US-12620893-B2 - Converter arrangement and method for operating a converter arrangement

US12620893B2US 12620893 B2US12620893 B2US 12620893B2US-12620893-B2

Abstract

A converter arrangement comprises a converter with a first side and a second side, a first connection line connected to the first side of the converter, a short-circuit switch connected to the first connection line, and a controller having a terminal coupled to the converter and an output connected to a control terminal of the short-circuit switch. A method for operating a converter arrangement comprises providing a detection signal by a converter, receiving the detection signal by a controller, providing a set signal to a short-circuit switch by the controller in case the controller determines a fault of the converter by evaluating the detection signal, and setting the short-circuit switch in a conducting state by the set signal.

Inventors

Christoph HAEDERLI

Assignees

HITACHI ENERGY LTD

Dates

Publication Date: 20260505
Application Date: 20201203

Claims (19)

1 . A converter arrangement, comprising: a converter with a first side and a second side, a first connection line connected to the first side of the converter, a short-circuit switch connected to the first connection line, a controller having a terminal coupled to the converter and an output connected to a control terminal of the short-circuit switch, a further first connection line connected to the second side of the converter, an auxiliary short-circuit switch connected to the further first connection line, and a machine coupled to the second side of the converter via the further first connection line, wherein the converter is configured to provide a detection signal, wherein the controller is configured to receive and evaluate the detection signal, and wherein upon detection of a converter internal fault, the controller triggers fast shorting of the first side via the short-circuit switch and blocks converter pulses simultaneously, driving currents to zero and making full converter blocking voltage available on the machine side.
2 . The converter arrangement according to claim 1 , wherein the short-circuit switch comprises an ultrafast switch.
3 . The converter arrangement according to claim 1 , wherein the short-circuit switch includes a crowbar.
4 . The converter arrangement according to claim 1 , wherein the short-circuit switch connects the first connection line to an earth terminal.
5 . The converter arrangement according to claim 1 , wherein the converter arrangement includes a second connection line connected to the first side of the converter, and wherein the short-circuit switch is coupled to the first connection line and to the second connection line.
6 . The converter arrangement according to claim 1 , wherein the converter is configured to provide the detection signal, wherein the controller is configured to receive the detection signal at the terminal of the controller and to provide a set signal to the control terminal of the short-circuit switch in case a fault is detected by evaluation of the detection signal, and wherein the short-circuit switch is configured to be set in a conducting state by the set signal.
7 . The converter arrangement according to claim 1 , wherein the converter arrangement comprises a first circuit breaker and a transformer, wherein the first circuit breaker is coupled via the transformer to the first connection line, and wherein the controller comprises a further output connected to a control terminal of the first circuit breaker.
8 . The converter arrangement according to claim 1 , wherein the controller is coupled to the auxiliary short-circuit switch for providing an additional set signal to the auxiliary short-circuit switch.
9 . The converter arrangement according to claim 1 , wherein the converter arrangement comprises a current sensor configured to measure a current of the further first connection line, and wherein an output of the current sensor is connected to an input of the auxiliary short-circuit switch.
10 . The converter arrangement according to claim 1 , wherein the converter is implemented as an AC/AC converter and includes a modular multi-level converter.
11 . The converter arrangement according to claim 1 , wherein the controller is configured to block the converter pulses within less than 4 milliseconds of detecting the converter internal fault.
12 . The converter arrangement according to claim 1 , wherein the converter comprises a modular multi-level converter having phase legs with a voltage blocking capability configured to cover a sum of AC voltages at both the first side and the second side.
13 . The converter arrangement according to claim 1 , wherein the controller is configured to: trigger the short-circuit switch to create a short circuit on the first side, wherein short circuit currents are limited by a transformer short circuit impedance; and trip a main circuit breaker on the first side.
14 . The converter arrangement according to claim 1 , wherein the controller is configured to detect the converter internal fault by: analyzing internal voltages and currents of the converter; combining different signals representing the internal voltages and currents; and generating a set signal to trigger the short-circuit switch based on the analyzing and combining.
15 . The converter arrangement according to claim 1 , wherein the controller is configured to: detect the converter internal fault by evaluating a maximum available phase-leg voltage compared to a present voltage across a phase-leg of the converter; and trigger the short-circuit switch when the maximum available phase-leg voltage is less than the present voltage across the phase-leg.
16 . A method for operating a converter arrangement, comprising providing a converter with a first side and a second side, providing a detection signal by the converter, receiving the detection signal by a controller, providing a set signal to a short-circuit switch by the controller in case the controller determines a fault of the converter by evaluating the detection signal, and setting the short-circuit switch in a conducting state by the set signal, wherein the converter arrangement comprises a further first connection line connected to the second side of the converter, an auxiliary short-circuit switch connected to the further first connection line, and a machine coupled to the second side of the converter via the further first connection line, wherein upon detection of a converter internal fault, the controller triggers fast shorting of the first side via the short-circuit switch and blocks converter pulses simultaneously, driving currents to zero and making full converter blocking voltage available on the machine side.
17 . The method according to claim 16 , wherein the detection signal includes at least one information of a group comprising: a measurement of a DC voltage of the converter, a measurement of an AC voltage of the converter, a measurement of a current of the converter, a measurement of a present voltage across a phase-leg of the converter, an information of a status of a cell of the converter, an information of a status of a phase-leg of the converter, and an information of a detected light generated by an arc.
18 . The method according to claim 16 , wherein the controller determines the fault of the converter by performing at least one evaluation of a group comprising: comparing a DC voltage of the converter with an AC voltage of the converter, comparing a maximum available phase-leg voltage with a present voltage across a phase-leg of the converter, comparing a current of the converter with a predetermined value, comparing a number of cells of the converter with a status indicating a short-circuit with a predetermined number, determining a presence of a phase-leg of the converter with a status indicating out-of-order, and determining a presence of an arc.
19 . The method according to claim 16 , wherein upon detection of a sustained machine side short circuit after the fast shorting of the first side, the controller is configured to trigger the auxiliary short-circuit switch after a delay.

