CN104166940A

CN104166940A - Method and system for assessing power distribution network operation risk

Info

Publication number: CN104166940A
Application number: CN201410309585.5A
Authority: CN
Inventors: 施慎行; 尚宇炜; 董新洲; 刘健
Original assignee: Tsinghua University; State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Shaanxi Electric Power Co Ltd
Current assignee: Tsinghua University; State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Shaanxi Electric Power Co Ltd
Priority date: 2014-07-01
Filing date: 2014-07-01
Publication date: 2014-11-26
Anticipated expiration: 2034-07-01
Also published as: CN104166940B

Abstract

The invention provides a method and a system for evaluating distribution network operation risks. The method comprises steps of determining fault state collection in a power distribution grid network, calculating the fault generation probability of each fault in the fault state collection, calculating the evaluation index value corresponding to each happened fault in the fault state collection according to a preset calculation rule, obtaining the risk evaluation index value of each fault according to the evaluation index value and the generation probability of each fault which are corresponding to each fault, and determining operation risk evaluation index value according to the risk evaluation index value of each fault. Correspondingly, the invention also provides a power distribution network operation risk evaluation system. Through the technical scheme, the invention can be adaptable to various practical needs to integrate, abstract and analyze the massive operation information in the power distribution network, and can enhance the control of the risk level.

Description

Power distribution network operation risk assessment method and evaluating system

Technical field

The present invention relates to technical field of power systems, in particular to a kind of power distribution network operation risk assessment method and a kind of power distribution network operation risk assessment system.

Background technology

Study of Risk Evaluation Analysis for Power System can be divided into Power System Planning risk assessment and Operation of Electric Systems risk assessment according to its assessment feature.Power System Planning risk assessment is used for analyzing the quality of different programmes, for Power System Planning and operation steady in a long-term provide instruction; Operation of Electric Systems risk assessment is on existing electrical network basis, utilize the information of system real time execution to provide assessment and early warning to the system operation risk in the current and following short time, operation risk assessment has been applied in power transmission network, has obtained good actual effect.

But compared with power transmission network, all there is difference the aspects such as the object that power distribution network is paid close attention in network topology structure, the method for operation, number of devices and traffic control, cause power distribution network also different from the method for the operation risk assessment of power transmission network.In recent years, the power distribution network scale of China is increasing, and network topology structure also becomes increasingly complex, and power supply reliability, the quality of power supply and the service quality requirement of people to power distribution network is more and more higher; In addition, power distribution network comprises distributed power source, microgrid and energy storage device etc., the power distribution situation of power distribution network is easily changed, dispatcher is difficult to grasp the variation that drops into, sends meritorious and reactive power, make the adjustment control of distribution circuit electric voltage very difficult, the generation of fault may change the failed shorted levels of current of expectation and affect voltage and the distribution of short-circuit current, and the potential operation risk of power distribution network is increased greatly.

Therefore, need a kind of new technical scheme, can adapt to different actual needs, help dispatcher to integrate, analyze, refine a large amount of operation information in power distribution network, important directive function is played in safe early warning and stable operation for power distribution network, and in providing fast every risk assessment index, guarantee the degree of accuracy of risk assessment, strengthen the control to risk level.

Summary of the invention

The present invention is just based on the problems referred to above, a kind of new technical scheme has been proposed, can adapt to different actual needs, help dispatcher to integrate, analyze, refine a large amount of operation information in power distribution network, important directive function is played in safe early warning and stable operation for power distribution network, and in providing fast every risk assessment index, guarantee the degree of accuracy of risk assessment, strengthen the control to risk level.

In view of this, the present invention proposes a kind of power distribution network operation risk assessment method, comprising: determine the malfunction set in power distribution network, according to default probability of malfunction assignment rule, calculate the probability that in described malfunction set, each fault occurs, according to default computation rule, calculate in described malfunction set evaluation index value corresponding when each fault occurs, and according to the probability of evaluation index value corresponding to described each fault and described each fault generation, obtain the risk assessment desired value of described each fault, wherein, described evaluation index value comprises overall operation desired value and individual event operating index value, described overall operation desired value comprises node voltage mean value specification value, described individual event operating index value comprises the too high more line desired value of node voltage, the too low more line desired value of node voltage, circuit transmission overload desired value and equipment operating overload desired value and mistake load index value, determine the operation risk assessment desired value of described power distribution network according to the risk assessment desired value of described each fault.

In this technical scheme, by brand-new probability of malfunction assignment rule is set, utilize Fault enumeration algorithm, the imaginary fault collection of Ergodic Theory, be multiplied by the probability of this fault generation by the operation risk desired value of fault, calculate fast out of order risk assessment desired value, the risk assessment desired value of stack gained is to obtain power distribution network operation risk assessment desired value, in having ensured risk assessment high-speed, also ensured the accuracy of assessment, widen usage range, strengthened the control to risk level, improved the safety coefficient of power distribution network.

