher than PE , That is, PV- is a positive voltage relative to PE, this solution is equivalent to raising the voltage of PV-to-ground, therefore, when the output voltage of the photovoltaic module is less than the preset voltage, the PID effect of the photovoltaic module during the day can be reversed Compensation improves the power generation efficiency of photovoltaic modules, thereby improving the efficiency of the power station.
  • the controller is also used to control the switch S to open when the output voltage of the photovoltaic module is greater than or equal to the preset voltage, at this time, the compensation circuit is disconnected from the entire system and does not work. Furthermore, no current flows on R1, and no loss is generated, thereby saving power.
  • FIG. 2 is a schematic diagram of another compensation circuit for potential-induced attenuation provided by an embodiment of the present application.
  • the compensation circuit may further include: a diode D1;
  • the diode D1 is connected in series with the switch S and the first resistor R1;
  • the anode of the diode D1 is connected to one side of the input end of the inverter 100, and the cathode of the diode D1 is connected to one side of the PV+.
  • the role of D1 is to prevent the reverse flow of current, that is, to prevent the switch S from malfunctioning when the output voltage of the photovoltaic module is greater than or equal to the preset voltage and the current flows from the PV+ to the input terminal of the inverter 100 when it is closed, that is, the path of the daylight compensation circuit It is disconnected and no current flows.
  • D1, S, and R1 are only required to be connected in series.
  • S may be close to the side of the inverter 100 or S may be close to the side of the photovoltaic module.
  • the anode of D1 is close to the side of the inverter 100
  • the cathode of D1 is close to the side of the photovoltaic module, that is, the order of the anode and cathode of D1 cannot be reversed, otherwise the above effect cannot be achieved.
  • the embodiments of the present application do not limit other devices connected in series in the compensation circuit, for example, a resistor may be connected in series, or a diode may be connected in series.
  • the compensation circuit in this embodiment may further include a voltage detection circuit (not shown in the figure);
  • the voltage detection circuit is used for detecting the output voltage of the photovoltaic component; and sending the output voltage to the controller.
  • the photovoltaic module can generate electricity using solar energy during the day, the photovoltaic module has an output voltage, but at night, the photovoltaic module does not output a voltage because there is no solar energy. Of course, if it rains or is cloudy and there is no sun, the output voltage of the photovoltaic module is very low, lower than the preset voltage, and it is also regarded as night. Therefore, the voltage detection circuit can be used to detect the output voltage of the photovoltaic module to determine whether the compensation circuit is required to work.
  • FIG. 3 is a schematic diagram of another compensation circuit for potential-induced attenuation provided by an embodiment of the present application.
  • the photovoltaic system corresponding to the compensation circuit provided in this embodiment further includes: a second DC-DC converter 500;
  • the input end of the second DC-DC converter 500 is connected to the photovoltaic module, that is, the positive input end of the second DC-DC converter 500 is connected to the PV+ of the photovoltaic module, and the negative input end of the second DC-DC converter 500 is connected to the photovoltaic PV- of components.
  • the output end of the second DC-DC converter 500 is connected to the input end of the inverter 100; that is, the positive output end of the second DC-DC converter 500 is connected to the positive input end of the inverter 100, the second DC -The negative output terminal of the DC converter 500 is connected to the negative input terminal of the inverter 100.
  • the specific selection of the second DC-DC converter 500 may be determined according to actual application scenarios, and is not specifically limited in the embodiments of the present application. For example, it is related to the output voltage of the photovoltaic module. It can be a boost boost converter, a buck buck converter, or a buck-boost buck-boost converter.
  • the positive input terminal of the inverter 100 is connected to the positive bus BUS+, and the negative input terminal of the inverter 100 is connected to the negative bus BUS-.
  • the second DC-DC converter 500 may be a boost converter, and the implemented function is to boost the output voltage of the photovoltaic module and provide it to the inverter 100.
  • the compensation circuit 400 provided in this embodiment includes only simple devices such as resistors, switches, and diodes.
  • the devices are few and small in size, and can be used in conjunction with the first DC-DC converter 200 and the second DC-DC converter.
  • Both 500 and inverter 500 are integrated inside the power module, so they can be used in scenarios where the cabinet space is tight. At present, other technical solutions are placed outside the power module due to their complicated size and volume. Therefore, it is necessary to reserve other space inside the cabinet to specifically place PID suppression equipment.
  • the first DC-DC converter 200 is a bidirectional DC-DC converter
  • the controller is further used to sequentially pass the second DC-DC converter 500 and the photovoltaic module when the output voltage of the photovoltaic component is greater than or equal to a preset voltage and the power of the battery 300 is lower than the preset power.
  • the first DC-DC converter 200 charges the battery 300.
  • the first DC-DC converter 200 charges the battery 300
  • the current flows to the battery 300 via the first DC-DC converter 200 from the bus bar at the input end of the inverter 100.
  • the first DC-DC converter 200 is used to charge the battery 300.
  • the battery 300 passes through the first DC-DC converter 200 as the electrical energy of the compensation circuit, and then the compensation circuit feeds the electrical energy back to the output end of the photovoltaic module, so that the PV- Positive voltage with respect to PE. Since PV- is 0 or positive voltage with respect to PE, PID can be suppressed.
  • the solution provided by the embodiment of the present application can realize that PV- is positive voltage with respect to PE, so PID compensation can be achieved.
