Abstract: A linkage protection system includes an inverter, an anti-potential-induced degradation (PID) apparatus, and an insulation-monitoring apparatus. The anti-PID apparatus is configured to inject a voltage into an input end or an output end of the inverter, to increase or decrease a voltage-to-earth of a photovoltaic system. The insulation-monitoring apparatus is configured to inject an insulation-monitoring voltage into a direct current (DC) side or an alternating current (AC) side of the inverter. The anti-PID apparatus and the insulation-monitoring apparatus directly or indirectly communicate with each other, to learn of information about whether a peer apparatus is operating, and perform linkage control. The anti-PID apparatus and the insulation-monitoring apparatus operate in different time periods.

Abstract: A method and an apparatus for detecting a short circuit of an inverter, and an inverter are provided. A voltage of a common bus is increased when a plurality of boost circuits in the inverter are all in a non-working state, and after circuit parameters of input sides of all the plurality of boost circuits are detected, a boost circuit in which a diode is short-circuited in the plurality of boost circuits is further determined based on the circuit parameters of the input sides of the boost circuits. According to the method and the apparatus for detecting a short circuit of an inverter, and the inverter, circuit complexity of the inverter can be reduced, and circuit complexity of a photovoltaic power generation system including the inverter is reduced.

Abstract: This application discloses a photovoltaic device, a photovoltaic inverter, a system, and a power limit control method. The device includes a DC-DC converter circuit, an inverter circuit, and a controller. An input end of the DC-DC converter circuit is connected to a photovoltaic array, and an output end of the DC-DC converter circuit is connected to an input end of the inverter circuit. The controller is configured to: receive a power scheduling instruction, where the power scheduling instruction carries a power reference value; and when the power reference value is less than a power at a maximum power point, reduce an input current of the DC-DC converter circuit; or when an input voltage of the DC-DC converter circuit is greater than or equal to a preset voltage, increase an input current of the DC-DC converter circuit until an output power of an inverter becomes consistent with the power reference value.

Abstract: A converter includes a power conversion circuit, a switching device, and a controller, and includes N phases, where N is 2 or 3. An input end of the power conversion circuit is connected to a direct current power supply, and the power conversion circuit converts a direct current output by the direct current power supply into an alternating current. The switching device includes at least the following two stages: a first-stage switching device and a second-stage switching device. The first-stage switching device and the second-stage switching device separately include N switches, and the N switches are connected in series to the N phases respectively. An output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series.

Abstract: A method and an apparatus for detecting a solar cell of a photovoltaic plant. The method includes: obtaining a first infrared image and a second infrared image, where the first infrared image includes infrared image information corresponding to an ambient infrared signal reflected by a to-be-detected solar cell operating in a short-circuit state, the second infrared image includes infrared image information corresponding to an infrared signal emitted by the to-be-detected solar cell operating in a first state and infrared image information corresponding to an ambient infrared signal reflected by the to-be-detected solar cell, and the first state is another state other than the short-circuit state; and detecting, based on the first infrared image and the second infrared image, whether the to-be-detected solar cell has a defect.

Abstract: A photovoltaic power generation system includes an inverter, a controller, and at least two direct current branch circuits. The leakage current detection apparatus is configured to: detect a leakage current of the direct current branch circuit on which the leakage current detection apparatus is located and send the leakage current to the controller. The controller is further configured to: when the photovoltaic power generation system runs and a value of a leakage current of the direct current branch circuit exceeds a preset range, determine that an insulation fault occurs on the direct current branch circuit. The system can determine the direct current branch circuit on which the insulation fault occurs in the photovoltaic power generation system, so that measures are taken in time for the direct current branch circuit on which the insulation fault occurs, to eliminate a potential safety hazard.