Wherein, the node voltage mean value specification in overall operation index is for reflecting average voltage level and the residing degree of risk of power distribution network entirety of whole power distribution network operational process.In individual event operating index, the too high more line index of node voltage is for reflecting that operational system voltage exceedes the risk of setting limit, and the practical risk of its embodiment may cause protective relaying device action, or causes part electrical equipment to damage; Brownout is got over line index for reflecting that operational system voltage is lower than setting the risk of limit, the practical risk of its embodiment may be cause protective relaying device action, subregion overload to excise or distributed power source in islet operation state etc.; Circuit transmission overload index exceedes for the power that reflects the transmission of operational system circuit the risk that it can hold limit, and the practical risk of its embodiment may be the overload that causes protective relaying device action or subregion; Equipment operating overload index is damaged for reflecting the each transformer through-put power of power distribution network overload or causes the risk of self relay protection action.Lose load index, when examining important line fault, can corresponding dead electricity region turn and supply and restore electricity in the non-overloading situation of each circuit ensureing.

In technique scheme, preferably, described default probability of malfunction assignment rule specifically comprises: described malfunction set is divided into line fault collection and other fault collection, the probability that described line fault collection occurs is set to the first probability, the probability that described other fault collection occur is set to the second probability, wherein, described the first probability and described the second probability sum are 1; First probability of answering according to described line fault set pair, and described line fault concentrates the first ratio between the corresponding length of arbitrary circuit and the total length of all circuits that described line fault set pair is answered of arbitrary line fault, calculate the probability that described arbitrary line fault occurs; And second probability of answering according to described other fault set pairs, and described other faults concentrate the second ratio between the total long-term operating statistic probability of the every other fault that long-time running statistical probability corresponding to arbitrary other faults and described other fault set pairs answer, calculate the probability of described arbitrary other faults generations.

In this technical scheme, a kind of probability of malfunction assignment rule has been proposed, make risk assessment index there is stronger comparability under the different times of running of power distribution network, different operation topology.The traditional method that the probability occurring for fault carries out assignment is to carry out assignment according to the chromic trouble statistics of this element, this just causes the probability of malfunction summation difference of power distribution network under the different times of running, different operation topology, but the network operation topological structure of power distribution network is very flexible, not in the same time under, the not identical meeting of total failare probability of system causes cannot accurate comparison risk assessment index.Therefore, in the present invention, the probability sum that setting is broken down is always 1, think under any time that power distribution network can not be perfectly safe, in addition, for different network topologies, be fixed value 1 by total probability of malfunction sum is set, make risk assessment index under heterogeneous networks topology, still there is comparability, thereby the trend of reflected well power distribution network operation risk.Simultaneously, at the power distribution network of China, especially in urban power distribution network, underground cable just progressively replaces overhead transmission line, more than 80% underground cable coverage rate has been realized in urban, underground cable is subject to that the impact of the conditions such as weather is less, and its line fault probability is relatively fixing, has higher degree of accuracy with being uniformly distributed its line fault probability of simulation.

In technique scheme, preferably, for described evaluation index value arranges important level, and be that described evaluation index value arranges corresponding weighted value according to described important level.

In this technical scheme, be operation risk setup measures important level, can make power distribution network can inspiration under different working times and/or different topology structure revise important level and the respective weights of each operation risk index.Different power distribution networks due to towards terminal client difference, even if same power distribution network also may have different management objectives in the different times of running, for example, in the time that user participates in great social activities, power distribution network can be paid close attention to the reliability to this customer power supply, in addition, even if the operation conditions of power distribution network is identical, due to different outsides and/or internal factor, still can cause power distribution network to there is different degrees of risk.Therefore, set flexibly the important level of operation risk index, can adapt to the needs of power distribution network actual motion, increased the practicality of power distribution network assessment.

In technique scheme, preferably, by the weighted value of every operation risk index in power distribution network described in default disposal methods;

Described default disposal route comprises: according to the first default formula and the second default formula, the weighted value of described every operation risk index is carried out to matching, wherein: the first default formula is:

The second default formula is:

Wherein, in the time that operation risk index is node voltage index, a _maxfor upper critical value, a of described node voltage _minfor the lower critical value of described node voltage, q (x) _rise, q (x) _fallfor the weighted value of described node voltage, x is node voltage value, and k is for adjusting coefficient, A _rise, A _fall, B _rise, B _fallbe setting value, wherein, A _rise, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _rise, B _fallbe used for setting tolerance size;

In the time that operation risk index is the too high more line index of node voltage, a _maxfor the upper critical value of described node voltage, q (x) _risefor the weighted value of described node voltage, x is node voltage value, and k is for adjusting coefficient, A _rise, B _risebe setting value, wherein, A _risefor magnification function value, make functional value in [0.005,1] interval, B _risebe used for setting tolerance size;

In the time that operation risk index is the too low more line index of node voltage, a _minfor the lower critical value of described node voltage, q (x) _fallfor the weighted value of described node voltage, x is node voltage value, and k is for adjusting coefficient, A _fall, B _fallbe setting value, wherein, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _fallbe used for setting tolerance size;

In the time that operation risk index is circuit transmission overload index, a _maxfor upper critical value, a of circuit through-put power _minfor the lower critical value of described circuit through-put power, q (x) _rise, q (x) _fallfor the weighted value of described circuit through-put power, x is circuit transmission power value, and k is for adjusting coefficient, A _rise, A _fall, B _rise, B _fallbe setting value, wherein, A _rise, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _rise, B _fallbe used for setting tolerance size;

