CN109001574B - Reliability analysis method for thyristor converter valve system of extra-high voltage direct current transmission project - Google Patents
Reliability analysis method for thyristor converter valve system of extra-high voltage direct current transmission project Download PDFInfo
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Abstract
The invention discloses a reliability analysis method for a thyristor converter valve system of an extra-high voltage direct current transmission project, which comprises the following steps: 1) calculating the reliability of a single valve of a thyristor converter valve system in the extra-high voltage direct current transmission project; 2)12, calculating the reliability of the pulsating current converter; 3) calculating the reliability of the single-pole converter; 4) and (4) calculating the reliability of the bipolar converter to obtain an index capable of evaluating the reliability of the thyristor converter valve system of the ultra-high voltage direct current transmission project. The invention fully considers the multi-layer structure and the function range of the converter valve control system in the analysis process, and can fully reflect the influence of each layer on the operation and the reliability of the converter valve.
Description
[ technical field ] A method for producing a semiconductor device
The invention belongs to the field of reliability of extra-high voltage direct-current transmission engineering, and particularly relates to a reliability analysis method based on a multi-layer structure of an extra-high voltage direct-current transmission thyristor converter valve system.
[ background of the invention ]
The reliability of the extra-high voltage project has very important influence on the whole power system, and the improvement of the reliability of the extra-high voltage project brings great benefits to the safety, reliability and economy of the power system. The thyristor converter valve system is used as the core equipment of the existing extra-high voltage direct current transmission, and the reliability of the thyristor converter valve system directly determines the safe and stable operation of the whole transmission system, so that the reliability of the extra-high voltage direct current transmission engineering converter valve system is evaluated, the influence of various factors is analyzed, and the thyristor converter valve system has important significance for effectively improving the reliability of the transmission system and providing a quantitative decision basis for practical engineering.
In the aspect of reliability evaluation of the converter valve, most scholars simply consider the auxiliary system of the converter valve as a whole, and do not fully consider different configuration levels and function ranges of the auxiliary system in actual engineering. In addition, a single valve is often used as a basic unit for analysis in the evaluation of the converter valve, and the reliability analysis of the internal structure of the converter valve is lacked.
[ summary of the invention ]
The invention provides a reliability analysis method for an extra-high voltage direct current transmission thyristor converter valve system, which aims to solve the technical problem. The invention analyzes the internal reliability of the single valve of the converter valve and fully considers the self composition of the converter valve and the multi-level structure and the function range of different levels of the auxiliary system.
In order to achieve the purpose, the invention adopts the following technical scheme:
the reliability analysis method of the thyristor converter valve system in the extra-high voltage direct current transmission project comprises the following steps:
1) calculating the reliability of a single valve of a thyristor converter valve system in the extra-high voltage direct current transmission project;
2)12, calculating the reliability of the pulsating current converter;
3) calculating the reliability of the single-pole converter;
4) and (4) calculating the reliability of the bipolar converter to obtain an index capable of evaluating the reliability of the thyristor converter valve system of the ultra-high voltage direct current transmission project.
Further, the step 1) specifically comprises: 1.1) acquiring failure rates of a thyristor, a damping resistor, a damping capacitor and a thyristor control unit TCU in a thyristor converter valve system of the extra-high voltage direct current transmission project; substituting thyristor failure rate lambdaThyDamping of failure rate of resistance
Damping capacitor failure rate
And failure rate λ of TCUTCUTo obtain the failure rate lambda of the thyristor levelTL：
1.2) substituting the number of thyristors of the single valve to obtain the integral reliability function of all thyristor levels in the single valve:
1.3) substituting the number and the failure rate of the saturable reactors of the single valve to obtain the integral reliability function of all the saturable reactors in the single valve:
1.4) obtaining a single valve reliability function and a single valve equivalent failure rate based on a redundant system model:
RSV(t)＝RTTL(t)·RTSR(t)
further, the step 2) specifically comprises:
2.1) substitution statistics: failure rate lambda of internal water coolingICSExternal water cooling failure rate lambdaOCSFailure rate lambda with monitoring systemMCSTo obtain the equivalent failure rate lambda of a set of cooling systemCSO：
λCSO＝λICS+λOCS+λMCS
2.2) obtaining a reliability function and an equivalent failure rate of the whole cooling system under the consideration of the standby based on the redundancy system model:
2.3) substitution statistics: and (3) obtaining the failure rate of the valve base electrons, and obtaining the reliability function and the equivalent failure rate of the 12-pulse current converter:
further, the step 3) specifically comprises:
3.1) substitution statistics: failure rate lambda of one set of unipolar control layerPCOAnd obtaining a reliability function and an equivalent failure rate of the whole unipolar control layer under consideration of standby:
3.2) analyzing all possible operation states of the single-pole converter and the transfer relation among different states to obtain a state transfer diagram of the single-pole converter, and obtaining a transfer density matrix A of the whole state transfer rate of the single-pole converter according to the state transfer diagram of the single-pole converterSPAs shown in formula (17).
