CN110137996B - Method and system for evaluating reliability of flexible direct-current transmission MMC converter valve - Google Patents

Method and system for evaluating reliability of flexible direct-current transmission MMC converter valve Download PDF

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Publication number
CN110137996B
CN110137996B CN201810107497.5A CN201810107497A CN110137996B CN 110137996 B CN110137996 B CN 110137996B CN 201810107497 A CN201810107497 A CN 201810107497A CN 110137996 B CN110137996 B CN 110137996B
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reliability
converter valve
mmc converter
faults
valve
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CN110137996A (en
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潘艳
李金元
李尧圣
陈中圆
王鹏
孙帅
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Global Energy Interconnection Research Institute
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The invention relates to a method and a system for evaluating the reliability of a flexible direct-current power transmission MMC converter valve, wherein the method comprises the following steps: establishing an MMC converter valve fault tree based on a topological structure of the flexible direct-current power transmission MMC converter valve; determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve; and determining the reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve. According to the method, the reliability evaluation index expression of the MMC converter valve is obtained by establishing the fault tree of the MMC converter valve and qualitatively analyzing the fault tree, so that the reliability relation of each part is more clearly and definitely displayed, and the weak link of the converter valve can be further researched.

Description

Method and system for evaluating reliability of flexible direct-current transmission MMC converter valve
Technical Field
The invention relates to the field of converter valves for high-voltage direct-current power transmission, in particular to a method and a system for evaluating the reliability of a flexible direct-current power transmission MMC converter valve.
Background
With the improvement of the voltage grade and the transmission capability of the high-voltage direct-current transmission system, higher requirements are put forward on the reliability of power electronic equipment such as a converter. Due to the advantages of low switching frequency and low loss, modular multi-level converters (MMC) are widely applied to actual flexible direct-current transmission engineering. The MMC converter valve used as the core equipment of the flexible direct-current transmission system has multiple component types and a complex structure, and the reliability of the MMC converter valve is difficult to accurately evaluate.
In addition, in practical application, various factors such as different topological structures and the reliability level of elements also have different degrees of influence on the reliability of the converter valve, and finally the service life of the converter is shortened. Therefore, the reliability of the MMC converter valve is evaluated, and the method has important practical significance for operation maintenance of the converter valve equipment and improvement of the reliability of the whole flexible direct-current transmission system.
The reliability of the MMC converter valve is closely related to the reliability of a topological structure and elements of the MMC converter valve, the existing research aiming at the topology of the MMC converter valve and the reliability of a power electronic device is mainly focused on the reliability of the power electronic device for the MMC converter valve, and important components of converter valve components such as a power supply, a control protection system, a valve cooling system and the like are often ignored, so that the reliability evaluation result has serious deviation.
Therefore, it is desirable to provide an evaluation method and system for reliability of an MMC converter valve to meet the needs of the prior art.
Disclosure of Invention
Aiming at the technical problems, the invention provides a method and a system for evaluating the reliability of a flexible direct-current power transmission MMC converter valve.
A method for evaluating the reliability of a flexible direct-current transmission MMC converter valve comprises the following steps: establishing an MMC converter valve fault tree based on a topological structure of the flexible direct-current power transmission MMC converter valve; determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve; and determining the reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve.
Topological structure of flexible direct current transmission MMC converter valve includes: the system comprises n half-bridge structure sub-modules, a current converter control protection system and a valve cooling system; the converter control protection system includes: polar control and station control; the valve cooling system includes: an inner cooling system, an outer cooling system and a monitoring system; the half-bridge structure sub-module includes: the IGBT driving circuit comprises at least two IGBT units, a capacitor connected with the at least two IGBT units in parallel, a control system connected with emitting electrodes of the IGBT units respectively and a power supply.
Establishing an MMC converter valve fault tree, comprising: setting the fault state of the MMC converter valve as a top event T; deriving intermediate events M based on the top event T i (ii) a Based on the intermediate event M i Deriving at least 5n +5 bottom events; intermediate event M i The method comprises the following steps: half-bridge structure submodule fault, converter station control protection system fault and valve cooling systemA failure; the bottom event comprises the following steps: at least two IGBT unit faults, capacitance faults, submodule control system faults and power supply faults in the n half-bridge structure submodules, pole control faults and station control faults in the converter station control protection system faults, internal cooling system faults, external cooling system faults and monitoring system faults in the valve cooling system faults.
