EP-4742478-A1 - IMPROVEMENTS RELATING TO THE OPERATION OF ENERGY DISSIPATION CIRCUITS IN POWER TRANSMISSION NETWORKS

EP4742478A1EP 4742478 A1EP4742478 A1EP 4742478A1EP-4742478-A1

Abstract

There is provided a computer-implemented method (400) of controlling an energy dissipation means for dynamic braking in a power transmission network, the method (400) comprising: monitoring (410) one or more first parameters associated with the power transmission network; determining (420), based on the one or more first parameters, a fault status of the power transmission network; and controlling (430), based on the fault status, the energy dissipation means to perform dynamic braking for the power transmission network; wherein the controlling (430), based on the fault status, the energy dissipation means, comprises adaptively controlling by either of: adjusting (430a) a threshold voltage for activating the energy dissipation means or controlling (430b) the energy dissipation means to perform dynamic braking until the MCB is determined to be in a non-conducting state.

Inventors

KUMAR, AMIT
SINGH, AMIT
THAKUR, Amit Kumar

Assignees

GE Vernova Technology GmbH

Dates

Publication Date: 20260513
Application Date: 20241108

Claims (15)

A computer-implemented method of controlling an energy dissipation means for dynamic braking in a power transmission network, the power transmission network comprising a first power conversion means having a first alternating current `AC' side and a first direct current `DC' side, the first AC side being connected to a first AC network via a main circuit breaker 'MCB', the first DC side being connected to a power transmission means, wherein the power transmission network further comprises a second power conversion means having a second AC side and a second DC side, the second AC side being connected to a second AC network, the second DC side being connected to the power transmission means, wherein the energy dissipation means is operably connected to the power transmission means, the method comprising: monitoring one or more first parameters associated the power transmission network; determining, based on the one or more first parameters, a fault status of the power transmission network; and controlling, based on the fault status, the energy dissipation means to perform dynamic braking for the power transmission network; wherein the controlling, based on the fault status, the energy dissipation means, comprises adaptively controlling the energy dissipation means by either of: adjusting a threshold voltage for activating the energy dissipation means, and controlling the energy dissipation means to perform the dynamic braking when a DC voltage on the power transmission means exceeds the adjusted threshold voltage; or controlling the energy dissipation means to perform dynamic braking until the MCB is determined to be in a non-conducting state.
The computer-implemented method of claim 1, wherein the one or more first parameters are associated with a first protection zone of the power transmission network.
The computer-implemented method of any one of claims 1-2, wherein the method comprises adjusting the threshold voltage for activating the energy dissipation means, wherein the method further comprises: determining whether the MCB is in the non-conducting state and, if the MCB is in the non-conducting state, blocking the energy dissipation means from performing the dynamic braking.
The computer-implemented method of any one of claims 1-2, wherein controlling the energy dissipation means to perform dynamic braking until the MCB is determined to be in a non-conducting state, comprises: controlling the energy dissipation means to perform the dynamic braking until a signal is received that is indicative of the MCB being in the non-conducting state; or controlling the energy dissipation means to perform the dynamic braking for a first predetermined time period, the first predetermined time period corresponding to a time for switching the main circuit breaker from a conducting state to the non-conducting state.
The computer-implemented method of any one of the preceding claims, where the controlling, based on the fault status, the energy dissipation means to perform dynamic braking in the power transmission network, comprises: determining whether the fault status is indicative of a permanent fault whereby the first power conversion means is blocked; and then if the fault status is indicative of the permanent fault, adaptively controlling the energy dissipation means.
The computer-implemented method of any one of the preceding claims, wherein the one or more first parameters comprises parameters selected from the list of parameters consisting of: a block status of the first power conversion means; an operational state of the main circuit breaker; a time delay until a command for switching the main circuit breaker is issued; a location of a fault; a zone of the fault; and one or more measurements of one or more electrical quantities.
The computer-implemented method of any one of the preceding claims, wherein the first protection zone is on the first AC side of the first power conversion means.
The computer-implemented method of any one of the preceding claims, wherein the method further comprises: determining whether a telecommunication link is available between the first power conversion means and the second power conversion means; and if the telecommunication link is not available, controlling, based on the fault status, the energy dissipation means to perform the dynamic braking in the power transmission network.
The computer-implemented method of any one of the preceding claims, wherein the method comprises: determining if the DC voltage on the power transmission medium is greater than the second threshold voltage for a second predetermined time period; and if so blocking and tripping the second power conversion means.
The computer-implemented method of any one of the preceding claims, wherein the method comprises: determining a DC current of the power transmission means; and if the DC current is substantially zero, operating one or more components on the power transmission means to isolate the power transmission means.
The computer-implemented method of any one of the preceding claims, wherein the second AC network comprises a power generation network, wherein optionally the power generation network comprises a renewable power generation network selected from the list of renewable power generation networks consisting of: a wind-power generation network; a solar-power generation network; and a bio-power generation network.
A controller for controlling an energy dissipation means for dynamic braking in a power transmission network, the power transmission network comprising a first power conversion means having a first AC side and a first DC side, the first AC side being connected to a first AC network via a MCB, the first DC side being connected to a power transmission means, wherein the power transmission network further comprises a second power conversion means having a second AC side and a second DC side, the second AC side being connected to a second AC network, the second DC side being connected to the power transmission means, wherein the energy dissipation means is operably connected to the power transmission means, the controller comprising: a memory; and at least one processor; wherein the memory comprises computer-readable instructions which when executed by the at least one processor cause the controller to: monitor one or more first parameters associated with the power transmission network, optionally associated with a first protection zone of the power transmission network; determine, based on the one or more first parameters, a fault status of the power transmission network; and control, based on the fault status, the energy dissipation means to perform dynamic braking for the power transmission network, wherein the control is adaptive to cause the controller to: adjust a threshold voltage for activating the energy dissipation means, and control the energy dissipation means to perform the dynamic braking when a DC voltage on the power transmission means exceeds the adjusted threshold voltage; or control the energy dissipation means to perform dynamic braking until the MCB is determined to be in a non-conducting state.
The controller of claim 12, wherein the at least one processor causes the controller to control the energy dissipation means to perform the dynamic braking until the MCB is determined to be in a non-conducting state, by causing the controller to: control the energy dissipation means to perform the dynamic braking until a signal is received that is indicative of the MCB being in the non-conducting state; or control the energy dissipation means to perform the dynamic braking for a first predetermined time period, the first predetermined time period corresponding to a time for switching the main circuit breaker from a conducting state to the non-conducting state.
A power transmission network, comprising: a first power conversion means having a first AC side and a first DC side; a first AC network; a MCB; a second power conversion means having a second AC side and a second DC side; a second AC network; a power transmission means; wherein the first AC side of the first power conversion means is connected to the first AC network via the MCB, the first DC side of the first power conversion means being connected to a power transmission means; wherein the second AC side of the second power conversion means is connected to the second AC network, the second DC side of the second power conversion means is connected to the power transmission means; an energy dissipation means operably connected to the power transmission means; and the controller of any one of claims 12-13 for controlling the energy dissipation means.
A computer program comprising instructions which when executed by a processor of a controller for an energy dissipation means, causes the controller to perform the method of any one of claims 1-11.