In the time that operation risk index is equipment operating overload index, a _maxfor upper critical value, a of equipment operate power _minfor the lower critical value of described equipment operate power, q (x) _rise, q (x) _fallfor the weighted value of described equipment operate power, x is equipment operate power value, and k is for adjusting coefficient, A _rise, A _fall, B _rise, B _fallbe setting value, wherein, A _rise, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _rise, B _fallbe used for setting tolerance size;

When operation risk index is while losing load index, a _maxfor the upper critical value of circuit through-put power, q (x) _risefor the weighted value of described circuit through-put power, x is circuit transmission power value, and k is for adjusting coefficient, A _rise, B _risebe setting value, wherein, A _risefor magnification function value, make functional value in [0.005,1] interval, B _risebe used for setting tolerance size.

In this technical scheme, taking the too high more line index of node voltage as example, the out-of-limit voltage of node of finally selecting is to compare and obtain with the critical value of setting, when certain node voltage approaches and during lower than critical value, traditional this voltage of method general estimation is normal, overtension is got over to line index not to be contributed, though but this node voltage is lower than critical point, but be positioned at Near The Critical Point, although this voltage contribution weight that other node voltages are got over line index to final overtension is relatively slightly low, but really also there is a small amount of contribution, cast out simply it and can reduce computational accuracy, obviously be irrational, so address the above problem by Determination of Membership Function in fuzzy mathematics, can ensure the degree of accuracy of risk assessment.

In technique scheme, preferably, the computing formula of described node voltage mean value specification value is:

The too low more computing formula of line desired value of described node voltage is:

The too high more computing formula of line desired value of described node voltage is:

Wherein, U _avgfor the mean value of described node voltage, U _overvoltage for described node voltage during higher than described critical value, U _lowervoltage for described node voltage during lower than described critical value, q (x) _{rise θ}, q (x) _{θ falls}for the described weighted value of described node voltage, pi is the probability that in described malfunction set, arbitrary circuit or equipment i break down, Wi is the important level of circuit or fault i, and θ is numbering corresponding to all described nodes under described arbitrary circuit or equipment i malfunction, U _{superpotential node θ meter} _{calculation value}for the magnitude of voltage higher than standard voltage value in all described node voltages, U _{lower voltage node θ calculated value}for the magnitude of voltage lower than standard voltage value in all described node voltages, U _{superpotential critical value}for default overtension critical value, U _{low-voltage critical value}for default brownout critical value,

The computing formula of described circuit transmission overload desired value is:

Wherein, Lover is the through-put power that exceedes through-put power ratings in circuit transmitting procedure, and q (x) rises the described weighted value that θ is circuit through-put power, and pi is the probability that arbitrary circuit described in described malfunction set or equipment i occur, W _ifor the important level of described arbitrary circuit or equipment i, θ is numbering corresponding to all described circuits under described arbitrary circuit or equipment i malfunction, I _{overload circuit θ calculated value}for through-put power is greater than the through-put power of the circuit of the described through-put power ratings of described circuit; I _{the effective limit of circuit θ}for the described through-put power ratings of described circuit,

The computing formula of described equipment operating overload desired value is:

Wherein, E _overfor exceeding the operate power of operate power ratings in equipment running process, q (x) _{rise θ}for the weighted value of equipment operate power, pi is the probability that in described malfunction set, arbitrary circuit or equipment i break down, Wi is the important level of described arbitrary circuit or equipment i, and θ is numbering corresponding to all described equipment under described arbitrary circuit or equipment i malfunction, S _{overload equipment θ calculated value}for operate power is greater than the operate power of the equipment of the described operate power ratings of described equipment; S _{the effective limit of equipment θ}refer to the described operate power ratings of described equipment;

The computing formula of described mistake load index value is:

Can wherein, θ represents specified stoppage in transit circuit, by supposing described stoppage in transit circuit line fault stoppage in transit, assess corresponding dead electricity region and ensure that each circuit turn the in the situation that of there is not overload for load, restore electricity, L _lossthe payload of distribution system loss while exiting for described stoppage in transit circuit θ, i represents to provide the circuit number of load transfer; W _ifor the important level of circuit i of load transfer is provided; C _{the current capacity of i}for circuit i provides the power transmitting after described load transfer; C _{i design capacity}for the specified through-put power size of circuit i.

In this technical scheme, all faults in malfunction set are traveled through, calculate out of order node voltage mean value specification value, the too high more line of node voltage desired value, the too low more line of node voltage desired value, circuit transmission overload desired value and equipment operating overload desired value, the risk assessment desired value of each fault in malfunction set is added, just can draws power distribution network operation risk assessment desired value.Like this, can provide quickly and accurately detailed every risk assessment index of each fault, the degree of accuracy of the power distribution network risk assessment greatly improving, in addition, can also be according to different actual needs, revise flexibly the important level of each risk assessment index of each fault, practicality and the dirigibility of power distribution network risk assessment are greatly improved, widen usage range, strengthened the control to risk level, improved the safety coefficient of power distribution network.

