Abstract: The present disclosure provides a three-phase AC system and a control method thereof. The method includes: receiving an output signal of the three-phase AC system and obtaining a characteristic value of the output signal according to the output signal; performing virtual synchronous generator control on the inverter to obtain a fundamental electric potential; extracting a harmonic component from the output signal and obtaining an error signal according to the harmonic component and a reference value of the harmonic component; controlling the error signal to obtain a harmonic compensation electric potential; obtaining a control electric potential by superimposing the harmonic compensation electric potential with the fundamental electric potential; obtaining a pulse signal by modulating the control electric potential, and obtaining a switching signal of the inverter according to the pulse signal.

Abstract: A high-voltage DC transformation apparatus, a power system and a control method of the power system. The high-voltage DC transformation apparatus is electrically connected to at least one high-voltage DC power generator. The high-voltage DC transformation apparatus includes at least one bidirectional AC/DC conversion module, at least one first transformer and at least one unidirectional rectifier module. A DC terminal of the bidirectional AC/DC conversion module is electrically connected to the corresponding high-voltage DC power generator. The first transformer includes a first transmission terminal and a second transmission terminal. The first transmission terminal is electrically connected to an AC terminal of the corresponding bidirectional AC/DC conversion module. The unidirectional rectifier module includes an input terminal and an output terminal.

Abstract: The application relates to battery internal resistance detection device and method for power conversion device. The detection device includes a data acquisition module for acquiring a battery voltage and a battery current to obtain a DC voltage, an AC voltage, a DC current and an AC current, a first calculation module for receiving the AC current and the AC voltage at a certain instant to output a first internal resistance value and a battery capacitance, a second calculation module for receiving a plurality of DC currents and a plurality of DC voltages at multiple instants and the battery capacitance to output a second internal resistance value, and a selection module for receiving the first and second internal resistance value and selecting one of the first and second internal resistance value as battery internal resistance value. The application improves detection accuracy of battery internal resistance by combining DC and AC algorithms.

Abstract: The present disclosure provides an islanding detection method for an inverter and a corresponding apparatus. The islanding detection method includes: step A1: obtaining a parameter of an output voltage of a three-phase AC system and a steady-state value corresponding to the parameter within a period of time; step A2: obtaining a disturbance signal based on the parameter and the steady-state value; step A3: superimposing the disturbance signal on at least one reference value of a droop control; and step A4: detecting the parameter added with the disturbance signal, and determining that island occurs in response to the parameter greater than an upper limit or less than a lower limit.

Abstract: An energy storage device for a power system is provided. The energy storage device is electrically connected with a high voltage DC transmission grid. The energy storage device includes at least one energy storage element, at least one bidirectional inverter module, at least one medium frequency transformer and at least one bidirectional AC/DC conversion module. A DC terminal of each bidirectional inverter module is electrically connected with the corresponding energy storage element. A first transmission terminal of each medium frequency transformer is electrically connected with an AC terminal of the corresponding bidirectional inverter module. An AC terminal of each bidirectional AC/DC conversion module is electrically connected with a second transmission terminal of the corresponding medium frequency transformer. A DC terminal of each bidirectional AC/DC conversion module is electrically connected with the high voltage DC transmission grid.

Abstract: The present disclosure provides a power supply system method for an AC load. The system includes a power supply device and a DC/AC converter. An AC side of the DC/AC converter is coupled to an AC grid and the AC load through an AC bus. The power supply device outputs DC electric energy and is coupled to a DC side of the DC/AC converter through a DC bus. The power supply device includes an energy storage circuit and a controller. The energy storage circuit includes a first energy storage circuitry and a second energy storage circuitry. The controller is configured to control a conversion operation of the first energy storage circuitry to output a low-frequency power to the DC bus, and a conversion operation of the second energy storage circuitry to output a high-frequency power to the DC bus.