Abstract: A power conversion device includes a positive direct current bus, a negative direct current bus, a first capacitor, a second capacitor, a first inductor, a first discharge unit. The first capacitor is connected between the positive direct current bus and the negative direct current bus. The second capacitor is connected in series to the first inductor and then connected in parallel to the first capacitor, where a capacitance value of the second capacitor is greater than a capacitance value of the first capacitor. The first discharge unit is connected in parallel to the first inductor, and is configured to be in a conducted state when a voltage of the first inductor is greater than a first action voltage threshold. In the embodiments, a case in which a semiconductor device in the power conversion device has a risk of voltage overstress caused by a differential mode lightning strike can be avoided.

Abstract: A power system is disclosed. Output terminals of a power supply or a DC-to-DC unit are cascaded to increase an output voltage, so as to reduce a current between the power supply or the DC-to-DC unit and the DC-to-AC unit, and resolve cost and loss problems of the cable from the power supply or the DC-to-DC unit to the DC-to-AC unit. In addition, according to the power system provided in the embodiments of this application, a quantity of cables from the power supply or the DC-to-DC unit to the DC-to-AC unit may be further reduced by cascading output terminals of the power supply or the DC-to-DC unit and cascading inputs of the DC-to-AC unit, thereby reducing system costs. In addition, in the power system provided in the embodiments of this application, cascaded input and isolated output of the DC-to-AC unit can reduce a specification of a power conversion device.

Abstract: Embodiments of this application provide a power system. An output terminal of a power supply or a DC-to-DC unit is cascaded. In addition, according to the power system provided in embodiments of this application, a quantity of cables from the power supply or the DC-to-DC unit to the DC-to-AC unit may be further reduced by cascading an output terminal of the power supply or the DC-to-DC unit and cascading an input of the DC-to-AC unit.

Abstract: This application relates to the field of circuit technologies, and provides a step-up circuit and a step-up circuit control method. The step-up circuit includes a power supply, an inductor, N switch components, N-1 flying capacitors, N flyback diodes, a pre-charge unit, and an output unit. The N switch components are connected in series, a first switch component of the N switch components is connected to a first terminal of the power supply through the inductor, and an Nth switch component is connected to a second terminal of the power supply. At least two switch components of the N switch components have withstand voltage specifications different from each other. Values of voltages withstood by switch components with different withstand voltage specifications during normal operation are also different from each other. N is a positive integer.

Abstract: A fault detection apparatus includes an image capture module and a detection module, and the fault detection apparatus is configured to capturing an image of the photovoltaic module in a light emitting state, and performing fault detection on the photovoltaic module based on the image when a signal-to-noise ratio of the image is maximized, to identify a fault type of the photovoltaic module.

Abstract: A breaker apparatus and an inverter system are configured to disconnect an electrical connection when a fault occurs in a protected circuit. The breaker apparatus is connected in series in a protected circuit, and is configured to disconnect the electrical connection when a fault occurs in the protected circuit. The breaker apparatus includes a first branch, and a second branch. The first branch includes an overcurrent-automatic-disconnection unit and a first current limiting unit that are connected in series, where the overcurrent-automatic-disconnection unit is configured to be automatically disconnected when a current flowing through the overcurrent-automatic-disconnection unit exceeds a breaking current threshold. The a second branch is configured to be open or closed under control of the controller.

Abstract: A photovoltaic power generation system and a conversion circuit. Two groups of photovoltaic arrays are cascaded by using the conversion circuit disposed in the photovoltaic power generation system to effectively increase an input voltage of a DC/AC conversion circuit. In this way, a cable with an existing diameter specification can improve current transmission in the photovoltaic power generation system, to effectively reduce costs of the photovoltaic power generation system. A voltage to earth at an intermediate node in the conversion circuit is adjusted to a first preset value, so that both an absolute value of a voltage to earth of a first group of photovoltaic arrays and an absolute value of a voltage to earth of a second group of photovoltaic arrays are less than a first threshold.