According to a further aspect in the invention, also provide a kind of power distribution network operation risk assessment system, having comprised: determining unit, for determining the malfunction set of power distribution network, the first computing unit, according to default probability of malfunction assignment rule, calculates the probability that in described malfunction set, each fault occurs, the second computing unit, according to default computation rule, corresponding evaluation index value while calculating each fault in described malfunction set, the probability occurring by evaluation index value corresponding to described each fault and described each fault, obtain the risk assessment desired value of described each fault, wherein, described evaluation index value comprises overall operation desired value and individual event operating index value, wherein, described overall operation desired value comprises node voltage mean value specification value, described individual event operating index value comprises the too high more line desired value of node voltage, the too low more line desired value of node voltage, circuit transmission overload desired value and equipment operating overload desired value, the 3rd computing unit, determines the operation risk assessment desired value of described power distribution network according to the risk assessment desired value of described each fault.

In technique scheme, preferably, described the first computing unit specifically for: described malfunction set is divided into line fault collection and other fault collection, the probability that described line fault collection occurs is set to the first probability, the probability that described other fault collection occur is set to the second probability, wherein, described the first probability and described the second probability sum are 1; First probability of answering according to described line fault set pair, and described line fault concentrates the first ratio between the corresponding length of arbitrary circuit and the total length of all circuits that described line fault set pair is answered of arbitrary line fault, calculate the probability that described arbitrary line fault occurs; And second probability of answering according to described other fault set pairs, and described other faults concentrate the second ratio between the total long-term operating statistic probability of the every other fault that long-time running statistical probability corresponding to arbitrary other faults and described other fault set pairs answer, calculate the probability of described arbitrary other faults generations.

In technique scheme, preferably, also comprise: the second setting unit, for described evaluation index value arranges important level, and the 3rd setting unit, be that described evaluation index value arranges corresponding weighted value according to described important level.

In technique scheme, preferably, also comprise: critical numerical value processing unit, by the weighted value of every operation risk index in power distribution network described in default disposal methods;

The second default formula is:

Wherein, in the time that operation risk index is node voltage mean value specification, a _maxfor upper critical value, a of described node voltage _minfor the lower critical value of described node voltage, q (x) _rise, q (x) _fallfor the weighted value of described node voltage, x is node voltage value, and k is for adjusting coefficient, A _rise, A _fall, B _rise, B _fallbe setting value, wherein, A _rise, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _rise, B _fallbe used for setting tolerance size;

Wherein, U _avgfor the mean value of described node voltage, U _overvoltage for described node voltage during higher than described critical value, U _lowervoltage for described node voltage during lower than described critical value, q (x) _{rise θ},

Q (x) _{θ falls}for the described weighted value of described node voltage, pi is the probability that in described malfunction set, arbitrary circuit or equipment i break down, Wi is the important level of circuit or fault i, and θ is numbering corresponding to all described nodes under described arbitrary circuit or equipment i malfunction, U _{superpotential node θ calculated value}for the magnitude of voltage higher than standard voltage value in all described node voltages, U _{lower voltage node θ calculated value}for the magnitude of voltage lower than standard voltage value in all described node voltages, U _{superpotential critical value}for default overtension critical value, U _{low-voltage critical value}for default brownout critical value,

Wherein, L _overfor exceeding the through-put power of through-put power ratings in circuit transmitting procedure, q (x) _{rise θ}for the weighted value of described circuit through-put power, pi is the probability that arbitrary circuit described in described malfunction set or equipment i occur, Wi is the important level of described arbitrary circuit or fault i, and θ is numbering corresponding to all described circuits under described arbitrary circuit or equipment i malfunction, I _{overload circuit θ calculated value}for through-put power is greater than the through-put power of the circuit of the described through-put power ratings of described circuit; I _{the effective limit of circuit θ}for the described through-put power ratings of described circuit,

Wherein, E _overfor exceeding the operate power of operate power ratings in equipment running process, q (x) _{rise θ}for the weighted value of described equipment operate power, pi is the probability that in described malfunction set, arbitrary circuit or equipment i break down, Wi is the important level of described arbitrary circuit or equipment i, and θ is numbering corresponding to all described equipment under described arbitrary circuit or equipment i malfunction, S _{overload equipment θ calculated value}for operate power is greater than the operate power of the equipment of the described operate power ratings of described equipment; S _{the effective limit of equipment θ}refer to the described operate power ratings of described equipment;

The computing formula of described mistake load index value is:

By above technical scheme, can be according to different power distribution networks or same power distribution network the actual needs in different working times, can revise flexibly the important level of each risk indicator, and can be respectively provide the risk level of system from entirety and/or single index, help dispatcher to integrate, analyze, refine a large amount of operation information in power distribution network, important directive function is played in safe early warning and stable operation for power distribution network, and in providing fast every risk assessment index, guarantee the degree of accuracy of risk assessment, strengthen the control to risk level.

Brief description of the drawings

Fig. 1 shows the process flow diagram of power distribution network operation risk assessment method according to an embodiment of the invention;

Fig. 2 shows the particular flow sheet of power distribution network operation risk assessment method according to an embodiment of the invention;

Fig. 3 shows the block diagram of power distribution network operation risk assessment device according to an embodiment of the invention;

Fig. 4 shows the calculation flow chart of power distribution network operation risk assessment method according to another embodiment of the invention;

Fig. 5 shows the power distribution network 33 node distribution system schematic diagram of power distribution network operation risk assessment method according to another embodiment of the invention.