Abstract: The present disclosure provides an islanding detection method for an inverter and a corresponding apparatus. The islanding detection method includes: step A1: obtaining a parameter of an output voltage of a three-phase AC system and a steady-state value corresponding to the parameter within a period of time; step A2: obtaining a disturbance signal based on the parameter and the steady-state value; step A3: superimposing the disturbance signal on at least one reference value of a droop control; and step A4: detecting the parameter added with the disturbance signal, and determining that island occurs in response to the parameter greater than an upper limit or less than a lower limit.

Abstract: The present disclosure provides a three-phase AC system and a control method thereof. The method includes: receiving an output signal of the three-phase AC system and obtaining a characteristic value of the output signal according to the output signal; performing virtual synchronous generator control on the inverter to obtain a fundamental electric potential; extracting a harmonic component from the output signal and obtaining an error signal according to the harmonic component and a reference value of the harmonic component; controlling the error signal to obtain a harmonic compensation electric potential; obtaining a control electric potential by superimposing the harmonic compensation electric potential with the fundamental electric potential; obtaining a pulse signal by modulating the control electric potential, and obtaining a switching signal of the inverter according to the pulse signal.

Abstract: The application relates to battery internal resistance detection device and method for power conversion device. The detection device includes a data acquisition module for acquiring a battery voltage and a battery current to obtain a DC voltage, an AC voltage, a DC current and an AC current, a first calculation module for receiving the AC current and the AC voltage at a certain instant to output a first internal resistance value and a battery capacitance, a second calculation module for receiving a plurality of DC currents and a plurality of DC voltages at multiple instants and the battery capacitance to output a second internal resistance value, and a selection module for receiving the first and second internal resistance value and selecting one of the first and second internal resistance value as battery internal resistance value. The application improves detection accuracy of battery internal resistance by combining DC and AC algorithms.

Abstract: A high-voltage DC transformation apparatus, a power system and a control method of the power system. The high-voltage DC transformation apparatus is electrically connected to at least one high-voltage DC power generator. The high-voltage DC transformation apparatus includes at least one bidirectional AC/DC conversion module, at least one first transformer and at least one unidirectional rectifier module. A DC terminal of the bidirectional AC/DC conversion module is electrically connected to the corresponding high-voltage DC power generator. The first transformer includes a first transmission terminal and a second transmission terminal. The first transmission terminal is electrically connected to an AC terminal of the corresponding bidirectional AC/DC conversion module. The unidirectional rectifier module includes an input terminal and an output terminal.

Abstract: An energy storage device for a power system is provided. The energy storage device is electrically connected with a high voltage DC transmission grid. The energy storage device includes at least one energy storage element, at least one bidirectional inverter module, at least one medium frequency transformer and at least one bidirectional AC/DC conversion module. A DC terminal of each bidirectional inverter module is electrically connected with the corresponding energy storage element. A first transmission terminal of each medium frequency transformer is electrically connected with an AC terminal of the corresponding bidirectional inverter module. An AC terminal of each bidirectional AC/DC conversion module is electrically connected with a second transmission terminal of the corresponding medium frequency transformer. A DC terminal of each bidirectional AC/DC conversion module is electrically connected with the high voltage DC transmission grid.

Abstract: The present disclosure provides a power supply system method for an AC load. The system includes a power supply device and a DC/AC converter. An AC side of the DC/AC converter is coupled to an AC grid and the AC load through an AC bus. The power supply device outputs DC electric energy and is coupled to a DC side of the DC/AC converter through a DC bus. The power supply device includes an energy storage circuit and a controller. The energy storage circuit includes a first energy storage circuitry and a second energy storage circuitry. The controller is configured to control a conversion operation of the first energy storage circuitry to output a low-frequency power to the DC bus, and a conversion operation of the second energy storage circuitry to output a high-frequency power to the DC bus.

Abstract: The present application provides a method of controlling an electrical power system and an apparatus using the same. The electrical power system includes a DC bus and a DC bus capacitor connected to the DC bus. The method includes: receiving a virtual DC bus capacitance value of the DC bus capacitor; detecting a DC bus voltage; calculating an expected value of a DC bus current based on the virtual DC bus capacitance value and the DC bus voltage; and adjusting the DC bus current, so that the DC bus current reaches the expected value and thus the DC bus capacitor is equivalent to the virtual DC bus capacitance value.

