US-12620805-B2 - Electrical assembly

US12620805B2US 12620805 B2US12620805 B2US 12620805B2US-12620805-B2

Abstract

An electrical assembly including a voltage sourced converter for connection to an AC network, a controller programmed so that, responsive to detection of a fault in the AC network, the controller obtains a first set of voltage and current measurements taken at an interface connection point, change operation of the voltage sourced converter to inject a modified fault current, and then obtain a second set of voltage and current measurements, determine operating parameters of the voltage sourced converter for injecting a target fault current having a target phase angle that is substantially the same as a phase angle of a reference fault current that would have resulted from operation of the voltage sourced converter in accordance with pre-fault steady-state voltage phase and magnitude values, and operate the voltage sourced converter in accordance with the determined operating parameters so as to inject the target fault current at the target phase angle.

Inventors

Li Zou
Andrzej Adamczyk
Carl Barker
John Fradley

Assignees

GE INFRASTRUCTURE TECHNOLOGY LLC

Dates

Publication Date: 20260505
Application Date: 20220428
Priority Date: 20210505

Claims (12)

1 . An electrical assembly comprising: a voltage sourced converter for connection to an AC network; a controller programmed so that, responsive to detection of a fault in the AC network, the controller: obtains a first set of voltage and current measurements taken at an interface connection point (PCC) between the voltage sourced converter and the AC network; after obtaining the first set of voltage and current measurements, change operation of the voltage sourced converter to inject a modified fault current, and then obtain a second set of voltage and current measurements taken at the interface connection point (PCC); using the first and second sets of voltage and current measurements, determine operating parameters of the voltage sourced converter for injecting a target fault current having a target phase angle that is the same, or substantially the same, as a phase angle of a reference fault current that would have resulted from operation of the voltage sourced converter in accordance with pre-fault steady-state voltage phase and magnitude values; and operate the voltage sourced converter in accordance with the determined operating parameters so as to inject the target fault current at the target phase angle.
2 . An electrical assembly according to claim 1 , wherein the determined operating parameters of the voltage sourced converter include voltage phase and magnitude.
3 . An electrical assembly according to claim 1 , wherein the determination of the operating parameters of the voltage sourced converter using the first and second sets of voltage and current measurements includes determining system parameters of the faulted AC network based on the first and second sets of voltage and current measurements and then determining the operating parameters of the voltage source converter based on the determined system parameters of the faulted AC network.
4 . An electrical assembly according to claim 3 , wherein the determined system parameters of the faulted AC network includes: a magnitude of a voltage source of the faulted AC network; a phase of a voltage source of the faulted AC network; and/or an impedance of the AC network.
5 . An electrical assembly according to claim 3 , wherein the determination of the operating parameters of the voltage source converter using the first and second sets of voltage and current measurements includes determining system parameters of the faulted AC network based on the first and second sets of voltage and current measurements and then determining the operating parameters of the voltage source converter based on the determined system parameters of the faulted AC network and a fundamental frequency reactance of the voltage sourced converter.
6 . An electrical assembly according to claim 1 , including a fault detection device for detecting a fault in the AC network, wherein the fault detection device is configured to communicate a fault detection event to the controller.
7 . A method of operating an electrical assembly comprising a voltage sourced converter for connection to an AC network, the method comprising the steps of, responsive to detection of a fault in the AC network: obtaining a first set of voltage and current measurements taken at an interface connection point between the voltage sourced converter and the AC network; after obtaining the first set of voltage and current measurements, changing operation of the voltage sourced converter to inject a modified fault current, and then obtain a second set of voltage and current measurements taken at the interface connection point; using the first and second sets of voltage and current measurements, determining operating parameters of the voltage sourced converter for injecting a target fault current having a target phase angle that is the same, or substantially the same, as a phase angle of a reference fault current that would have resulted from operation of the voltage sourced converter in accordance with pre-fault steady-state voltage phase and magnitude values; and operating the voltage sourced converter in accordance with the determined operating parameters so as to inject the target fault current at the target phase angle.
8 . A method according to claim 7 , wherein the determined operating parameters of the voltage sourced converter include voltage phase and magnitude.
9 . A method according to claim 7 , wherein the determination of the operating parameters of the voltage sourced converter using the first and second sets of voltage and current measurements includes determining system parameters of the faulted AC network based on the first and second sets of voltage and current measurements and then determining the operating parameters of the voltage source converter based on the determined system parameters of the faulted AC network.
10 . A method according to claim 9 , wherein the determined system parameters of the faulted AC network includes: a magnitude of a voltage source of the faulted AC network; a phase of a voltage source of the faulted AC network; and/or an impedance of the AC network.
11 . A method according to claim 9 , wherein the determination of the operating parameters of the voltage source converter using the first and second sets of voltage and current measurements includes determining system parameters of the faulted AC network based on the first and second sets of voltage and current measurements and then determining the operating parameters of the voltage source converter based on the determined system parameters of the faulted AC network and a fundamental frequency reactance of the voltage sourced converter.
12 . A method according to claim 7 , including the step of detecting a fault in the AC network.