Embodiment

In order more clearly to understand above-mentioned purpose of the present invention, feature and advantage, below in conjunction with the drawings and specific embodiments, the present invention is further described in detail.It should be noted that, in the situation that not conflicting, the feature in the application's embodiment and embodiment can combine mutually.

A lot of details are set forth in the following description so that fully understand the present invention; but; the present invention can also adopt other to be different from other modes described here and implement, and therefore, protection scope of the present invention is not subject to the restriction of following public specific embodiment.

Fig. 1 shows the process flow diagram of power distribution network operation risk assessment method according to an embodiment of the invention.

As shown in Figure 1, power distribution network operation risk assessment method according to an embodiment of the invention, comprises the following steps:

Step 102, determines the malfunction set in power distribution network;

Step 104, according to default probability of malfunction assignment rule, calculates the probability that in malfunction set, each fault occurs;

Step 106, according to default computation rule, calculates in malfunction set evaluation index value corresponding when each fault occurs, and according to the probability that evaluation index value corresponding to each fault and each fault occur, obtains the risk assessment desired value of each fault;

Step 108, determines the operation risk assessment desired value of power distribution network according to the risk assessment desired value of each fault.

In technique scheme, preferably, default probability of malfunction assignment rule specifically comprises: malfunction set is divided into line fault collection and other fault collection, the probability that line fault collection occurs is set to the first probability, the probability that other fault collection occur is set to the second probability, wherein, the first probability and the second probability sum are 1; First probability of answering according to line fault set pair, and line fault concentrates the first ratio between the corresponding length of arbitrary circuit and the total length of all circuits that line fault set pair is answered of arbitrary line fault, calculates the probability that arbitrary line fault occurs; And second probability of answering according to other fault set pairs, and other faults concentrate the second ratio between the total long-term operating statistic probability of the every other fault that long-time running statistical probability corresponding to arbitrary other faults and other fault set pairs answer, calculate the probability of arbitrary other faults generations.

In technique scheme, preferably, for evaluation index value arranges important level, and be that evaluation index value arranges corresponding weighted value according to important level.

The second default formula is:

In technique scheme, preferably, the computing formula of node voltage mean value specification value is:

The too low more computing formula of line desired value of node voltage is:

The too high more computing formula of line desired value of node voltage is:

Wherein, U _avgfor the mean value of node voltage, U _overvoltage for node voltage during higher than critical value, U _lowervoltage for node voltage during lower than critical value, q (x) _{rise θ}, q (x) _{θ falls}for the weighted value of node voltage, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of arbitrary circuit or fault i, and θ is numbering corresponding to all described nodes under described arbitrary circuit or equipment i malfunction, U _{superpotential node θ calculated value}for the magnitude of voltage higher than standard voltage value in all node voltages, U _{lower voltage node θ calculated value}for the magnitude of voltage lower than standard voltage value in all node voltages, U _{superpotential is critical} _valuefor default overtension critical value, U _{low-voltage critical value}for default brownout critical value,

The computing formula of circuit transmission overload desired value is:

Wherein, L _overfor exceeding the through-put power of through-put power ratings in circuit transmitting procedure, q (x) _{rise θ}for the weighted value of circuit through-put power, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of described arbitrary circuit or fault i, and θ is numbering corresponding to all circuits under arbitrary circuit or equipment i malfunction, I _{overload circuit} _{θ calculated value}for through-put power is greater than the through-put power of the circuit of the through-put power ratings of circuit; I _{the effective limit of circuit θ}for the through-put power ratings of circuit,

The computing formula of equipment operating overload desired value is:

Wherein, E _overfor exceeding the operate power of operate power ratings in equipment running process, q (x) _{rise θ}for the weighted value of equipment operate power, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of described arbitrary circuit or equipment i, and θ is numbering corresponding to all devices under arbitrary circuit or equipment i malfunction, S _{overload equipment} _{θ calculated value}for operate power is greater than the operate power of the equipment of the operate power ratings of equipment; S _{the effective limit of equipment θ}the operate power ratings of finger equipment;

The computing formula of described mistake load index value is:

Fig. 2 shows the particular flow sheet of power distribution network operation risk assessment method according to an embodiment of the invention.

As shown in Figure 2, power distribution network operation risk assessment method according to an embodiment of the invention, specifically comprises the following steps:

Step 202, determines malfunction set and probability of malfunction assignment rule;

Step 204, according to probability of malfunction assignment rule, the probability that the probability that line fault is occurred and other faults occur respectively assignment is p, q, makes p+q=1, total probability of malfunction sum is set is fixed value 1, makes risk assessment index under heterogeneous networks topology, still have comparability;

Step 206, whether failure judgement i is line fault, when judged result is when being, enters step 208, when judged result is while being no, fault i is other faults, enters step 210;

Step 208, making the total line length that in malfunction set, all line fault elements are corresponding is L _sum, the length that records the circuit at fault i place is L _i, the probability that fault i occurs is p _i=pL _i/ L _sum;

