CN112968462A

CN112968462A - Converter station overvoltage control method, pole control system and overvoltage control system

Info

Publication number: CN112968462A
Application number: CN202110192522.6A
Authority: CN
Inventors: 刘宪辉; 李振动; 安海清; 刘靖国; 李帅; 张建兴; 金海望; 田凯哲; 李金卜; 张晓飞; 滕孟锋; 柳杨; 李涛; 赵凯曼; 翟永尚; 董海飞; 高宏达; 穆凌杰; 陈学良
Original assignee: State Grid Corp of China SGCC; Maintenance Branch of State Grid Jibei Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; Maintenance Branch of State Grid Jibei Electric Power Co Ltd
Priority date: 2021-02-20
Filing date: 2021-02-20
Publication date: 2021-06-15
Anticipated expiration: 2041-02-20
Also published as: CN112968462B

Abstract

The invention provides an overvoltage control method, a pole control system and an overvoltage control system for a converter station, wherein the method is suitable for the pole control system, and is used for judging that the measured converter valve outlet voltage Udp of the converter station is abnormal and measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not on the basis of N voltage measuring devices; if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result; if the direct current bus voltage Udlb is normal, executing detection of a second direct current outlet voltage Udc2 to obtain a second detection result; and when the first detection result or the second detection result indicates that the current state is in an overvoltage state, executing overvoltage protection operation. In the scheme, based on N voltage measuring devices, when the converter valve outlet voltage Udp is detected to be abnormal, the direct current bus voltage Udlb of the converter station is selected to participate in measurement, overvoltage misjudgment caused by abnormal measurement of the voltage measuring devices is avoided, the overvoltage operation quality of an island converter station is improved, and the operation of a flexible direct current power grid is guaranteed.

Description

Converter station overvoltage control method, pole control system and overvoltage control system

Technical Field

The invention relates to the technical field of flexible direct current transmission, in particular to an overvoltage control method, an electrode control system and an overvoltage control system for a converter station.

Background

At present, large-scale power resources are mostly distributed in remote areas far away from loads in the world, the direct current transmission has the outstanding advantages of long-distance and large-capacity power transmission, the flexible direct current transmission technology can flexibly control active power and reactive power and can supply power to a weak alternating current system, the renewable energy power generation has intermittency and uncertainty, and the traditional alternating current power grid cannot be normally consumed, so the flexible direct current transmission becomes the optimal choice for solving the problems of new energy power generation grid connection and long-distance transmission.

In the prior art, in a flexible direct-current power grid, a new energy island converter station is used as a sending end converter station, and when equipment in the flexible direct-current power grid is abnormal or fails, an overvoltage is generated in a direct-current system of the island converter station, so that direct-current equipment in the flexible direct-current power grid can be damaged, and even the direct-current power grid can be shut down.

Disclosure of Invention

In view of this, embodiments of the present invention provide an island converter station overvoltage control method, an island converter station pole control system, and an island converter station overvoltage control system, so as to achieve the purposes of improving the overvoltage operation quality of an island converter station and ensuring the operation of a flexible direct current power grid.

In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

the first aspect of the embodiment of the invention discloses a converter station overvoltage control method, which is suitable for a pole control system (PCP), and comprises the following steps:

under the running state of the converter station, judging whether converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal, wherein N is a natural number and is more than or equal to 3;

if the measurement result is normal, performing detection on a first direct current outlet voltage Udc1 to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station;

if the measurement result is abnormal, measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on N voltage measuring devices;

if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result;

if the direct-current bus voltage Udlb is normal, executing detection of a second direct-current outlet voltage Udc2 to obtain a second detection result, wherein the second direct-current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station;

and when the first detection result or the second detection result indicates that the current device is in an overvoltage state, executing corresponding overvoltage protection operation.

Optionally, the method further includes:

and when the second detection result indicates that the voltage measurement of the outlet of the converter valve is abnormal, generating alarm information and outputting the alarm information.

Optionally, the determining whether the converter valve outlet voltage Udp of the converter station measured based on the N voltage measurement devices is abnormal includes:

acquiring converter valve outlet voltage Udp of the converter station, which is measured by N voltage measuring devices respectively;

judging whether the maximum value of the outlet voltages Udp of the N converter valves is larger than the upper limit voltage value and the minimum value is smaller than the lower limit voltage value;

if so, determining that the measurement result is normal;

if not, determining that the measurement result is abnormal.

Optionally, the detecting whether the dc bus voltage Udlb of the converter station is abnormal based on the N voltage measuring devices includes:

acquiring direct-current bus voltage Udlb of the converter station, which is measured by N voltage measuring devices respectively;

judging whether the difference between the maximum value and the minimum value in the N direct current bus voltages Udlb is less than or equal to a preset difference value or not;

if so, determining that the direct current bus voltage Udlb is measured normally;

if not, determining that the direct current bus voltage Udlb is abnormal in measurement.

Optionally, the performing the first dc outlet voltage Udc1 detection to obtain a first detection result includes:

detecting whether the first dc outlet voltage Udc1 is greater than or equal to a first voltage threshold;

if not, returning to continuously judge whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measuring devices is abnormal or not;

and if so, obtaining a first detection result indicating that the current overvoltage state is achieved.

Optionally, the performing of the detection of the second dc outlet voltage Udc2 to obtain a second detection result includes:

detecting whether the second direct current outlet voltage Udc2 is greater than or equal to a first voltage threshold;

if so, obtaining a second detection result indicating that the current overvoltage state is achieved;

and if not, obtaining a second detection result indicating that the voltage measurement of the converter valve outlet is abnormal.

Optionally, the overvoltage protection operation comprises:

issuing a power speed-down instruction to a safety and stability control device, and starting timing to enable the safety and stability control device to control the converter station to reduce power based on the power speed-down instruction;

detecting in real time whether the first dc outlet voltage Udc1 or the second dc outlet voltage Udc2 drops below a second voltage threshold within an accumulated time T;

if so, issuing a power rapid reduction stopping instruction to the safety and stability control device, and resetting the accumulated time to ensure that the converter station maintains the current power operation;

and if not, controlling the AC circuit breaker and the DC circuit breaker in the converter station to trip off, so that the AC energy consumption device in the converter station is accessed.