3.3) obtaining the steady-state probability corresponding to each state of the monopole converter by the Markov process probability formulas (18) and (19) under the steady state, and calculating the equivalent state transition rate lambda after the states are combinedSPiAnd muSPi，i＝1,2,3,4：
Further, the step 4) specifically comprises:
4.1) substitution statistics: and the failure rate of one set of bipolar control layer obtains the reliability function and the equivalent failure rate of the whole bipolar control layer under the standby condition:
4.2) for the state transition caused by the 12-pulse converter, the bipolar control layer of the control system and the cooling system fault, obtaining the bipolarState transition of the inverter FIG. 1, the corresponding transition density matrix is denoted ABP1As shown in formula (23):
4.3) obtaining a state transition diagram 2 of the bipolar converter for the state transition caused by the fault of the control layer of the unipolar control system, wherein the corresponding transition density matrix is marked ABP2As shown in formula (24):
4.4) the total transfer density matrix of the converter valve system is the sum of the transfer density matrices in the two sub-cases;
ABP＝ABP1+ABP2
4.5) mixing A withBPSubstituting an equation (18) and an equation (19), obtaining steady-state probabilities corresponding to all the states of the bipolar converter, summing the probabilities of all the same capacity states to obtain the steady-state probabilities of different available capacity states, and calculating other reliability indexes; other reliability indicators include: transfer frequency, average duration, energy unavailability.
And further, adopting one or more of steady-state probability, transfer frequency, average duration and energy unavailability of different available capacity states to carry out reliability evaluation on the thyristor converter valve system in the ultra-high voltage direct current transmission engineering.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a reliability analysis method based on a multi-layer structure of an extra-high voltage direct current transmission thyristor converter valve system, which fully considers the multi-layer structure and the function range of the converter valve control system in the analysis process and can fully reflect the influence of each layer on the operation and the reliability of a converter valve.
The invention analyzes the topological structure in the single valve of the converter valve in detail, analyzes the reliability thereof, analyzes the reliability more carefully and comprehensively, and can intuitively embody the influence of the devices in the single valve on the reliability of the converter valve.
The invention classifies different types of faults of the converter valve system and considers all possible states, so that the obtained state transition matrix has more dimensions and is closer to the actual engineering.
According to the steady-state probability, the transfer frequency, the average duration and the energy unavailability of different available capacity states obtained by the method, a person skilled in the art can objectively and truly evaluate the reliability of the thyristor converter valve system in the ultra-high voltage direct current transmission engineering.
The converter valve control system of the extra-high voltage direct current transmission converter station adopts a layered distributed structure, and is divided into a plurality of layers according to the level in structure and function, so that the operation reliability can be effectively improved, the influence and the harm degree caused by the fault of any control link can be minimized, and the convenience and the flexibility of operation and maintenance can be improved.
The method analyzes the multi-layer structure and the function range of the auxiliary system, particularly the control system in the actual engineering, respectively introduces the influences of different layers of the auxiliary system into the system models of the corresponding layers in the process of gradually constructing the reliability models, and more accurately describes the reliability of the converter valve system.
The invention adopts a Markov model, measures the reliability by taking the available capacity of the converter valve system as a fundamental basis, innovatively defines a plurality of new failure sub-states, and distinguishes and treats the valve body fault and the auxiliary system fault, so that the description of the whole process is more reasonable.
The invention provides a complete and detailed reliability model and analysis method for an extra-high voltage direct current transmission thyristor valve system on the basis of comprehensively analyzing a multilayer structure of a thyristor valve topology and auxiliary system, including a control system and a cooling system, according to basic reliability theories such as a redundancy model and a state space method, and comprehensively considering all components of the system, and simultaneously analyzing the influence of different factors on the system reliability. The invention still adopts the basic premise of generally accepted reliability evaluation in the existing literature, namely, the failure rates of all elements in the converter valve are considered to be constant values which do not change along with time, and the reliability function of the elements is an exponential function.