  • an electromagnetic interference prevention circuit may be included between the photovoltaic module and the input end of the second DC-DC converter 500 to suppress the electromagnetic interference generated by the output voltage of the photovoltaic module, which will output the suppressed voltage To the input of the second DC-DC converter 500.
  • FIG. 4 is a flowchart of a compensation method for potential-induced attenuation provided by this application.
  • the compensation method for the induced potential attenuation of the photovoltaic module provided in this embodiment is applied to the compensation circuit provided in the above embodiment.
  • the method includes:
  • S401 Determine whether the output voltage of the photovoltaic module is less than the preset voltage, and if so, execute S402.
  • S402 controlling the switch to close so that the first DC-DC converter supplies the power of the battery to the second end of the compensation circuit; the connection between the positive output terminal PV+ and the negative output terminal PV- of the photovoltaic module There is a second resistance.
  • the PID effect is due to the high voltage existing between the output terminal of the photovoltaic module and the ground, and the output terminal of the photovoltaic module outputs the voltage during the daytime, the PID effect is generated during the daytime. At night, there is almost no output voltage from the output terminal of the photovoltaic module, so there is no PID effect.
  • the technical solution provided by the embodiment of the present application is to compensate the PID effect when the output voltage of the photovoltaic module is less than the preset voltage.
  • the photovoltaic modules rely on sunlight to generate electricity, when there is no sun at night, the photovoltaic modules output almost no electrical energy, that is, the output voltage of the photovoltaic modules is less than the preset voltage.
  • the battery provides electrical energy for the compensation circuit and controls the switches in the compensation circuit Closed, the first resistance and the second resistance and the equivalent resistance (third resistance) between the negative output terminal PV- and the ground PE of the photovoltaic module divide the voltage at the second terminal of the first DC-DC converter, because PE is 0 potential, the voltage of PV- is the voltage on the third resistance, so the voltage of PV- is higher than PE, that is, PV- is a positive voltage relative to PE, this scheme is equivalent to raising the voltage of PV-to ground, so , When the output voltage of the photovoltaic module is less than the preset voltage, the PID effect of the photovoltaic module can be reversely compensated to improve the power generation efficiency of the photovoltaic module, thereby improving the efficiency of the power station.
  • the switch S can be controlled to open, at this time the compensation circuit is disconnected from the entire system, does not work, and then no current flows on R1, R1 will not cause power loss, and Can save electricity.
  • a battery when the output voltage of the photovoltaic component is less than a preset voltage, a battery is used to provide a voltage for the bus. When the battery power is low, you can use the electrical energy output by the photovoltaic module to charge the battery during the day.
  • the embodiments of the present application also provide a power module applied to a photovoltaic system.
  • the photovoltaic system includes: a photovoltaic component, an inverter, a first DC-DC converter, and a battery The first end of the first DC-DC converter is connected to the battery, and the second end of the first DC-DC converter is connected to the input end of the inverter; the power module includes the second DC-DC converter and the one provided by the above embodiment Compensation circuit
  • the input end of the second DC-DC converter is connected to the output end of the photovoltaic module, and the output end of the second DC-DC converter is connected to the input end of the inverter;
  • the second DC-DC converter is used to boost the output voltage of the photovoltaic module and provide it to the input terminal of the inverter.
  • the compensation circuit may be integrated inside the second DC-DC converter, which can reduce the volume of the overall hardware device and save the space occupied by it.
  • FIG. 5 is a schematic diagram of a photovoltaic system provided by an embodiment of the present application.
  • the photovoltaic system provided in this embodiment includes the compensation circuit 400 provided in the above embodiment; and further includes: a photovoltaic module PV, an inverter 100, a first DC-DC converter 200, and a battery 300;
  • the compensation circuit 400 is used for compensating the potential induced attenuation of the photovoltaic module PV during the day when the output voltage of the photovoltaic module is less than a preset voltage.
  • the photovoltaic module PV can be a series-parallel connection of multiple solar panels. Photovoltaic modules PV can convert solar energy into DC power output.
  • the PID effect is due to the high voltage existing between the output terminal of the photovoltaic module and the ground, and the output terminal of the photovoltaic module outputs the voltage during the daytime, the PID effect is generated during the daytime. At night, the output of the photovoltaic module does not output voltage, so no PID effect will occur.
  • the technical solution provided by the embodiments of the present application is to compensate for the PID effect of the photovoltaic module PV when the output voltage of the photovoltaic module is less than the preset voltage.
  • the photovoltaic modules rely on sunlight to generate electricity, when there is no sun at night, the photovoltaic modules output almost no electrical energy, that is, the output voltage of the photovoltaic modules is less than the preset voltage.
  • the battery provides electrical energy for the compensation circuit and controls the switches in the compensation circuit Closed, the first resistance and the second resistance and the equivalent resistance (third resistance) between the negative output terminal PV- and the ground PE of the photovoltaic module divide the voltage at the second terminal of the first DC-DC converter, because PE is 0 potential, the voltage of PV- is the voltage on the third resistance, so the voltage of PV- is higher than PE, that is, PV- is a positive voltage relative to PE, this scheme is equivalent to raising the voltage of PV-to ground, so , When the output voltage of the photovoltaic module is less than the preset voltage, the PID effect of the photovoltaic module can be reversely compensated to improve the power generation efficiency of the photovoltaic module, thereby improving the efficiency of the power station.
