Abstract: A voltage drop Vzs is calculated based on an output current detection value Iac and a virtual synchronous impedance Zs or a corrected virtual synchronous impedance Zs?, and a value obtained by subtracting the voltage drop Vzs from an internal induced voltage Ef is output as a grid voltage command value Vac*. Zs calculation unit 7 limits an output current phase ? so that the output current phase ? is within an effective range by a phase limiter 12a, and calculates the corrected virtual synchronous impedance Zs? based on a limited output current phase ?, the internal induced voltage Ef, a grid voltage detection value Vac and a current limit value Ilim. Accordingly, in grid interconnection power conversion device that controls a virtual synchronous generator, it is possible to continue operation while suppressing an overcurrent and possess a synchronizing power generated by action or working of a virtual synchronous impedance.

Abstract: A control system is provided for a power conversion system having a power converter that controls a virtual synchronous generator simulating a synchronous generator and interconnected to a power grid. The control system has a virtual synchronous impedance compensation block inputting an output current detection value of the power converter and a set voltage amplitude command value, simulating a voltage drop due to a virtual synchronous impedance, and calculating an output voltage command value and an internal induced voltage according to the simulated voltage drop; a virtual synchronous generator model determining an angular frequency simulating the synchronous generator; and a PCS output voltage control unit performing control so that an output voltage of the power conversion system coincides with the output voltage command value calculated by the virtual synchronous impedance compensation block.

Abstract: A voltage drop Vzs is calculated based on an output current detection value Iac and a virtual synchronous impedance Zs or a corrected virtual synchronous impedance Zs?, and a value obtained by subtracting the voltage drop Vzs from an internal induced voltage Ef is output as a grid voltage command value Vac*. Zs calculation unit 7 limits an output current phase ? so that the output current phase ? is within an effective range by a phase limiter 12a, and calculates the corrected virtual synchronous impedance Zs? based on a limited output current phase ?, the internal induced voltage Ef, a grid voltage detection value Vac and a current limit value Ilim. Accordingly, in grid interconnection power conversion device that controls a virtual synchronous generator, it is possible to continue operation while suppressing an overcurrent and possess a synchronizing power generated by action or working of a virtual synchronous impedance.

Abstract: A series compensating electric power transmission system has an insulated type DC-DC converter that operates in the first through fourth quadrants, first and second DC voltage sources, and first and second power converters. In the converter, a first I/O positive terminal is connected to a first voltage source positive terminal. A first I/O negative terminal is connected to a first voltage source negative terminal. One of second I/O positive and negative terminals is connected to the first voltage source positive terminal. The other of the second I/O positive and negative terminals is connected to a second voltage source positive terminal. The first power converter converts power between the first I/O positive and negative terminals and first AC I/O terminals. The second power converter converts power between the second I/O positive and negative terminals and second AC I/O terminals. The second power converter is configured with a plurality of bidirectional switches.

Abstract: A series compensating electric power transmission system has an insulated type DC-DC converter that operates in the first through fourth quadrants, first and second DC voltage sources, and first and second power converters. In the converter, a first I/O positive terminal is connected to a first voltage source positive terminal. A first I/O negative terminal is connected to a first voltage source negative terminal. One of second I/O positive and negative terminals is connected to the first voltage source positive terminal. The other of the second I/O positive and negative terminals is connected to a second voltage source positive terminal. The first power converter converts power between the first I/O positive and negative terminals and first AC I/O terminals. The second power converter converts power between the second I/O positive and negative terminals and second AC I/O terminals. The second power converter is configured with a plurality of bidirectional switches.