[ description of the drawings ]
Fig. 1 is a thyristor level topology.
Fig. 2 is a valve assembly topology.
FIG. 3 shows a connection mode of converter valves in an extra-high voltage DC converter station.
Fig. 4 is a multi-level structure of the control system.
Fig. 5 is a state transition diagram of a unipolar inverter.
The first number of each state box in the figure represents the number of the state, the N and the previous number represent the number of 12 pulsating current converters which are in single-pole normal operation in the state, the S and the previous number represent the number of 12 pulsating current converters which have no fault and can be connected into a single pole and are to be installed, the number represented by a percentage number represents the available capacity of the single pole corresponding to the state, and the number beside an arrow is marked as a state transition rate which indicates the probability of different state transitions at two ends of the arrow in unit time.
Fig. 6 is an equivalent state transition diagram of the unipolar converter.
Fig. 7 and 8 represent state transition diagrams of bipolar converters in different situations.
Fig. 7 is a state transition diagram for a bipolar inverter (case 1). The first number of each state box also represents a state number, two N and the previous numbers respectively represent the number of 12 pulsating converters with the unipolar converters on two sides working normally, and the percentile number represents the available capacity of the state.
Fig. 8 is a state transition diagram for a bipolar inverter (case 2).
[ detailed description ] embodiments
Converter valve topological structure
The thyristor is the core element of the converter valve, and needs to be used together with other auxiliary devices to form the basic switch unit of the converter valve, namely the thyristor level, which comprises the thyristor and the damping loop capacitor CdAnd a resistor RdDC voltage equalizing resistor RdcAnd crystalA Thyristor Control Unit (TCU) having a topology as shown in fig. 1.
The valve assembly is a structural unit formed by connecting several to tens of thyristor stages in series and simultaneously assembling the thyristor stages and one or two saturable reactors in series, and can be used as a complete single valve in function or become a proportional unit of the single valve, as shown in fig. 2.
A single valve is a leg of the converter, also called valve arm, and is made up of several valve components connected in series. Due to the development of thyristor technology and the consideration of filter design, 12-pulse converters are widely adopted at present to form the basic converter unit of the converter station, and the basic converter unit consists of two 6-pulse converters which are connected in series at the AC side and are staggered by 30 degrees at the AC side.
A wiring mode of a bipolar double 12-pulse converter is generally adopted in a domestic extra-high voltage direct current transmission system converter station, and each pole is formed by connecting two 12-pulse converters in series, as shown in figure 3.
Multi-layer structure of auxiliary system
The auxiliary system of the converter valve mainly comprises a control system and a cooling system. The control system of the converter valve control system of the extra-high voltage direct current transmission converter station adopts a layered distributed structure and complete redundancy configuration, and can be divided into a bipolar control layer, a unipolar control layer, a converter unit control layer and a converter switch control layer as shown in fig. 4. The control system of the converter valve comprises two sets of mutually redundant systems, the switching of the two systems is realized by the system selection switching control unit, the two sets of systems are mutually standby, and the switching is timely carried out when any one system fails, so that the reliability of the converter valve is effectively improved.
When the converter valve operates, large current passes through the valve body, and high heat is generated, so that the temperature of devices such as a thyristor, a reactor and the like is increased rapidly. In order to prevent the damage of elements caused by high temperature, a cooling system is configured in a unit of a 12-pulse converter in the engineering for cooling. And the cooling system is divided into an inner water cooling system and an outer water cooling system, and is provided with a monitoring system to realize monitoring and control and complete the information interaction with the corresponding pole control system. In addition, the cooling system also has a redundant backup system, which can be switched in time in the event of a fault.
(III) Single valve reliability model based on redundancy system model
For the thyristor level, damage of the thyristor can directly cause the fault of the thyristor level, and damage of the capacitance and resistance of the damping loop and the TCU can also cause the failure of the thyristor level. The dc voltage-sharing resistor generally serves as a high-potential voltage-sharing arm of the thyristor control unit, besides the dc voltage-sharing function, and is used for monitoring the thyristor-level voltage, and may be regarded as a part of the TCU. Therefore, each element in the thyristor level is in a reliability relation of series connection, and the reliability function is shown as the formula (1). Wherein R isThy(t)，RRd(t)，RCd(t)，RTCUAnd (t) is the reliability functions of the thyristor, the damping resistor, the damping capacitor and the TCU respectively, and the equivalent failure rate of each element is as shown in the formula (2) as the service life of each element follows exponential distribution. Wherein λThy，λRd，λCd，λTCUThyristor, damping resistor, damping capacitor and TCU failure rate.