A second aspect of the embodiments of the present invention discloses a pole control system, including:

the measuring module is used for judging whether a converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not under the operation state of the converter station, N is a natural number and is more than or equal to 3, if the measuring result is normal, executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, Udn is the converter valve neutral line outlet voltage of the converter station, if the measuring result is abnormal, the measuring module is used for executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, if the direct current bus voltage Udlb is normal, executing a second direct current outlet voltage Udc2 detection to obtain a second detection result, and the second direct current outlet voltage Udc2 is Udlb-Udn, udn is the converter valve neutral line outlet voltage of the converter station;

and the control module is used for executing corresponding overvoltage protection operation when the first detection result or the second detection result indicates that the current overvoltage state is achieved.

Optionally, the control module includes:

the issuing unit is used for issuing a power speed-down instruction to a safety and stability control device and starting timing to enable the safety and stability control device to control the converter station to reduce power based on the power speed-down instruction;

and the control unit is used for detecting whether the first direct current outlet voltage Udc1 or the second direct current outlet voltage Udc2 is reduced to be lower than a second voltage threshold value or not in real time within the accumulated time T, if so, issuing a power quick reduction stopping instruction to the safety and stability control device, clearing the accumulated time to zero to enable the converter station to maintain the current power operation, and if not, controlling an alternating current breaker and a direct current breaker in the converter station to trip off to enable an alternating current energy consumption device in the converter station to be connected.

A third aspect of an embodiment of the present invention discloses an overvoltage control system for a converter station, where the system includes: the pole control system, the N voltage measurement devices, and the safety and stability control device according to any one of the second aspects, where N is a natural number and is equal to or greater than 3;

the pole control system is used for judging whether a converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not under the operation state of the converter station, N is a natural number and is more than or equal to 3, if the measurement result is normal, executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, Udn is the converter valve neutral line outlet voltage of the converter station, if the measurement result is abnormal, executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, if the direct current bus voltage Udlb is normal, executing a second direct current outlet voltage Udc2 detection to obtain a second detection result, and the second direct current outlet voltage Udc2 is Ub-Udn, udn is the neutral line outlet voltage of the converter valve of the converter station, and when the first detection result or the second detection result indicates that the converter valve is in an overvoltage state at present, corresponding overvoltage protection operation is executed;

n voltage measuring devices, configured to measure whether a converter valve outlet voltage Udp of the converter station is abnormal, if the measurement result is normal, execute a first dc outlet voltage Udc1 detection to obtain a first detection result, where the first dc outlet voltage Udc1 is Udp-Udn, and Udn is a converter valve neutral line outlet voltage of the converter station, if the measurement result is abnormal, measure whether a dc bus voltage Udlb of the converter station is abnormal based on the N voltage measuring devices, if the dc bus voltage Udlb is abnormal, execute a first dc outlet voltage Udc1 detection to obtain a first detection result, and if the dc bus voltage Udlb is normal, execute a second dc outlet voltage Udc2 detection to obtain a second detection result, where the second dc outlet voltage Udc2 is Udlb-Udn, and Udn is a converter valve neutral line outlet voltage of the converter station;

and the safety and stability control device is used for controlling the converter station to reduce power based on the power speed reduction command.

Based on the above-mentioned island converter station overvoltage control method, pole control system and overvoltage control system provided by the embodiments of the present invention, the method is applicable to pole control system, and includes: under the running state of the converter station, judging whether converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal, wherein N is a natural number and is more than or equal to 3; if the measurement result is normal, performing detection on a first direct current outlet voltage Udc1 to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; if the measurement result is abnormal, measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on N voltage measuring devices; if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result; if the direct-current bus voltage Udlb is normal, executing detection of a second direct-current outlet voltage Udc2 to obtain a second detection result, wherein the second direct-current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; and when the first detection result or the second detection result indicates that the current device is in an overvoltage state, executing corresponding overvoltage protection operation. In the scheme, based on N voltage measuring devices, when the converter valve outlet voltage Udp is detected to be abnormal, the direct current bus voltage Udlb of the converter station is selected to participate in measurement, and overvoltage misjudgment caused by abnormal measurement of the voltage measuring devices is avoided, so that the overvoltage operation quality of the island converter station is improved, and the operation of the flexible direct current power grid is guaranteed.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic flow chart of an overvoltage control method for a converter station according to an embodiment of the present invention;

fig. 2 is a schematic flow chart for determining whether a measured converter valve outlet voltage Udp of a converter station is abnormal according to an embodiment of the present invention;

fig. 3 is a schematic flow chart of another converter station overvoltage control method according to an embodiment of the present invention;

fig. 4 is a schematic flow chart illustrating a process of determining whether the measured dc bus voltage Udlb of the converter station is abnormal according to the embodiment of the present invention;

fig. 5 is a schematic flow chart of obtaining a second detection result according to an embodiment of the present invention;

fig. 6 is a schematic flowchart illustrating a corresponding operation of performing overvoltage protection according to an embodiment of the present invention;

fig. 7 is an application scenario diagram provided in the embodiment of the present invention;

fig. 8 is a diagram of another application scenario provided by the embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a pole control system according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of another pole control system according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of an overvoltage control system of a converter station according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

As can be known from the background art, in a flexible direct current power grid, a new energy island converter station is used as a sending end converter station, and when equipment in the flexible direct current power grid is abnormal or fails, an overvoltage is generated in a direct current system of the island converter station, so that direct current equipment in the flexible direct current power grid is damaged, and even the direct current power grid is shut down.

Therefore, the embodiment of the invention provides an overvoltage control method, a pole control system and an overvoltage control system for a converter station.

As shown in fig. 1, a flow diagram of a converter station overvoltage Control method provided by an embodiment of the present invention is shown, where the converter station overvoltage Control method is applicable to a Polar Control and Protection System (PCP), and the method includes the following steps:

step S101: and under the operation state of the converter station, judging whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measuring devices is abnormal or not, if so, executing the step S102, and if so, executing the step S103.