  • the switch S can be controlled to open, at this time the compensation circuit is disconnected from the entire system, does not work, and then no current flows on R1, R1 will not cause power loss, and Can save electricity.
  • a battery when the output voltage of the photovoltaic component is less than a preset voltage, a battery is used to provide a voltage for the bus. When the battery power is low, you can use the electrical energy output by the photovoltaic module to charge the battery during the day.
  • the photovoltaic system may further include that the input end of the second second DC-DC converter 500 is connected to the photovoltaic assembly, that is, the positive input end of the second DC-DC converter 500 is connected to the PV+ of the photovoltaic assembly, and the second DC- The negative input terminal of the DC converter 500 is connected to the PV- of the photovoltaic module.
  • the output end of the second DC-DC converter 500 is connected to the input end of the inverter 100; that is, the positive output end of the second DC-DC converter 500 is connected to the positive input end of the inverter 100, the second DC -The negative output terminal of the DC converter 500 is connected to the negative input terminal of the inverter 100.
  • the second DC-DC converter 500 may be a boost converter, and the implemented function is to boost the output voltage of the photovoltaic module and provide it to the inverter 100.
  • the compensation circuit 400 provided in this embodiment includes only simple devices such as resistors, switches, and diodes.
  • the devices are few and small in size, and can be used in conjunction with the first DC-DC converter 200 and the second DC-DC converter.
  • Both 500 and inverter 500 are integrated inside the power module, so they can be used in scenarios where the cabinet space is tight. At present, other technical solutions are placed outside the power module due to their complicated size and volume. Therefore, it is necessary to reserve other space inside the cabinet to specifically place PID suppression equipment.
  • the photovoltaic system provided in this embodiment may further include an electromagnetic interference prevention circuit 600 between the photovoltaic module and the input end of the second DC-DC converter 500 for suppressing electromagnetic interference generated by the output voltage of the photovoltaic module, The suppressed voltage is output to the input terminal of the second DC-DC converter 500.
