WO2022166931A1 - 一种可短路保护的功率优化器和光伏发电系统 - Google Patents

一种可短路保护的功率优化器和光伏发电系统 Download PDF

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Publication number
WO2022166931A1
WO2022166931A1 PCT/CN2022/075228 CN2022075228W WO2022166931A1 WO 2022166931 A1 WO2022166931 A1 WO 2022166931A1 CN 2022075228 W CN2022075228 W CN 2022075228W WO 2022166931 A1 WO2022166931 A1 WO 2022166931A1
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Prior art keywords
power
circuit
switching element
photovoltaic
unit
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PCT/CN2022/075228
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English (en)
French (fr)
Inventor
宋悦
陈泽熙
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深圳市中旭新能源有限公司
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Publication of WO2022166931A1 publication Critical patent/WO2022166931A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/08—Limitation or suppression of earth fault currents, e.g. Petersen coil
    • 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • 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

Definitions

  • the utility model relates to the technical field of photovoltaic grid-connected power generation, in particular to a power optimizer capable of short-circuit protection and a photovoltaic power generation system.
  • the DC input terminal of the current grid-connected photovoltaic system is generally a DC system with a system voltage of 500V-1500V formed by photovoltaic cells in series and parallel. Therefore, arc faults will occur when insulation damage, loose metal joints, aging components, animal bites, etc. occur. .
  • the DC arc is different from the AC arc. The current has no zero-crossing point, so the arc cannot be automatically extinguished. Once the arc is not dealt with in time, it will often cause economic losses or possible personal safety losses. DC arcing is an important safety issue for photovoltaic systems and needs attention.
  • DC arcs can be divided into parallel DC arcs and serial DC arcs according to where they are generated.
  • the serial arc fault is mainly caused by the connection line arc fault caused by the connection between the photovoltaic cells, the connection terminal of the DC combiner box and the inverter, and the broken DC cable.
  • Parallel arc faults are mainly caused by insulation damage, which can be divided into ground arcs and line arcs.
  • the DC circuit that produces parallel arcs can be considered as short circuits.
  • the short-circuit current of photovoltaic cells is related to the irradiation temperature, which is difficult to detect and determine.
  • the arc detection device installed in the inverter or DC combiner box detects an arc fault in the circuit and disconnects the photovoltaic DC circuit, it can only eliminate the serial arc, not the parallel arc. Because even after the DC circuit loop is disconnected, the ground and line loops caused by insulation damage still exist.
  • the existing technology is to disconnect the external power supply of the photovoltaic cell by installing a photovoltaic power optimizer or a switch at the output end of the photovoltaic cell.
  • the central controller is used to continuously send a heartbeat communication signal, or the shutdown control module located on the DC bus is used to send a periodic excitation pulse source to control the power optimizer or shutdown device to turn off the output of the photovoltaic cell , so that it stops generating electricity; when the safety fault disappears, the photovoltaic power optimizer or shutdown device of each photovoltaic cell power is turned on again, so that the photovoltaic cells connected to itself can realize the power output.
  • the main purpose of the present invention is to provide a power optimizer and a photovoltaic power generation system capable of short-circuit protection. It will start automatically after the situation is resolved; on the other hand, on the basis of realizing the fast arc fault detection on the DC side of the photovoltaic power generation system and the arc extinguishing of the shutdown circuit, it reduces the signal source receiving module of the shutdown circuit in the photovoltaic cell and the photovoltaic inverter system. The signal source sending module. On the whole, it not only reduces the cost of rapid shutdown of arc and short circuit protection, but also improves the safety and reliability of photovoltaic power generation systems.
  • the utility model adopts the following technical scheme:
  • the present invention provides a power optimizer capable of short-circuit protection.
  • the optimizer includes a power conversion module, a control module and an auxiliary power supply.
  • the input end of the power conversion module can be connected to the output end of the photovoltaic unit.
  • the output end of the module can be connected to the power acquisition system, the auxiliary power supply is connected to the output end of the photovoltaic unit for power supply, and the power supply is connected to the control module, the control module is controlled to be connected to the power conversion module, and the optimizer is also equipped with a short circuit protection circuit;
  • the short-circuit protection circuit includes a first switch element, a second switch element and an energy storage element, and the control module is controlled and connected to the first switch element and the second switch element by a switch signal;
  • the first switching element and the second switching element are connected to the connection loop between the photovoltaic unit and the power acquisition system, and when any one of the first switching element and the second switching element is turned off, the photovoltaic unit is connected to the power acquisition system. Disconnect; the energy storage element is connected between the first switch element and the second switch element, the conduction of the first switch element can connect the photovoltaic unit and the energy storage element, and the conduction of the second switch element can connect the energy storage element and power acquisition systems;
  • any one of the first switching element and the second switching element will be turned off, and the connection between the photovoltaic unit and the power acquisition system will be disconnected;
  • the control module separately controls the conduction of the first switching element and the second switching element, so that the energy storage element is connected to the power acquisition system after the power is drawn from the photovoltaic unit, and the power is obtained and received. It is judged whether the short-circuit condition is satisfied according to the difference of the electrical parameters of the energy storage element, and after it is determined that the short-circuit condition is not satisfied, the first switching element and the second switching element are turned on at the same time, so as to try to restore the photovoltaic unit and the power acquisition system after the short-circuit test. Connected.
  • the energy storage element is a capacitive element connected in parallel to the positive and negative loops of the power conversion module, and the control module obtains and judges whether the short-circuit condition is satisfied according to the difference in voltage parameters of the capacitive element.
  • the power conversion module (E1) is a Buck-type or Boost-type or Boost-Buck-type DC chopper circuit with an output capacitor (C2); the output capacitor (C2) is used as a DC chopper circuit.
  • the control module (E2) obtains electricity by separately collecting and recording the output capacitor (C2) conducting to the photovoltaic unit, and the output capacitor (C2) conducting the voltage parameter of the power acquisition system to obtain electricity. Obtain the voltage parameter difference used to judge whether the short-circuit condition is met.
  • the power conversion module (E1) is a Buck-type or Boost-type or Boost-Buck-type DC chopper circuit with an output capacitor (C2); the output capacitor (C2) is used as a DC chopper circuit.
  • the control module (E2) obtains electricity by separately collecting and recording the output capacitor (C2) conducting to the photovoltaic unit, and the output capacitor (C2) conducting the voltage parameter of the power acquisition system to obtain electricity. Obtain the voltage parameter difference used to judge whether the short-circuit condition is met.
  • the power conversion module (E1) is a Buck-type or Boost-type or Boost-Buck-type DC chopper circuit with switching elements; the first switching element (S1) is a DC chopper circuit; A switching element connected in series on a positive or negative loop in a chopper circuit.
  • the second switching element (S2) is a switching element connected in series between the output end of the DC chopper circuit and the output end of the optimizer (E) on a positive or negative loop, at least
  • the first switch element (S1) and the second switch element (S2) of one of them are normally open switch elements.
  • the power conversion module is a step-down Buck DC chopper circuit, which includes an input capacitor, a switching element as the first switching element, an inductor, a freewheeling diode, and a freewheeling diode as the first switching element.
  • the output capacitance of the energy storage element; the first switching element, the inductor and the second switching element are sequentially connected in series with the positive circuit of the DC chopper circuit, and the positive and negative circuits of the freewheeling diode are connected in parallel between the first switching element and the between the inductors, the positive and negative loops of the input capacitor are connected in parallel between the input end of the power conversion module and the first switch element, and the positive and negative electrodes of the output capacitor are connected in parallel between the inductor and the second switch element;
  • a bypass diode is connected in parallel between the positive and negative electrodes of the second switching element and the output end of the power conversion module.
  • control module includes a control unit, a collection unit, an arithmetic unit, a judgment unit, a count unit, a drive unit and a communication unit for controlling the operation of the short-circuit protection circuit;
  • the control unit is used for controlling the second switching element to keep off, and then controlling the first switching element to be turned on, so that the energy storage element obtains power from the photovoltaic unit, and controlling the first switching element to be turned off, and then controlling the second switching element to be turned on.