Step 210, establishes in other faults and comprises m the element that may break down, and the substance probability of malfunction of this m element is designated as respectively to q ₁, q ₂..., q _m, meanwhile, by element manufacturing specification or the long-term observation to this m element, the long-time running statistical probability that this m element is broken down is designated as a ₁, a ₂..., a _m, (probability that i ∈ m) occurs is fault i

q_{i} = q \frac{a_{i}}{Σ_{i = 1}^{m} a_{i}};

Step 212, for operation risk setup measures important level, comprise particular importance, important and important, and be the weighted value that operation risk setup measures is corresponding according to important level, particular importance, weighted value important, important correspondence are set to respectively to 5,2,1;

Step 214, by the weighted value of every operation risk index in power distribution network described in default disposal methods;

The second default formula is:

Step 216, calculate respectively the operation risk desired value of fault i, operation risk desired value comprises node voltage mean value specification value, the too high more line of node voltage desired value, the too low more line of node voltage desired value, circuit transmission overload desired value and/or equipment operating overload desired value:

The computing formula of node voltage mean value specification value is:

The too low more computing formula of line desired value of node voltage is:

The too high more computing formula of line desired value of node voltage is:

Wherein, U _avgfor the mean value of node voltage, U _overvoltage for node voltage during higher than critical value, U _lowervoltage for node voltage during lower than critical value, q (x) _{rise θ}, q (x) _{θ falls}for the weighted value of node voltage, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of circuit or fault i, and θ is numbering corresponding to all described nodes under described arbitrary circuit or equipment i malfunction, U _{superpotential node θ calculated value}for the magnitude of voltage higher than standard voltage value in all node voltages, U _{lower voltage node θ calculated value}for the magnitude of voltage lower than standard voltage value in all node voltages, U _{superpotential critical value}for default overtension critical value, U _{low-voltage critical value}for default brownout critical value,

The computing formula of circuit transmission overload desired value is:

Wherein, Lover is the through-put power that exceedes through-put power ratings in circuit transmitting procedure, q (x) _{rise θ}for the weighted value of circuit through-put power, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of described arbitrary circuit or fault i, and θ is numbering corresponding to all circuits under arbitrary circuit or equipment i malfunction, I _overload _{circuit θ calculated value}for through-put power is greater than the through-put power of the circuit of the through-put power ratings of circuit; I _{the effective limit of circuit θ}for the through-put power ratings of circuit,

The computing formula of equipment operating overload desired value is:

Wherein, Eover is the operate power that exceedes operate power ratings in equipment running process, q (x) _{rise θ}for the weighted value of equipment operate power, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of described arbitrary circuit or equipment i, and θ is numbering corresponding to all devices under arbitrary circuit or equipment i malfunction, S _overload _{equipment θ calculated value}for operate power is greater than the operate power of the equipment of the operate power ratings of equipment; S _{the effective limit in equipment θ road}the operate power ratings of finger equipment;

The computing formula of described mistake load index value is:

Step 218, is multiplied by the probability of fault i generation by the operation risk desired value of fault i, obtain the ultimate risk evaluation index value of fault i:

R _isk(x,t)＝∑p _i×V _i

Wherein, R _isk(x, t) refers in the time of t and inscribes, and for the risk assessment numerical value of index x, x can be node voltage mean value specification, the too high more line of node voltage index, the too low more line of node voltage index, circuit transmission overload index and/or equipment operating overload index, p _ifor the probability of the i that breaks down; V _ifor breaking down after i, the order of severity size that fault i causes system, i.e. various risk assessment desired values, comprise node voltage mean value specification value V (U _avg), the too high more line desired value V (U of node voltage _over), the too low more line desired value V (U of node voltage _lower), circuit transmission overload desired value V (L _over) and/or equipment operating overload desired value V (E _over);

Step 220, travels through all faults in malfunction set, when all faults being gone through all over after completing, the risk assessment desired value of each fault is added, and obtains power distribution network operation risk assessment desired value R=∑ R _isk(x, t).

In this technical scheme, by brand-new probability of malfunction assignment rule is set, utilize Fault enumeration algorithm, the imaginary fault collection of Ergodic Theory, be multiplied by the probability of this fault generation by the operation risk desired value of fault, calculate fast out of order risk assessment desired value, the risk assessment desired value of stack gained is to obtain power distribution network operation risk assessment desired value, can be according to different power distribution networks or same power distribution network the actual needs in different working times, can revise flexibly the important level of each risk indicator, and can be respectively provide the risk level of system from entirety and/or single index, help dispatcher to integrate, analyze, refine a large amount of operation information in power distribution network, important directive function is played in safe early warning and stable operation for power distribution network, and in providing fast every risk assessment index, guarantee the degree of accuracy of risk assessment, strengthen the control to risk level.

Fig. 3 shows the block diagram of power distribution network operation risk assessment device according to an embodiment of the invention.

