Huawei Digital Power Technologies Co., Ltd.

Huawei Technologies Co., Limited

Zhiwu Xu

Yan Zhang

Lin Li

Haibin Guo

Hualei Ju

Yu Wang

Guilei Gu

Kai Xin

Yanzhong Zhang

Yongbing Gao

Xinyu Yu

Huan Zhao

Fei Xu

Xiaofeng Yao

Junjie Li

He Zhou

Zhiqing Wu

Kai Yin

Yuandong Meng

Hongmiao Fang

Jialong Xu

Changshuan Sun

Niantao Jiang

Chongyue Huang

Lingjie Zhang

Boping Yang

A power supply system including three output ends of a power converter respectively connected to a first end of a positive/negative direct current bus and a first end of a neutral bus; two input ends of a first inverter respectively connected to a second end of the positive direct current bus and a second end of the neutral bus; two input ends of a second inverter respectively connected to a second end of the neutral bus and a second end of the negative direct current bus; a controller outputs an overvoltage alarm signal when at least one of the following conditions is met: a to-ground voltage of the positive/negative direct current bus or a to-ground voltage of the neutral bus is greater than or equal to the preset threshold.

Bipolar photovoltaic system, power supply system, and redundancy protection method

This application provides a photovoltaic system and a power supply current control method thereof. The photovoltaic system includes a direct current bus and at least two power supply units connected in parallel to the direct current bus. The power supply current control method of a photovoltaic system includes: obtaining a current power supply state parameter of each of the at least two power supply units, determining a reference power supply current value of each power supply unit based on the current power supply state parameter of each power supply unit, and adjusting a current supply power of each power supply unit based on the reference power supply current value of each power supply unit. According to this application, appropriate load distribution between power supply units can be ensured, and applicability is high.

Photovoltaic system and power supply current control method thereof

A power conversion module includes a power transistor and a sampling control unit. The sampling control unit determines a given duty cycle of the power conversion module based on the bus reference duty cycle, the power supply reference duty cycle, and the current limiting reference duty cycle, and controls, based on the given duty cycle, the power transistor to work, to control the direct current bus to have a target bus voltage and enable the power conversion module to run at the maximum power point. In this application, the direct current bus can be stabilized and the power conversion module can be controlled to run at the maximum power point.

Power conversion module and power supply system

A method and apparatus for suppressing cross current including: obtaining a common-mode current and a common-mode injection voltage of each inverter in an inverter parallel system; determining a virtual damping voltage of each inverter based on the common-mode current of each inverter and a preset common-mode damping factor, where if a direction in which a current flows out of the inverter is a positive direction, the preset common-mode damping factor is a negative value, or if a direction in which a current flows into the inverter is a positive direction, the preset common-mode damping factor is a positive value; superimposing the virtual damping voltage on the common-mode injection voltage of each inverter, to obtain a target common-mode voltage of each inverter; and controlling operation of each inverter based on the target common-mode voltage of each inverter and a differential mode voltage of each inverter.

Method and apparatus for suppressing cross current in inverter parallel system

Example three-level inverters, control methods, and systems are provided. One example three-level inverter includes a first bus capacitor, a second bus capacitor, a power conversion circuit, and a controller. The first bus capacitor is connected in the middle of the current bus and the power conversion circuit. The power conversion circuit is configured to convert a direct current into a three-phase alternating current for output. The controller is configured to determine a balance reference by using a difference between absolute values of voltages of the positive and negative direct current buses and an even harmonic current in a grid-connected current, where the balance reference is used to enable the three-level inverter to generate a current signal for balancing the voltages of the positive and negative direct current buses.

Three-level inverter, control method, and system

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.

Method and apparatus for detecting short circuit of inverter, and inverter

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.

Photovoltaic device, photovoltaic inverter, system, and power limit control method

A photovoltaic system includes at least one DC/DC converter and the inverter. An input terminal of the at least one DC/DC converter is configured to connect to a photovoltaic module, an output terminal is configured to connect to an input terminal of the inverter by using a direct current bus, and an output terminal of the inverter is connected to an alternating current grid. When the inverter is switched from a non-power-limited working state to a power-limited working state, the inverter adjusts a bus voltage of the inverter to rise from a first voltage to a second voltage. After running in the power-limited working state for a time interval, the inverter adjusts the bus voltage to drop from the second voltage to a third voltage, where the third voltage is less than or equal to the first voltage.