Description

The present disclosure is related to a converter arrangement and a method for operating a converter arrangement. A converter arrangement comprises a converter having a first and a second side. The first side of the converter is e.g. coupled to a transformer and the second side of the converter is e.g. coupled to a machine such as a motor. A short circuit may occur with a certain probability in such a converter arrangement. Thus, a converter arrangement should be configured such that damage in case of a short circuit is kept small. Document WO 2017/129252 A1 describes a method and a control device for controlling a modular multilevel converter. The method comprises detecting a fault condition and applying, in response to the detecting, a pulse blocking procedure. It is an object to provide a converter arrangement and a method for operating a converter arrangement which react in case of a fault of the converter. The object is achieved by the subject-matter of the independent claims. Further developments are described in the dependent claims. There is provided a converter arrangement which comprises a converter with a first side and a second side, a first connection line, a short-circuit switch and a controller. The first connection line is connected to the first side of the converter. The short-circuit switch is connected to the first connection line. The controller includes a terminal coupled to the converter and an output connected to a control terminal of the short-circuit switch. Advantageously, the converter is coupled via the controller to the short-circuit switch. In case of a fault of the converter, the short-circuit switch can reduce a voltage at the first connection line with only a short delay. Thus, measures to reduce a possible effect of the fault are implemented on the first side of the converter. In a development, the first side of the converter may be a supply side and the second side of the converter may be a load side. Alternatively, the first side of the converter may be a load side and the second side of the converter may be a supply side. In a development of the converter arrangement, the short-circuit switch is realized as an ultrafast switch. The ultrafast switch may include a micro gas generator. A gas generation by the micro gas generator may set the short-circuit switch in a conducting state with a very short delay. In a development of the converter arrangement, the short-circuit switch includes a crowbar, e.g. a thyristor crowbar. The crowbar includes at least one thyristor. The crowbar comprises e.g. a thyristor bridge. The short-circuit switch is fabricated using a semiconductor device. In a development of the converter arrangement, the short-circuit switch connects the first connection line to an earth terminal. In case of a fault, the voltage at the first connection line is quickly reduced to zero. In a development of the converter arrangement, the short-circuit switch is realized as an ultrafast earthing switch, abbreviated UFES. The ultrafast earthing switch is able to short circuit the first connection line to the earth terminal with an extremely low delay. In a development, the converter arrangement includes a second connection line connected to the first side of the converter. The short-circuit switch is e.g. coupled to the first connection line and to the second connection line. The short-circuit switch e.g. connects the first connection line to the second connection line. In an example, the short-circuit switch directly connects the first connection line to the second connection line. In case of a fault, the short-circuit switch provides a short circuit between the first and the second connection line. Advantageously, an energy provided to the first side of the converter is quickly reduced by the short circuit between the first and the second connection line. Advantageously, shorting the input line such as the first and the second connection lines prevents further energy input from a grid side into the converter. Moreover, shorting the input side removes the input AC voltage, allowing for a higher output voltage without the converter going into rectification mode (e.g. by free-wheeling diodes in each cell). In a development, the converter arrangement comprises a third connection line connected to the first side of the converter. The first, second and third connection line form a three phase system. In a development, the converter arrangement comprises a further short-circuit switch and an additional short-circuit switch. Thus, the converter arrangement comprises three connection lines which are connected to the first side of the converter, namely the first, second and third connection line. The converter arrangement includes three short-circuit switches, namely the short-circuit switch, the further short-circuit switch and the additional short-circuit switch which are arranged at the first, second and third connection line and, thus, at the first side of the converter. Th