Abstract: This application discloses a photovoltaic power generation system control method, a photovoltaic power generation system, and a switching apparatus, to reduce a loss of the photovoltaic power generation system. The switching apparatus includes: a switching unit, a detection unit, and a controller. The switching unit includes a first output end, a second output end, a first input end connected to each first DC/DC converter in a one-to-one correspondence, and a second input end connected to each second DC/DC converter in a one-to-one correspondence. The first output end is connected to an input end of a first DC/AC converter, and the second output end is connected to an input end of a second DC/AC converter. The detection unit is separately connected to the first DC/AC converter, the second DC/AC converter, a plurality of first DC/DC converters, and a plurality of second DC/DC converters.

Abstract: This application describes examples of a direct current combiner box, a photovoltaic power generation system, and a fault detection method. In one example, the direct current combiner box includes a fault detection unit, a protection circuit, and a boost circuit. The fault detection unit detects an operating parameter of the direct current combiner box. The protection circuit sends a protection signal to the boost circuit when the operating parameter meets a specified condition. The protection signal is used to enable the boost circuit to adjust a first voltage of a photovoltaic array at an input end of the direct current combiner box to a second voltage. After receiving the protection signal, the boost circuit adjusts the first voltage of the photovoltaic array at the input end of the direct current combiner box to the second voltage.

Abstract: A power supply system includes direct current combiner boxes and an inverter, where output terminals of all direct current combiner boxes are connected in series and/or in parallel and then coupled to an input terminal of the inverter, and the direct current combiner box includes a controller, a detection circuit, and a direct current conversion circuit. The direct current conversion circuit performs direct current conversion on an input terminal voltage of the direct current combiner box to obtain an output terminal voltage of the direct current combiner box. The detection circuit detects an output terminal parameter of the direct current combiner box, and sends the output terminal parameter of the direct current combiner box to the controller. The controller controls an output voltage of the direct current conversion circuit based on the output terminal parameter of the direct current combiner box.

Abstract: A power sourcing equipment includes a residual current detection unit, a voltage detection unit, and a controller. The controller determines an insulation resistance value at the input end of the power sourcing equipment based on a first preset voltage parameter value, a first residual current value, a second preset voltage parameter value, and a second residual current value. The first residual current value is a residual current value of the power sourcing equipment when a voltage parameter of the power sourcing equipment includes the first preset voltage parameter value. The second residual current value is a residual current value of the power sourcing equipment when the voltage parameter of the power sourcing equipment includes the second preset voltage parameter value.

Abstract: A photovoltaic system, a power supply system, and an insulation fault detection method. An insulation impedance detection circuit is connected between a bus and the ground. The bus includes the direct current positive bus, the neutral bus, or the direct current negative bus. The insulation impedance detection circuit includes at least a switch. The direct current negative bus is connected to the neutral bus by using an electrical element or a voltage source. A controller obtains insulation impedance based on voltages to ground of the bus that are separately corresponding to the switch before and after the switch is turned on, and determines, based on the insulation impedance, whether there is an insulation fault in the photovoltaic system, to perform protection in a timely manner.

Abstract: A photovoltaic system and a leakage current control method for the photovoltaic system includes at least one photovoltaic module group, at least one photovoltaic inverter, a grounded metal frame, and a sampling control unit. The photovoltaic module group is mounted on the grounded metal frame. An output end of the photovoltaic module group is connected to an input end of the photovoltaic inverter, and an output end of the photovoltaic inverter is connected to a power grid. The sampling control unit is coupled to both the photovoltaic module group and the photovoltaic inverter and is configured to detect a current value of a leakage current formed by a common-mode voltage of the photovoltaic inverter on a parasitic capacitor. Herein, the parasitic capacitor exists between the photovoltaic module group and the grounded metal frame.

Abstract: An impedance detection method and a photovoltaic system are provided to help reduce complexity and costs of impedance detection. The method includes: sampling a voltage between a direct current bus and a protective earthing at each of a first time point and a second time point, to obtain a first voltage value and a second voltage value; sampling a leakage current on the direct current bus at each of the first time point and the second time point, to obtain a first current value and a second current value; and calculating an insulation impedance value of a combiner box based on a difference between the first voltage value and the second voltage value and a difference between the first current value and the second current value, to determine whether impedance of the combiner box is abnormal.