Based on MMC converter valve fault tree, confirm the minimum cut set of MMC converter valve fault tree, include:
minimum cut set B for determining fault tree of MMC converter valve by utilizing downlink method i
Wherein, { X i 、X j …X m The set of bottom events of the half-bridge sub-modules, { X } is l The method comprises the steps that a bottom event set of a converter station control protection system and a valve cooling system is set;
the minimum cut set total number of the fault tree of the MMC converter valve is
The reliability evaluation indexes of the MMC converter valve comprise: reliability R (t), fault probability P (T) and working life t of MMC converter valve MTBF And failure rate λ T
The reliability of the MMC converter valve is as follows:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t);
wherein R is SM (t) represents the reliability of n half-bridge sub-modules, R 5 (t) represents the reliability of the polar control, R 6 (t) reliability of station control, R 7 (t) reliability of the internal cooling system, R 8 (t) reliability of external cooling system, R 9 (t) represents the reliability of the monitoring system.
n half-bridge sub-modules R SM The calculation formula of the reliability of (t) is as follows:
wherein R is SMi The reliability of a single submodule is represented, j is the number of submodule faults, k-1 is the redundancy number of the submodule, and j is less than or equal to k-1.
Single submodule R SMi The calculation formula of the reliability is as follows:
wherein R is 1 (t) reliability of IGBT cell, R 2 (t) reliability of capacitance, R 3 (t) reliability of the submodule control system, R 4 (t) represents the reliability of the power supply.
R 1 (t)~R 9 (t) the calculation formula of the reliability is as follows:
wherein λ is i To the failure rate, t is the failure time.
The calculation formula of the failure probability p (t) is as follows:
P(T)=1-R(t)。
working life t MTBF The calculation formula of (a) is as follows:
failure rate λ T The calculation formula of (a) is as follows:
a system for evaluating reliability of a flexible direct current transmission MMC converter valve comprises: the fault tree building module of the MMC converter valve is used for building the fault tree of the MMC converter valve based on the topological structure of the flexible direct-current power transmission MMC converter valve; the minimum cut set determining module is used for determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve; and the reliability evaluation index determining module is used for determining the reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve.
Topological structure of flexible direct current transmission MMC converter valve includes: the system comprises n half-bridge structure sub-modules, a current converter control protection system and a valve cooling system; the converter control protection system includes: polar control and station control; the valve cooling system includes: an internal cooling system, an external cooling system and a monitoring system; the half-bridge structure sub-module includes: the IGBT driving circuit comprises at least two IGBT units, a capacitor connected with the at least two IGBT units in parallel, a control system connected with emitting electrodes of the IGBT units respectively and a power supply.
MMC converter valve fault tree establishes the module, includes:
the top event module is used for setting the fault state of the MMC converter valve as a top event T;
an intermediate event module for deriving an intermediate event M based on the top event T i
A bottom event module for based on the intermediate event M i Deriving at least 5n +5 bottom events;
intermediate event M i The method comprises the following steps: the method comprises the following steps that (1) a half-bridge structure submodule fault, a converter station control protection system fault and a valve cooling system fault are detected;
the bottom event comprises the following steps: at least two IGBT unit faults, capacitance faults, submodule control system faults and power supply faults in the n half-bridge structure submodules, pole control faults and station control faults in the converter station control protection system faults, internal cooling system faults, external cooling system faults and monitoring system faults in the valve cooling system faults.
A minimal cut set determination module comprising: an algorithm module and a quantity module;
an algorithm module for determining the minimum cut set B of the fault tree of the MMC converter valve by utilizing a downlink method i
Wherein, { X i 、X j …X m The set of bottom events of the half-bridge sub-modules, { X } is l The method comprises the steps that a bottom event set of a converter station control protection system and a valve cooling system is obtained;
a quantity module for determining a minimum cut set total number of the MMC converter valve fault tree as
The reliability evaluation indexes of the MMC converter valve comprise: reliability R (t), fault probability P (T) and working life t of MMC converter valve MTBF And failure rate λ T
The reliability R (t) of the MMC converter valve is as follows:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t);
wherein R is SM (t) represents the reliability of n half-bridge sub-modules, R 5 (t) represents the reliability of the polar control, R 6 (t) reliability of station control, R 7 (t) reliability of the internal cooling system, R 8 (t) reliability of external cooling system, R 9 (t) represents the reliability of the monitoring system.
n half-bridge sub-modules R SM (t) is:
wherein R is SMi J is the reliability of a single sub-module, j is the number of sub-module faults, k-1 is the redundancy number of the sub-module, and j is less than or equal to k-1.
