Abstract: 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.

Abstract: A photovoltaic power generation system includes a single-stage inverter, an anti-backflow circuit, a photovoltaic string, and a coupling capacitor. The anti-backflow circuit is connected to one input end of the single-stage inverter, one output end of the photovoltaic string is connected to the other input end of the single-stage inverter, and the other output end of the photovoltaic string is connected to the anti-backflow circuit. The photovoltaic string includes a buck optimizer and a photovoltaic panel. The anti-backflow circuit is configured to prevent a backflow current from flowing back to the photovoltaic string. The coupling capacitor is connected in parallel to two ends of the anti-backflow circuit and is configured to transmit a signal between each buck optimizer in the photovoltaic string and the single-stage inverter, to control backflow of the backflow current when the anti-backflow circuit fails.

Abstract: This application provides a photovoltaic energy storage control module and a photovoltaic energy storage control method. A control component included in the photovoltaic energy storage control module can set reference values of bus voltages of a first direct-current converter, a second direct-current converter, and an inverter. Further, the first direct-current converter, the second direct-current converter, and the inverter can automatically adjust a power supply relationship among the first direct-current converter, the second direct-current converter, and the inverter based on a value relationship among the reference values of the bus voltages of the first direct-current converter, the second direct-current converter, and the inverter. In this way, flexibility of the photovoltaic energy storage control module is improved.

Abstract: 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.

Abstract: The present disclosure discloses a method for producing raw cotton of machine-harvested long-staple cotton with a modal length of greater than or equal to 35 mm, including the steps: planting sea-island long-staple cotton and machining seed cotton, wherein planting the sea-island long-staple cotton includes preparation before machine harvesting, defoliation and ripening, choosing a cotton variety, etc.; and machining the seed cotton includes preparation before seed cotton ginning, mechanical separation of cotton seeds and raw cotton, and finishing the separated raw cotton. Raw cotton fibers obtained by the method of the present disclosure have main quality indexes that: a fiber length is 36.5-38.4 mm, a specific strength is 42.3-46.1 cN/tex, a uniformity is 86.2-87.0%, a foreign-fiber content is 0.2-0.4 g/t, and an impurity content is 2.6-3.4%.

Abstract: A power system includes N direct current coupling units, N direct current buses, and a main controller. The main controller is configured to: obtain a total network input demand power (a network input power required by the power grid); obtain first amplitude limiting values (indicate a maximum discharging power that can be supplied by each energy unit to the power grid); and determine first network input power values (a power value allocated to each energy unit and that is input to the power grid, and at least one direct current coupling unit is in a first amplitude limiting state) based on the total network input demand power and the first amplitude limiting values, and the first amplitude limiting state is that a first network input power value of direct current coupling unit is equal to a first amplitude limiting value corresponding to the direct current coupling unit.

Abstract: A battery charging and discharging system includes: the battery charging and discharging circuit and a control circuit. The control circuit includes a processor. The processor is configured to: determine a first target current value corresponding to each of at least two feedback controls based on sampled data corresponding to the at least two feedback controls; determine a second target current value based on the first target current value corresponding to each of the at least two feedback controls; and comprehensively balance a first target current value of each feedback control, to adaptively determine a second target current value. A drive signal is generated based on the second target current value, and the drive signal is output to the DC/DC converter.

Abstract: A photovoltaic power generation system includes a plurality of photovoltaic batteries, a DC/DC module, a direct current bus capacitor, an energy storage component, and a power control apparatus, where an input side of the DC/DC module is coupled to the plurality of photovoltaic batteries, an output side of the DC/DC module is coupled to the direct current bus capacitor, and output electric energy provided by the photovoltaic batteries to the direct current bus capacitor; the energy storage component is coupled to the direct current bus capacitor, the power control apparatus is separately coupled to the direct current bus capacitor and the energy storage component, and is configured to: detect a first voltage of the direct current bus capacitor, and when the first voltage meets a preset compensation condition, control the energy storage component to charge the direct current bus capacitor.

Abstract: 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.

Abstract: A power supply system and an IV curve scanning method for a power supply system. The power supply system includes at least a first inverter and a second inverter. The first inverter starts, at an IV curve scanning start time of the first inverter, to perform IV curve scanning on a string connected to the first inverter, and the second inverter starts, at an IV curve scanning start time of the second inverter, to perform IV curve scanning on a string connected to the second inverter. Their IV curve scanning start time is different. In addition, a time interval between the IV curve scanning their start time is less than a preset IV curve scanning period. In the embodiments, fluctuation of an output power of the power supply system during IV curve scanning can be reduced, thereby improving system stability of the power supply system.

Abstract: An energy system mainly includes a charging and discharging control apparatus and an energy storage battery. When a battery level is not greater than a discharging level threshold and a charging current of the energy storage battery is less than a charging current threshold, the charging and discharging control apparatus may control the energy storage battery to stop charging and discharging. When the battery level is not less than a charging level threshold and a discharging current of the energy storage battery is less than a discharging current threshold, the charging and discharging control apparatus may also control the energy storage battery to stop charging and discharging.

Abstract: 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.

Abstract: 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.

Abstract: Embodiments of this application relate to the field of control technologies, and provide a control method and a distributed power system. The method includes: controlling an inverter to work in a current source mode, where the current source mode means that the inverter serves as a current source to convert a direct current generated by a power supply device into an alternating current and output the alternating current to the alternating current grid; and controlling the inverter to switch from the current source mode to a voltage source mode when it is detected that a voltage at a first target port jumps. In this way, an output voltage of the inverter may be controlled within a safety range, so that a local load can be protected before a cause of an abnormal voltage is detected, and comparatively, power may be continuously supplied to the local load.

Abstract: A detection method and a related apparatus. Whether a first converter and a second converter are connected to a same combiner device is determined by determining an output port voltage signal of the first converter and an output port voltage signal of the second converter, so that first information or second information is generated and notified to staff. Generally, if a first converter and a second converter in a combiner system are not connected to a same combiner device, it may be considered as that a wire connection of the first converter or the second converter is incorrect. In the detection method and the related apparatus, whether there is a wiring error in the combiner system of the converters can be quickly and accurately determined in an application scenario in which voltage information at a combiner point cannot be obtained.

Abstract: 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.

Abstract: 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.

Abstract: This application relates to a method for controlling a busbar voltage of a photovoltaic system. The photovoltaic system includes a DC/DC converter and a DC/AC converter. The DC/DC converter, the DC/AC converter, and an energy storage battery are connected via a busbar. The DC/DC converter is connected to a photovoltaic direct current source and performs maximum power point tracking on an input power from the photovoltaic direct current source. A load connected to the DC/AC converter has a load power. The energy storage battery has a maximum charging power and a maximum discharging power. The method includes: controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of comparison between a maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power. The plurality of different discontinuous voltage intervals correspond to different operating states of the inverter.

Abstract: 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.

Abstract: 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.