  • the switching element is turned on, so that the energy storage element is connected to the power acquisition system;
  • the collection unit is used to collect the electric parameter information of the energy storage element in the acquisition of electric power and included in the electric power acquisition system;
  • the computing unit is used to obtain the difference of the electrical parameter information in the power state and the access system state;
  • the judging unit is used for judging the electrical parameter information parameters, and driving the control unit to perform corresponding operations;
  • control unit controls the first switching element and the second switching element to be turned on at the same time with the switching value; when it is determined that the short circuit is determined, the first switching element and the second switching element are controlled with the switching value. If it is judged as not confirming the short circuit, the control unit will perform short circuit detection again after delaying the set time;
  • the counting unit measures the number of executions of the first control unit performed because the short-circuit is not confirmed, and determines that the short-circuit is confirmed when the preset number of times is exceeded;
  • the driving unit controls the turn-off and turn-on of the first switching element and the second switch with driving power according to the switching quantity control command;
  • the control module further includes a communication unit, and the communication unit issues an alarm to the power acquisition system after it is determined that the short circuit is confirmed.
  • control module is further configured to control the power conversion module to perform power conversion
  • the collection unit is used to collect voltage and current parameters at the output end of the photovoltaic unit
  • the arithmetic unit is used to calculate the power parameter from the voltage and current parameters
  • the judging unit is used for judging the variation characteristics of the power parameter, and driving the control unit to perform corresponding operations;
  • the control unit is configured to output the pulse modulation signal according to the change of the power parameter
  • the driving unit is used to control the operation of the switching element of the power conversion module with the pulse-modulated driving signal, so as to set the electrical parameter of the output terminal of the photovoltaic unit at the maximum power point.
  • the present invention also provides a photovoltaic power generation system, which includes a plurality of photovoltaic units, the output ends of the photovoltaic units are connected with the above-mentioned power optimizer, and the output ends of the many optimizers are connected in series to form a photovoltaic series body.
  • the output end of the series body is connected to the DC input side of the inverter or the input end of the DC combiner box, and it is characterized in that it also includes an arc fault detection device, and the arc fault detection device is arranged on the output side of the photovoltaic series body. When an arc is detected, disconnect the PV series connection to the inverter or DC combiner box.
  • the utility model uses the short-circuit protection circuit, when a short circuit occurs at the output end of the optimizer, the auxiliary power supply will stop supplying power because the voltage is too low, and the switching element will automatically disconnect the photovoltaic cell and the power acquisition system.
  • Shutdown protection at the same time, during the startup process of the optimizer, the principle that the energy storage element will produce electrical parameter changes when there is a short circuit will be used to detect whether there is a short circuit before restarting the optimizer.
  • the photovoltaic cell and the power acquisition system The circuit is kept disconnected to ensure that the photovoltaic cell does not output power to the outside before the short-circuit condition is removed; it responds quickly in the event of a short-circuit or parallel fault, isolates the photovoltaic cell from the power acquisition system, and uses only a small amount of power from the energy storage element for testing.
  • the measurement process Safe and reliable, it will not burden the system, and the output of photovoltaic cells can be quickly turned off when a safety fault occurs, and after the safety fault is eliminated, each photovoltaic cell can restart to generate electricity.
  • the utility model configures the short-circuit protection circuit in the photovoltaic power optimizer.
  • the photovoltaic power optimizer can make the photovoltaic cell run at the maximum power point, thereby improving the efficiency of power generation; on the other hand, the short-circuit protection circuit can be turned off
  • the control module of the optimizer is used for acquisition, calculation, judgment and control, and the switching devices and energy storage elements in the power conversion module of the optimizer can also be used.
  • the Buck-type topology optimizer which is equivalent to adding a second switch element at the output end of the power conversion module, which makes the short-circuit protection circuit simple in structure, easy to implement, and greatly improves the safety and reliability of power generation on the basis of local cost.
  • the dedicated receiver module and transmitter module are also reduced, which reduces the manufacturing cost of the power generation system.
  • the photovoltaic power generation system of the present utility model can extinguish the fault arc at the first time in the initial stage of arc generation, thereby avoiding more serious damage.
  • the short-circuit protection circuit configured in the power optimizer of each photovoltaic cell automatically extinguishes the arc, and keeps the optimizer disconnected from the external system before the short-circuit fault is resolved, so as to quickly eliminate the parallel arc without relying on
  • the arc fault detection device also does not need to configure a device for receiving carrier signals in each power optimizer, which saves costs; when a serial DC arc occurs, the first DC circuit is realized by disconnecting the DC combiner box or the inverter. Time annihilates serial arcs.
  • FIG. 1 is a schematic structural diagram of a short-circuit protection circuit configured in an optimizer according to an embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of an optimizer circuit with a short-circuit protection circuit according to an embodiment of the present invention
  • FIG. 3 is a schematic diagram of a short-circuit protection control structure of a control module according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of a power conversion control structure of a control module according to an embodiment of the present invention.
  • FIG. 5 is a schematic flowchart of a control method of a short-circuit protection circuit according to an embodiment of the present invention
  • FIG. 6 is a schematic structural diagram of a photovoltaic power generation system according to an embodiment of the present invention.
  • FIG. 7 is a schematic diagram of an arc fault occurring in a partial structure of a photovoltaic power generation system according to an embodiment of the present invention.
  • the optimizer E consists of a power conversion module E1, a control module E2, an auxiliary power supply E3 and a short-circuit protection circuit E4.
  • the input terminal of the power conversion module E1 is connected to the output of the photovoltaic unit through the interface, and the output terminals of many power conversion modules E1 are connected through the interface.
  • the interfaces are connected in series with each other and connected to the power acquisition system.
  • the photovoltaic unit is a photovoltaic module A in this embodiment, and may also be a photovoltaic string B containing a plurality of photovoltaic modules A in other implementations, or a series of photovoltaic cells in a photovoltaic module A.
  • the power conversion module E1 is used to convert the electrical parameter at the input end of the photovoltaic module A, and outputs another electrical parameter at the output end of the power conversion module E1.
  • the control module E2 is controlled and connected to the power conversion module E1, and can control the electric parameter conversion process of the power conversion module E1.
  • the auxiliary power source E3 is electrically connected to the photovoltaic module A, and is connected to the control module E2 for power supply, so as to supply power for the operation of the control module E2.
  • the short-circuit protection circuit E4 includes a first switching element S1 , a second switching element S2 and an energy storage element C in this embodiment.
  • the first switching element S1 and the second switching element S2 are connected in series on the positive loop of the optimizer E, and the circuit can be disconnected by turning off the first switching element S1 and the second switching element S2.
  • the energy storage element C is a capacitive element connected in parallel between the positive and negative loops between the first switching element S1 and the second switching element S2.
  • the first switching element S1 is turned on, the capacitive element is connected with the photovoltaic assembly A; when the second switching element S2 is turned on, the capacitive element is connected with the photovoltaic string B.
  • the auxiliary power source E3 is connected in parallel to the positive and negative loops of the output end of the photovoltaic module A, and the first switching element S1 and the second switching element S2 are normally open switching elements.
  • the control module E2 stops running, the first switching element S1 and the second switching element S2 become disconnected, so that the photovoltaic module A and the power acquisition system The connection circuit is disconnected.
  • the auxiliary power source E3 will be isolated from the short-circuit condition of the external circuit, and the power drawn from the photovoltaic module A will be resumed.
  • the control module E2 separately controls the conduction of the first switching element S1 and the second switching element S2, so that the capacitive element is connected to the power acquisition system after taking electricity from the photovoltaic module A, and is obtained and judged according to the difference between the voltage parameters at both ends of the capacitive element Whether the short-circuit condition is satisfied, and only after it is determined that the short-circuit condition is not satisfied, the first switching element S1 and the second switching element S2 are turned on at the same time to restore the connection between the photovoltaic unit and the power acquisition system.
  • the short-circuit protection circuit E4 of the present invention utilizes the first switching element S1 and the second switching element S2 to automatically turn off and perform short-circuit protection when the power acquisition system is short-circuited; Control the opening and closing of the first switching element S1 and the second switching element S2, and use the energy storage element C to test whether the external circuit is short-circuited.
  • this embodiment utilizes the control module E2 of the optimizer E to realize the automatic shutdown and automatic safe start of the photovoltaic module A in the event of a short circuit, which simplifies the safety guarantee structure in the photovoltaic power generation system and also simplifies the distributed system. Communication setup difficulty.
  • the energy storage element C may also be an inductance, and whether the external circuit is short-circuited is determined by measuring the current or energy storage condition of the inductance.
  • the power conversion module E1 of the optimizer E is a Buck-type DC chopper circuit structure with an output capacitor C2. It can be understood that, the power conversion module E1 may also be a Boost type or Boost-Buck type DC chopper circuit.