Photovoltaic system, inverter, and bus voltage control method for inverter

This application relates to a converter in a photovoltaic power generation system and a converter control method. An input end of the converter is connected to at least one photovoltaic module, and an output end is connected to an inverter. The control method includes: determining an output power-voltage (PV) curve of a converter based on an output PV curve of the photovoltaic module; and controlling a voltage output of the converter based on the output PV curve of the converter. The output PV curve includes at least a simulated voltage limiting section and a constant power section that are connected. In this application, an existing MPPT control policy of the inverter can be adapted when a voltage-limited output is implemented, to avoid a case in which a power of a photovoltaic string drops to zero.

Converter control method, converter, and photovoltaic power generation system

A converter system includes a plurality of converters, a sampling circuit, and a control circuit. The plurality of converters are connected in parallel. Each converter includes a detection circuit which includes a first switch and at least two resistors. The first switch is connected in parallel with one of the at least two resistors. The control circuit control the sampling circuit to collect a first voltage and a second voltage, where the first voltage is a voltage that is between a second bus and a ground cable and that is collected by the sampling circuit when first switches in detection circuits of a first quantity are in a turn-on state, the second voltage is a voltage that is between the second bus and the ground cable and that is collected by the sampling circuit when first switches in detection circuits of a second quantity are in a turn-on state.

Converter system, method and apparatus for detecting insulation resistance of system, and medium

A three-level converter includes a high-voltage side unit, a low-voltage side unit, a flying capacitor, a first switch to a fourth switch, and a control unit. When a voltage of the flying capacitor falls outside a safe target voltage range, the control unit may control the third switch and the fourth switch to be normally open, and control, based on the voltage of the flying capacitor and a voltage of the low-voltage side unit, each of the first switch and the second switch to be turned on or off, so that the voltage of the flying capacitor falls within the target voltage range. Alternatively, the control unit may control the first switch and the second switch to be normally open, and control, based on the voltage of the flying capacitor and a voltage of the low-voltage side unit.

Three-level converter, control method thereof, and power supply system

A voltage source inverter includes a bus capacitor, a bidirectional power tube, a filter inductor, and a filter capacitor. A voltage control method includes: respectively obtaining a first feedback current and a first feedback voltage from an output end of the filter inductor and an output end of the filter capacitor; obtaining a first duty cycle and a second duty cycle based on the first feedback current, a maximum current reference value, and a minimum current reference value in a current loop; obtaining a third duty cycle based on the first feedback voltage and a voltage reference value in a voltage loop; and selecting one of the first duty cycle, the second duty cycle, and the third duty cycle, and controlling the bidirectional power tube, so that a duty cycle of the bidirectional power tube is between the first duty cycle and the second duty cycle.

Voltage control method, inverter, and voltage control apparatus

A photovoltaic system includes a controller and plurality of photovoltaic strings that are independently controlled. The controller enables some photovoltaic strings to be in a maximum power point tracking state, and the remaining photovoltaic strings to be in a power output limited state. The system implements maximum power point tracking detection so that the maximum power point power and the maximum power point voltage are updated in real time. Further, the working status of the power supply system can be fed back in real time, so that the photovoltaic system can predict the capacity of an energy storage apparatus or regulate charging and discharging of the energy storage apparatus. After a curtailment state ends, the photovoltaic system is relatively quickly restored to the normal working state, so that a loss of generated power is reduced.

Method and apparatus for controlling power supply system, and system

A power system includes a controller, configured to adjust an output current of a first converter to a first current value based on a voltage of a direct current bus and a voltage threshold, where a difference between an adjusted voltage of the direct current bus and the voltage threshold is less than a difference between the unadjusted voltage of the direct current bus and the voltage threshold. The controller adjusts the output current of the first converter to a second current value based on output power of the first converter and a power threshold, where a difference between adjusted output power of the first converter and the power threshold is less than a difference between the unadjusted output power of the first converter and the power threshold. The controller adjusts the output current of the first converter based on the first current value and the second current value.

Power system and control method

This application relates to a converter in a photovoltaic power generation system and a parametric curve scanning method for a photovoltaic string. A parametric curve includes a current-voltage curve or a power-voltage curve. The scanning method includes: controlling an output voltage of the photovoltaic string to change from a first endpoint voltage of a first voltage range to a second endpoint voltage of the first voltage range according to a first preset rule, to scan a first parametric curve; controlling the output voltage of the photovoltaic string to change from a third endpoint voltage of a second voltage range to a fourth endpoint voltage of the second voltage range according to a second preset rule, to scan a second parametric curve. There is an intersection set between the first voltage range and the second voltage range. In this application, whether a scanned curve is affected by a light change may be determined based on the first parametric curve and the second parametric curve. This is convenient and fast, and no additional hardware test device is required.

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Shanghai, China

Zhiwu Xu