Single submodule R SMi The expression for the reliability is as follows:
wherein R is 1 (t) reliability of IGBT cell, R 2 (t) reliability of capacitance, R 3 (t) reliability of the submodule control system, R 4 (t) represents the reliability of the power supply.
R 1 (t)~R 9 The expression of (t) reliability is as follows:
wherein λ is i To the failure rate, t is the failure time.
The failure probability p (t) 1-r (t). Working lifeFailure rate
Compared with the closest prior art, the technical scheme provided by the invention has the following excellent effects:
1. according to the technical scheme provided by the invention, the reliability evaluation index expression of the MMC converter valve is obtained by establishing the fault tree of the MMC converter valve and qualitatively analyzing the fault tree, so that the reliability relation of each part is more clearly and definitely shown, and the weak link of the converter valve is further researched;
2. according to the technical scheme provided by the invention, important components influencing the reliability of the MMC converter valve, such as the sub-module, the control protection system, the valve cooling system and the like, are fully considered, so that the accuracy of reliability evaluation of the MMC converter valve is greatly improved;
3. the technical scheme provided by the invention is an MMC converter valve reliability evaluation method based on fault tree analysis, and can be widely applied to MMC converter valve reliability evaluation of a half-bridge sub-module structure.
Drawings
FIG. 1 is a design flow diagram of the present invention;
FIG. 2 is a topology diagram of the MMC of the present invention;
FIG. 3 is a block diagram of a half bridge sub-module of the present invention;
FIG. 4 is a fault tree diagram of a flexible DC power transmission MMC converter valve of the present invention;
FIG. 5 is a flow chart of reliability evaluation of a flexible direct current transmission MMC converter valve.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the method of the present invention comprises: establishing an MMC converter valve fault tree based on a topological structure of the flexible direct-current power transmission MMC converter valve; determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve; and determining the reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve.
The reliability evaluation method specifically comprises the following steps:
1. as shown in fig. 2 and 3, the flexible direct-current power transmission MMC converter valve topological structure based on the IGBT device takes into account the sub-module, the control protection system, the valve cooling system, and other components, and extracts important components that affect the reliability of the MMC converter valve;
extracting important components influencing the reliability of the MMC converter valve: the MMC converter valve comprises n sub-modules in a half-bridge structure, 1 converter control protection system and 1 valve cooling system.
Wherein, 1 submodule includes: 2 IGBT modules, capacitors, a sub-module control system, a power supply and other components; the converter control protection system comprises: polar control and station control; the valve cooling system comprises: an internal cooling system, an external cooling system and a monitoring system.
The submodule has a certain amount of redundancy, when a redundant element fails, the MMC converter valve can still normally operate, and once the converter control protection system or the valve cooling system fails, the MMC converter valve fails.
The main components of the MMC converter valve and the converter valve should meet the fault tree assumption conditions, the reliability of the components and the converter valve, i.e. the individual sub-modules:
R i (t)=e -λt
where λ is the failure rate and t is the failure time.
2. As shown in fig. 4, the establishing of the fault tree of the MMC converter valve based on the major constituent elements of the MMC comprises the steps of:
taking the fault state of the MMC converter valve as a top event T;
deriving sub-module fault, converter station control protection system and 3 intermediate events M of valve cooling system according to top event i
From these 3 intermediate events M i Deriving 5n +5 bottom events X i Wherein failure of the entire series of sub-modules results only from consideration of redundancy of the sub-modules, i.e. failure of at least k sub-modules;
and finally, listing the series of events into a logic diagram to generate an MMC converter valve fault tree.
3. Carrying out qualitative analysis on the fault tree to obtain an MMC converter valve reliability evaluation index expression;
carrying out qualitative analysis on the fault tree, and solving the minimum cut set of the fault tree of the MMC converter valve by adopting a downlink method:
wherein, B i Is a minimal cut set, X i 、X j And X m For the bottom event, i, j and m respectively represent the number of the bottom event, the length of the set B is k, and through analysis, the first-order minimal cut sets of the fault tree of the MMC converter valve are 5, and the k-order minimal cut sets areAnd (4) respectively.