  • the power conversion module E1 includes an input capacitor C1, a first switch M1, an inductor L, a freewheeling diode D1, an output capacitor C2, a second switch M2 and a bypass diode D2.
  • the first switch tube M1, the inductor L and the second switch tube M2 are serially connected to the positive path PV+ of the DC chopper circuit in sequence. More specifically, the first switch M1 and the second switch M2 are n-type normally-on switch field effect transistors. In other embodiments, the first switch M1 and the second switch M2 may also be other fully controlled transistors. turning tube.
  • the sources of the first switch M1 and the second switch M2 are connected towards the output side of PV+, the drains of the first switch M1 and the second switch M2 are connected towards the input side of PV+, and the first switch M1 and the second switch M2 are connected towards the input side of PV+.
  • the gates of the switch tube M2 are respectively connected to the control module E2.
  • the auxiliary capacitor element and the input capacitor C1 are respectively connected in parallel on the positive path PV+ and the negative path PV- of the DC chopper circuit, and are located between the input end of the DC chopper circuit and the second switch tube M2.
  • the anode of the freewheeling diode D1 is connected to the negative circuit PV-
  • the cathode of the freewheeling diode D1 is connected to the positive circuit PV+
  • the output capacitor C2 is connected in parallel on PV+ and PV- of the DC chopper circuit, and is located between the inductor L and the second switch tube M2.
  • the bypass diode D2 is connected in parallel on PV+ and PV- of the DC chopper circuit, and is located between the second switch tube M2 and the output end of the DC chopper circuit.
  • the input capacitor C1 and the output capacitor C2 are used for the filtering of the chopper circuit
  • the first switch M1 controls the chopper conversion of the inductor L by the photovoltaic assembly A
  • the freewheeling diode D1 is used to maintain the output level.
  • the first switch tube M1 constitutes a component of the Buck-type DC chopper circuit, which can be used to control the power conversion of the DC chopper circuit with a pulse modulation signal (pulse width modulation PWM or pulse frequency modulation PFM), and at the same time as a short circuit.
  • the first switching element S1 of the protection circuit E4; the output capacitor C2 is used as the energy storage element C of the short-circuit protection circuit E4;
  • the second switch M2 is added on the output side of the DC chopper circuit as the second switching element S2 of the short-circuit protection circuit E4.
  • the short-circuit protection circuit E4 and the DC chopper circuit have common components, so as to simplify the circuit of the photovoltaic power optimizer E. Wherein, when the bypass diode D2 is in the off state as the optimizer E, the current of the photovoltaic string B can be turned on through the bypass diode D2.
  • the voltage parameters of the output capacitor C2 when it is connected to the photovoltaic module A are collected and recorded respectively, and compared with the voltage parameters of the output capacitor C2 when it is connected to the photovoltaic string B to obtain The voltage difference of the output capacitor C2 during the short circuit test.
  • the input end of the DC chopper circuit is provided with a filtered input capacitor C1 to prevent the fluctuating current of power conversion from affecting the photovoltaic module A in the reverse direction.
  • the And compare the voltage parameters of the input capacitor C1 and the output capacitor C2 to obtain the voltage difference of the output capacitor C2 during the short-circuit test.
  • the process of output storage can be reduced, and the error of before and after measurement can be reduced at the same time.
  • the control module E2 includes a control unit 21 , a collection unit 22 , an arithmetic unit 23 , a judgment unit 24 , a counting unit 25 , a driving unit 26 and a communication unit 27 .
  • the acquisition unit 22 can collect the current parameter Ipv and the voltage parameter Vpv at the input end of the power conversion module, as well as the output capacitor C2, that is, the voltage parameter Vout at the output end of the power conversion module. It is realized by processing it into an operable electrical signal by a processor.
  • the operation unit 23 may be arranged in the processor to perform operations on the collected electrical parameters.
  • the judging unit 24 may be provided in the processor, and judge the short-circuit condition or the current power condition according to the operation result.
  • the control unit 21 can be set in the processor, including performing corresponding short-circuit detection control under triggering operating conditions, such as initial startup after power is supplied, and also performing corresponding control operations according to the judged structure.
  • the counting unit 25 can be set in the processor to measure a certain result of the judgment unit 24, or to measure a certain operation of the control unit 21, and output the result when the set counting limit is reached, or clear under the set condition .
  • the communication unit 27 can be Zibee or WIFI or Bluetooth wireless communication, and the centralized control module HE2 is configured in the inverter system J or the DC combiner box, and the centralized control module HE2 is configured with a communication device matching the optimizer E. When it occurs, the control module E2 can send an alarm to the centralized control module HE2 via the communication unit 27 .
  • the control unit 21 is used to control the second switch M2 to keep off, and then control the first switch M1 to turn on, so that the output
  • the capacitor C2 obtains power from the photovoltaic unit, and controls the first switch M1 to be turned off, and then controls the second switch M2 to be turned on, so that the output capacitor C2 is connected to the power acquisition system;
  • the acquisition unit 22 is used to collect the output capacitance C2 is acquiring power and taking into account the voltage parameter information of the power acquisition system;
  • the arithmetic unit 23 is used to acquire the voltage parameter information difference between the power state and the access system state;
  • the judging unit 24 is used to judge the voltage parameter information parameter , and drive the control unit 21 to perform the corresponding operation; when the control unit 21 determines that there is no short circuit, the control unit 21 controls the first switch M1 and the second switch M2 to be turned on at the same time with the switching quantity;
  • the switch quantity controls the turn-off of the first switch tube
  • the control unit 21 When it is determined that the short-circuit is not confirmed, the control unit 21 performs short-circuit detection again after a delay of the set time; the counting unit 25 does not confirm the short circuit. The number of executions performed by the first control unit 21 is measured, and when the preset number of times is exceeded, it is determined that the short circuit is determined; the driving unit 26 controls the turn-off and conduction of the first switch tube M1 and the second switch with driving power according to the switch quantity control command. The communication unit 27 alarms the centralized control module HE2 after it is determined that the short circuit is confirmed.
  • the collection unit 22 is used to collect the voltage and current parameters of the output end of the photovoltaic unit; the arithmetic unit 23 is used to calculate the power parameters from the voltage and current parameters.
  • the judging unit 24 is used for judging the change characteristic of the power parameter, and drives the control unit 21 to perform the corresponding operation; the control unit 21 is used for outputting the pulse modulation signal according to the change of the power parameter;
  • the switching element of the power conversion module E1 is controlled to operate, so as to set the electrical parameter of the output terminal of the photovoltaic unit at the maximum power point.
  • FIG. 5 it is a flow chart of a control method of a power optimizer capable of short circuit protection according to an embodiment.
  • the method includes: when the auxiliary power source E3 is turned off for the first time, and when the control module E2 is operated, the startup optimizer E that has been tested by the short-circuit condition is executed. Specifically, when the photovoltaic power optimizer E is powered off during operation or restarted the next day after it is shut down in the dark, before the optimizer E enters the working state, a circuit anti-short circuit detection is performed to avoid the risk of short circuit.
  • the second switch M2 is controlled to be turned off, and then the first switch M1 is controlled to be turned on, so that the input capacitor C1 and the input capacitor C1 obtain power from the photovoltaic module A, and detect and confirm that the voltage values of the two are close to the same.
  • the first switch M1 is controlled to be turned off, and then the second switch M2 is controlled to be turned on, so that the output capacitor C2 is connected to the photovoltaic string B, and the input capacitor C1 and the photovoltaic string B are in resistance.
  • the voltage value V1 of the input capacitor C1 is collected at this time, and the voltage value V2 of the output capacitor C2 is collected at this time; by comparing
  • the fourth step is to determine the relationship between
  • the output voltage of the optimizer E is confirmed by the input capacitor C1 of the inverter, and the energy storage is not completed in the input capacitor C1.
  • the confirmation of the uncertainty range can reduce the shutdown of the optimizer E due to short-circuit detection errors.
  • the confirmation of the uncertainty range can also reduce the impact and damage caused by the connection of the input capacitor C1 to the photovoltaic power generation system during a short circuit.
  • FIG. 6 it is a photovoltaic power generation system according to the embodiment, which is composed of a photovoltaic module A, a power optimizer E, and a photovoltaic inverter system J.
  • the output end of each photovoltaic module A is connected with a power optimizer E.
  • the number of photovoltaic modules A is multiple, and they are A-1, A-2, ..., A-n in the figure; the number of power optimizers E corresponds to the number of E-1, E-2, ..., E-n in the figure.
