Abstract: The present application discloses a multi-channel grid-connected power generation system and a control method therefor, which lowers the system cost while reducing no-load losses of all step-up transformers. Multi-channel energy conversion devices in the system are each connected in parallel, by means of a step-up transformer, to the same collector line, one end of the collector line is connected to the grid by means of a switch device, and the on-off switching of the switch device is controlled by a control unit. The control unit sends a switch-off command to the switch device when same has determined that all of the energy conversion devices have entered a non-operating state.

Abstract: An inverter and a method for detecting insulation impedance of the inverter are provided. During grid-connected operation of the inverter, the method includes: controlling a power supply to output two different test signals, and recording voltages of a power grid to ground corresponding to the two test signals; and calculating the insulation impedance to ground of the inverter during the grid-connected operation of the inverter according to the two test signals and the voltages of the power grid to ground corresponding to the two test signals. According to the present disclosure, the power supply outputs different test signals to disturb the voltage of the power grid to ground, so as to detect insulation impedance of the inverter during grid-connected operation of the inverter.

Abstract: A phase-change heat dissipater and a power module are provided according to the present application. The phase-change heat dissipater includes least two evaporators, at least one condenser and at least two sets of heat transfer pipelines, the at least two evaporators and at least one condenser form at least two circulating heat dissipation circuits through the at least two sets of heat transfer pipelines, and a phase-change medium is filled in the at least two circulating heat dissipation circuits; and the at least two evaporators are arranged sequentially along a vertical direction. The technical solution of the present application can improve the temperature difference of the at least two evaporators and maintain the temperature uniformity of the at least two evaporators.

Abstract: A method and a device for primary frequency modulation in new energy power generation are provided. An inverter performs a first power adjustment according to a p-f droop curve before receiving a power adjustment instruction sent by the power station controller, and performs a second power adjustment in response to the power adjustment instruction. Since the inverter performs the first power adjustment before responding to the power adjustment instruction sent by the power station controller, the response of the primary frequency modulation is speeded up, so that rapid control for the new energy generation power is achieved, thereby ensuring stable operation of a power grid for new energy power generation.

Abstract: A three-level Boost circuit is provided. The three-level Boost circuit includes: an input capacitor, an inductor, a first switch, a second switch, a first freewheeling diode, a second freewheeling diode, a flying capacitor, a balance capacitor, a charging diode, a clamp diode, a discharging diode and an output series capacitor bank. The output series capacitor bank includes multiple output capacitors connected in series, and has a first node and a second node; a potential of the first node is higher than a potential of a cathode of the charging diode, and a potential difference between a cathode of the second freewheeling diode and the second node does not exceed a withstand voltage of the second freewheeling diode.

Abstract: The present application discloses a multi-channel grid-connected power generation system and a control method therefor, which lowers the system cost while reducing no-load losses of all step-up transformers. Multi-channel energy conversion devices in the system are each connected in parallel, by means of a step-up transformer, to the same collector line, one end of the collector line is connected to the grid by means of a switch device, and the on-off switching of the switch device is controlled by a control unit. The control unit sends a switch-off command to the switch device when same has determined that all of the energy conversion devices have entered a non-operating state.

Abstract: A three-level Boost circuit is provided. The three-level Boost circuit includes: an input capacitor, an inductor, a first switch, a second switch, a first freewheeling diode, a second freewheeling diode, a flying capacitor, a balance capacitor, a charging diode, a clamp diode, a discharging diode and an output series capacitor bank.

Abstract: A method, a device, and a system for protecting parallel-connected topology units are provided. A target signal transmitted via the signal synchronization line is obtained, and the target signal is sent to other controllers based on a type of the target signal. If the target signal is a carrier synchronization signal, the current power module is controlled to perform carrier synchronization and to be in a working mode. If the target signal is a power module fault signal, the current power module is controlled to be in a shutdown mode. The signal synchronization lines between the parallel-connected topology units are shared in a time-sharing manner, where the carrier synchronization signal is transmitted if the power module works normally, and the power module fault signal is transmitted if the power module is faulty. The topology units monitor the transmitted target signal in real time for fast synchronous protection.

Abstract: A method and a device for primary frequency modulation in new energy power generation are provided. An inverter performs a first power adjustment according to a p-f droop curve before receiving a power adjustment instruction sent by the power station controller, and performs a second power adjustment in response to the power adjustment instruction. Since the inverter performs the first power adjustment before responding to the power adjustment instruction sent by the power station controller, the response of the primary frequency modulation is speeded up, so that rapid control for the new energy generation power is achieved, thereby ensuring stable operation of a power grid for new energy power generation.

Abstract: A method, a device, and a system for protecting parallel-connected topology units are provided. A target signal transmitted via the signal synchronization line is obtained, and the target signal is sent to other controllers based on a type of the target signal. If the target signal is a carrier synchronization signal, the current power module is controlled to perform carrier synchronization and to be in a working mode. If the target signal is a power module fault signal, the current power module is controlled to be in a shutdown mode. The signal synchronization lines between the parallel-connected topology units are shared in a time-sharing manner, where the carrier synchronization signal is transmitted if the power module works normally, and the power module fault signal is transmitted if the power module is faulty. The topology units monitor the transmitted target signal in real time for fast synchronous protection.