As shown in Figure 3, power distribution network operation risk assessment device 300 according to an embodiment of the invention, comprising: determining unit 302, for determining the malfunction set of power distribution network; The first computing unit 304, according to default probability of malfunction assignment rule, calculates the probability that in malfunction set, each fault occurs; The second computing unit 306, according to default computation rule, corresponding evaluation index value while calculating each fault in malfunction set, with the probability of evaluation index value corresponding to each fault and the generation of each fault, obtains the risk assessment desired value of each fault; The 3rd computing unit 308, determines the operation risk assessment desired value of power distribution network according to the risk assessment desired value of each fault.

In technique scheme, preferably, the first computing unit specifically for: malfunction set is divided into line fault collection and other fault collection, the probability that line fault collection occurs is set to the first probability, the probability that other fault collection occur is set to the second probability, wherein, the first probability and the second probability sum are 1; First probability of answering according to line fault set pair, and line fault concentrates the first ratio between the corresponding length of arbitrary circuit and the total length of all circuits that line fault set pair is answered of arbitrary line fault, calculates the probability that arbitrary line fault occurs; And second probability of answering according to other fault set pairs, and other faults concentrate the second ratio between the total long-term operating statistic probability of the every other fault that long-time running statistical probability corresponding to arbitrary other faults and other fault set pairs answer, calculate the probability of arbitrary other faults generations.

In technique scheme, preferably, also comprise: the second setting unit 310, for evaluation index value arranges important level, and the 3rd setting unit 312, be that evaluation index value arranges corresponding weighted value according to important level.

In technique scheme, preferably, also comprise: 314 critical numerical value processing units, by the weighted value of every operation risk index in power distribution network described in default disposal methods;

The second default formula is:

The too low more computing formula of line desired value of node voltage is:

The too high more computing formula of line desired value of node voltage is:

The computing formula of circuit transmission overload desired value is:

The computing formula of equipment operating overload desired value is:

Wherein, Eover is the operate power that exceedes operate power ratings in equipment running process, q (x) _{rise θ}for the weighted value of equipment operate power, pi is the probability that in malfunction set, arbitrary circuit or equipment i break down, and Wi is the important level of described arbitrary circuit or equipment i, and θ is numbering corresponding to all devices under arbitrary circuit or equipment i malfunction, S _overload _{equipment θ calculated value}for operate power is greater than the operate power of the equipment of the operate power ratings of equipment; S _{the effective limit of equipment θ}the operate power ratings of finger equipment;

The computing formula of described mistake load index value is:

Fig. 4 shows the calculation flow chart of power distribution network operation risk assessment method according to another embodiment of the invention.

As shown in Figure 4, the power distribution network operation risk assessment method of another embodiment according to an embodiment of the invention, comprises the following steps:

Step 402, the each node electric parameters of input power distribution network is calculated current trend, the large Small Indicators of input weight;

Step 404, determines the malfunction set { L of power distribution network ₁, L ₂..., L _n, O _n+1, O _n+2..., O _n+m, wherein, L refers to line fault element; N refers to total n bar branch road, and O refers to other fault elements, and as the transformer in distribution etc., m refers to that total m element has the possibility of other faults of generation;

Step 406, according to probability of malfunction assignment rule, the probability assignment that the each fault in malfunction set is occurred;

Step 408, enumerates respectively substance faults all in malfunction set, makes i=0;

Step 410, under certain malfunction i, power distribution network is by the mode of regulation and control part disconnector, interconnection switch etc., use has the application software (NOR) that realizes network reconfiguration function, switch by the real power distribution network running status of this software simulation, manage grid optimization and reconstruct, obtain new network topology, to shorten as much as possible user's power off time;

Step 412, calculates new network topology trend;

Step 414, the risk assessment desired value of each fault in the set of calculating malfunction;

Step 416, judges whether to travel through all elements in malfunction set, when judged result is while being no, enters step 418, when judged result is when being, enters step 420;

Step 418, makes i=i+1, returns to step 410, proceeds the calculating of next fault element;

Step 420, is added the risk assessment desired value of each fault, obtains power distribution network operation risk assessment desired value.

In the technical program, the randomness occurring for fault in power distribution network, design a kind of power distribution network operation risk assessment method based on Fault enumeration algorithm, taking all devices in the circuit that contains protective relaying device and power distribution network as malfunction set, all substance faults in the set of traversal malfunction, help dispatcher to integrate, analyze, refine a large amount of operation information in power distribution network, important directive function is played in safe early warning and stable operation for power distribution network, finally calculate power distribution network operation risk assessment index, and in providing fast every risk assessment index, guarantee the degree of accuracy of risk assessment, strengthen the control to risk level.

Power distribution network 33 node distribution systems as shown in Figure 5, in this net, there are 32 branch roads, 5 interconnection switch branch roads (shown in dotted line), 1 electric power network head end reference voltage 12.66kV, the accurate value of three phase power to get 10MVA, network total load 5084.26+j2547.32kVA, node numeral node number, corresponding node has the load of different sizes.When after certain line fault in power distribution network, corresponding interconnection switch can move, and recovers the power supply of faulty line two end nodes.

Table 1 shows the node load table of power distribution network 33 node distribution systems.