  • the output terminals of the power optimizer E are connected in series to form a photovoltaic string B, namely B-1, B-2, ..., B-m in the figure.
  • the output end of the PV string B can be connected to the DC side of the inverter system J, or connected to the input end of the DC combiner box and then connected to the output side of the inverter system J from the output end of the DC combiner box.
  • the photovoltaic string B is connected to the inverter system J.
  • Each optimizer E is equipped with the above-mentioned short-circuit protection circuit E4, and the inverter system J is equipped with an arc fault detection device F and a centralized control module HE2.
  • the arc fault detection device F is an arc fault detector (AFCI) and/or a residual current detection device (RCD), which is a common device for detecting arcs and other faults in the prior art.
  • the centralized control module HE2 can control the inverter circuit to close.
  • the centralized control module HE2 can establish a wireless communication connection with each optimizer E to obtain the alarm information of each optimizer E, or send a start-up instruction to the control module E2 of each optimizer E after maintenance, and actively control the optimizer E to start.
  • the optimizer E at the position where the parallel arc occurs will be turned off when the auxiliary power source E3 is lower than the operating voltage, and the optimizer E will be disconnected from the photovoltaic string B before confirming that the short-circuit state is relieved to eliminate the Parallel arc.
  • the optimizer E equipped with the above-mentioned short-circuit protection circuit E4 and the control method using the above-mentioned short-circuit protection circuit E4 can automatically detect the short-circuit situation, that is, the occurrence of parallel arcs, at the first time when the parallel arc occurs, and After the auxiliary power supply E3 is stopped due to the low voltage, the first switch tube M1 and the second switch tube M2 are kept off, so that the parallel arc is extinguished at the first time, and before the test short-circuit condition is eliminated, the Optimizer E is not started.
  • the optimizer E equipped with the above-mentioned short-circuit protection circuit E4, and the control method using the above-mentioned short-circuit protection circuit E4 can be completed after the short-circuit test. Start operation automatically without complicated communication structure.
  • FIG. 7 it is a part of the photovoltaic power generation system of the embodiment.
  • arc faults have occurred at locations with a to f.
  • position a is the serial arc generated between the connecting lines or joints of photovoltaic string B and the DC bus
  • position b is the serial arc generated at the disconnection of the connecting line between photovoltaic module A and photovoltaic module A
  • position c is The serial arc generated at the connection of the DC bus, or the connection joint between the single-line DC bus and the inverter system J is disconnected.
  • the arcs at positions a to c are serial arc faults.
  • the position d is the parallel arc caused by the damage between the two DC busbars
  • the position e is the parallel arc generated at the connection between the positive and negative DC busbars and the inverter system J
  • the position f is the arc connection between a DC busbar and the ground.
  • the arcs at positions d to f are parallel arc faults.
  • the local parallel arcs can still be connected into a loop, and the photovoltaic modules in the loop can still be connected. Power is obtained in A, the parallel arc still exists.
  • the parallel arc will cause the auxiliary power supply E3 in each optimizer E to be short-circuited, and under the condition that the voltage is equal to or close to zero, the auxiliary power supply E3 is turned off, and the normally-on type No. 1 is turned off.