In step S101, N is a natural number and is 3 or more.

For example: the voltage measuring device can be A, B, C triplets, and the voltage measuring device measures the converter valve outlet voltage Udp of the converter station, and the voltage measuring device can be marked as Udp A, Udp B and Udp C.

In the process of specifically implementing the step S101, under the precondition of the operation state of the converter station, on the basis of the N voltage measuring devices, it is determined whether the converter valve outlet voltage Udp of the converter station measured by the voltage measuring device is abnormal, if so, it is indicated that the measured result is normal, step S102 is executed, and if so, it is indicated that the measured result is abnormal, and step S103 is executed.

Step S102: and executing the detection of the first direct current outlet voltage Udc1 to obtain a first detection result, executing the step S105 if the first detection result indicates that the overvoltage state is currently existed, and returning to continue executing the step S101 if the first detection result indicates that the normal voltage state is currently existed.

In step S102, the first dc outlet voltage Udc1 is Udp-Udn, Udn being the converter valve neutral outlet voltage of the converter station.

In the process of specifically implementing the step S102, after determining that the measurement result of the converter valve outlet voltage Udp of the converter station is normal, executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, if the first detection result indicates that the converter station is currently in an overvoltage state, executing the step S105, and if the first detection result indicates that the converter station is currently in a normal voltage state, returning to continuously judge whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measurement devices is abnormal, that is, returning to continuously executing the step S101.

Step S103: and measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on the N voltage measuring devices, if the direct current bus voltage Udlb is abnormal, executing the step S102, and if the direct current bus voltage Udlb is normal, executing the step S104.

Taking the example in step S101 as an example, when the voltage measuring device measures the dc bus voltage Udlb of the converter station, it can be recorded as UdlbA, UdlbB and UdlbC.

In the process of specifically implementing the step S103, whether the dc bus voltage Udlb of the converter station measured by the voltage measuring device is abnormal is determined based on the N voltage measuring devices, if the dc bus voltage Udlb is abnormal, the step S102 is executed, and if the dc bus voltage Udlb is normal, the step S104 is executed.

Step S104: and executing the detection of the second direct current outlet voltage Udc2 to obtain a second detection result, executing step S105 if the second detection result indicates that the current voltage is in an overvoltage state, and executing step S106 if the second detection result indicates that the current voltage is in a normal voltage state.

In step S104, the second dc outlet voltage Udc2 is Udlb-Udn, Udn being the converter valve neutral outlet voltage of the converter station.

In the process of specifically implementing the step S104, after determining that the measurement result of the dc bus voltage Udlb of the converter station is normal, executing a second dc outlet voltage Udc2 detection to obtain a second detection result, if the second detection result indicates that the converter station is currently in an overvoltage state, executing the step S105, and if the second detection result indicates that the converter station is currently in a normal voltage state, indicating that the second detection result indicates that the measurement of the converter valve outlet voltage Udp is abnormal, executing the step S106.

Step S105: corresponding overvoltage protection operations are performed.

In step S105, the overvoltage protection operation may be: and cutting surplus power to reduce direct-current voltage and stop operation of the island converter station or cut off a fan.

In the process of specifically implementing step S105, it is determined that the measurement result of the converter valve outlet voltage Udp of the converter station is normal, and a first detection result obtained by detecting the first direct current outlet voltage Udc1 or a second detection result obtained by detecting the second direct current outlet voltage Udc2 indicates that the current is in an overvoltage state, and a corresponding overvoltage protection operation is performed.

Step S106: and generating and outputting alarm information.

In the process of specifically implementing the step S106, it is determined that the second detection result obtained by determining the second direct current outlet voltage Udc2 indicates that the converter valve outlet voltage Udp is measured abnormally, and alarm information is generated and output.

Based on the island converter station overvoltage control method provided by the embodiment of the invention, whether the converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not is judged under the operation state of the converter station, wherein N is a natural number and is more than or equal to 3; if the measurement result is normal, detecting a first direct current outlet voltage Udc1 to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; if the measurement result is abnormal, measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on the N voltage measuring devices; if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result; if the direct-current bus voltage Udlb is normal, executing detection of a second direct-current outlet voltage Udc2 to obtain a second detection result, wherein the second direct-current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; and when the first detection result or the second detection result indicates that the current device is in the overvoltage state, executing corresponding overvoltage protection operation. In the scheme, based on N voltage measuring devices, when the converter valve outlet voltage Udp is detected to be abnormal, the direct current bus voltage Udlb of the converter station is selected to participate in measurement, and overvoltage misjudgment caused by abnormal measurement of the voltage measuring devices is avoided, so that the overvoltage operation quality of the island converter station is improved, and the operation of the flexible direct current power grid is guaranteed.

Based on the above-mentioned overvoltage control method for an island converter station provided by the embodiment of the present invention, when step S101 is executed, a process of determining whether converter valve outlet voltage Udp of a converter station measured by N voltage measuring devices is abnormal is involved. As shown in fig. 2, a schematic flow chart for determining whether a measured converter valve outlet voltage Udp of a converter station is abnormal according to an embodiment of the present invention mainly includes the following steps:

step S201: and acquiring converter valve outlet voltage Udp of the converter station respectively measured by the N voltage measuring devices.

In the process of specifically implementing step S201, the converter valve outlet voltage Udp of the converter station measured by the voltage measuring devices is obtained based on the N voltage measuring devices.

Taking the example in step S101 as an example, the converter valve outlet voltages udp a, udp b and udp c of the converter station are obtained at this time.

Step S202: and judging whether the maximum value of the outlet voltages Udp of the N converter valves is larger than the upper limit voltage value and the minimum value is smaller than the lower limit voltage value, if so, executing the step S203, and if not, executing the step S204.

In step S202, the upper limit voltage value and the lower limit voltage value are determined by the specific model of the flexible converter station, or may be set by a technician based on the specific model of the flexible converter station, and the upper limit voltage value and the lower limit voltage value corresponding to the flexible converter stations of different models are different.