  • an electromagnetic interference prevention circuit 600 between the photovoltaic module and the input end of the second DC-DC converter 500 for suppressing electromagnetic interference generated by the output voltage of the photovoltaic module, The suppressed voltage is output to the input terminal of the second DC-DC converter 500.
  • At least one (item) refers to one or more, and “multiple” refers to two or more.
  • “And/or” is used to describe the association relationship of related objects, indicating that there can be three kinds of relationships, for example, “A and/or B” can mean: there are only A, only B, and A and B at the same time , Where A and B can be singular or plural.
  • the character “/” generally indicates that the related object is a "or” relationship.
  • At least one of the following” or a similar expression refers to any combination of these items, including any combination of a single item or a plurality of items.
  • At least one (a) of a, b, or c can be expressed as: a, b, c, "a and b", “a and c", “b and c", or "a and b and c" ", where a, b, c can be a single or multiple.

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Abstract

一种电势诱导衰减的补偿电路、方法、功率模块及光伏系统，补偿电路（400）包括：开关（S）、第一电阻（R1）和控制器；开关（S）和第一电阻（R1）串联；补偿电路（400）的第一端连接光伏组件的正输出端PV+；补偿电路（400）的第二端连接第一DC-DC变换器（200）的第二端；控制器，用于在光伏组件的输出电压小于预设电压时，控制开关（S）闭合，以使第一DC-DC变换器（200）将电池的电能提供给补偿电路（400）的第二端；光伏组件的正输出端PV+和负输出端PV-之间连接有第二电阻（R2）。地PE为0电位，PV-的电压为第三电阻（R3）上的电压，即PV-的电压比PE高，抬高PV-对地的电压，在光伏组件的输出电压小于预设电压时对PID效应进行反向补偿，提高发电效率，从而提高电站的效益。

Description

电势诱导衰减的补偿电路、方法、功率模块及光伏系统
本申请要求于2018年12月21日提交中国国家知识产权局、申请号为2018115735598、发明名称为“电势诱导衰减的补偿电路、方法、功率模块及光伏系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及电力电子技术领域，尤其涉及一种电势诱导衰减的补偿电路、方法、功率模块及光伏系统。
背景技术
随着世界各国对节能减排和能源转型的不断推进，可再生能源发电技术已经受到越来越多的重视，其中，光伏系统由于其技术成熟度以及经济性等因素被广泛应用于电力系统以及微型电网。
但是，光伏发电一直受发电效率的困扰，当光伏组件使用一段时间后，会出现发电性能衰减的问题，进而导致整个光伏系统的输出功率下降。研究发现，存在于晶体硅光伏组件中的电路与其接地金属边框之间的高压，会造成光伏组件发电性能的持续衰减，该现象称为电势诱导衰减(PID，Potential Induced Degradation)。
PID与环境因素、光伏组件的材料以及逆变器阵列接地方式等有关。但是，即使采用最先进材料的光伏组件，也不可避免PID效应。
PID效应的存在会造成整个光伏系统的输出功率降低，直接影响电站的效益。
发明内容
为了解决现有技术中存在的以上技术问题，本发明提供一种电势诱导衰减的补偿电路、方法、功率模块及光伏系统，能够对PID进行补偿，提高光伏组件的发电效率，增加电站的效益。
本申请实施例提供一种电势诱导衰减的补偿电路，应用于光伏系统，光伏系统包括：光伏组件、逆变器、第一DC-DC变换器和电池；第一DC-DC变换器的第一端连接电池，第一DC-DC变换器的第二端连接逆变器的输入端；补偿电路包括：开关、第一电阻和控制器；开关和第一电阻串联；补偿电路的第一端连接光伏组件的正输出端PV+；补偿电路的第二端连接第一DC-DC变换器的第二端；控制器，用于在光伏组件的输出电压小于预设电压时，控制开关闭合，以使第一DC-DC变换器将电池的电能提供给补偿电路的第二端；光伏组件的正输出端PV+和负输出端PV-之间连接有第二电阻。
第一电阻和第二电阻以及光伏组件的负输出端PV-和地PE之间的等效电阻(第三电阻)对第一DC-DC变换器的第二端的电压进行分压，由于PE为0电位，PV-的电压为第三电阻上的电压，因此PV-的电压比PE高，即PV-相对于PE为正电压，本方案相当于抬高PV-对地的电压，从而实现对PID进行补偿。
优选地，为了在不需要进行PID补偿时，避免补偿电路浪费电能，控制器还用于在光伏组件的输出电压大于或等于预设电压时，控制开关断开。