  • the first switch tube M1 and the second switch tube M2 keep disconnecting after losing driving power; at the same time, even if the auxiliary power E3 reaches the starting voltage again after disconnection, the control module E2 will keep the switch tube disconnected for the first time after it is started , and conduct a short-circuit test while keeping PV module A disconnected from the external circuit during the whole process. After the disconnection of the optimizer E, the PV module A and the DC circuit at the parallel arc position will be disconnected, so as to eliminate the parallel arc at the first time. Moreover, the optimizer E will keep shutting down until the short-circuit condition is resolved, and the optimizer E will be activated actively after the maintenance personnel carry out maintenance.
  • each PV module A will successfully pass the short-circuit test and restart automatically.

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Abstract

一种可短路保护的功率优化器和光伏发电系统，其中功率优化器包括短路保护电路，短路保护电路包括第一开关件、第二开关件和储能元件，第一开关件关断或第二开关件关断，则光伏单元与电力获取系统的连接断开，第一开关件和第二开关件的单独导通可使储能元件从光伏单元取电后接入电力获取系统，辅助电源的运行电压低于关闭电压，开关件能够断开光伏组件对外部的连接，并且利用储能元件进行短路测试，在短路未排除前保持优化器关断。本申请可实现短路的自动断开，并行电弧将在产生处自行关断消除，而在除短路的其他因素导致优化器停机的情况能安全地自启动。

Description

一种可短路保护的功率优化器和光伏发电系统 技术领域
本实用新型涉及光伏并网发电技术领域，特别是涉及一种可短路保护的功率优化器和光伏发电系统。
背景技术
当前并网光伏系统的直流输入端一般是由光伏电池串并联成的500V—1500V系统电压的直流系统，因此当发生绝缘破坏、金属接头松动、元件老化、动物呲咬等情况时都会产生电弧故障。而直流电弧不同于交流电弧，电流没有过零点，因而不能自动熄弧，一旦发生拉弧没有及时处理，往往会造成经济损失或可能存在的人身安全损失。直流拉弧对光伏系统来说是一个重要的安全问题，需要引起重视。
直流电弧根据其产生的位置可分为并行直流电弧和串行直流电弧。串行电弧故障主要由光伏电池间接头及直流汇流箱及逆变器的连接端子接触不良、直流电缆断裂等因素产生的连接线电弧故障。并行电弧故障主要是由于绝缘破坏引起的，可分为对地电弧与线线电弧，产生并行电弧的直流回路可认为发生短路。光伏电池的短路电流与辐照温度相关，难以检测确定。即使安装在逆变器或直流汇流箱中的电弧检测装置检测到回路中存在电弧故障，并通过断开光伏直流回路，也仅能消灭串行电弧，而不能消除并行电弧。因为即使直流电路回路被断开后，发生绝缘破坏而造成的对地与线线回路仍然存在。
为了消除并行电弧故障，现有技术是通过安装在光伏电池输出端光伏功率优化器或关断器断开光伏电池对外供电。在出现电弧或短路故障时，利用中央控制器持续发送心跳通讯信号，或者利用位于直流总线上的关断控制模块发送周期性激励脉冲源，控制功率优化器或关断器关断光伏电池的输出，使其停止发电；当安全故障消失后，各个光伏电池功率光伏功率优化器或关断器重新开通，使自身所连接的光伏电池实现电能输出。现有技术的两种方案中，不但在光伏逆变系统中需要增加相应的发送模块，并且在光伏电池的关断器或功率光伏功率优化器也需要设置额外的接收模块，从而不但增加了光伏系统的成本与系统自耗电，同时增加了新的信号源发送与接收模块的故障点。
实用新型内容
为解决现有技术存在的缺陷，本实用新型的主要目的在于提供一种可短路保护的功率优化器和光伏发电系统，一方面可通过光伏功率优化器实现短路时的自动关断保护，并且短路情况解除后自动启动；在另一方面在实现光伏发电系统直流侧的快速电弧故障检测和关断回路灭弧的基础上，减少光伏电池中关断电路的信号源接收模块、光伏逆变系统中的信号源发送模块。在整体上，不仅降低在电弧和短路防护的快速关断方面的成本，同时提升光伏发电系统安全性和可靠性。
为了实现上述目的，本实用新型采用如下的技术方案：
本实用新型在一方面提供了一种可短路保护的功率优化器，该优化器包括功率变换模块、控制模块和辅助电源，功率变换模块的输入端可接入到光伏单元的输出端，功率变换模块的输出端可接入至电力获取系统，辅助电源取电连接于光伏单元的输出端并供电连接于控制模块，控制模块控制连接于功率变换模块，该优化器还配置有短路保护电路；
所述短路保护电路包括第一开关件、第二开关件和储能元件，所述控制模块以开关信号控制连接于第一开关件和第二开关件；
所述第一开关件和第二开关件连接在光伏单元与电力获取系统的连接回路上，任一所述第一开关件和第二开关件的关断，则光伏单元与电力获取系统的连接断开；所述储能元件连接在第一开关件和第二开关件之间，第一开关件的导通可连通光伏单元与储能元件，第二开关件的导通可连通储能元件与电力获取系统；
至少在辅助电源的运行电压低于关闭电压，任一所述第一开关件和第二开关件将关断，并使光伏单元和电力获取系统的连接断开；
至少在辅助电源的运行电压高于启动电压，所述控制模块分别单独控制第一开关件和第二开关件的导通，使储能元件从光伏单元取电后接入电力获取系统，获取并根据储能元件的电参量差异情况判断是否满足短路条件，而在确定不满足短路条件后同时导通第一开关件和第二开关件，以经短路测试地尝试恢复光伏单元和电力获取系统的连通。
上述的功率优化器，可选的有，所述储能元件为并接在功率变换模块正负回路上的电容元件，所述控制模块获取并根据电容元件的电压参量差异情况判断是否满足短路条件。
上述的功率优化器，可选的有，所述功率变换模块(E1)为具有输出电容(C2)的Buck型或Boost型或Boost-Buck型直流斩波电路；所述输出电容(C2)作为短路保护电路(E4)的储能元件(C)；
在经短路测试过程中，所述控制模块(E2)通过分别采集并记录输出电容(C2)导通至光伏单元而获电，及输出电容(C2)导通至电力获取系统的电压参量，以获取用于判断是否满足短路条件的电压参量差异。
上述的功率优化器，可选的有，所述功率变换模块(E1)为具有输出电容(C2)的Buck型或Boost型或Boost-Buck型直流斩波电路；所述输出电容(C2)作为短路保护电路(E4)的储能元件(C)；
在经短路测试过程中，所述控制模块(E2)通过分别采集并记录输出电容(C2)导通至光伏单元而获电，及输出电容(C2)导通至电力获取系统的电压参量，以获取用于判断是否满足短路条件的电压参量差异。
上述的功率优化器，可选的有，所述功率变换模块(E1)为具有开关元件的Buck型或Boost型或Boost-Buck型直流斩波电路；所述第一开关件(S1)作为直流斩波电路中串接在正或负回路上的开关元件。
上述的功率优化器，可选的有，所述第二开关件(S2)为串接在直流斩波电路输出端和优化器(E)输出端之间正或负回路上的开关元件，至少其一的所述第一开关件(S1)和第二开关件(S2)为常开式开关件。
上述的功率优化器，可选的有，所述功率变换模块为降压式Buck直流斩波电路，其包括输入电容、作为所述第一开关件的开关元件、电感器、续流二极管、作为所述储能元件的输出电容；所述第一开关件、电感器和第二开关件依次串联于直流斩波电路的正极路，所述续流二极管正负回路并联连接在第一开关件和电感器之间，所述输入电容正负回路并联连接在功率变换模块的输入端和第一开关件之间，所述输出电容正负极并联地连接在电感器和第二开关件之间；所述第二开关件与功率变换模块的输出端之间正负极并联地连接有旁路二极管。
上述的功率优化器，可选的有，所述控制模块包括用于控制所述短路保护电路运行的控制单元、采集单元、运算单元、判断单元、计数单元、驱动单元和通讯单元；
所述控制单元用于控制第二开关件保持关断，而后控制第一开关件导通，以使储能元件从光伏单元获取电力，以及控制第一开关件变为关断，而后控制第二 开关件导通，以使储能元件接入到电力获取系统；
所述采集单元用于采集储能元件在获取电力及计入电力获取系统的电参量信息；
所述运算单元用于获取在电力状态下及在接入系统状态下的电参量信息差异；
所述判断单元用于对电参量信息参量进行判定，并驱使控制单元执行相应的操作；
所述控制单元在判定为不存在短路下，以开关量控制第一开关件和第二开关件的同时导通；在判定为确定短路下，以开关量控制第一开关件和第二开关件的关断，在判定为不确认短路下，延时设定时间后再次由控制单元执行短路检测；
所述计数单元对因不确认短路而执行的第一控制单元执行次数进行计量，在超出预设次数下，判定为确定短路；
所述驱动单元根据开关量控制命令以驱动电力控制第一开关件和第二开关的关断和导通；
所述控制模块还包括通讯单元，所述通讯单元在判定为确认短路后对电力获取系统进行报警。
上述的功率优化器，可选的有，所述控制模块还用于控制所述功率变换模块进行功率变换；
所述采集单元用于采集光伏单元输出端的电压电流参量；
所述运算单元用于由电压电流参量计算出功率参量；