For example, for a 500kV flexible converter station, the upper limit voltage value may be 515kV and the lower limit voltage value may be 10 kV.

In the process of specifically implementing step S202, based on the measured N converter valve outlet voltages Udp, it is determined whether a maximum value of the measured N converter valve outlet voltages Udp is greater than an upper limit voltage value, and whether a minimum value of the measured N converter valve outlet voltages Udp is less than a lower limit voltage value, if so, it is determined that the maximum value of the measured N converter valve outlet voltages Udp is greater than the upper limit voltage value, and the minimum value of the measured N converter valve outlet voltages Udp is less than the lower limit voltage value, step S203 is executed, otherwise, it is determined that the maximum value of the measured N converter valve outlet voltages Udp is less than or equal to the upper limit voltage value, and the minimum value of the.

Taking the example in step S201 as an example, according to the acquired converter valve outlet voltages UdpA, UdpB and UdpC of the converter station, wherein if the converter valve outlet voltage UdpA is the maximum value and the converter valve outlet voltage UdpC is the minimum value, the UdpA is compared with the upper limit voltage value and the UdpC is compared with the lower limit voltage value.

Step S203: and determining that the measurement result is normal.

In the process of specifically implementing the step S203, it is determined that the measurement result is normal according to that the maximum value of the outlet voltage Udp of the N converter valves is greater than the upper limit voltage value, and the minimum value is less than the lower limit voltage value.

Step S204: determining that the measurement result is abnormal.

In the process of specifically implementing the step S204, it is determined that the measurement result is abnormal according to that the maximum value of the outlet voltage Udp of the N converter valves is less than or equal to the upper limit voltage value, and the minimum value is greater than or equal to the lower limit voltage value.

Based on the above-mentioned overvoltage control method for the island converter station provided by the embodiment of the present invention, under the operation state of the converter station, converter valve outlet voltages Udp of the converter station respectively measured by N voltage measuring devices are obtained, and it is determined whether the maximum value of the N converter valve outlet voltages Udp is greater than the upper limit voltage value and the minimum value is less than the lower limit voltage value, if so, the measurement result is determined to be normal, if not, the measurement result is determined to be abnormal, and the process of determining and measuring is simplified, thereby improving the overvoltage operation quality of the island converter station and ensuring the operation of the flexible direct current power grid.

Based on the above overvoltage control method for the islanding converter station provided in the embodiment of the present invention, as shown in fig. 3, a flow diagram of another overvoltage control method for the islanding converter station provided in the embodiment of the present invention mainly includes the following steps:

step S301: and under the operation state of the converter station, judging whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measuring devices is abnormal or not, if so, executing a step S302, and if so, executing a step S304.

The specific implementation process of step S301 is the same as that of step S101 disclosed in fig. 1, and specific reference may be made to this step, which is not described herein again.

Step S302: it is detected whether the first dc outlet voltage Udc1 is equal to or higher than the first voltage threshold, and if so, step S303 is executed, and if not, step S301 is executed. In step S302, the first dc outlet voltage Udc1 is Udp-Udn, Udn being the converter valve neutral outlet voltage of the converter station.

In step S302, the first voltage threshold is also determined by the specific model of the flexible converter station, or may be set by a technician based on the specific model of the flexible converter station, and the first voltage thresholds corresponding to different models of flexible converter stations are different.

For example, for a 500kV flexible converter station, the first voltage threshold may be 527 kV.

In the process of specifically implementing step S302, it is detected whether the first dc outlet voltage Udc1 is greater than or equal to the first voltage threshold according to the converter valve outlet voltages Udp of the converter stations measured by the N voltage measuring devices, if so, it indicates that the converter station is currently in an overvoltage state, step S303 is executed, and if not, it indicates that the converter station is currently in a normal voltage state, step S301 is executed.

Taking a 500kV flexible converter station as an example, the converter valve outlet voltage Udp of the converter station is 555kV, the converter valve neutral line outlet voltage Udn of the converter station is 15kV, the first direct current outlet voltage Udc1 is Udp-Udn is 555kV-15kV is 540kV, the first voltage threshold is 527kV, and 540kV and 527kV are compared to obtain 540kV >527kV, then step S303 is executed.

Another example is: the converter valve outlet voltage Udp of the converter station is 525kV, the converter valve neutral line outlet voltage Udn of the converter station is 15kV, the first direct current outlet voltage Udc1 is equal to Udp-Udn is equal to 525kV-15kV is equal to 510kV, the first voltage threshold is 527kV, 510kV and 527kV are compared, 510kV <527kV is obtained, then it is returned to continuously judge whether the converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal, that is, step S301 is executed.

Step S303: a first detection result indicating that the overvoltage state is currently being performed is obtained, and step S306 is performed.

In the process of implementing step S303, on the premise that it is determined that the first dc outlet voltage Udc1 is equal to or higher than the first voltage threshold, a first detection result indicating that the overvoltage state is currently performed is obtained, and step S306 is executed.

Step S304: and measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on the N voltage measuring devices, if the direct current bus voltage Udlb is abnormal, executing the step S303, and if the direct current bus voltage Udlb is normal, executing the step S304.

Step S305: and executing the detection of the second direct current outlet voltage Udc2 to obtain a second detection result, executing step S306 if the second detection result indicates that the current voltage is in an overvoltage state, and executing step S307 if the second detection result indicates that the current voltage is in a normal voltage state.

Step S306: corresponding overvoltage protection operations are performed.

Step S307: and generating and outputting alarm information.

The specific execution process of step S304 to step S307 is the same as that of step S103 to step S106 disclosed in fig. 1, and specific reference may be made, and details are not repeated here.

