阅读说明：本技术 一种过压保护方法、装置和模块化多电平换流阀 (Overvoltage protection method and device and modular multi-level converter valve ) 是由 安海清 李振动 刘亚新 贺俊杰 张恩伟 王珣 田凯哲 李金卜 张晓飞 金海望 岳 于 2019-09-27 设计创作，主要内容包括：本申请公开了一种过压保护方法、装置和模块化多电平换流阀,具体为获取每个子模块的电容电压,并根据所有电容电压计算每一桥臂上所有子模块的平均电容电压；若换流阀处于解锁状态,根据电容电压是否超过第一预设保护定值判断是否有子模块出现过压；如果出现过压的子模块的个数与已旁路子模块个数之和大于冗余模块数量,则闭锁换流阀并跳闸；如果它们之和小于或等于冗余模块数量,则闭锁并旁路掉出现过压的子模块。若换流阀处于闭锁状态；如果任一桥臂子模块平均电容电压大于预设定值,旁路掉电容电压大于第二预设保护定值的子模块；如果任一桥臂子模块平均电容电压小于预设定值,旁路掉电容电压大于第三预设保护定值的子模块。通过上述操作,实现了对子模块的过压保护。(The application discloses an overvoltage protection method, an overvoltage protection device and a modular multilevel converter valve, and particularly aims to obtain the capacitance voltage of each submodule and calculate the average capacitance voltage of all submodules on each bridge arm according to all the capacitance voltages; if the converter valve is in an unlocking state, judging whether the sub-module has overvoltage according to whether the capacitor voltage exceeds a first preset protection fixed value; if the sum of the number of the sub-modules with overvoltage and the number of the bypassed sub-modules is larger than the number of the redundant modules, locking the converter valve and tripping; if the sum of the two is less than or equal to the number of redundant modules, the submodule in which an overvoltage occurs is locked out and bypassed. If the converter valve is in a locked state; if the average capacitance voltage of any bridge arm submodule is larger than a preset value, bypassing the submodule with the capacitance voltage larger than a second preset protection fixed value; and if the average capacitance voltage of any bridge arm submodule is smaller than a preset value, bypassing the submodule with the capacitance voltage larger than a third preset protection fixed value. Through the operation, the overvoltage protection of the sub-module is realized.)

1. An overvoltage protection method is applied to a modular multi-level converter valve, the converter valve comprises 6 bridge arms, each bridge arm comprises a plurality of sub-modules, and the overvoltage protection method is characterized by comprising the following steps:

acquiring the capacitance voltage of each submodule, and calculating the average capacitance voltage of all the submodules on each bridge arm according to all the capacitance voltages;

judging whether the converter valve is wholly in a locking state or not;

if the converter valve is in an unlocking state, judging whether overvoltage occurs to the submodule according to whether the capacitor voltage exceeds a first preset protection fixed value, wherein the first preset protection fixed value is between the rated voltage and the maximum tolerance voltage of the submodule;

when one or more sub-modules are judged to be over-pressurized, judging whether the total number of the sub-modules with over-pressurization and the sub-modules which are bypassed before is larger than the number of redundant modules;

if the total number is larger than the number of the redundant modules, locking the converter valve and tripping;

bypassing said sub-modules that are experiencing overvoltage if said total number is less than or equal to said number of redundant modules;

if the converter valve is in the locking state, judging whether the average capacitance voltage of any bridge arm is larger than a preset value, wherein the preset value is between the rated voltage and the maximum withstand voltage;

bypassing the sub-module having the capacitor voltage greater than a second preset protection fixed value if the average capacitor voltage is greater than the preset value, the second preset protection fixed value being between the rated voltage and the maximum withstand voltage;

and if the average capacitor voltage is smaller than the preset value, bypassing the sub-module with the capacitor voltage larger than a third preset protection fixed value, wherein the third preset protection fixed value is between the rated voltage and the maximum withstand voltage.

2. The method of claim 1, wherein the first predetermined protection setting is greater than the predetermined setting, the second predetermined protection setting is greater than the first predetermined protection setting, and the third predetermined protection setting is greater than the second predetermined protection setting.

3. The overvoltage protection method of claim 1, wherein all of the sub-modules do not include sub-modules that have been previously bypassed.