所述判断单元用于判断功率参量的变化特征，并驱使控制单元执行相应的操作；
所述控制单元用于根据功率参量的变化输出脉冲调制信号；
所述驱动单元用于以经脉冲调制的驱动信号控制功率变换模块的开关元件运行，以将光伏单元输出端的电参量设置在最大功率点。
本实用新型在另一方面还提供了一种光伏发电系统，包括诸多光伏单元，所述光伏单元的输出端连接有上述的功率优化器，诸多优化器的输出端相串联成光伏串联体，光伏串联体的输出端接入至逆变器的直流输入侧或直流汇流箱的输入端，其特征是，还包括电弧故障检测装置，所述电弧故障检测装置配置于光伏串联体的输出侧，在检测到电弧时，关断光伏串联体对逆变器或直流汇流箱的连接。
与现有技术相比，本实用新型有益效果如下：
(1)本实用新型通过短路保护电路，在优化器输出端发生短路时，辅助电源将因电压过低而停止供电，开关件将自行断开光伏电池与电力获取系统的连通，实现短路时的关断保护；同时，在优化器的启动过程中，将利用存在短路时储能元件将产生电参量变化的原理，在重新启动优化器前检测是否存在短路情况，通过在光伏电池和电力获取电路的连接回路上设有至少两个开关件，该开关件单独导通时，可分别使储能元件从光伏电池取电和使储能元件接入电力获取系统，检测过程中光伏电池和电力获取电路维持断开，确保在短路情况解除之前，光伏电池不对外部输出电力；发生短路或并联故障时快速响应，将光伏电池隔离于电力获取系统，仅利用储能元件的少量电力进行测试，测量过程安全可靠，不会对系统造成负担，实现在安全故障发生时能够快速关闭光伏电池输出，而安全故障排除后，各光伏电池能重新运行发电。
(2)本实用新型通过将短路保护电路配置在光伏功率优化器当中，一方面光伏功率优化器可使光伏电池运行在最大功率点，提高发电的效率；另一方面，短路保护电路可以在关断和启动时，利用到优化器的控制模块进行采集、运算、判断和控制，也可以利用到优化器的功率变换模块中的开关件和储能元件，相比于Buck型拓扑结构的优化器，相当于在功率变换模块的输出端增设第二开关件，使得短路保护电路结构简单，易于实施，成本地的基础上极大地提供了发电的安全性和可靠性。相对于传统关断器和优化器，还减少了专用的接收模块和发送模块，降低了发电系统的制造成本。
(3)本实用新型的光伏发电系统，针对并行电弧和串行电弧的不同，在电弧产生的初始阶段，可在第一时间对故障电弧进行灭弧，从而避免造成更严重的伤害。在发生并行直流电弧时，各光伏电池的功率优化器所配置的短路保护电路自动进行灭弧，且在短路故障未解除前保持优化器对外部系统的断开，实现快速消除并行电弧，可不依靠电弧故障检测装置，也无需在每个功率优化器内配置接收载波信号的装置，节省成本；在发生串行直流电弧时，则通过断开直流汇流箱或逆变器的直流回路，实现第一时间消灭串行电弧。
下面结合附图对本实用新型作进一步的说明。
附图说明
图1为本实用新型实施例的配置于优化器的短路保护电路的结构示意图；
图2为本实用新型实施例的具有短路保护电路的优化器电路的结构示意图；
图3为本实用新型实施例的控制模块的短路保护控制结构示意图；
图4为本实用新型实施例的控制模块的功率变换控制结构示意图；
图5为本实用新型实施例的短路保护电路的控制方法流程示意图；
图6为本实用新型实施例的光伏发电系统的结构示意图；
图7为本实用新型实施例的光伏发电系统的局部结构发生电弧故障的示意图。
具体实施方式
为更好的说明本实用新型的目的、技术方案和优点，下面结合附图和实施例对本实用新型的具体实施方式作进一步详细描述。以下实施例用于说明本实用新型，但不作为限值本实用新型的范围。
如图1所示，是实施例的一种可短路保护的功率优化器。该优化器E由功率变换模块E1、控制模块E2、辅助电源E3和短路保护电路E4组成，功率变换模块E1的输入端通过接口接入到的光伏单元输出，诸多功率变换模块E1的输出端通过接口相互串接而接入至电力获取系统。所述的光伏单元在本实施例是光伏组件A，在其他实施中还可以是含有多个光伏组件A的光伏组串B，或一光伏组件A中部分光伏电池片串联体。功率变换模块E1用于对光伏组件A输入端的电参量进行变换，而在功率变换模块E1的输出端以另一电参量输出。控制模块E2控制连接于功率变换模块E1，可控制功率变换模块E1的电参量变换过程。辅助电源E3取电连接于光伏组件A，并供电连接于控制模块E2，以为控制模块E2的运行供电。
本实施例具体地，参考图1，短路保护电路E4包括第一开关件S1、第二开关件S2和储能元件C。第一开关件S1和第二开关件S2串接在优化器E的正回路上，第一开关件S1和第二开关件S2的关断可断开回路。在本实施例中，储能元件C是并联连接在正负回路位于第一开关件S1和第二开关件S2之间的电容元件。当第一开关件S1导通时，该电容元件与光伏组件A相连通；当第二开关件S2导通时，该电容元件于光伏组串B相连通。辅助电源E3并接在光伏组件A输出端的正负回路上，第一开关件S1和第二开关件S2是常开型开关件。当出现短路等情况而使得正负回路电压低于辅助电源E3的电压，控制模块E2停止运行，第一开关件S1和第二开关件S2变为断开状态，使光伏组件A与电力获取系统的连接回路 断开。在第一开关件S1和第二开关件S2的关断后，辅助电源E3将与外部电路的短路情况隔离，而恢复从光伏组件A的取电。控制模块E2分别单独控制第一开关件S1和第二开关件S2的导通，使该电容元件从光伏组件A取电后接入电力获取系统，获取并根据电容元件两端电压参量差异情况判断是否满足短路条件，而仅在确定不满足短路条件后同时导通第一开关件S1和第二开关件S2，恢复光伏单元和电力获取系统的连通。
可以理解的是，本实用新型的短路保护电路E4，一方面利用第一开关件S1和第二开关件S2，在电力获取系统发生短路时，自动关断并进行短路保护；另一方面，利用对第一开关件S1和第二开关件S2的启闭控制，并以储能元件C测试外部电路是否短路。相比于现有，本实施例利用了优化器E的控制模块E2，实现光伏组件A在短路时的自动关闭和自动安全启动，简化了在光伏发电系统安全保障结构，也简化了分布式系统通讯的设置难度。在其他实施例中，储能元件C还可以是电感，而通过测量电感的电流或储能情况判断外部电路是否短路。
如图2所示，是实施例的具体的可短路保护的功率优化器，配置在BUCK降压式的光伏功率优化器E当中。优化器E的功率变换模块E1为具有输出电容C2的Buck型直流斩波电路结构。可以理解的是，功率变换模块E1还可以是Boost型或Boost-Buck型直流斩波电路。该功率变换模块E1包括，输入电容C1、第一开关管M1、电感器L、续流二极管D1、输出电容C2、第二开关管M2和旁路二极管D2。该第一开关管M1、电感器L和第二开关管M2依次串接在直流斩波电路的正极路PV+上。更具体地有，第一开关管M1和第二开关管M2是n型常开型开关场效应管，在其他实施例中，第一开关管M1和第二开关管M2还可以是其他全控开关管。第一开关管M1和第二开关管M2的源极朝向PV+的输出侧连接，第一开关管M1和第二开关管M2的漏极朝向PV+的输入侧连接，第一开关管M1和第二开关管M2的栅极分别连接于控制模块E2。辅助电容元件和输入电容C1分别并联在直流斩波电路的正极路PV+和负极路PV-之上，位于直流斩波电路的输入端和第二开关管M2之间。续流二极管D1的阳极连接在负极回路PV-上，续流二极管D1的阴极连接在正极回路PV+上，并且位于第一开关管M1和电感之间。输出电容C2并联在直流斩波电路的PV+和PV-之上，位于电感器L和第二开关管M2之间。旁路二极管D2并联在直流斩波电路的PV+和PV-之上，位于第二开关管M2和直流斩波电路的输出端之间。其中，输入电容C1和输出电容C2用于斩波电路的滤波，第一开关管M1控 制光伏组件A对电感器L的斩波转换，续流二极管D1用于维持输出电平。
需要说明的是，第一开关管M1组成Buck型直流斩波电路的元件，可用于以脉冲调制信号(脉冲宽度调制PWM或脉冲频率调制PFM)控制实现直流斩波电路的功率转换，同时作为短路保护电路E4的第一开关件S1；输出电容C2作为短路保护电路E4的储能元件C；第二开关管M2增设在直流斩波电路输出侧，作为短路保护电路E4的第二开关件S2。其中，短路保护电路E4和直流斩波电路有共用的元器件，实现简化光伏功率优化器E的电路。其中，旁路二极管D2作为优化器E关断状态下，光伏组串B的电流可经旁路二极管D2导通。
需要说明的是，在储能元件C在开关件的两种控制状态下电参量差异方面有。一方面地，在两种控制状态下，分别采集并记录输出电容C2在接入光伏组件A时的电压参量，与输出电容C2在接入到光伏组串B时的电压参量进行比较，以获取在短路测试过程的输出电容C2的电压差异。在另一方面，直流斩波电路的输入端设置有滤波的输入电容C1，以防止功率转换的波动电流反向影响到光伏组件A，可在输出电容C2在接入光伏组串B时，采集并比较输入电容C1和输出电容C2的电压参量，以获取在短路测试过程的输出电容C2的电压差异。在后者的方案当中，可减少输出储存的过程，同时降低前后测量的误差。
如图3和4所示，是实施例的可短路保护的功率优化器的控制模块结构。该控制模块E2包括控制单元21、采集单元22、运算单元23、判断单元24、计数单元25、驱动单元26和通讯单元27。其中，采集单元22可采集功率转换模块输入端的电流参量Ipv和电压参量Vpv，以及输出电容C2，也即功率转换模块输出端的电压参量Vout，采集是通过设于采集位置的传感器，经放大器放大并经处理器处理为可运算的电信号而实现。运算单元23可设置在处理器中，对所采集电参量进行运算。判断单元24可设置在处理器，根据运算的结果判断短路的情况或当前功率的情况。控制单元21可设置在处理器，包括在触发运行条件下，如获电后初始启动，进行相应的短路检测控制；也包括根据判断的结构进行相应的控制操作。计数单元25可设置在处理器中，对判断单元24的某结果进行计量，或对控制单元21的某操作进行计量，在达到设定的计数限度下输出结果，或在设定条件下清零。通讯单元27可为Zibee或WIFI或蓝牙无线通信，而在逆变系统J或直流汇流箱中配置有集中控制模块HE2，集中控制模块HE2配置有与优化器E相匹配的通讯装置，在短路故障出现时控制模块E2可经通讯单元27向集中控制模块HE2报 警。