Based on the island converter station overvoltage control method provided by the embodiment of the invention, whether the converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not is judged under the operation state of the converter station, wherein N is a natural number and is more than or equal to 3; if the measurement result is normal, detecting whether the first direct current outlet voltage Udc1 is larger than or equal to a first voltage threshold, if not, returning to continuously judging whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measurement devices is abnormal, if so, obtaining a first detection result indicating that the converter station is in an overvoltage state at present; if the measurement result is abnormal, measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on the N voltage measuring devices; if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result; if the direct-current bus voltage Udlb is normal, executing detection of a second direct-current outlet voltage Udc2 to obtain a second detection result, wherein the second direct-current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; and when the first detection result or the second detection result indicates that the current device is in the overvoltage state, executing corresponding overvoltage protection operation. In the scheme, based on N voltage measuring devices, when the converter valve outlet voltage Udp is detected to be abnormal, the direct current bus voltage Udlb of the converter station is selected to participate in measurement, and overvoltage misjudgment caused by abnormal measurement of the voltage measuring devices is avoided, so that the overvoltage operation quality of the island converter station is improved, and the operation of the flexible direct current power grid is guaranteed.

Based on the above-mentioned overvoltage control method for the islanding converter station provided by the embodiment of the present invention, when step S103 is executed, a process of measuring whether the dc bus voltage Udlb of the converter station is abnormal or not based on N voltage measuring devices is involved. As shown in fig. 4, a schematic flow chart for determining whether the measured dc bus voltage Udlb of the converter station is abnormal according to an embodiment of the present invention mainly includes the following steps:

step S401: and acquiring direct-current bus voltage Udlb of the converter station respectively measured by the N voltage measuring devices.

In the process of specifically implementing step S401, the dc bus voltage Udlb of the converter station measured by the voltage measuring devices is obtained based on the N voltage measuring devices.

Taking the example in step S103 as an example, the dc bus voltages UdlbA, UdlbB and UdlbC of the converter station are acquired at this time.

Step S402: and judging whether the difference between the maximum value and the minimum value in the N direct current bus voltages Udlb is less than or equal to a preset difference value, if so, executing step S403, and if not, executing step S404.

In step S402, the preset difference is also determined by the specific model of the flexible converter station, or may be set by a technician based on the specific model of the flexible converter station, where the preset differences corresponding to different models of flexible converter stations are different.

For example, for a 500kV flexible converter station, the preset difference may be 5 kV.

In the process of specifically implementing the step S402, based on the measured dc bus voltages Udlb of the N converter stations, it is determined whether a difference between a maximum value and a minimum value of the N dc bus voltages Udlb is less than or equal to a preset difference value, if so, the step S403 is executed, and if not, the step S404 is executed.

Taking the example in the step S401 as an example, according to the acquired dc bus voltages UdlbA, UdlbB and UdlbC of the converter station, wherein if the dc bus voltage UdlbA is the maximum value and the dc bus voltage UdlbC is the minimum value, the UdlbA and UdlbC are subjected to subtraction operation, that is, UdlbA-UdlbC, and it is determined whether the result of UdlbA-UdlbC is less than or equal to the preset difference value.

Step S403: and determining that the direct current bus voltage Udlb is measured normally.

In the process of implementing step S403 specifically, it is determined that the direct current bus voltage Udlb is measured normally according to the fact that the difference between the maximum value and the minimum value of the obtained N direct current bus voltages Udlb is less than or equal to a preset difference value.

Step S404: and determining that the direct current bus voltage Udlb is abnormal in measurement.

In the process of specifically implementing the step S404, it is determined that the direct current bus voltage Udlb is abnormal in measurement according to the fact that the difference between the maximum value and the minimum value of the obtained N direct current bus voltages Udlb is greater than a preset difference value.

Based on the above-mentioned overvoltage control method for the isolated island converter station provided by the embodiment of the present invention, under the operating state of the converter station, the dc bus voltage Udlb of the converter station respectively measured by N voltage measuring devices is obtained, and it is determined whether the difference between the maximum value and the minimum value of the N dc bus voltages Udlb is less than or equal to the preset difference value, if so, it is determined that the dc bus voltage Udlb is measured normally, if not, it is determined that the dc bus voltage Udlb is measured abnormally, and the determination and measurement process is simplified, thereby improving the overvoltage operating quality of the isolated island converter station and ensuring the operation of the flexible dc power grid.

With reference to fig. 1, the island converter station overvoltage control method provided based on the above embodiment of the present invention involves performing a second dc outlet voltage Udc2 detection to obtain a second detection result when performing step S104. As shown in fig. 5, a schematic flow chart for obtaining a second detection result according to an embodiment of the present invention mainly includes the following steps:

step S501: it is detected whether the second dc outlet voltage Udc2 is greater than or equal to the first voltage threshold, if so, step S502 is executed, and if not, step S503 is executed.

In step S501, the second dc outlet voltage Udc2 is Udlb-Udn, Udn being the converter valve neutral outlet voltage of the converter station.

In the process of implementing step S501 specifically, it is detected whether the second dc outlet voltage Udc2 is greater than or equal to the first voltage threshold according to the dc bus voltage Udlb of the converter station measured by the N voltage measuring devices, if so, step S502 is executed, and if not, step S503 is executed.

Taking a 500kV flexible converter station as an example, the dc bus voltage Udlb of the converter station is 548kV, the neutral line outlet voltage Udn of the converter valve of the converter station is 15kV, the second dc outlet voltage Udc 2-Udlb-Udn-548 kV-15 kV-533 kV, the first voltage threshold is 527kV, and 540kV and 527kV are compared to obtain that 540kV >527kV, then step S502 is executed.

Another example is: the direct current bus voltage Udlb of the converter station is 517kV, the neutral line outlet voltage Udn of the converter valve of the converter station is 15kV, the second direct current outlet voltage Udc2 ═ Udlb-Udn ═ 517kV-15kV ═ 502kV, the first voltage threshold value is 527kV, 502kV and 527kV are compared, and 502kV <527kV is obtained, then step S503 is executed.

Step S502: a second detection result indicating that the current overvoltage state is obtained.

In the process of implementing step S502 specifically, on the premise that it is determined that the second dc outlet voltage Udc2 is greater than or equal to the first voltage threshold, a second detection result indicating that the current overvoltage state is obtained.