4. An overvoltage protection device applied to a modular multi-level converter valve, wherein the converter valve comprises 6 bridge arms, each bridge arm comprises a plurality of sub-modules, the overvoltage protection device is characterized by comprising:

the voltage acquisition module is used for acquiring the capacitance voltage of each submodule and calculating the average capacitance voltage of all the submodules on each bridge arm according to all the capacitance voltages;

the first judgment module is used for judging whether the converter valve is wholly in a locking state;

the second judgment module is used for judging whether the sub-module has overvoltage according to whether the capacitor voltage exceeds a first preset protection fixed value or not if the converter valve is in an unlocking state, wherein the first preset protection fixed value is between the rated voltage and the maximum tolerance voltage of the sub-module;

a third judging module, configured to, when the second judging module judges that one or more of the sub-modules has an overvoltage, judge whether a total number of the sub-modules having the overvoltage and the sub-modules bypassed before is greater than a number of redundant modules;

a first execution module for latching and tripping the converter valves if the total number is greater than the number of redundant modules;

a second execution module for bypassing the sub-modules experiencing overvoltage if the total number is less than or equal to the number of redundant modules;

a fourth determining module, configured to determine whether the average capacitor voltage is greater than a preset value if the converter valve is in the locked state, where the preset value is between the rated voltage and the maximum withstand voltage;

a third execution module, configured to bypass the sub-module with the capacitor voltage greater than a second preset protection fixed value if the average capacitor voltage is greater than the preset value, where the second preset protection fixed value is between the rated voltage and the maximum withstand voltage;

and the fourth execution module is used for bypassing the sub-module with the capacitor voltage larger than a third preset protection fixed value if the average capacitor voltage is smaller than the preset value, wherein the third preset protection fixed value is between the rated voltage and the maximum withstand voltage.

5. The overvoltage protection device according to claim 4, wherein the first predetermined protection setting is greater than the predetermined setting, the second predetermined protection setting is greater than the first predetermined protection setting, and the third predetermined protection setting is greater than the second predetermined protection setting.

6. The overvoltage protection device of claim 4, wherein all of the sub-modules do not include sub-modules that have been previously bypassed.

7. A modular multilevel converter valve, characterized in that an overvoltage protection device according to any of claims 4-6 is provided.

Technical Field

The application relates to the technical field of power grids, in particular to an overvoltage protection method, an overvoltage protection device and a modular multi-level converter valve.

Background

The flexible direct-current transmission technology based on the modular multilevel converter valve can independently and quickly control the active power and the reactive power of a system, improves the stability of the system, and is widely applied to the field of new energy grid connection such as large-scale wind power generation. The converter valve is the most core equipment of flexible direct current transmission engineering, and is formed by connecting submodules consisting of a large number of power electronic devices in series and in parallel, and for some submodules of large-capacity converter valves, the single price is more than 20 ten thousand yuan RMB.

The sub-modules of the converter valve are easy to generate overvoltage under some abnormal working conditions, once the expensive sub-modules are damaged due to overvoltage, economic losses are heavy, the operation condition of the whole converter valve can be influenced, and even the stable operation of the whole flexible direct current converter station is influenced, so that the sub-modules are necessary to be subjected to overvoltage protection.

Disclosure of Invention

In view of this, the present application provides an overvoltage protection method, an overvoltage protection device and a modular multi-level converter valve, which are used for performing overvoltage protection on a sub-module of the modular multi-level converter valve to prevent the sub-module from overvoltage damage.

In order to achieve the above object, the following solutions are proposed:

an overvoltage protection method is applied to a modular multi-level converter valve, the converter valve comprises 6 bridge arms, each bridge arm comprises a plurality of sub-modules, and the overvoltage protection method comprises the following steps:

acquiring the capacitance voltage of each submodule, and calculating the average capacitance voltage of all the submodules on each bridge arm according to all the capacitance voltages;

judging whether the converter valve is wholly in a locking state or not;

if the converter valve is in an unlocking state, judging whether overvoltage occurs to the submodule according to whether the capacitor voltage exceeds a first preset protection fixed value, wherein the first preset protection fixed value is between the rated voltage and the maximum tolerance voltage of the submodule;

when one or more sub-modules are judged to be over-pressurized, judging whether the total number of the sub-modules with over-pressurization and the sub-modules which are bypassed before is larger than the number of redundant modules;

if the total number is larger than the number of the redundant modules, locking the converter valve and tripping;

bypassing said sub-modules that are experiencing overvoltage if said total number is less than or equal to said number of redundant modules.

If the converter valve is in the locking state, judging whether the average capacitor voltage is larger than a preset value, wherein the preset value is between the rated voltage and the maximum withstand voltage;

bypassing the sub-module having the capacitor voltage greater than a second preset protection fixed value if the average capacitor voltage is greater than the preset value, the second preset protection fixed value being between the rated voltage and the maximum withstand voltage;

and if the average capacitor voltage is smaller than the preset value, bypassing the sub-module with the capacitor voltage larger than a third preset protection fixed value, wherein the third preset protection fixed value is between the rated voltage and the maximum withstand voltage.