优选地，为了防止电流反向流动，补偿电路还可以包括：二极管；二极管与开关和第一电阻均串联；二极管的阳极靠近第一DC-DC变换器的第二端的一侧，二极管的 阴极靠近PV+的一侧。即防止在光伏组件的输出电压大于或等于预设电压时开关误动作而闭合时电流从PV+流向逆变器的输入端，即白天补偿电路的通路是断开的，不流过电流。
优选地，补偿电路还可以包括：电压检测电路；用来检测光伏组件的输出电压，将输出电压发送给控制器，以使控制器根据输出电压判断何时控制开关闭合以及何时断开。
优选地，开关可以根据实际需要来选择，例如可以为继电器、接触器、断路器或绝缘栅双极型晶体管IGBT中的一种，或多种的组合。
第二方面，本申请实施例还提供一种电势诱导衰减的补偿方法，应用于以上介绍的补偿电路，该方法包括：在光伏组件的输出电压小于预设电压时，控制开关闭合，以使第一DC-DC变换器工作将电池的电能提供给补偿电路的第二端；光伏组件的正输出端PV+和负输出端PV-之间连接有第二电阻。可以有效对光伏组件产生的PID进行补偿，从而提高发电效率。
第三方面，本申请实施例还提供一种应用于光伏系统的功率模块，以上介绍的补偿电路集成于该功率模块中，该功率模块应用于光伏系统，光伏系统包括：光伏组件、逆变器、第一DC-DC变换器和电池；第一DC-DC变换器的第一端连接电池，第一DC-DC变换器的第二端连接逆变器的输入端；功率模块还包括第二DC-DC变换器；第二DC-DC变换器的输入端连接光伏组件的输出端，第二DC-DC变换器的输出端连接逆变器的输入端；第二DC-DC变换器将光伏组件的输出电压进行升压后提供给逆变器的输入端。该功率模块不仅可以对光伏组件的输出电压进行升压，而且可以为光伏组件产生的PID进行补偿，提高光伏组件的发电效率。
第四方面，本申请实施例还提供一种光伏系统，包括以上介绍的补偿电路；还包括：光伏组件、逆变器、第一DC-DC变换器和电池；第一DC-DC变换器的第一端连接电池，第一DC-DC变换器的第二端连接逆变器的输入端；补偿电路，用于在光伏组件的输出电压小于预设电压时，对光伏组件的电势诱导衰减进行补偿。该光伏系统可以通过补偿电路对光伏组件的PID进行补偿，从而提高光伏系统的发电效率。
优选地，光伏系统还包括：第二DC-DC变换器，第二DC-DC变换器的输入端连接光伏组件的输出端，第二DC-DC变换器的输出端连接逆变器的输入端；第二DC-DC变换器，用于将光伏组件的输出电压进行升压后提供给逆变器的输入端。
优选地，第一DC-DC变换器为双向DC-DC变换器；控制器，还用于在光伏组件的输出电压大于或等于预设电压，且电池的电量低于预设电量时利用光伏组件依次经过第二DC-DC变换器和第一DC-DC变换器为电池充电。第一DC-DC变换器既可以利用光伏组件输出的电能为电池充电，又可以在光伏组件不输出电能或输出电能较低时，为光伏组件产生的PID进行补偿。
与现有技术相比，本发明至少具有以下优点：
本申请在逆变器的正输入端和光伏组件的正输出端PV+之间添加了补偿电路，并且光伏组件的正输出端PV+和负输出端PV-之间连接第二电阻。
由于光伏组件依靠太阳光进行发电，因此夜间没有太阳时，光伏组件几乎不输出电能，即光伏组件的输出电压小于预设电压，此时由电池来为补偿电路提供电能，控制补偿电路中的开关闭合，第一电阻和第二电阻以及光伏组件的负输出端PV-和地PE之间的等效电阻(第三电阻)对第一DC-DC变换器的第二端的电压进行分压，由于PE为0电位，PV-的电压为第三电阻上的电压，因此PV-的电压比PE高，即PV-相对于PE为正电压，本方案相当于抬高PV-对地的电压，因此，可以在光伏组件的输出电压小于预设电压时对光伏组件的PID效应进行反向补偿，提高光伏组件的发电效率，从而提高电站的效益。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请中记载的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图。
图1为本申请实施例提供的一种电势诱导衰减的补偿电路示意图；
图2为本申请实施例提供的另一种电势诱导衰减的补偿电路示意图；
图3为本申请实施例提供的又一种电势诱导衰减的补偿电路示意图；
图4为本申请实施例提供的一种电势诱导衰减的补偿方法流程图；
图5为本申请实施例提供的一种光伏系统示意图。
具体实施方式
理论上，光伏组件的负极电位对地是负电位时，容易出现PID效应，为了抑制PID效应，可以将光伏组件的负极电位设置为0电位或者正电位，从而缓解PID效应。但是，将光伏组件的负极PV-接地，提高了PV+与地PE之间的高电压，从而提高了直流线缆对地工作电压的要求，增加安全风险以及成本。另外，将PV-接地，对于集中式逆变器没有剩余电流装置的保护，触碰PV+以后会造成人员电击事故，对人身造成伤害。而且PV-接地，如果PV+或光伏组件之间的电缆产生接地故障，则会通过接地线产生故障电流或者产生电弧放电，容易引起火灾。
因此，为了抑制PID，将光伏组件的PV-直接接地存在以上问题，本申请实施例提供以下技术方案：
由于PID现象是因为光伏组件输出端与地之间存在的高压，而白天时光伏组件的输出端才会输出电压，因此PID效应是在白天产生的。夜晚由于光伏组件的输出端不输出电压，不会产生PID效应。本申请实施例提供的技术方案是在所述光伏组件的输出电压小于预设电压时对PID效应进行补偿。通过在所述光伏组件的输出电压小于预设电压时，将母线电压引到PV-，使PV-到PE形成一个正的电压，对光伏组件的PID进行反向补偿，从而提高光伏组件的发电效率。
为了使本领域技术人员更好地理解本申请实施例提供的技术方案，下面结合附图对其进行详细介绍。
实施例一：
参见图1，该图为本申请实施例提供的一种电势诱导衰减的补偿电路示意图。
本实施例提供的光伏组件电势诱导衰减的补偿电路，应用于光伏系统，所述光伏系统包括：光伏组件PV、逆变器100、第一DC-DC变换器200和电池300；所述第一DC-DC变换器200的第一端连接电池300，所述第一DC-DC变换器200的第二端连接所述逆变器100的输入端；