Step S503: and obtaining a second detection result indicating that the voltage measurement of the outlet of the converter valve is abnormal.

In the process of specifically implementing step S503, on the premise that it is determined that the second dc outlet voltage Udc2 is smaller than the first voltage threshold, a second detection result indicating that the measurement of the converter valve outlet voltage is abnormal is obtained.

Based on the island converter station overvoltage control method provided by the embodiment of the invention, the detection process is simplified by detecting whether the second direct current outlet voltage Udc2 is greater than or equal to the first voltage threshold value, if so, obtaining a second detection result indicating that the current overvoltage state is present, and if not, obtaining a second detection result indicating that the measurement of the converter valve outlet voltage is abnormal, so that the overvoltage operation quality of the island converter station is improved and the operation of the flexible direct current power grid is ensured.

Based on the above overvoltage control method for the island converter station provided by the embodiment of the present invention, when step S106 is executed, a corresponding overvoltage protection operation is executed. As shown in fig. 6, a schematic flow chart for executing a corresponding overvoltage protection operation according to an embodiment of the present invention mainly includes the following steps:

step S601: and issuing a power speed-down instruction to the safety and stability control device, and starting timing to enable the safety and stability control device to control the converter station to reduce the power based on the power speed-down instruction.

In step S601, the power fast-down refers to reducing the power, and the speed of the power reduction may be 0.1p.u, where 0.1p.u refers to 10% of the rated power, and p.u refers to a per unit value with the rated power as a reference per unit value.

In the process of specifically implementing the step S601, a measurement result of the converter valve outlet voltage Udp of the converter station is normal, and a first detection result obtained by detecting the first dc outlet voltage Udc1 or a second detection result obtained by detecting the second dc outlet voltage Udc2 indicates that the converter station is currently in an overvoltage state, issues a power speed reduction command to the safety and stability control device, and starts timing, so that the safety and stability control device controls the converter station to reduce power based on the power speed reduction command.

Step S602: during the cumulative time T, it is detected in real time whether the first dc outlet voltage Udc1 or the second dc outlet voltage Udc2 has decreased to a value below the second voltage threshold, if so, step S603 is executed, and if not, step S604 is executed.

In step S602, the second voltage threshold is also determined by the specific model of the flexible converter station, or may be set by a technician based on the specific model of the flexible converter station, and the second voltage thresholds corresponding to different models of flexible converter stations are different.

For example, for a 500kV flexible converter station, the second voltage threshold may be 525 kV.

In the process of implementing step S602 specifically, in the accumulated time T, if the first dc outlet voltage Udc1 or the second dc outlet voltage Udc2 is detected in real time to be decreased to be lower than the second voltage threshold, step S603 is executed, and if the first dc outlet voltage Udc1 or the second dc outlet voltage Udc2 is detected in real time to be not decreased to be lower than the second voltage threshold, step S604 is executed.

Step S603: and issuing a power rapid reduction stopping instruction to the safety and stability control device, and clearing the accumulated time to ensure that the converter station maintains the current power operation.

Step S604: and controlling the AC circuit breaker and the DC circuit breaker in the converter station to trip off, so that the AC energy consumption device in the converter station is accessed.

In step S604, the converter needs to be locked, because the converter station voltage is higher than the second voltage threshold, the converter station voltage cannot be reduced by cutting off power, and major tripping accidents such as equipment damage may be caused by long-time overvoltage operation, so that when the dc outlet voltage Udc cannot be reduced by cutting off, the converter is locked, thereby protecting the power grid equipment from overvoltage breakdown damage.

In the process of specifically realizing the steps S603 to S604, when the first dc outlet voltage Udc1 is Udp-Udn and the second dc outlet voltage Udc2 is Udlp-Udn are both increased, the surplus power of the converter station is absorbed by the ac energy consumption device through the accumulated time T, and the dc outlet voltage is reduced. If the first direct-current outlet voltage Udc1 ═ Udp-Udn and the second direct-current outlet voltage Udc2 ═ Udlp-Udn are reduced to be below a second voltage threshold value within the accumulated time T, issuing a power quick reduction stopping instruction to a safety and stability control device, and clearing the accumulated time to zero so that the converter station maintains the current power operation; and if the first direct-current outlet voltage Udc1 ═ Udp-Udn and the second direct-current outlet voltage Udc2 ═ Udlp-Udn do not decrease below the second voltage threshold value within the accumulated time T, carrying out the operation of the converter station shutdown or the fan cut-off operation according to the principle that the total power of the sending end does not exceed the total power of the receiving end, and then the receiving end converter station stops operating or the converter station is connected with all lines to stop operating.

Based on the island converter station overvoltage control method provided by the embodiment of the invention, the safety and stability control device controls the converter station to reduce power based on the power speed reduction instruction by issuing the power speed reduction instruction to the safety and stability control device and starting timing; detecting in real time whether the first dc outlet voltage Udc1 or the second dc outlet voltage Udc2 drops below a second voltage threshold during the accumulated time T; if so, issuing a power rapid reduction stopping instruction to the safety and stability control device, and resetting the accumulated time to ensure that the converter station maintains the current power operation; if not, controlling the AC circuit breaker and the DC circuit breaker in the convertor station to trip off, enabling an AC energy consumption device in the convertor station to access, effectively controlling overvoltage, and protecting power grid equipment from being damaged by overvoltage breakdown, thereby improving the overvoltage operation quality of the isolated island convertor station and ensuring the operation of the flexible DC power grid.

As shown in fig. 7, a schematic structural diagram of a primary wiring of a direct current field of a true bipolar structure isolated island converter station in an application scenario is provided, where the structure mainly includes: the system comprises an alternating current energy consumption device, an alternating current bus, a new energy grid-connected alternating current circuit, a positive and negative converter transformer, a positive and negative converter valve outlet voltage Udp, a positive and negative direct current bus voltage Udlb, a positive and negative converter valve neutral line outlet voltage Udn, a positive and negative direct current outlet line and neutral line, a direct current breaker and the like, wherein the direct current breaker is used for fault isolation of a direct current power grid.