RTL(t)＝RThy(t)×RRd(t)×RCd(t)×RTCU(t) (1)
λTL＝λThy+λRd+λCd+λTCU(2)
A plurality of valve components are connected in series to form a single valve, and the valve components are in a structure that a plurality of thyristor stages and a saturable reactor are connected in series and then are connected in parallel with a voltage-sharing capacitor. Considering that the failure of the voltage-sharing capacitor increases the risk of failure of the valve assembly, but does not directly cause failure, the influence of the voltage-sharing capacitor can be ignored in the reliability model of the single valve, and the reliability model is regarded as a series combination of a plurality of thyristor stages and a saturable reactor.
The number of thyristors in the single valve adopts a redundancy design, and the single valve presents a short-circuit performance under the condition of thyristor failure, so that the normal operation of the converter valve is ensured. Assuming a single valve has n in commonTLAt the level of the individual thyristors, and at least k is requiredTLThe individual thyristor levels can only operate when they are in a normal state, and the reliability function of these thyristor levels is shown in equation (3). At the same time, the user can select the desired position,the failure of the single valve can be directly caused by the electrical or mechanical damage of the single saturable reactor in design, so that the reliability relations of all saturable reactors in the single valve are in series connection, the corresponding reliability function is shown as a formula (4), wherein lambda isSRAnd nSRRespectively, the failure rate of the saturable reactor and the number of saturable reactors in the single valve.
The reliability function of the single valve can be expressed as a series structure of all thyristor stages and the whole saturable reactor based on a redundancy system model, as shown in formula (5). Mean Time To Failure (MTTF) of corresponding single valveSVAnd equivalent failure rate lambdaSVAre respectively shown as formulas (6) and (7).
RSV(t)＝RTTL(t)·RTSR(t) (5)
(IV) redundancy system model-based 12-pulse current converter reliability model
A 12-pulse converter includes 12 single valves, and the failure of each single valve directly causes the shutdown of the entire converter. In the control system, a converter unit control layer controls the operation of the 12-pulse converter, and actually corresponding instructions are executed by a valve base electronic VBE. In addition, the cooling system is configured by taking the 12-pulse current converter as a unit in engineering, and the operation of different systems is relatively independent. The set of cooling system comprises an internal cooling system, an external cooling system and a monitoring system, and the reliability function is shown as a formula (26), wherein RICS(t)，ROCS(t)，RMCS(t) is the reliability function of the internal water cooling, external water cooling and monitoring system respectively. The equivalent failure rate of a cooling system is shown as formula (27), wherein lambdaICS、λOCS、λMCSThe failure rates of the internal cooling system, the external cooling system and the monitoring system are respectively.
RCSO(t)＝RICS(t)×ROCS(t)×RMCS(t) (26)
λCSO＝λICS+λOCS+λMCS(27)
Since the hot standby system is provided, the reliability function of the cooling system as a whole under consideration of the standby can be represented by a redundant system model, as shown in equation (8), and the Mean Time To Failure (MTTF) of the corresponding cooling system as a wholeCSAnd equivalent failure rate lambdaCSAs shown in formulas (9) and (10).
In summary, the reliability model of the 12-pulse converter is expressed as a series model of all single-valve, valve-based electronic and cooling systems based on the redundancy system model, and the reliability function thereof is shown in formula (11), wherein λVBEIs the failure rate of the valve base electronics. Mean Time To Failure (MTTF) of 12-pulse converterVBAnd equivalent failure rate lambdaVBAs shown in formulas (12) and (13), respectively.
(V) monopole current converter reliability model based on state space method
The operation of the two 12-pulse current converters with single poles is independent, and the possible state processes are as follows: work-failure-repair-installation-work. The process of the unipolar available capacity state change caused by the different operating states of the 12-pulse inverter can be represented by a homogeneous markov process.