The reliability evaluation indexes of the MMC converter valve comprise: reliability R (t), fault probability P and service life t of MMC converter valve MTBF And failure rate λ T And is and
the reliability of the MMC converter valve is as follows:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t)
wherein the subscript SM denotes a sub-module, and the subscripts 5, 6, … …, 9 denote, in order, a pole control, a station control, an internal cooling system, an external cooling system, and a monitoring system.
The sub-module reliability is:
wherein, R is the reliability of a single sub-module, n is the number of sub-modules, j is the number of sub-module faults, k-1 is the redundancy number of the sub-modules, and j is less than or equal to k-1. Since each submodule is independent of the others, submodule redundancy forms voting gates in the fault tree.
The reliability of a single sub-module is:
wherein n is the number of the sub-modules, and the subscript SM represents the sub-modules.
The fault probability of the MMC converter valve is as follows:
P(T)=1-R(t)
the service life (year) of the MMC converter valve is as follows:
the fault rate (times/year) of the MMC converter valve is as follows:
example 1:
a specific example is given below, where certain MMC converter valve parameters are as follows: the bridge arm is formed by 250 submodule pieces with rated voltage of 1.6kV and rated current of 1kA, the submodule pieces have no redundancy, namely k is 1, the rated direct voltage of the MMC current converter is +/-200 kV, and the parameters of main elements of the MMC current converter are respectively as follows: lambda [ alpha ] 1 0.000876 times-Annual, lambda 2 0.001752 times/year, lambda 3 0.035040 times/year, lambda 4 0.001402 times/year, lambda 5 0.015 times/year, lambda 6 0.015 times/year, lambda 7 0.014 times/year λ 8 λ 0.006 times per year 9 0.020 times per year, where 1 ,λ 2 ,……,λ 9 And the fault rates of the IGBT module, the capacitor, the submodule control system, the power supply, the pole control system, the station control system, the inner cooling system, the outer cooling system and the monitoring system are sequentially represented.
As shown in fig. 5, the method for evaluating the reliability of the flexible direct-current power transmission MMC converter valve specifically comprises the following steps:
1) the flexible direct-current power transmission MMC converter valve topological structure based on the IGBT device considers the sub-module, the control protection system, the valve cooling system and other components, and extracts important components influencing the reliability of the MMC converter valve;
2) establishing an MMC converter valve fault tree based on MMC main constituent elements;
3) and carrying out qualitative analysis on the fault tree to obtain an MMC converter valve reliability evaluation index expression.
The important parts influencing the reliability of the MMC converter valve are extracted as follows:
the MMC converter valve comprises 250 sub-modules in a half-bridge structure, 1 converter control protection system and 1 valve cooling system.
Wherein, 1 sub-module comprises 2 IGBT modules, capacitors, a sub-module control system, a power supply and other parts; the converter control protection system comprises pole control and station control; the valve cooling system comprises an inner cooling system, an outer cooling system and a monitoring system. The submodule has a certain amount of redundancy, redundant elements are failed, and the MMC converter valve can still normally operate. Once the converter control protection system or the valve cooling system fails, the MMC converter valve fails.
MMC converter valve essential element and converter valve satisfy the fault tree hypothesis condition, and the degree of reliability of every component does in proper order: r 1 (t)=e -0.000876t 、R 2 (t)=e -0.001752t 、R 3 (t)=e -0.035040t 、R 4 (t)=e -0.001402t 、R 5 (t)=e -0.015t 、R 6 (t)=e -0.015t 、R 7 (t)=e -0.014t 、R 8 (t)=e -0.006t 、R 9 (t)=e -0.020t
The fault tree of the flexible direct current transmission MMC converter valve is established, and the step of establishing the fault tree of the MMC converter valve comprises the following steps:
taking the fault state of the MMC converter valve as a top event T;
deriving 3 intermediate events M of submodule faults, converter station control protection system and valve cooling system according to top event i
From these 3 intermediate events M i Deriving 5n +5 bottom events X i Wherein failure of the entire series of sub-modules results only if redundancy of the sub-modules is considered, i.e. at least k sub-module failures.
And finally, listing the series of events into a logic diagram to generate an MMC converter valve fault tree.