Abstract: A medium-high voltage photovoltaic (PV) power generation system is provided. A PV string of the system is insulated from the ground via an insulator of a medium-high voltage withstanding level, so that the PV string is applicable under a high voltage level. The PV strings are connected to cascade modules. An output voltage of series-connected cascade modules is grid-connected to a 10 kV power grid through a three-phase filter, without a power booster transformer or a high-frequency isolated DC/DC converter in a conventional power station, thereby improving the system efficiency.

Abstract: A wire connection terminal for a photovoltaic string is provided. The wire connection terminal includes: a terminal connector, a fuse and a printed circuit board (PCB). The terminal connector is connected to a positive electrode or a negative electrode of the photovoltaic string. The fuse is configured to prevent the photovoltaic string from outputting an excessive current. The PCB is configured to sample an output current and an output voltage of the photovoltaic string, communicate with an inverter, and control the photovoltaic string to disconnect from a direct current bus and output abnormal data for display when the output current and/or the output voltage of the photovoltaic string is abnormal or a system failure occurs.

Abstract: A medium-high voltage photovoltaic (PV) power generation system is provided. A PV string of the system is insulated from the ground via an insulator of a medium-high voltage withstanding level, so that the PV string is applicable under a high voltage level. The PV strings are connected to cascade modules. An output voltage of series-connected cascade modules is grid-connected to a 10 kV power grid through a three-phase filter, without a power booster transformer or a high-frequency isolated DC/DC converter in a conventional power station, thereby improving the system efficiency.

Abstract: Disclosed are a medium and high voltage grid-connected power generation system, a medium and high voltage grid-connected system, and a control circuitry thereof. The voltage of the medium and high voltage power grid is collected through the control circuitry. A power grid amplitude and a power grid phase synchronization signal are obtained, and then sent to an inverter unit through a communication line.

Abstract: A wire connection terminal for a photovoltaic string is provided. The wire connection terminal includes: a terminal connector, a fuse and a printed circuit board (PCB). The terminal connector is connected to a positive electrode or a negative electrode of the photovoltaic string. The fuse is configured to prevent the photovoltaic string from outputting an excessive current. The PCB is configured to sample an output current and an output voltage of the photovoltaic string, communicate with an inverter, and control the photovoltaic string to disconnect from a direct current bus and output abnormal data for display when the output current and/or the output voltage of the photovoltaic string is abnormal or a system failure occurs.

Abstract: A control method and apparatus for photovoltaic inverters connected in parallel at an AC side are provided and the method includes the following steps: detecting a first direct voltage of the first inverter and a second direct voltage of the second inverter; obtaining a difference between the first direct voltage and the second direct voltage; and adjusting the direct voltages of the inverters to control the difference to be within a predetermined range and control a common-mode voltage in the common-mode loop to be within a predetermined common-mode voltage range.

Abstract: A method and device for monitoring and suppressing a resonance are provided, which are applied to a grid-connected generation system. A current sample voltage of a preset sample point of the grid-connected generation system is monitored in a real time manner; amplitudes of harmonics of the current sample voltage are acquired using a preset algorithm; it is verified whether a resonance occurs in the grid-connected generation system currently based on the acquired amplitudes of the harmonics; in a case that the resonance occurs in the grid-connected generation system, current corrections of parameters of inverters in the grid-connected generation system are acquired according to a preset rule and the parameters of the inverters are adjusted using the current corrections and a selected resonance suppressing algorithm.

Abstract: A charging and discharging system, a charging and discharging method, and a photovoltaic power generation system are provided. The charging and discharging system includes: a unidirectional converter, a unidirectional switch, an energy storage device and a controller; where an input terminal of the unidirectional converter is connected to an output terminal of a photovoltaic device of a photovoltaic power generation system to which the charging and discharging system is applied, and an output terminal of the unidirectional converter is connected to an input terminal of the energy storage device; the unidirectional switch is connected between an output terminal of the energy storage device and an input terminal of a bidirectional inverter of the photovoltaic power generation system to which the charging and discharging system is applied; the controller is connected to the unidirectional converter, the unidirectional switch, the energy storage device and the bidirectional inverter.

Abstract: Disclosed are a medium and high voltage grid-connected power generation system, a medium and high voltage grid-connected system, and a control circuitry thereof. The voltage of the medium and high voltage power grid is collected through the control circuitry. A power grid amplitude and a power grid phase synchronization signal are obtained, and then sent to an inverter unit through a communication line.

Abstract: Provided are a parallel inverter system, and a shutdown control method and a shutdown control device for the parallel inverter system. A shutdown instruction is determined and responded according to a level of the shutdown instruction. The shutdown instruction is determined to be an emergency shutdown instruction under certain emergency shutdown conditions, and a driving signal for the power switch devices of the inverter apparatus is needed to be instantly locked out. The shutdown instruction is determined to be a normal shutdown instruction under non-emergency shutdown conditions, a switch-off signal is transmitted to alternating-current switches connected to the inverter apparatus to be shut down, states of the alternating-current switches connected to the inverter apparatus to be shut down are detected, the driving signal for the power switch devices of the inverter apparatus to be shut down is instantly locked out in a case that the alternating-current switches are switched off.