Based on the wiring mode shown in fig. 7 and the converter station overvoltage control method shown in fig. 1, related devices are correspondingly connected together, when the voltage measuring device is used for measuring the direct current outlet voltage Udp of the converter station or the direct current bus voltage Udlb of the converter station, corresponding operations can be performed by the converter station overvoltage control method disclosed above, the direct current outlet voltage of the converter station is prefabricated, and the problem that the direct current grid is shut down due to the fact that the direct current outlet voltage rises due to the fault of the converter station voltage measuring device is avoided.

As shown in fig. 8, a schematic structural diagram of a four-terminal north flexible direct current transmission project in an application scenario is shown, where the structure mainly includes: the system comprises a converter station 1, a converter station 2, a converter station 3, a converter station 4, a direct current circuit breaker, a positive circuit, a negative circuit, a neutral circuit and the like, wherein the direct current circuit breaker is used for fault isolation of a direct current power grid.

In fig. 8, a positive electrode 1 is a positive electrode, and a negative electrode 2 is a negative electrode.

In the embodiment of the invention, the converter station is used as a sending end converter station in the flexible direct current transmission system, because the alternating current system is in an 'island' operation mode without networking, the stability of the alternating current system is weak when the alternating current system is operated in the 'island' operation mode, and the voltage of the alternating current system and the direct current voltage are increased due to the fault of the receiving end converter station or a direct current line of the flexible power grid, so that the overvoltage damage of equipment of the converter station is caused.

The flexible direct current transmission system comprises N converter stations which are connected, wherein N is a natural number and is more than or equal to 3.

That is, the converter station should be connected to multiple stations, and include N outgoing dc lines, where N is a natural number and is greater than or equal to 2.

In a four-terminal flexible direct current transmission system ring network, converter stations are a Yanqing station, a Zhongdu station, a Combaroner station and a Fukang station respectively, wherein the Zhongdu station and the Combaroner station are island converter stations, the Yanqing station and the Fukang station are receiving-end converter stations, and the Fengning station is an adjusting converter station.

Based on the four-terminal north flexible direct current transmission project shown in fig. 8 and the converter station overvoltage control method shown in fig. 1, related devices are correspondingly connected together, when the voltage measuring device is used for measuring the direct current outlet voltage Udp of the converter station or the direct current bus voltage Udlb of the converter station, corresponding operation can be performed through the converter station overvoltage control method disclosed above, the direct current outlet voltage of the converter station is prefabricated, and the problem that the direct current power grid stops due to the fact that the direct current outlet voltage rises due to the fault of the converter station voltage measuring device is solved.

Corresponding to the overvoltage control method of the converter station shown in fig. 1 in the embodiment of the present invention, an embodiment of the present invention further provides a pole control system, as shown in fig. 9, where the pole control system includes: a measurement module 91 and a control module 92.

The measuring module 91 is used for judging whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measuring devices is abnormal or not under the running state of the converter station, wherein N is a natural number, and the voltage is greater than or equal to 3, if the measurement result is normal, detecting a first direct current outlet voltage Udc1 to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, Udn is the converter valve neutral line outlet voltage of the converter station, if the measurement result is abnormal, whether a direct current bus voltage Udlb of the converter station is abnormal is measured based on N voltage measuring devices, if the direct current bus voltage Udlb is abnormal, detecting a first direct current outlet voltage Udc1 to obtain a first detection result, if the direct current bus voltage Udlb is normal, detecting a second direct current outlet voltage Udc2 to obtain a second detection result, wherein the second direct current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station.

Optionally, the measurement module 91 is specifically configured to:

obtaining converter valve outlet voltages Udp of the converter station respectively measured by the N voltage measuring devices, judging whether the maximum value of the N converter valve outlet voltages Udp is larger than an upper limit voltage value, and whether the minimum value is smaller than a lower limit voltage value, if so, determining that the measuring result is normal, and if not, determining that the measuring result is abnormal.

Optionally, the measurement module 91 is further specifically configured to:

the method comprises the steps of obtaining direct current bus voltage Udlb of a converter station respectively measured by N voltage measuring devices, judging whether the difference between the maximum value and the minimum value in the N direct current bus voltage Udlb is smaller than or equal to a preset difference value, if yes, determining that the direct current bus voltage Udlb is measured normally, and if not, determining that the direct current bus voltage Udlb is measured abnormally.

Optionally, the measurement module 91 is further specifically configured to:

and detecting whether the first direct current outlet voltage Udc1 is greater than or equal to a first voltage threshold value, if not, returning to continuously judging whether the converter valve outlet voltage Udp of the converter station measured by the N voltage measuring devices is abnormal, and if so, obtaining a first detection result indicating that the converter valve is in an overvoltage state at present.

Optionally, the measurement module 91 is further specifically configured to:

and detecting whether the second direct current outlet voltage Udc2 is greater than or equal to the first voltage threshold, if so, obtaining a second detection result indicating that the current overvoltage state is achieved, and if not, obtaining a second detection result indicating that the measurement of the outlet voltage of the converter valve is abnormal.

And the control module 92 is configured to execute a corresponding overvoltage protection operation when the first detection result or the second detection result indicates that the current overvoltage state is reached.

Based on the pole control system provided by the embodiment of the invention, whether the converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not is judged under the running state of the converter station, wherein N is a natural number and is more than or equal to 3; if the measurement result is normal, detecting a first direct current outlet voltage Udc1 to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; if the measurement result is abnormal, measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on the N voltage measuring devices; if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result; if the direct-current bus voltage Udlb is normal, executing detection of a second direct-current outlet voltage Udc2 to obtain a second detection result, wherein the second direct-current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; and when the first detection result or the second detection result indicates that the current device is in the overvoltage state, executing corresponding overvoltage protection operation. In the scheme, based on N voltage measuring devices, when the converter valve outlet voltage Udp is detected to be abnormal, the direct current bus voltage Udlb of the converter station is selected to participate in measurement, and overvoltage misjudgment caused by abnormal measurement of the voltage measuring devices is avoided, so that the overvoltage operation quality of the island converter station is improved, and the operation of the flexible direct current power grid is guaranteed.