And (3) carrying out qualitative analysis on the fault tree, wherein k is 1, and solving the minimum cut set of the fault tree of the MMC converter valve by adopting a following method:
B i ={X i },i=1,2,…,5n+5
wherein, B i For the minimal cut set, n is 250. At this time, the minimum cut sets of the fault tree of the MMC converter valve are 5n +5 in total and are first-order minimum cut sets.
The reliability evaluation indexes of the MMC converter valve comprise: reliability R (t), fault probability P and service life t of MMC converter valve MTBF And failure rate λ T
The reliability of a single sub-module is:
wherein n is the number of the sub-modules, and the subscript SM represents the sub-modules.
The sub-module reliability is:
wherein, R is the reliability of a single sub-module, n is the number of sub-modules, j is the number of sub-module faults, k-1 is the redundancy number of the sub-modules, and j is less than or equal to k-1. Since each submodule is independent of the others, submodule redundancy forms voting gates in the fault tree.
The reliability of the MMC converter valve is as follows:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t)=e -(9.9750+0.015+0.015+0.014+0.006+0.020)t =e -10.0450t
wherein the subscript SM denotes a sub-module, and the subscripts 5, 6, … …, 9 denote, in order, a pole control, a station control, an internal cooling system, an external cooling system, and a monitoring system.
The probability that the MMC converter valve fails within t years is as follows:
P(T)=1-R(t)=1-e -10.0450t
the service life (year) of the MMC converter valve is as follows:
the fault rate (times/year) of the MMC converter valve is as follows:
therefore, by adopting the reliability evaluation method for the flexible direct-current transmission MMC converter valve, which is provided by the invention, important components influencing the reliability of the MMC converter valve, such as a sub-module, a control protection system, a valve cooling system and the like, can be fully considered, and the reliability evaluation accuracy of the MMC converter valve is greatly improved; the reliability relation between the elements and the converter valve is displayed more clearly and definitely, and the weak link of the converter valve is further researched; the method can be widely applied to reliability evaluation of the MMC converter valve with the half-bridge sub-module structure.
Based on the same inventive concept, the invention also provides a system for evaluating the reliability of the flexible direct-current transmission MMC converter valve, which is explained below.
The system provided by the invention comprises: the fault tree building module of the MMC converter valve is used for building the fault tree of the MMC converter valve based on the topological structure of the flexible direct-current power transmission MMC converter valve; the minimum cut set determining module is used for determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve; and the reliability evaluation index determining module is used for determining the reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve.
Topological structure of flexible direct current transmission MMC converter valve includes: the system comprises n half-bridge structure sub-modules, a current converter control protection system and a valve cooling system; the converter control protection system includes: polar control and station control; the valve cooling system includes: an internal cooling system, an external cooling system and a monitoring system; the half-bridge structure sub-module includes: the IGBT driving circuit comprises at least two IGBT units, a capacitor connected with the at least two IGBT units in parallel, a control system connected with emitting electrodes of the IGBT units respectively and a power supply.
MMC converter valve fault tree establishes the module, includes:
the top event module is used for setting the fault state of the MMC converter valve as a top event T;
an intermediate event module for deriving an intermediate event M based on the top event T i
A bottom event module for based on the intermediate event M i Deriving at least 5n +5 bottom events;
intermediate event M i The method comprises the following steps: the method comprises the following steps that (1) a half-bridge structure submodule fault, a converter station control protection system fault and a valve cooling system fault are detected;
the bottom event comprises the following steps: at least two IGBT unit faults, capacitance faults, submodule control system faults and power supply faults in the n half-bridge structure submodules, pole control faults and station control faults in the converter station control protection system faults, internal cooling system faults, external cooling system faults and monitoring system faults in the valve cooling system faults.
A minimal cut set determination module comprising: an algorithm module and a quantity module;
an algorithm module for determining the fault tree of the MMC converter valve by using a downlink methodMinimum cut set B of i
Wherein, { X i 、X j …X m The set of bottom events of the half-bridge sub-modules, { X } is l The method comprises the steps that a bottom event set of a converter station control protection system and a valve cooling system is obtained;
a quantity module for determining a minimum cut set total number of the MMC converter valve fault tree as
The reliability evaluation indexes of the MMC converter valve comprise: reliability R (t), fault probability P (T) and working life t of MMC converter valve MTBF And failure rate λ T
The reliability R (t) of the MMC converter valve is as follows:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t);
wherein R is SM (t) represents the reliability of n half-bridge sub-modules, R 5 (t) represents the reliability of the polar control, R 6 (t) reliability of station control, R 7 (t) reliability of the internal cooling system, R 8 (t) reliability of external cooling system, R 9 (t) represents the reliability of the monitoring system.
n half-bridge sub-modules R SM (t) is:
wherein R is SMi The reliability of a single submodule is represented, j is the number of submodule faults, k-1 is the redundancy number of the submodule, and j is less than or equal to k-1.