The reliability of the unipolar converter is influenced by not only the 12-pulse converter, but also the control system of the corresponding level needs to be considered. From fig. 3, the unipolar control layer of the control system directly affects the operating state of all the unipolar 12-pulse converters, and in case of a fault, all the converters will be shut down. Considering the hot standby control system, the reliability of the single-pole control layer as a whole can be represented by a redundant system model, as shown in formula (14), wherein λPCOIs the failure rate of a set of unipolar control layers. Mean Time To Failure (MTTF) taking into account the whole of the unipolar control layer under standbyPCAnd equivalent failure rate lambdaPCAs shown in formula (15) and formula (16).
The 12-pulse converter comprises a state to be installed after fault repair besides normal operation and fault. Recording the repair rate and the installation rate of the 12-pulse current converter as mu respectivelyVBAnd gammaVBThe repair rate of the unipolar control layer is muPCAnd establishing a reliability model of the monopole converter according to a state space method. The transition process of all possible states of the unipolar converter is shown in fig. 5 and includes 7A possible state. In addition, when the single-pole control layer fails, the single-pole converter is immediately shut down, but the 12-pulse converter is noticed not to have a fault, the operation state can be recovered after the control layer is repaired, and the 12-pulse converter is not involved in state transition. So here a new state 7 is defined, indicating a Forced Failure (FF) of the system state at the failure of the unipolar control layer, with an available capacity of 0.
According to FIG. 5, the transition density matrix A of the overall state transition rate of the unipolar converterSPAs shown in equation (17), where the element in the ith row and jth column represents the state transition rate from state i to state j. Substituting A into homogeneous Markov process probability formulas (18) and (19) under steady stateSPThe steady-state probability corresponding to each state of the monopole converter can be obtained in a formula
Is a row vector corresponding to each state steady-state probability.
The equivalent state transition process after the merging of the states of the unipolar converter is shown in fig. 7, wherein the state of each available capacity represents the state set of all the capacities in fig. 6, the state 4 of fig. 7 represents the state 7 of fig. 6, and λSP1，μSP1，λSP2，μSP2，λSP3，μSP3，λSP4，μSP4Representing the equivalent state transition rate between the states in the equivalent process, from the transition density matrix ASPAnd combining the state of the Markov process with the state of the Markov process and calculating by a formula.
Reliability model of (six) bipolar current converter
A bipolar converter can be seen as a series configuration of two unipolar converters, but due to the relative independence of its operation, the different operating states of a 12-pulse converter, similar to the unipolar case, determine different available capacity levels of the bipolar converter, while the switching between the states can still be described in a markov process. In addition, the failure of the bipolar control layer in the control system can also directly cause the shutdown of the bipolar converter, the overall reliability function of the bipolar control layer is shown as the following formula in consideration of the hot standby system of the station control layer and the hot standby system thereof, wherein the λSCOFailure rate of a bipolar control layer. Correspondingly, the Mean Time To Failure (MTTF) of the standby lower bipolar control layer is consideredSCAnd equivalent failure rate lambdaSCAre represented by the formulae (21) and (22), respectively.
According to the equivalent state transition rate of the unipolar converter, the reliability model of the bipolar converter needs to be discussed according to different fault reasons.
Case 1: for the state transition caused by the faults of the 12-pulse converter, the bipolar control layer of the control system and the cooling system, the state transition diagram of the bipolar converter is shown in FIG. 7, and the corresponding transition density matrix is marked as ABP1As shown in formula (23).
Case 2: for the state transition caused by the fault of the control layer of the unipolar control system, the state transition diagram of the bipolar converter is shown in fig. 8, and the transition density matrix corresponding to fig. 8 is marked as aBP2As shown in equation (24).
Therefore, the two conditions are considered together to be all state transition processes of the bipolar converter, and the overall transition density matrix is the sum of the transition density matrices of the two sub-conditions, as shown in formula (25):
ABP＝ABP1+ABP2(25)
a is to beBPAnd (3) substituting the formula (18) and the formula (19), obtaining the steady-state probabilities corresponding to all the states of the bipolar converter, summing the probabilities of all the states with the same capacity, obtaining the steady-state probabilities of all the available capacity states and calculating other reliability indexes.