该补偿电路400包括：开关S、第一电阻R1和控制器(图中未示出)；所述开关S和所述第一电阻R1串联；
所述补偿电路400的第一端连接所述光伏组件的正输出端PV+；所述补偿电路400的第二端连接第一DC-DC(直流-直流)变换器200的第二端；
需要说明的是，补偿电路400中的R1和S串联即可，可以S连接逆变器100的输入端，也可以R1连接逆变器100的输入端，本实施例中不做具体限定。
其中开关S的作用是控制补偿电路400与第一DC-DC变换器200的第二端的连接状态，当S闭合时，补偿电路400与第一DC-DC变换器200的第二端连接；当S断开时，补偿电路400与第一DC-DC变换器200的第二端断开。
由于光伏组件输出的为直流电，因此，需要逆变器将直流电逆变为交流电反馈给电网或交流用电设备。
所述控制器，用于在所述光伏组件的输出电压小于预设电压时，控制所述开关S闭合，以使第一DC-DC变换器200将所述电池的电能提供给补偿电路400的第二端；所述光伏组件的正输出端PV+和负输出端PV-之间连接有第二电阻R2。R2是电路端口的放电电阻，需要符合安规要求。
需要说明的是，PV-和地PE之间存在等效电阻，即第三电阻R3，R3并不是实际接入的电阻，而是为了分析电路的工作原理，示意的等效电阻，一般R3的阻值较大。
控制器用于控制开关S的开关状态，即控制S断开还是闭合。S为可控开关，本申请实施例中不具体限定S的具体类型，例如开关可以为继电器、接触器、断路器、绝缘栅双极型晶体管(IGBT，Insulated Gate Bipolar Transistor)或金属氧化物半导体(MOS，Metal Oxide Semiconductor)管中的一种或多种的组合。
由于光伏组件依靠太阳光进行发电，因此夜间没有太阳时，即此时对应光伏组件的输出电压小于预设电压，此时由电池来为逆变器输入端的母线提供电能，建立母线电压，此时控制补偿电路中的开关闭合，R1、R2和R3对母线电压分压，PV-通过R3连接PE，由于PE为0电位，PV-的电压为R3上的电压，因此PV-的电压比PE高，即PV-相对于PE为正电压，本方案相当于抬高PV-对地的电压，因此，可以在光伏组件的输出电压小于预设电压时，对光伏组件白天发生的PID效应进行反向补偿，提高光伏组件的发电效率，从而提高电站的效益。
另外，为了节省损耗，所述控制器还用于在光伏组件的输出电压大于或等于预设电压时，控制所述开关S断开，此时补偿电路从整个系统中断开，不起作用，进而R1上无电流流过，不会产生损耗，进而可以节省电能。
实施例二：
参见图2，该图为本申请实施例提供的另一种电势诱导衰减的补偿电路示意图。
本实施例中，所述补偿电路还可以包括：二极管D1；
所述二极管D1与所述开关S和第一电阻R1均串联；
所述二极管D1的阳极连接所述逆变器100的输入端的一侧，所述二极管D1的阴极连接所述PV+的一侧。
D1的作用是防止电流反向流动，即防止在光伏组件的输出电压大于或等于预设电压时开关S误动作而闭合时电流从PV+流向逆变器100的输入端，即白天补偿电路的通路是断开的，不流过电流。
需要说明的是，D1、S和R1三者串联即可，本申请实施例中不具体限定具体的串联顺序，例如可以S靠近逆变器100的一侧，也可以S靠近光伏组件的一侧，但是D1的阳极是靠近逆变器100的一侧，D1的阴极是靠近光伏组件的一侧，即D1的阳极和阴极的顺序不能颠倒，否则无法起到以上的作用。
另外，本申请实施例中不限定补偿电路中串联的其他器件，例如，可以再串联一个电阻，或者再串联一个二极管等。
另外，本实施例中的补偿电路，还可以包括电压检测电路(图中未示出)；
所述电压检测电路，用于检测所述光伏组件的输出电压；将所述输出电压发送给所述控制器。
因为白天时，光伏组件利用太阳能可以发电，因此光伏组件具有输出电压，但是夜间时，由于没有太阳能，因此光伏组件不输出电压。当然，如果下雨或者阴天，没有太阳，光伏组件的输出电压很低，低于预设电压，也视为夜间。因此，可以利用电压检测电路检测光伏组件的输出电压来判断是否需要补偿电路工作。
实施例三：
参见图3，该图为本申请实施例提供的又一种电势诱导衰减的补偿电路示意图。
本实施例提供的补偿电路对应的光伏系统还包括：第二DC-DC变换器500；
所述第二DC-DC变换器500的输入端连接光伏组件，即第二DC-DC变换器500的正输入端连接光伏组件的PV+，第二DC-DC变换器500的负输入端连接光伏组件的PV-。
所述第二DC-DC变换器500的输出端连接所述逆变器100的输入端；即第二DC-DC变换器500的正输出端连接逆变器100的正输入端，第二DC-DC变换器500的负输出端连接逆变器100的负输入端。
第二DC-DC变换器500的具体选择可以根据实际应用场景来确定，本申请实施例中不做具体限定。例如与光伏组件的输出电压有关。可以为升压Boost变换器，也可以为降压Buck变换器，也可以为降压-升压Buck-Boost变换器。
逆变器100的正输入端连接的是正母线BUS+，逆变器100的负输入端连接的是负母线BUS-。
所述第二DC-DC变换器500可以为Boost变换器，实现的作用为将光伏组件的输出电压进行升压后提供给逆变器100。
可以理解的是，当所述光伏组件的输出电压小于预设电压时，S闭合，补偿电路将第一DC-DC200的输出电压回引到PV+，此时第二DC-DC变换器500不工作。
需要说明的是，所述第二DC-DC变换器500输出端的中点N连接PE，即N点的电位为0。
另外，本实施例中提供的所述补偿电路400仅包括电阻、开关和二极管等简单器件，器件少而且体积小，可以与所述第一DC-DC变换器200、第二DC-DC变换器500和逆变器500均集成在功率模块内部，因此可以适用于机柜空间紧张的场景。而目前其他技术方案由于器件复杂体积大均放置在功率模块外部，因此需要在机柜内部预留其他空间专门放置抑制PID的设备。
另外，本实施例中，所述第一DC-DC变换器200为双向DC-DC变换器；
所述控制器，还用于当光伏组件的输出电压大于或等于预设电压且所述电池300的电量低于预设电量时，利用所述光伏组件依次通过第二DC-DC变换器500和所述第一DC-DC变换器200为所述电池300充电。