Referring to fig. 9, as shown in fig. 10, another pole control system according to the embodiment of the present invention is provided, wherein the control module 92 includes a sending unit 921 and a control unit 922.

And the issuing unit 921 is configured to issue a power fast-down instruction to the safety and stability control device, and start timing, so that the safety and stability control device controls the converter station to reduce power based on the power fast-down instruction.

And the control unit 922 is used for detecting whether the first direct current outlet voltage Udc1 or the second direct current outlet voltage Udc2 is reduced below a second voltage threshold value in real time within the accumulated time T, if so, issuing a power quick reduction stopping instruction to the safety and stability control device, clearing the accumulated time to zero to enable the converter station to maintain the current power operation, and if not, controlling an alternating current breaker and a direct current breaker in the converter station to trip off to enable an alternating current energy consumption device in the converter station to be connected.

Based on the pole control system provided by the embodiment of the invention, based on N voltage measuring devices, when the voltage Udp at the outlet of the converter valve is detected to be abnormal, the direct-current bus voltage Udlb of the converter station is selected to participate in measurement, so that the overvoltage misjudgment caused by the abnormal measurement of the voltage measuring devices is avoided, the overvoltage operation quality of the island converter station is improved, and the operation of a flexible direct-current power grid is guaranteed.

Corresponding to the above island converter station overvoltage control method shown in fig. 1 and the pole control system shown in fig. 9 in the embodiment of the present invention, an embodiment of the present invention further provides a converter station overvoltage control system, as shown in fig. 11, where the system includes: the device comprises a pole control system 111, N voltage measuring devices 112 and a safety and stability control device 113, wherein N is a natural number and is more than or equal to 3.

The pole control system 111 is used for judging whether a converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not under the operation state of the converter station, N is a natural number and is more than or equal to 3, if the measuring result is normal, executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, the first direct current outlet voltage Udc1 is Udp-Udn, Udn is a converter valve neutral line outlet voltage of the converter station, if the measuring result is abnormal, executing a first direct current outlet voltage Udc1 detection to obtain a first detection result, if the direct current bus voltage Udlb is normal, executing a second direct current outlet voltage Udc2 detection to obtain a second detection result, the second direct current outlet voltage Udc2 is Udlb-Udn, and Udn is a converter valve neutral line outlet voltage of the converter station, and when the first detection result or the second detection result indicates that the current device is in the overvoltage state, executing corresponding overvoltage protection operation.

The N voltage measuring devices 112 are configured to measure whether a converter valve outlet voltage Udp of the converter station is abnormal, execute a first dc outlet voltage Udc1 test to obtain a first test result if the measurement result is normal, where the first dc outlet voltage Udc1 is Udp-Udn, and Udn is a converter valve neutral line outlet voltage of the converter station, measure whether a dc bus voltage Udlb of the converter station is abnormal based on the N voltage measuring devices if the measurement result is abnormal, execute a first dc outlet voltage Udc1 test to obtain a first test result if the dc bus voltage Udlb is abnormal, execute a second dc outlet voltage Udc2 test to obtain a second test result if the dc bus voltage Udlb is normal, where the second dc outlet voltage Udc2 is Udlb-Udn and Udn is a converter valve neutral line outlet voltage of the converter station.

And the safety and stability control device 113 is used for controlling the converter station to reduce power based on the power speed reduction command.

Based on the converter station overvoltage control system provided by the embodiment of the invention, whether the converter valve outlet voltage Udp of the converter station measured by N voltage measuring devices is abnormal or not is judged under the operation state of the converter station, wherein N is a natural number and is more than or equal to 3; if the measurement result is normal, detecting a first direct current outlet voltage Udc1 to obtain a first detection result, wherein the first direct current outlet voltage Udc1 is Udp-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; if the measurement result is abnormal, measuring whether the direct current bus voltage Udlb of the converter station is abnormal or not based on the N voltage measuring devices; if the direct current bus voltage Udlb is abnormal, executing detection of a first direct current outlet voltage Udc1 to obtain a first detection result; if the direct-current bus voltage Udlb is normal, executing detection of a second direct-current outlet voltage Udc2 to obtain a second detection result, wherein the second direct-current outlet voltage Udc2 is Udlb-Udn, and Udn is the converter valve neutral line outlet voltage of the converter station; and when the first detection result or the second detection result indicates that the current device is in the overvoltage state, executing corresponding overvoltage protection operation. In the scheme, based on N voltage measuring devices, when the converter valve outlet voltage Udp is detected to be abnormal, the direct current bus voltage Udlb of the converter station is selected to participate in measurement, and overvoltage misjudgment caused by abnormal measurement of the voltage measuring devices is avoided, so that the overvoltage operation quality of the island converter station is improved, and the operation of the flexible direct current power grid is guaranteed.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A converter station overvoltage control method, adapted for a pole control system PCP, the method comprising:

2. The method of claim 1, further comprising:

3. The method according to claim 1, wherein said determining whether a converter valve outlet voltage Udp of said converter station measured on the basis of N voltage measuring devices is abnormal comprises:

if so, determining that the measurement result is normal;

if not, determining that the measurement result is abnormal.

4. The method according to claim 1, wherein said detecting whether the dc bus voltage Udlb of the converter station is abnormal based on N voltage measuring devices comprises:

5. The method of claim 1, wherein said performing a first dc outlet voltage Udc1 test resulting in a first test result comprises:

6. The method according to claim 1, wherein the performing a second dc outlet voltage Udc2 test resulting in a second test result comprises:

7. The method of any of claims 1 to 5, wherein the overvoltage protection operation comprises:

8. A pole control system, comprising:

9. The pole control system of claim 8 wherein the control module comprises:

10. A converter station overvoltage control system, characterized in that the system comprises: the pole control system, the N voltage measuring devices, and the safety and stability control device of any one of claims 8 to 9, N being a natural number and 3 or more;