The invention relates to a reliability analysis method of an extra-high voltage direct current transmission thyristor converter valve system based on a state space method. Firstly, establishing a reliability model of a single valve and even a 12-pulse converter based on a redundancy system model, then establishing a reliability model of an extra-high voltage direct current thyristor converter valve system based on a state space method according to a wiring mode of an extra-high voltage direct current engineering converter, and calculating a corresponding reliability index; the specific implementation steps are as follows:
1) single valve reliability calculation of thyristor converter valve system in extra-high voltage direct current transmission project
1.1) acquiring failure rates of a thyristor, a damping resistor, a damping capacitor and a TCU in a thyristor converter valve system of an extra-high voltage direct current transmission project; substituting thyristor failure rate lambdaThyDamping of failure rate of resistance
Damping capacitor failure rate
And failure rate λ of TCUTCUTo obtain the failure rate lambda of the thyristor levelTL：
1.2) substituting the number of the thyristors of the single valve to obtain the integral reliability function of all thyristor levels.
1.3) substituting the number and the failure rate of the saturable reactors of the single valve to obtain the integral reliability function of all the saturable reactors.
1.4) obtaining a single valve reliability function and a single valve equivalent failure rate based on a redundant system model.
RSV(t)＝RTTL(t)·RTSR(t)
2)12 ripple converter reliability calculation
2.1) substitution statistics: failure rate lambda of internal water coolingICSExternal water cooling failure rate lambdaOCSFailure rate lambda with monitoring systemMCSObtaining the equivalent failure rate R of a set of cooling systemCSO(t)。
λCSO＝λICS+λOCS+λMCS
2.2) obtaining a cooling system function under the consideration of the standby and equivalent failure rate based on the redundancy system model.
2.3) substitution statistics: and the failure rate of the valve base electrons is obtained to obtain the reliability function and the equivalent failure rate of the 12-pulse current converter.
3) Unipolar converter reliability calculation
3.1) substitution statistics: and the failure rate of a set of single-pole control layers obtains the integral reliability function and equivalent failure rate of the single-pole control layer under the standby condition.
3.2) analyzing all possible operation states of the single-pole converter and the transition relation among different states to obtain a state transition diagram (as shown in figure 5) of the single-pole converter, and obtaining a transition density matrix A of the integral state transition rate of the single-pole converter according to the state transition diagram of the single-pole converterSPAs shown in formula (17).
And 3.3) obtaining the equivalent state transition rate after the states of the single-pole current converter are combined by homogeneous Markov process probability formulas (18) and (19) under the steady state.
4) Bipolar converter reliability calculation
4.1) substitution statistics: and obtaining the integral reliability function and equivalent failure rate of the bipolar control layer under consideration by using the failure rate of the bipolar control layer.
4.2) for the state transitions caused by 12-pulse converters, bipolar control layers of the control system and faults of the cooling system, for the state transitions caused by this type, the state transition diagram of the bipolar converter is obtained as shown in FIG. 7, and the corresponding transition density matrix is denoted ABP1As shown in formula (23).
4.3) for the state transition caused by the fault of the control layer of the unipolar control system, for the state transition caused by this type, the state transition diagram of the bipolar converter is obtained as shown in FIG. 8, and the transition density matrix corresponding to FIG. 8 is denoted ABP2As shown in equation (24).
4.4) the overall transition density matrix is the sum of the transition density matrices in the two sub-cases.
ABP＝ABP1+ABP2
4.5) mixing A withBPSubstituting an equation (18) and an equation (19), obtaining steady-state probabilities corresponding to all the states of the bipolar converter, summing the probabilities of all the same capacity states to obtain the steady-state probabilities of different available capacity states, and calculating other reliability indexes; other reliability indicators include: transfer frequency, average duration, energy unavailability.
And adopting one or more of steady-state probability, transfer frequency, average duration and energy unavailability of different available capacity states to carry out reliability evaluation on the thyristor converter valve system in the ultra-high voltage direct current transmission project.