即，当第一DC-DC变换器200为电池300充电时，电流流向为从逆变器100输入端的母线经过第一DC-DC变换器200流向电池300。当电池电量低时，利用所述第一DC-DC变换器200为所述电池300充电。
当电池300为逆变器100输入端的母线提供电能时，电流流向为从电池300经过第一DC-DC变换器200流向逆变器100输入端的母线。
本实施例，在光伏组件的输出电压小于预设电压时，利用电池300经过第一DC-DC变换器200为补偿电路电能，进而补偿电路将电能反馈到光伏组件的输出端，从而使PV-相对于PE为正电压。由于PV-相对于PE为0或者为正电压时，可以抑制PID，本申请实施例提供的方案可以实现PV-相对于PE为正电压，因此可以实现PID的补偿。
另外，本实施例中在光伏组件和第二DC-DC变换器500的输入端之间还可以包括防止电磁干扰电路，用于抑制光伏组件的输出电压产生的电磁干扰，将抑制后的电压输出给第二DC-DC变换器500的输入端。
方法实施例：
参见图4，该图为本申请提供的一种电势诱导衰减的补偿方法流程图。
本实施例提供的光伏组件电势诱导衰减的补偿方法，应用于以上实施例提供的补偿电路，该方法包括：
S401：判断光伏组件的输出电压是否小于预设电压，如果是，执行S402。
S402：控制所述开关闭合，以使第一DC-DC变换器将所述电池的电能提供给补偿电路的第二端；所述光伏组件的正输出端PV+和负输出端PV-之间连接有第二电阻。
由于PID效应是因为光伏组件输出端与地之间存在的高压，而白天时光伏组件的输出端才会输出电压，因此，PID效应是在白天产生的。夜晚由于光伏组件的输出端 几乎不输出电压，因此不会产生PID效应。本申请实施例提供的技术方案是在光伏组件的输出电压小于预设电压时，对PID效应进行补偿。
由于光伏组件依靠太阳光进行发电，因此夜间没有太阳时，光伏组件几乎不输出电能，即光伏组件的输出电压小于预设电压，此时由电池来为补偿电路提供电能，控制补偿电路中的开关闭合，第一电阻和第二电阻以及光伏组件的负输出端PV-和地PE之间的等效电阻(第三电阻)对第一DC-DC变换器的第二端的电压进行分压，由于PE为0电位，PV-的电压为第三电阻上的电压，因此PV-的电压比PE高，即PV-相对于PE为正电压，本方案相当于抬高PV-对地的电压，因此，可以在光伏组件的输出电压小于预设电压时对光伏组件的PID效应进行反向补偿，提高光伏组件的发电效率，从而提高电站的效益。
另外，在白天时，为了节省损耗，可以控制所述开关S断开，此时补偿电路从整个系统中断开，不起作用，进而R1上无电流流过，R1不会产生电能损耗，进而可以节省电能。
本申请实施例中，所述光伏组件的输出电压小于预设电压时，利用电池为母线提供电压。当电池的电量低时，可以在白天时，利用光伏组件输出的电能为电池充电。
功率模块实施例：
基于以上实施例提供的一种补偿电路和补偿方法，本申请实施例还提供一种应用于光伏系统的功率模块，光伏系统包括：光伏组件、逆变器、第一DC-DC变换器和电池；第一DC-DC变换器的第一端连接电池，第一DC-DC变换器的第二端连接逆变器的输入端；功率模块包括第二DC-DC变换器和以上实施例提供的补偿电路；
其中，第二DC-DC变换器的输入端连接所述光伏组件的输出端，所述第二DC-DC变换器的输出端连接所述逆变器的输入端；
所述第二DC-DC变换器，用于将所述光伏组件的输出电压进行升压后提供给所述逆变器的输入端。
可以理解的是，实际应用中，补偿电路可以集成在第二DC-DC变换器的内部，这样可以缩小整体硬件设备的体积，节省其所占用的空间。
光伏系统实施例：
参见图5，该图为本申请实施例提供的一种光伏系统示意图。
本实施例提供的光伏系统，包括以上实施例提供的所述补偿电路400；还包括：光伏组件PV、逆变器100、第一DC-DC变换器200和电池300；
所述补偿电路400，用于在所述光伏组件的输出电压小于预设电压时，对光伏组件PV在白天产生的电势诱导衰减进行补偿。
其中光伏组件PV可以为多个太阳能电池板的串并联。光伏组件PV可以将太阳能转换为直流电能输出。
由于PID效应是因为光伏组件输出端与地之间存在的高压，而白天时光伏组件的 输出端才会输出电压，因此，PID效应是在白天产生的。夜晚由于光伏组件的输出端不输出电压，因此不会产生PID效应。本申请实施例提供的技术方案是在所述光伏组件的输出电压小于预设电压时，对光伏组件PV的PID效应进行补偿。
由于光伏组件依靠太阳光进行发电，因此夜间没有太阳时，光伏组件几乎不输出电能，即光伏组件的输出电压小于预设电压，此时由电池来为补偿电路提供电能，控制补偿电路中的开关闭合，第一电阻和第二电阻以及光伏组件的负输出端PV-和地PE之间的等效电阻(第三电阻)对第一DC-DC变换器的第二端的电压进行分压，由于PE为0电位，PV-的电压为第三电阻上的电压，因此PV-的电压比PE高，即PV-相对于PE为正电压，本方案相当于抬高PV-对地的电压，因此，可以在光伏组件的输出电压小于预设电压时对光伏组件的PID效应进行反向补偿，提高光伏组件的发电效率，从而提高电站的效益。
另外，在白天时，为了节省损耗，可以控制所述开关S断开，此时补偿电路从整个系统中断开，不起作用，进而R1上无电流流过，R1不会产生电能损耗，进而可以节省电能。
本申请实施例中，所述光伏组件的输出电压小于预设电压时，利用电池为母线提供电压。当电池的电量低时，可以在白天时，利用光伏组件输出的电能为电池充电。
另外，该光伏系统还可以包括第二所述第二DC-DC变换器500的输入端连接光伏组件，即第二DC-DC变换器500的正输入端连接光伏组件的PV+，第二DC-DC变换器500的负输入端连接光伏组件的PV-。
所述第二DC-DC变换器500的输出端连接所述逆变器100的输入端；即第二DC-DC变换器500的正输出端连接逆变器100的正输入端，第二DC-DC变换器500的负输出端连接逆变器100的负输入端。
所述第二DC-DC变换器500可以为Boost变换器，实现的作用为将光伏组件的输出电压进行升压后提供给逆变器100。