Optionally, the first preset protection fixed value is greater than the preset value, the second preset protection fixed value is greater than the first preset protection fixed value, and the third preset protection fixed value is greater than the second preset protection fixed value.

Optionally, all of the sub-modules do not include sub-modules that have been previously bypassed.

An overvoltage protection device applied to a modular multi-level converter valve, wherein the converter valve comprises 6 bridge arms, each bridge arm comprises a plurality of sub-modules, and the overvoltage protection device comprises:

the voltage acquisition module is used for acquiring the capacitance voltage of each submodule and calculating the average capacitance voltage of all the submodules on each bridge arm according to all the capacitance voltages;

the first judgment module is used for judging whether the converter valve is wholly in a locking state;

the second judgment module is used for judging whether the sub-module has overvoltage according to whether the capacitor voltage exceeds a first preset protection fixed value or not if the converter valve is in an unlocking state, wherein the first preset protection fixed value is between the rated voltage and the maximum tolerance voltage of the sub-module;

a third judging module, configured to, when the second judging module judges that one or more of the sub-modules has an overvoltage, judge whether a total number of the sub-modules having the overvoltage and the sub-modules bypassed before is greater than a number of redundant modules;

a first execution module for latching and tripping the converter valves if the total number is greater than the number of redundant modules;

a second execution module for bypassing the sub-modules experiencing overvoltage if the total number is less than or equal to the number of redundant modules.

A fourth determining module, configured to determine whether the average capacitor voltage is greater than a preset value if the converter valve is in the locked state, where the preset value is between the rated voltage and the maximum withstand voltage;

a third execution module, configured to bypass the sub-module with the capacitor voltage greater than a second preset protection fixed value if the average capacitor voltage is greater than the preset value, where the second preset protection fixed value is between the rated voltage and the maximum withstand voltage;

and the fourth execution module is used for bypassing the sub-module with the capacitor voltage larger than a third preset protection fixed value if the average capacitor voltage is smaller than the preset value, wherein the third preset protection fixed value is between the rated voltage and the maximum withstand voltage.

Optionally, the first preset protection fixed value is greater than the preset value, the second preset protection fixed value is greater than the first preset protection fixed value, and the third preset protection fixed value is greater than the second preset protection fixed value.

Optionally, all of the sub-modules do not include sub-modules that have been previously bypassed.

A modular multilevel converter valve provided with an overvoltage protection device as described above.

According to the technical scheme, the overvoltage protection method, the overvoltage protection device and the modular multilevel converter valve are disclosed, and specifically, the method comprises the steps of obtaining the capacitance voltage of each submodule and calculating the average capacitance voltage of all the submodules on each bridge arm according to all the capacitance voltages; judging whether the converter valve is wholly in a locking state; if the converter valve is in an unlocking state, judging whether overvoltage occurs to a submodule according to whether the capacitor voltage exceeds a first preset protection fixed value, wherein the first preset protection fixed value is between the rated voltage and the maximum withstand voltage of the submodule; when judging that one or more sub-modules are over-pressurized, judging whether the total number of the sub-modules with over-pressure and the sub-modules which are bypassed before is larger than the number of redundant modules; if the total number is larger than the number of the redundant modules, the converter valve is locked and tripped; if the total number is less than or equal to the number of redundant modules, the sub-modules that appear over-pressurized are bypassed. If the converter valve is in a locked state, judging whether the average capacitance voltage of any bridge arm is larger than a preset value, wherein the preset value is between a rated voltage and a maximum withstand voltage; if the average capacitor voltage is larger than a preset value, bypassing the sub-module of which the capacitor voltage is larger than a second preset protection fixed value, wherein the second preset protection fixed value is between the rated voltage and the maximum withstand voltage; and if the average capacitor voltage is smaller than the preset value, bypassing the sub-module with the capacitor voltage larger than a third preset protection fixed value, wherein the third preset protection fixed value is between the rated voltage and the maximum withstand voltage. Through the operation, the overvoltage protection of the submodule is realized, namely the submodule which is about to generate overvoltage is bypassed, so that the submodule can be prevented from being damaged due to overvoltage.

Drawings

In order to more clearly illustrate the embodiments of the present application 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 some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flow chart of a method of overvoltage protection according to an embodiment of the present application;

FIG. 2 is a circuit diagram of a modular multilevel converter valve of the present application;

FIG. 3 is a circuit diagram of a sub-module of the modular multilevel converter valve of the present application;

fig. 4 is a block diagram of an overvoltage protection device according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.