Claims (4)
1. The reliability analysis method of the thyristor converter valve system in the extra-high voltage direct current transmission project is characterized by comprising the following steps:
1) calculating the reliability of a single valve of a thyristor converter valve system in the extra-high voltage direct current transmission project;
2)12, calculating the reliability of the pulsating current converter;
3) calculating the reliability of the single-pole converter;
4) calculating the reliability of the bipolar converter to obtain an index capable of evaluating the reliability of the thyristor converter valve system of the ultra-high voltage direct current transmission project;
the step 1) specifically comprises the following steps: 1.1) acquiring failure rates of a thyristor, a damping resistor, a damping capacitor and a thyristor control unit TCU in a thyristor converter valve system of the extra-high voltage direct current transmission project; substituting thyristor failure rate lambdaThyDamping of failure rate of resistance
Damping capacitor failure rate
And failure rate λ of TCUTCUTo obtain the failure rate lambda of the thyristor levelTL：
1.2) substituting the number of thyristors of the single valve to obtain the integral reliability function of all thyristor levels in the single valve:
1.3) substituting the number and the failure rate of the saturable reactors of the single valve to obtain the integral reliability function of all the saturable reactors in the single valve:
1.4) obtaining a single valve reliability function and a single valve equivalent failure rate based on a redundant system model:
RSV(t)＝RTTL(t)·RTSR(t)
wherein a single valve has nTLAt the level of the individual thyristors, and at least k is requiredTLThe single thyristor level can work only when in a normal state; lambda [ alpha ]SRAnd nSRThe failure rate of the saturable reactor and the number of saturable reactors in the single valve are respectively;
the step 2) specifically comprises the following steps:
2.1) substitution statistics: failure rate lambda of internal water coolingICSExternal water cooling failure rate lambdaOCSFailure rate lambda with monitoring systemMCSTo obtain the equivalent failure rate lambda of a set of cooling systemCSO：
λCSO＝λICS+λOCS+λMCS
2.2) obtaining a reliability function and an equivalent failure rate of the whole cooling system under the consideration of the standby based on the redundancy system model:
2.3) substitution statistics: and (3) obtaining the failure rate of the valve base electrons, and obtaining the reliability function and the equivalent failure rate of the 12-pulse current converter:
wherein λ isVBEIs the failure rate of the valve base electronics.
2. The reliability analysis method for the thyristor converter valve system in the extra-high voltage direct current transmission project according to claim 1, wherein the step 3) specifically comprises the following steps:
3.1) substitution statistics: failure rate lambda of one set of unipolar control layerPCOAnd obtaining a reliability function and an equivalent failure rate of the whole unipolar control layer under consideration of standby:
3.2) analyzing all possible operation states of the single-pole converter and the transfer relation among different states to obtain a state transfer diagram of the single-pole converter, and obtaining a transfer density matrix A of the whole state transfer rate of the single-pole converter according to the state transfer diagram of the single-pole converterSPAs shown in formula (17):
3.3) obtaining the steady-state probability corresponding to each state of the monopole converter by the Markov process probability formulas (18) and (19) under the steady state, and calculating the equivalent state transition rate lambda after the states are combinedSPiAnd muSPi，i＝1,2,3,4：
The repair rate and the installation rate of the 12-pulse current converter are respectively muVBAnd gammaVBThe repair rate of the unipolar control layer is muPC。
3. The reliability analysis method for the thyristor converter valve system in the extra-high voltage direct current transmission project according to claim 2, wherein the step 4) specifically comprises the following steps:
4.1) substitution statistics: and the failure rate of one set of bipolar control layer obtains the reliability function and the equivalent failure rate of the whole bipolar control layer under the standby condition:
4.2) obtaining the state transition diagram 1 of the bipolar converter for the state transition caused by the faults of the 12-pulse converter, the bipolar control layer of the control system and the cooling system, wherein the corresponding transition density matrix is marked as ABP1As shown in formula (23):
4.3) obtaining a state transition diagram 2 of the bipolar converter for the state transition caused by the fault of the control layer of the unipolar control system, wherein the corresponding transition density matrix is marked ABP2As shown in formula (24):
4.4) the total transfer density matrix of the converter valve system is the sum of the transfer density matrices in the two sub-cases;
ABP＝ABP1+ABP2
4.5) mixing A withBPSubstituting an equation (18) and an equation (19), obtaining steady-state probabilities corresponding to all the states of the bipolar converter, and summing the probabilities of all the same capacity states to obtain the steady-state probabilities of different available capacity states; calculating other reliability indexes; other reliability indicators include: transfer frequency, average duration, energy unavailability;
λSCOfailure rate of a bipolar control layer.
4. The reliability analysis method for the extra-high voltage direct current transmission engineering thyristor converter valve system according to claim 3, characterized in that one or more of steady-state probability, transfer frequency, average duration and energy unavailability of different available capacity states are adopted to perform reliability evaluation on the extra-high voltage direct current transmission engineering thyristor converter valve system.
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