具体参照图3，在经短路测试地重启优化器E的控制过程中，具体的，控制单元21用于控制第二开关管M2保持关断，而后控制第一开关管M1导通，以使输出电容C2从光伏单元获取电力，以及控制第一开关管M1变为关断，而后控制第二开关管M2导通，以使输出电容C2接入到电力获取系统；采集单元22用于采集输出电容C2在获取电力及计入电力获取系统的电压参量信息；运算单元23用于获取在电力状态下及在接入系统状态下的电压参量信息差异；判断单元24用于对电压参量信息参量进行判定，并驱使控制单元21执行相应的操作；控制单元21在判定为不存在短路下，以开关量控制第一开关管M1和第二开关管M2的同时导通；在判定为确定短路下，以开关量控制第一开关管M1和第二开关管M2的关断，在判定为不确认短路下，延时设定时间后再次由控制单元21执行短路检测；计数单元25对因不确认短路而执行的第一控制单元21执行次数进行计量，在超出预设次数下，判定为确定短路；驱动单元26根据开关量控制命令以驱动电力控制第一开关管M1和第二开关的关断和导通；通讯单元27在判定为确认短路后对集中控制模块HE2进行报警。
具体参照图4，在优化器E正常运行时对功率转换的控制过程中，具体的，采集单元22用于采集光伏单元输出端的电压电流参量；运算单元23用于由电压电流参量计算出功率参量；判断单元24用于判断功率参量的变化特征，并驱使控制单元21执行相应的操作；控制单元21用于根据功率参量的变化输出脉冲调制信号；驱动单元26用于以经脉冲调制的驱动信号控制功率变换模块E1的开关元件运行，以将光伏单元输出端的电参量设置在最大功率点。
如图5所示，是实施例的可短路保护的功率优化器的控制方法的流程。该方法包括：在辅助电源E3关闭后首次获取电力，并使控制模块E2运行时，执行经短路情况测试的启动优化器E。具体是，光伏功率优化器E工作中断电开机或天黑停机后翌日重新开机时，在优化器E进入工作状态前，进行电路防短路检测规避短路风险。
第一步，控制第二开关管M2保持关断，而后控制第一开关管M1导通，以使输入电容C1和输入电容C1从光伏组件A获取电力，检测并确认两者电压值接近一致。第二步，控制第一开关管M1变为关断，而后控制第二开关管M2导通，以使输出电容C2接入到光伏组串B当中，而输入电容C1与光伏组串B相阻断，采 集此时输入电容C1的电压值V1，采集此时输出电容C2的电压值V2；通过|V1-V2|/V2比较在获取输出电容C2在接入光伏组串B后的电压信息差异。第四部，判断|V1-V2|/V2与第一预设差异限值10％，以及与第二预设差异限值50％的关系：
若|V1-V2|/V2≤10％，则确认所接入系统不存在短路情况，而同时导通第一开关管M1和第二开关管M2，而恢复优化器E运行；若10％＜|V1-V2|/V2＜50％，则所接入系统为不确定短路的情况，而在延时3分钟后，再次执行经短路情况测试地启动优化器E。对该情况进行第一计数，若满足在连续的短路测试过程当中不确定的情况达到3次，则确认所接入系统存在短路情况，而维持第一开关管M1和第二开关的关闭，停止功率优化器E运行；若|V1-V2|/V2≥50％，则确认所接入系统存在短路情况，而维持第一开关管M1和第二开关的关闭，停止功率优化器E运行。在判断确认所接入系统存在短路情况后，对集中控制模块HE2进行报警和/或报修。
需要说明的是，在短路检测的过程当中，存在不确定的范围，可再次尝试短路检测，如优化器E的输出端电压由逆变器的输入电容C1确认，在输入电容C1未储能完毕前，存在电压变化的可能。综合地，对不确定范围的确认，可减少因短路检测误差所导致的优化器E关闭。同时，对不确定范围的确认，也可减少在短路时，输入电容C1接入到光伏发电系统当中造成的冲击和损害。
如图6所示，是实施例的一种光伏发电系统，由光伏组件A、功率优化器E、光伏逆变系统J组成。各光伏组件A的输出端连接有功率优化器E。光伏组件A数量有多个，及图中的A-1、A-2、…、A-n；功率优化器E的数量相对应，及图中的E-1、E-2、…、E-n。功率优化器E的输出端相串联形成光伏组串B，即图中的B-1、B-2、…、B-m。光伏组串B的输出端可接入至逆变系统J的直流侧，或经接入到直流汇流箱的输入端后再由直流汇流箱的输出端接入到逆变系统J的输出侧。在本实施例中，光伏组串B接入到逆变系统J当中。各优化器E配置有上述短路保护电路E4，而逆变系统J中配置有电弧故障检测装置F和集中控制模块HE2。电弧故障检测装置F为电弧故障探测器(AFCI)和/或剩余电流检测装置(RCD)，是现有技术检测电弧等故障的常用装置，通过检测所接入回路的电参量在时域和/或频域特征性，并判断是否有故障电弧产生。在电弧故障检测装置F检测到电弧时，可经集中控制模块HE2控制逆变电路关闭。集中控制模块HE2可与各个优化器E建立无线通讯连接，以获取各优化器E的报警信息，或在维修后发送启动指令至各优化器E的控制模块E2，主动控制优化器E启动。
可以理解的是，快速消除光伏发电系统中的电弧故障过程中，在电弧故障检测装置F检测到串行电弧时，逆变器或直流汇流箱将断开光伏组串B的输出回路，以消灭串行电弧。该方案可以在电弧发生的第一时间，向光伏组串B所连接的光伏逆变系统J或直流汇流箱发出警示信息，从而驱动光伏逆变系统J或直流回流箱断开产生串行电弧的回路，从而第一时间进行灭弧，而避免造成更为严重的后果。
在发生并行电弧时，并行电弧发生位置的所述优化器E，将在辅助电源E3低于运行电压下而关闭，在确认短路状态解除前优化器E将断开于光伏组串B，以消灭并行电弧。该方案可以在并行电弧发生的第一时间，由配有上述短路保护电路E4的优化器E，以及使用上述短路保护电路E4的控制方法，自行检测到短路的情况，即并行电弧的发生，并在辅助电源E3因电压过低而停运之后，保持第一开关管M1和第二开关管M2的关断，从而第一时间进行并行电弧的灭弧，并且在测试短路情况未排除之前，将不启动优化器E。另一方面，对于因为其他原因而导致的优化器E停机后重新启动，则配有上述短路保护电路E4的优化器E，以及使用上述短路保护电路E4的控制方法，可在完成短路测试之后，自动启动运行，无需复杂的通讯结构。
如图7所示，是实施例的光伏发电系统的局部。图中，具有a到f的位置发生了电弧故障。其中，位置a是光伏组串B和直流母线的连接线或接头之间产生的串行电弧；位置b是光伏组件A和光伏组件A的连接线断开处产生的串行电弧；位置c是直流母线连接处，或者单线直流母线与逆变系统J的连接接头断开吃处所产生的串行电弧。位置a至c的电弧是串行电弧故障，在本实用新型的光伏发电系统的运行过程，将被电弧故障检测装置F所检测到，并经由逆变器关断其交流侧开关件，实现电力获取系统回路的断开，而完成第一时间的串行电弧灭弧。其中，位置d是两根直流母线之间的破损导致的并行电弧，位置e是正负直流母线与逆变系统J连接处所产生的并行电弧，位置f是一根直流母线与地端产生电弧连接所产生的并行电弧。位置d至f的电弧是并行电弧故障，即使由电弧故障检测装置F所检测到，并且关断整个光伏发电系统的供电回，但局部的并行电弧仍然可连接成回路，并从回路的光伏组件A中获得电力，并行电弧仍然存在。在本实用新型的光伏发电系统的运行过程，并行电弧将导致各优化器E中的辅助电源E3短路，而在电压等于或接近零的条件下，辅助电源E3关闭，并使常开型的 第一开关管M1和第二开关管M2在失去驱动电力而保持断开；同时，断开后即使辅助电源E3重新达到启动电压，而控制模块E2启动后，将第一时间保持开关管的断开，并在全程保持光伏组件A与外部电路断开的情况下进行短路测试。优化器E的断开后，光伏组件A和并行电弧位置处的直流回路将断开，实现第一时间消灭并行电弧。并且，在短路情况未曾解除之前，优化器E将保持停机，直至维修人员进行维修后，主动地启动优化器E。
同时，其他因素作用下，控制模块E2的重新启动，如天黑所导致的优化器E停机而后第二天早上的优化器E重启，或者其他诸如过流因素而导致的优化器E停机而后的重启，各个光伏组件A将顺利通过短路测试，而自动重新开机。
以上实施例主要描述了本实用新型的基本原理、主要特征和优点。本行业的技术人员应该了解，本实用新型不受上述实施例的限值，上述实施例和说明书中描述的只是说明本实用新型的原理，在不脱离本实用新型精神和范围的前提下，本实用新型还会有各种变化和改进，这些变化和改进都落入要求保护的本实用新型范围内。

Claims (10)

  1. 一种可短路保护的功率优化器，该优化器(E)包括功率变换模块(E1)、控制模块(E2)和辅助电源(E3)，功率变换模块(E1)的输入端可接入到光伏单元的输出端，功率变换模块(E1)的输出端可接入至电力获取系统，辅助电源(E3)取电连接于光伏单元的输出端并供电连接于控制模块(E2)，控制模块(E2)控制连接于功率变换模块(E1)，其特征是，该优化器(E)还配置有短路保护电路(E4)；
    所述短路保护电路(E4)包括第一开关件(S1)、第二开关件(S2)和储能元件(C)，所述控制模块(E2)以开关信号控制连接于第一开关件(S1)和第二开关件(S2)；
    所述第一开关件(S1)和第二开关件(S2)连接在光伏单元与电力获取系统的连接回路上，任一所述第一开关件(S1)和第二开关件(S2)的关断，则光伏单元与电力获取系统的连接断开；所述储能元件(C)连接在第一开关件(S1)和第二开关件(S2)之间，第一开关件(S1)的导通可连通光伏单元与储能元件(C)，第二开关件(S2)的导通可连通储能元件(C)与电力获取系统；