Abstract: The present application provides a method of controlling an electrical power system and an apparatus using the same. The electrical power system includes a DC bus and a DC bus capacitor connected to the DC bus. The method includes: receiving a virtual DC bus capacitance value of the DC bus capacitor; detecting a DC bus voltage; calculating an expected value of a DC bus current based on the virtual DC bus capacitance value and the DC bus voltage; and adjusting the DC bus current, so that the DC bus current reaches the expected value and thus the DC bus capacitor is equivalent to the virtual DC bus capacitance value.

Abstract: Provided is a doubly-fed induction generator system and a self-test method for the active crowbar circuit of the doubly-fed induction generator system. The invention is featured by using the controller of the doubly-fed induction generator system to carry out a self-test procedure to detect the loop current of the active crowbar circuit for determining if the active crowbar circuit can be turned on and off normally. Also, the rotor-side converter and the active crowbar circuit of the doubly-fed induction generator system are forbidden to turn on simultaneously during the execution of the self-test procedure.

Abstract: Provided is a doubly-fed induction generator system and a self-test method for the active crowbar circuit of the doubly-fed induction generator system. The invention is featured by using the controller of the doubly-fed induction generator system to carry out a self-test procedure to detect the loop current of the active crowbar circuit for determining if the active crowbar circuit can be turned on and off normally. Also, the rotor-side converter and the active crowbar circuit of the doubly-fed induction generator system are forbidden to turn on simultaneously during the execution of the self-test procedure.

Abstract: Provided is a flux regulation method for use in a power converter, wherein the method is carried out by a flux bias controller. The flux bias controller includes a current detector which is configured to detect the primary current of the transformer of the power converter in a predetermined switching cycle, a DC bias processor which is configured to obtain the duty ratio control signal according to the sampled primary current outputted from the current detector for a switching cycle later than the predetermined switching cycle, and a PWM controller which is configured to generate driving signals to control the on/off operations of the switching circuit of the power converter according to the duty ratio control signal, thereby suppressing the DC bias of the transformer by regulating the duty ratio of the switch circuit.

Abstract: Provided is a flux regulation method for use in a power converter, wherein the method is carried out by a flux bias controller. The flux bias controller includes a current detector which is configured to detect the primary current of the transformer of the power converter in a predetermined switching cycle, a DC bias processor which is configured to obtain the duty ratio control signal according to the sampled primary current outputted from the current detector for a switching cycle later than the predetermined switching cycle, and a PWM controller which is configured to generate driving signals to control the on/off operations of the switching circuit of the power converter according to the duty ratio control signal, thereby suppressing the DC bias of the transformer by regulating the duty ratio of the switch circuit.

Abstract: The provided method and control circuit are employed to alternately control the dual boost PFC circuits. The control circuit for alternately controlling parallel-connected first and second boost circuits of a dual boost PFC circuit to achieve a current-sharing of the first and the second boost circuits includes: a first control circuit having a first current control loop for employing an output voltage of the PFC circuit, a feed-forward voltage, and an input reference voltage to generate a current reference, and sending the current reference to an input terminal of the first current control loop to generate a first PWM signal to drive the first boost circuit, and a second control circuit having a second current control loop for receiving the current reference through an input terminal of the second current control loop to generate a second PWM signal to drive the second boost circuit.

Abstract: An apparatus for reducing the heat losses caused by the DC Bus capacitor current is proposed. The apparatus includes: a double frequency boost converter circuit having two boost converter circuits coupled in parallel, in which two switches, respectively disposed on the two boost converter circuits, are turned on and off alternately to produce an output current having a frequency twice that of control signals of the two switches, and to offer a DC bus respectively, a full-bridge DC-DC converter coupled to an output terminal of the double frequency boost converter circuit for transforming an output of the DC bus to a DC voltage, and a DC bus capacitor coupled to the double frequency boost converter circuit and the full-bridge DC-DC converter in parallel for balancing two corresponding transient powers of the double frequency boost converter circuit and the full-bridge DC-DC converter respectively.