Description

TECHNICAL FIELD This invention relates to an electrical assembly, preferably for use in high voltage direct current (HVDC) power transmission networks. BACKGROUND OF THE INVENTION In HVDC power transmission networks alternating current (AC) power is typically converted to direct current (DC) power for transmission via overhead lines, under-sea cables and/or underground cables. This conversion removes the need to compensate for the AC capacitive load effects imposed by the power transmission medium, i.e. the transmission line or cable, and reduces the cost per kilometre of the lines and/or cables, and thus becomes cost-effective when power needs to be transmitted over a long distance. The conversion between DC power and AC power is utilised in power transmission networks where it is necessary to interconnect the DC and AC networks. In any such power transmission network, converters are required at each interface between AC and DC power to effect the required conversion from AC to DC or from DC to AC. SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided an electrical assembly comprising: a voltage sourced converter for connection to an AC network;a controller programmed so that, responsive to detection of a fault in the AC network, the controller: obtains a first set of voltage and current measurements taken at an interface connection point between the voltage sourced converter and the AC network;after obtaining the first set of voltage and current measurements, change operation of the voltage sourced converter to inject a modified fault current, and then obtain a second set of voltage and current measurements taken at the interface connection point;using the first and second sets of voltage and current measurements, determine operating parameters of the voltage sourced converter for injecting a target fault current having a target phase angle that is the same, or substantially the same, as a phase angle of a reference fault current that would have resulted from operation of the voltage sourced converter in accordance with pre-fault steady-state voltage phase and magnitude values; and operate the voltage sourced converter in accordance with the determined operating parameters so as to inject the target fault current at the target phase angle. The configuration of the controller of the invention provides the electrical assembly with a fault current phase control capability that enables operation of the voltage sourced converter to inject a target fault current in phase with the reference fault current. In contrast, in the absence of the fault current phase control capability, a phase angle of the fault current would be uncontrolled and thereby arbitrary when a magnitude of an output voltage of the voltage sourced converter is reduced to lower the fault current, for example, to be equal to or below a rated current limit of the voltage sourced converter. The ability to control the phase angle of the fault current in accordance with the invention provides reliable information about the state of the faulted AC network that is beneficial for a wide range of AC network applications, such as current differential protection and phase comparison protection. Moreover the fault current phase control capability is straightforward to integrate into existing control architecture for power transmission networks and voltage sourced converters. The voltage sourced converter may be an AC/DC, DC/AC or AC/AC voltage sourced converter. The interface connection point may be, but is not limited to, a point of common coupling, a grid entry point, or a transmission interface point. In a preferred embodiment of the electrical assembly of the invention, the reference fault current resulting from operation of the voltage sourced converter in accordance with pre-fault steady-state voltage phase and magnitude values would not have been subjected to any limitation. The determined operating parameters of the voltage sourced converter may include voltage phase and magnitude. In embodiments of the invention, the determination of the operating parameters of the voltage sourced converter using the first and second sets of voltage and current measurements may include determining system parameters of the faulted AC network based on the first and second sets of voltage and current measurements and then determining the operating parameters of the voltage source converter based on the determined system parameters of the faulted AC network. Examples of the determined system parameters of the faulted AC network may include: a magnitude of a voltage source of the faulted AC network; a phase of a voltage source of the faulted AC network; and/or an impedance of the AC network. In further embodiments of the invention, the determination of the operating parameters of the voltage source converter using the first and second sets of voltage and current measurements may include determining system parameters of