    在辅助电源(E3)关闭，任一所述第一开关件(S1)和第二开关件(S2)将关断，并使光伏单元和电力获取系统的连接断开；
    在辅助电源(E3)启动，所述控制模块(E2)分别单独控制第一开关件(S1)和第二开关件(S2)的导通，使储能元件(C)从光伏单元取电后接入电力获取系统，获取并根据储能元件(C)的电参量差异情况判断是否满足短路条件，而在确定不满足短路条件后同时导通第一开关件(S1)和第二开关件(S2)，以经短路测试地尝试恢复光伏单元和电力获取系统的连通。
  2. 如权利要求1所述的功率优化器，其特征是，所述储能元件(C)为并接在功率变换模块(E1)正负回路上的电容元件，所述控制模块(E2)获取并根据电容元件的电压参量差异情况判断是否满足短路条件。
  3. 如权利要求2所述的功率优化器，其特征是，所述功率变换模块(E1)为具有输出电容(C2)的Buck型或Boost型或Boost-Buck型直流斩波电路；所述输出电容(C2)作为短路保护电路(E4)的储能元件(C)；
    在经短路测试过程中，所述控制模块(E2)通过分别采集并记录输出电容(C2)导通至光伏单元而获电，及输出电容(C2)导通至电力获取系统的电压参量，以获取用于判断是否满足短路条件的电压参量差异。
  4. 如权利要求2所述的功率优化器，其特征是，所述功率变换模块(E1)为具有输入电容(C1)和输出电容(C2)的Buck型或Boost型或Boost-Buck型直流斩波电路；
    在经短路测试过程中，所述控制模块(E2)通过在集输出电容(C2)导通至电力获取系统时分别采输入电容(C1)和输出电容(C2)的电压参量差异，以获取用于判断是否满足短路条件的电压参量差异。
  5. 如权利要求1所述的功率优化器，其特征是，所述功率变换模块(E1)为具有开关元件的Buck型或Boost型或Boost-Buck型直流斩波电路；所述第一开关件(S1)作为直流斩波电路中串接在正或负回路上的开关元件。
  6. 如权利要求1所述的功率优化器，其特征是，所述第二开关件(S2)为串接在直流斩波电路输出端和优化器(E)输出端之间正或负回路上的开关元件，至少其一的所述第一开关件(S1)和第二开关件(S2)为常开式开关件。
  7. 如权利要求1所述的功率优化器，其特征是，所述功率变换模块(E1)为降压式Buck直流斩波电路，其包括输入电容(C1)、作为所述第一开关件(S1)的开关元件、电感器(L)、作为所述储能元件(C)的输出电容(C2)；所述第一开关件(S1)、电感器(L)和第二开关件(S2)依次串联于直流斩波电路的正极路，所述输入电容(C1)正负回路并联连接在功率变换模块(E1)的输入端和第一开关件(S1)之间，所述输出电容(C2)正负极并联地连接在电感器(L)和第二开关件(S2)之间。
  8. 如权利要求1所述的功率优化器，其特征是，所述控制模块(E2)包括用于控制所述短路保护电路(E4)运行的控制单元(21)、采集单元(22)、运算单元(23)、判断单元(24)、计数单元(25)和驱动单元(26)；
    所述控制单元(21)用于控制第二开关件(S2)保持关断，而后控制第一开关件(S1)导通，以使储能元件(C)从光伏单元获取电力，以及控制第一开关件(S1)变为关断，而后控制第二开关件(S2)导通，以使储能元件(C)接入到电力获取系统；
    所述采集单元(22)用于采集储能元件(C)在获取电力及计入电力获取系统的电参量信息；
    所述运算单元(23)用于获取在电力状态下及在接入系统状态下的电参量信息差异；
    所述判断单元(24)用于对电参量信息参量进行判定，并驱使控制单元(21) 执行相应的操作；
    所述控制单元(21)在判定为不存在短路下，以开关量控制第一开关件(S1)和第二开关件(S2)的同时导通；在判定为确定短路下，以开关量控制第一开关件(S1)和第二开关件(S2)的关断，在判定为不确认短路下，延时设定时间后再次由控制单元(21)执行短路检测；
    所述计数单元(25)对因不确认短路而执行的第一控制单元(21)执行次数进行计量，在超出预设次数下，判定为确定短路；
    所述驱动单元(26)根据开关量控制命令以驱动电力控制第一开关件(S1)和第二开关的关断和导通。
  9. 如权利要求8所述的功率优化器，其特征是，所述控制模块(E2)还包括通讯单元(27)，所述通讯单元(27)在判定为确认短路后对电力获取系统进行报警；
    控制模块(E2)还用于控制所述功率变换模块(E1)进行功率变换；
    所述采集单元(22)用于采集光伏单元输出端的电压电流参量；
    所述运算单元(23)用于由电压电流参量计算出功率参量；
    所述判断单元(24)用于判断功率参量的变化特征，并驱使控制单元(21)执行相应的操作；
    所述控制单元(21)用于根据功率参量的变化输出脉冲调制信号；
    所述驱动单元(26)用于以经脉冲调制的驱动信号控制功率变换模块(E1)的开关元件运行，以将光伏单元输出端的电参量设置在最大功率点。
  10. 一种光伏发电系统，包括诸多光伏单元，所述光伏单元的输出端连接有如权利要求1至9任一项所述的功率优化器，诸多优化器(E)的输出端相串联成光伏串联体，光伏串联体的输出端接入至逆变器的直流输入侧或直流汇流箱的输入端，其特征是，还包括电弧故障检测装置(F)，所述电弧故障检测装置(F)配置于光伏串联体的输出侧，在检测到电弧时，关断光伏串联体对逆变器或直流汇流箱的连接。
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115663769A (zh) * 2022-12-29 2023-01-31 深圳市中旭新能源有限公司 光伏发电系统直流并联电弧保护及定位系统和方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN215498288U (zh) * 2021-02-04 2022-01-11 广州中旭新能源有限公司 一种可短路保护的功率优化器和光伏发电系统
CN114336622A (zh) * 2022-02-22 2022-04-12 浙江英达威芯电子有限公司 一种关断器控制方法、系统、装置及关断控制器

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN203456934U (zh) * 2013-09-03 2014-02-26 深圳市金威源科技股份有限公司 一种太阳能光伏系统控制装置
US20160285264A1 (en) * 2015-03-25 2016-09-29 Zyntony, Inc. Short-string parallel-dc optimizer for photovoltaic systems
CN109038669A (zh) * 2018-08-23 2018-12-18 嘉兴爱索乐信息技术有限公司 实现组件级自动关断的光伏系统
CN111585307A (zh) * 2020-06-15 2020-08-25 阳光电源股份有限公司 一种光伏快速关断系统的启动方法、应用装置和系统
CN215498288U (zh) * 2021-02-04 2022-01-11 广州中旭新能源有限公司 一种可短路保护的功率优化器和光伏发电系统
CN215498289U (zh) * 2021-02-04 2022-01-11 广州中旭新能源有限公司 一种光伏并网发电的快速关断系统

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN203456934U (zh) * 2013-09-03 2014-02-26 深圳市金威源科技股份有限公司 一种太阳能光伏系统控制装置
US20160285264A1 (en) * 2015-03-25 2016-09-29 Zyntony, Inc. Short-string parallel-dc optimizer for photovoltaic systems
CN109038669A (zh) * 2018-08-23 2018-12-18 嘉兴爱索乐信息技术有限公司 实现组件级自动关断的光伏系统
CN111585307A (zh) * 2020-06-15 2020-08-25 阳光电源股份有限公司 一种光伏快速关断系统的启动方法、应用装置和系统
CN215498288U (zh) * 2021-02-04 2022-01-11 广州中旭新能源有限公司 一种可短路保护的功率优化器和光伏发电系统
CN215498289U (zh) * 2021-02-04 2022-01-11 广州中旭新能源有限公司 一种光伏并网发电的快速关断系统

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LIN, LIZHI ET AL.: "Study of Distributed Photovoltaic Optimizer Based on Simplified Buck Circuit", RENEWABLE ENERGY RESOURCES, vol. 31, no. 4, 30 April 2013 (2013-04-30), pages 27 - 30, XP055957768, ISSN: 1671-5292 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115663769A (zh) * 2022-12-29 2023-01-31 深圳市中旭新能源有限公司 光伏发电系统直流并联电弧保护及定位系统和方法

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