Description

Field The subject matter herein relates generally to the field of power transmission networks and more specifically to the operation of energy dissipation circuits in power transmission networks. Introduction In high voltage direct current (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 reactive/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. DC power can also be transmitted directly from offshore wind parks to onshore AC power transmission networks, for instance. The conversion between DC power and AC power is utilised where it is necessary to interconnect DC and AC networks. In any such power transmission network, power conversion means also known as converters (i.e., power converters in converter stations) are required at each interface between AC and DC power to effect the required conversion from AC to DC or from DC to AC. The choice of the most suitable HVDC power transmission network or scheme depends on the particular application and scheme features. Examples of power transmission networks include monopole power transmission networks and bipole power transmission networks. Dynamic braking systems (DBS') provide a means of DC line discharge for a power transmission network and are normally installed at the power conversion means. A DBS is a form of energy dissipation system that utilizes a resistive circuit to divert excess energy, giving a power transmission network a temporary disturbance ride-through capability. A DBS will typically regulate the power dissipated in a resistance, with a separate DBS provided and independently controlled for each DC electrical pole of a power transmission network. A DBS may be more generically referred to as a line discharge circuit. Summary HVDC power transmission networks (such as voltage sourced converter (VSC) networks) are typically used to provide an interconnection system between an onshore converter station (which itself is connected to an onshore AC grid) and an offshore converter station (which itself may be connected to an offshore windfarm, for instance). The onshore converter station comprises a first AC:DC power conversion means with the offshore converter station comprising an AC:DC second power conversion means. A power transmission means interconnects the onshore and offshore converter stations. The power transmission means may comprise one or more DC electrical pole lines and may further comprise a neutral arrangement. A DBS is typically provided as a means of DC line discharge for the power transmission medium located at the onshore converter station. Typically, in such a power transmission network, a telecommunication system is provided between the first and second converter stations. When such a telecommunication system is in service and there is a fault local to the onshore converter station, which causes a block and trip of the respective power conversion means (one or more converter/s), a protection block signal is sent to the offshore station enabling the power conversion means (one or more converter/s) of the offshore station to be blocked and tripped. This tends to mitigate the offshore station continuing to push energy into the power transmission means (the DC electrical pole lines) during 'permanent' fault conditions. However, when the telecommunication system is out of service, the offshore converter station may not detect the faults at the onshore converter station. This tends to be a particular issue where the fault is on the AC side of the onshore power conversion means. In such scenarios, the offshore converter station tends only to detect the fault owing to a rise in DC voltage on the power transmission means interconnecting the converter stations. The DC voltage rise tends to occur owing to the offshore converter station continuing to push excessive energy into the power transmission means despite the fault. A DBS is generally expected to function whether the telecommunication system is in-service or out-of-service. To allow the offshore converter station to detect faults without telecommunication service, the DBS tends to be configured to be initially blocked from operating to allow the DC voltage on the power transmission means to rise above an overvoltage threshold, after which the DBS can operate to dissipate excess energy. Whilst this may indeed enable indirect detection of faults by observing the DC voltage rise, the protection strategy tends to cause excessive DC voltage stress on the power transmission medium and indeed on components connected to the DC system of the power transmission network as a whole. More spe