Single submodule R SMi The expression of the reliability is as follows:
wherein R is 1 (t) reliability of IGBT cell, R 2 (t) reliability of capacitance, R 3 (t) reliability of the submodule control system, R 4 (t) represents the reliability of the power supply.
R 1 (t)~R 9 (t) the expression of the reliability is as follows:
wherein λ is i To the failure rate, t is the failure time.
The failure probability p (t) 1-r (t). Working lifeFailure rate
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (20)

1. A method for evaluating the reliability of a flexible direct-current transmission MMC converter valve is characterized by comprising the following steps:
establishing an MMC converter valve fault tree based on a topological structure of the flexible direct-current power transmission MMC converter valve;
determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve;
determining a reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve;
the MMC converter valve fault tree building method comprises the following steps:
setting the fault state of the MMC converter valve as a top event T;
deriving intermediate events M based on the top events T i
Based on the intermediate event M i Deriving at least 5n +5 bottom events;
the intermediate event M i The method comprises the following steps: the method comprises the following steps that (1) a half-bridge structure submodule fault, a converter station control protection system fault and a valve cooling system fault are detected;
the bottom event comprises the following steps: at least two IGBT unit faults, capacitance faults, submodule control system faults and power supply faults in the n half-bridge structure submodules, pole control faults and station control faults in the converter station control protection system faults, internal cooling system faults, external cooling system faults and monitoring system faults in the valve cooling system faults;
based on MMC converter valve fault tree, confirm the minimum cut set of MMC converter valve fault tree includes:
determining minimum cut set B of fault tree of MMC converter valve by utilizing downlink method i
Wherein, { X i 、X j …X m The set of bottom events of the half-bridge sub-modules, { X } is l The method comprises the steps that a bottom event set of a converter station control protection system and a valve cooling system is obtained;
the minimum cut set total number of the fault tree of the MMC converter valve is
The reliability evaluation indexes of the MMC converter valve comprise: reliability R (t), fault probability P (t) and service life t of MMC converter valve MTBF And failure rate lambda T
Reliability of the MMC converter valve is as follows:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t);
wherein R is SM (t) represents the reliability of n half-bridge sub-modules, R 5 (t) represents the reliability of the polar control, R 6 (t) reliability of station control, R 7 (t) reliability of the internal cooling system, R 8 (t) reliability of external cooling system, R 9 (t) represents the reliability of the monitoring system.
2. The method according to claim 1, wherein the topology of the MMC converter valve for flexible direct current power transmission comprises: the system comprises n half-bridge structure sub-modules, a current converter control protection system and a valve cooling system;
the converter control protection system comprises: polar control and station control; the valve cooling system includes: an internal cooling system, an external cooling system and a monitoring system; the half-bridge structure sub-module includes: the IGBT driving circuit comprises at least two IGBT units, a capacitor connected with the at least two IGBT units in parallel, a control system and a power supply, wherein the control system and the power supply are respectively connected with emitting electrodes of the IGBT units.
3. The method of claim 1, wherein the reliability R of the n half-bridge sub-modules is calculated as follows SM (t):
Wherein R is SMi The reliability of a single submodule is represented, j is the number of submodule faults, k-1 is the redundancy number of the submodule, and j is less than or equal to k-1.
4. The method of claim 3, wherein the reliability R of an individual submodule is calculated as follows SMi
Wherein R is 1 (t) reliability of IGBT cell, R 2 (t) reliability of capacitance, R 3 (t) reliability of the submodule control system, R 4 (t) represents the reliability of the power supply.
5. The method according to claim 1 or 4, wherein the reliability R is calculated as follows 1 (t)~R 9 (t):
Wherein λ is i To the failure rate, t is the failure time.
