Mitsubishi Electric Corporation

Masahiro Hario

Noriyuki Imada

Keisuke Ishida

Yasunori Ido

Tomohiro Adachi

A power conversion device included in a self-excited DC power transmission system connected to an AC system includes a self-excited converter and a control device. The control device includes: a storage to store first vibration information and a first control parameter of the self-excited converter in association with each other for each of a plurality of pieces of first vibration information, a vibration detector to detect a vibration component of an AC voltage of the AC system; a determination unit to determine whether first similar vibration information similar to first detected vibration information including the vibration component of the AC voltage of the detected AC system exists in the plurality of pieces of first vibration information; and a setting unit to set the first control parameter associated with the first similar vibration information as a new control parameter of the self-excited converter when the first similar vibration information exists.

Power conversion device and estimation device

A power converter includes first and second arms, each having switching elements, and performs power conversion between a DC system and an AC system. An AC circuit breaker and a current control circuit are connected in series between the AC system and the power converter. The current control circuit includes a current-limiting resistor and a disconnector connected in parallel. A controller instructs a disconnector to close after an initial charge of the power converter and opens the AC circuit breaker when an impedance of a line between a first node located on a first end side of the current control circuit and a second node located on a second end side of the current control circuit is not less than a first threshold and an accumulated value of a current flowing through the current control circuit within a certain period of time is not less than a second threshold.

Power control system and controller for power control system

In a multi-terminal DC power transmission system, a common control device is connected to a plurality of individual protective devices via a first communication network. Each of the individual protective devices is configured, when detecting change in current or voltage in a corresponding protection zone, to output a fault signal to the common control device via the first communication network and open the corresponding DC circuit breaker such that the corresponding protection zone is disconnected from the multi-terminal DC power grid and deenergized. The common control device estimates a fault occurrence zone where a fault occurs among a plurality of protection zones, based on a plurality of received fault signals. The common control device requests an individual protective device corresponding to a deenergized protection zone of the protection zones excluding the fault occurrence zone to reclose the DC circuit breaker such that the deenergized protection zone is restored.

Multi-terminal DC power transmission system, common control device thereof, and fault recovery method for multi-terminal DC power transmission system

A power conversion device that performs power conversion between a DC circuit and an AC circuit includes a power conversion circuit including a plurality of sub-modules, a failure detection device that detects an internal failure of the power conversion circuit, and a control device that generates an operation command controlling operation of each of the plurality of sub-modules. The control device acquires a voltage value of a capacitor included in each sub-module, calculates a deviation between a variance value indicating a variation in the voltage value of the capacitor included in the sub-module in a reference period and a reference variance value in the sub-module for each of a plurality of sub-modules, determines a failure section of an internal failure based on the deviation in each sub-module when the internal failure is detected, and outputs an operation command based on a determination result to each sub-module.

Power conversion device

In one embodiment, a power conversion device that converts power between a DC circuit and an AC circuit includes a plurality of leg circuits connected in parallel between first and second DC terminals and electrically connected to the AC circuit. Each of the plurality of leg circuits includes at least one first converter cell and a plurality of second converter cells other than the first converter cell. A first control signal that controls switching of a semiconductor switching element included in at least one first converter cell is higher in frequency than a second control signal that controls switching of a semiconductor switching element included in each of the plurality of second converter cells.

Power conversion device having a frequency of a first control signal higher than a frequency of a second control signal

A power conversion device includes: first and second control devices that generate first and second control commands respectively; and first and second relay devices that transmit, to each sub module, the first and second control commands respectively. The first and second control devices receive instruction information indicating a system that is to control operation of each sub module. The first and second control commands each include a drive command, abnormality determination information about the control device, and instruction information. Even when the instruction information indicates a first system, each sub module selects a second system as a system to control operation of each sub module in response to detection of occurrence of abnormality to the first control device, and performs PWM control for a switching element in accordance with the drive command included in the second control command for the second system.

Fault tolerant multilevel modular power conversion device

A power conversion device includes an MMC-type power conversion circuit and a central controller. The central controller limits an active power command value and a reactive power command value to a value corresponding to an active power limit value and a value corresponding to a reactive power limit value, respectively, and controls an operation of the power conversion circuit according to the limited active power command value and the limited reactive power command value. The central controller includes: an index value calculation unit configured to calculate an index value that shows an extent of a variation among voltages of energy storage devices included in a plurality of converter cells; and a limiter controller configured to change the active power limit value to a value smaller than the active power limit value when the index value exceeds a threshold value.

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Tokyo, Japan

Masahiro Hario