可以理解的是，当所述光伏组件的输出电压小于预设电压S闭合时，补偿电路将母线电压回引到PV+，此时第二DC-DC变换器500不工作。
需要说明的是，所述第二DC-DC变换器500输出端的中点N连接PE，即N点的电位为0。
另外，本实施例中提供的所述补偿电路400仅包括电阻、开关和二极管等简单器件，器件少而且体积小，可以与所述第一DC-DC变换器200、第二DC-DC变换器500和逆变器500均集成在功率模块内部，因此可以适用于机柜空间紧张的场景。而目前其他技术方案由于器件复杂体积大均放置在功率模块外部，因此需要在机柜内部预留其他空间专门放置抑制PID的设备。
另外，本实施例中提供的光伏系统，在光伏组件和第二DC-DC变换器500的输入端之间还可以包括防止电磁干扰电路600，用于抑制光伏组件的输出电压产生的电磁干扰，将抑制后的电压输出给第二DC-DC变换器500的输入端。
应当理解，在本申请中，“至少一个(项)”是指一个或者多个，“多个”是指两个或 两个以上。“和/或”，用于描述关联对象的关联关系，表示可以存在三种关系，例如，“A和/或B”可以表示：只存在A，只存在B以及同时存在A和B三种情况，其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a，b或c中的至少一项(个)，可以表示：a，b，c，“a和b”，“a和c”，“b和c”，或“a和b和c”，其中a，b，c可以是单个，也可以是多个。
以上所述，仅是本发明的较佳实施例而已，并非对本发明作任何形式上的限制。虽然本发明已以较佳实施例揭露如上，然而并非用以限定本发明。任何熟悉本领域的技术人员，在不脱离本发明技术方案范围情况下，都可利用上述揭示的方法和技术内容对本发明技术方案做出许多可能的变动和修饰，或修改为等同变化的等效实施例。因此，凡是未脱离本发明技术方案的内容，依据本发明的技术实质对以上实施例所做的任何简单修改、等同变化及修饰，均仍属于本发明技术方案保护的范围内。

Claims (10)

  1. 一种电势诱导衰减的补偿电路，其特征在于，应用于光伏系统，所述光伏系统包括：光伏组件、逆变器、第一DC-DC变换器和电池；所述第一DC-DC变换器的第一端连接所述电池，所述第一DC-DC变换器的第二端连接所述逆变器的输入端；
    所述补偿电路包括：开关、第一电阻和控制器；所述开关和所述第一电阻串联；
    所述补偿电路的第一端连接所述光伏组件的正输出端PV+；所述补偿电路的第二端连接所述第一DC-DC变换器的第二端；
    所述控制器，用于在所述光伏组件的输出电压小于预设电压时，控制所述开关闭合，以使所述第一DC-DC变换器将所述电池的电能提供给所述补偿电路的第二端；所述光伏组件的所述正输出端PV+和负输出端PV-之间连接有第二电阻。
  2. 根据权利要求1所述的补偿电路，其特征在于，所述控制器，还用于在所述光伏组件的输出电压大于或等于所述预设电压时，控制所述开关断开。
  3. 根据权利要求1所述的补偿电路，其特征在于，还包括：二极管；
    所述二极管与所述开关和第一电阻均串联；
    所述二极管的阳极靠近所述第一DC-DC变换器的第二端的一侧，所述二极管的阴极靠近所述PV+的一侧。
  4. 根据权利要求1-3任一项所述的补偿电路，其特征在于，还包括：电压检测电路；
    所述电压检测电路，用于检测所述光伏组件的输出电压，将所述输出电压发送给所述控制器。
  5. 根据权利要求1-4任一项所述的补偿电路，其特征在于，所述开关为继电器、接触器、断路器或绝缘栅双极型晶体管IGBT中的一种，或多种的组合。
  6. 一种电势诱导衰减的补偿方法，其特征在于，应用于权利要求1-5任一项所述的补偿电路，该方法包括：
    在所述光伏组件的输出电压小于预设电压时，控制所述开关闭合，以使所述第一DC-DC变换器工作将所述电池的电能提供给所述补偿电路的第二端；所述光伏组件的正输出端PV+和负输出端PV-之间连接有第二电阻。
  7. 一种应用于光伏系统的功率模块，其特征在于，应用于光伏系统，所述光伏系统包括：光伏组件、逆变器、第一DC-DC变换器和电池；所述第一DC-DC变换器的第一端连接所述电池，所述第一DC-DC变换器的第二端连接所述逆变器的输入端；
    所述功率模块包括第二DC-DC变换器和权利要求1-5任一项所述的补偿电路；
    所述第二DC-DC变换器的输入端连接所述光伏组件的输出端，所述第二DC-DC变换器的输出端连接所述逆变器的输入端；
    所述第二DC-DC变换器，用于将所述光伏组件的输出电压进行升压后提供给所述逆变器的输入端。
  8. 一种光伏系统，其特征在于，包括权利要求1-5任一项所述补偿电路；还包括：光伏组件、逆变器、第一DC-DC变换器和电池；
    所述第一DC-DC变换器的第一端连接所述电池，所述第一DC-DC变换器的第二端连接所述逆变器的输入端；
    所述补偿电路，用于在所述光伏组件的输出电压小于预设电压时，对所述光伏组件的电势诱导衰减进行补偿。
  9. 根据权利要求8所述的光伏系统，其特征在于，所述光伏系统还包括：第二DC-DC变换器，所述第二DC-DC变换器的输入端连接所述光伏组件的输出端，所述第二DC-DC变换器的输出端连接所述逆变器的输入端；
    所述第二DC-DC变换器，用于将所述光伏组件的输出电压进行升压后提供给所述逆变器的输入端。
  10. 根据权利要求9所述的光伏系统，其特征在于，所述第一DC-DC变换器为双向DC-DC变换器；
    所述控制器，还用于在所述光伏组件的输出电压大于或等于所述预设电压，且所述电池的电量低于预设电量时利用所述光伏组件依次经过所述第二DC-DC变换器和所述第一DC-DC变换器为所述电池充电。
PCT/CN2019/117314 2018-12-21 2019-11-12 电势诱导衰减的补偿电路、方法、功率模块及光伏系统 WO2020125270A1 (zh)

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