6. The method according to claim 1, wherein the probability of occurrence p (t) is calculated as:
P(t)=1-R(t)。
7. the method of claim 1, wherein the operating life t is calculated as follows MTBF
8. The method of claim 1, wherein the failure rate λ is calculated as follows T
9. A system for evaluating reliability of a flexible direct current power transmission MMC converter valve for use in the method for evaluating reliability of a flexible direct current power transmission MMC converter valve of claim 1, comprising:
the fault tree building module of the MMC converter valve is used for building the fault tree of the MMC converter valve based on the topological structure of the flexible direct-current power transmission MMC converter valve;
the minimum cut set determining module is used for determining a minimum cut set of the fault tree of the MMC converter valve based on the fault tree of the MMC converter valve;
and the reliability evaluation index determining module is used for determining the reliability evaluation index of the MMC converter valve based on the minimum cut set of the fault tree of the MMC converter valve.
10. The system of claim 9, wherein the topology of the flexible direct current power transmission MMC converter valve comprises: the system comprises n half-bridge structure sub-modules, a current converter control protection system and a valve cooling system;
the converter control protection system comprises: polar control and station control; the valve cooling system includes: an internal cooling system, an external cooling system and a monitoring system; the half-bridge structure sub-module includes: the IGBT driving circuit comprises at least two IGBT units, a capacitor connected with the at least two IGBT units in parallel, a control system and a power supply, wherein the control system and the power supply are respectively connected with emitting electrodes of the IGBT units.
11. The system according to claim 9, wherein said MMC converter valve fault tree building module comprises:
the top event module is used for setting the fault state of the MMC converter valve as a top event T;
an intermediate event module for deriving an intermediate event M based on the top event T i
A bottom event module for generating a bottom event based on the intermediate event M i Deriving at least 5n +5 bottom events;
the intermediate event M i The method comprises the following steps: the method comprises the following steps that (1) a half-bridge structure submodule fault, a converter station control protection system fault and a valve cooling system fault are detected;
the bottom event comprises the following steps: at least two IGBT unit faults, capacitance faults, submodule control system faults and power supply faults in the n half-bridge structure submodules, pole control faults and station control faults in the converter station control protection system faults, internal cooling system faults, external cooling system faults and monitoring system faults in the valve cooling system faults.
12. The system of claim 9, wherein the minimal cut set determination module comprises: an algorithm module and a quantity module;
the algorithm module is used for determining the minimum cut set B of the fault tree of the MMC converter valve by utilizing a downlink method i
Wherein, { X i 、X j …X m The set of bottom events of the half-bridge sub-modules, { X } is l The method comprises the steps that a bottom event set of a converter station control protection system and a valve cooling system is obtained;
the quantity module is used for determining the minimum cut set total number of the fault tree of the MMC converter valve
13. The system of claim 9, wherein the MMC converter valve reliability evaluation indicator comprises: reliability R (t), fault probability P (t) and service life t of MMC converter valve MTBF And failure rate λ T
14. The system of claim 9, wherein the reliability r (t) of the MMC converter valve is:
R(t)=R SM (t)×R 5 (t)×R 6 (t)×R 7 (t)×R 8 (t)×R 9 (t);
wherein R is SM (t) represents the reliability of n half-bridge sub-modules, R 5 (t) represents the reliability of the polar control, R 6 (t) reliability of station control, R 7 (t) reliability of the internal cooling system, R 8 (t) reliability of external cooling system, R 9 (t) represents the reliability of the monitoring system.
15. The system of claim 14, wherein n half-bridge sub-modules R SM (t) is:
wherein R is SMi The reliability of a single submodule is represented, j is the number of submodule faults, k-1 is the redundancy number of the submodule, and j is less than or equal to k-1.
16. The system of claim 15, wherein a single submodule R SMi The expression for the reliability is as follows:
wherein R is 1 (t) reliability of IGBT cell, R 2 (t) represents the reliability of the capacitor, R 3 (t) reliability of the submodule control system, R 4 (t) represents the reliability of the power supply.
17. The system of claim 14 or 16, wherein R is 1 (t)~R 9 (t) the expression of the reliability is as follows:
wherein λ is i To the failure rate, t is the failure time.
18. The system of claim 13, wherein the probability of failure p (t) is 1-r (t).
19. The system of claim 13, wherein the operational life is the operational life
20. The system of claim 13, wherein the failure rate is
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