Table 1

Nonserviceable set in comprised 10,15,20 Nodes 3 common transformer, the probability of malfunction under 3 transformer long-time running is identical; Have a photovoltaic generation to access this power distribution network at 15 nodes, calculate the moment at operation risk assessment, its capacity is set as 230KVA; All circuits are underground cable, and 0-1,1-2,2-3,3-4,4-5 line length are 1km, 5-6,6-7,7-8 ..., 31-32 line length is 2km; In power distribution network, overtension critical value is made as 1.05p.u., and brownout critical value is made as 0.93p.u.; Power distribution network obtains the electric current and voltage situation of each node in real time, for the node that cannot obtain or region, obtains the parameters such as this node voltage electric current by method of estimation; When power distribution network line fault, system can be by the power supply of cut-offfing combination and recovering faulty line of interconnection switch etc.; In the time of certain line fault, establishing node corresponding to circuit two ends is i, i+1, and two nearest node j of node of distance have interconnection switch for action, recover rapidly the power supply between malfunctioning node i and i+1.

Establish according to above-mentioned condition, probability of malfunction distributes only relevant with line length, meanwhile, other fault elements contain 3 common transformer equipment, and the total failare probability of setting 3 common transformer is 0.2, long-term observation data show, 3 transformer fault probability are identical, 3 transformer weighteds, and node 10 place's transformer weights are 5, node 15 place's transformer weights are 2, and node 20 place's transformer weights are 2; Therefore, the probability of malfunction of node 10,15,20 place's transformers is respectively by following 3 formula gained:

The general probability of line failure is 0.8, unit length circuit probability of happening is 0.8/ (5 × 1+27 × 2)=0.01355932203, each circuit is multiplied by line length with unit length circuit probability of happening and is this line failure probability, for example, the probability of 1-2 line failure is 0.01355932203 × 1=0.01355932203.

Obtain in real time the information such as electric current and voltage of distribution by the sensor in power distribution network, carry out trend and calculate emulation, obtain the Power Flow Information such as the electric current and voltage of each node and the power of each circuit transmission; The present embodiment, by matlab software programming risk assessment algorithm, is realized trend calculating by calling matpower software package.

Under normal circumstances, calculate and obtain power distribution network operation information by trend, enumerate following information:

In each node, voltage minimum is 0.913p.u., and node number is 18; Voltage mxm. is 1p.u., and node number is 1;

Malfunction set is carried out to fault traversal, an element fault in each assumed fault state set, if this line fault does not directly cause the each load bus dead electricity of distribution network systems, illustrate that the topology of now distribution does not change, the distribution trend of directly carrying out after fault is calculated; Otherwise the relevant needs such as interconnection switch, block switch action restores electricity to ensure faulty line two end nodes, and then, calculate the system load flow changing in situation in distribution, calculate corresponding risk factors value V according to the computing formula of each index _i;

Provide respectively 5-6 line fault below, and when node 10 place transformer fault, computing method and the process of node voltage average risk indicator; Other each individual event operating index are undertaken by identical method

In the time of 5-6 line fault,

1) 5-6 line fault probability P _5-6be 0.02711864406;

2), by calculating, after fault, 0～No. 32 node voltage perunit value is respectively: 1.0000,0.9971,0.9876,0.9835,0.9796,0.9697,0.9518,0.9529,0.9476,0.9427,0.9420,0.9409,0.9360,0.9342,0.9333,0.9326,0.9306,0.9302,0.9950,0.9773,0.9723,0.9717,0.9840,0.9774,0.9741,0.9679,0.9653,0.9542,0.9461,0.9426,0.9386,0.9377,0.9374;

3) corresponding node voltage average risk indicator is when 5-6 circuit substance fault:

Wherein, circuit 5-6 weights W _5-6be 1, q (x) _rise, q (x) _fallcorresponding formula (7) (8), and A in this example respectively _rise, A _fall, B _rise, B _fallget respectively 4000,4000,0.99,1.02;

In the time of No. 10 Nodes transformer faults,

1) No. 10 Nodes transformer fault probability P ₁₀be 0.1111111, weights W ₁₀be 5;

2), after fault, 0～No. 32 node voltage perunit value is respectively: 1.0000,0.9971,0.9833,0.9760,0.9688,0.9509,0.9477,0.9432,0.9375,0.9323,0.9316,0.9303,0.9242,0.9219,0.9205,0.9192,0.9171,0.9167,0.9966,0.9930,0.9923,0.9916,0.9797,0.9730,0.9697,0.9490,0.9465,0.9350,0.9268,0.9233,0.9191,0.9182,0.9179;

3) No. 10 Nodes transformer substance faults, institute's computing node average voltage risk single index numerical value is:

Wherein, q (x) _rise, q (x) _fallcorresponding formula (7) (8) respectively, A in example _rise, A _fall, B _rise, B _fallvalue keeps identical with the value of computational scheme 5-6 fault in A;

Wherein, lose load index, when examining important line fault, can corresponding dead electricity region turn and supply and restore electricity in the non-overloading situation of each circuit ensureing.The object of its examination is critical circuits, specifically specifies according to dispatcher's needs.Following Fig. 5 is example, supposes the line failure between node 15,16, and the interconnection switch between 17,32 nodes should transfer UNICOM's state to by disconnection and turn for loop to provide.And then, calculate the topological trend after changing, judgement provides to turn for circuit whether circuit overload operation occurs.If there is running overload, think that load cannot normally turn confession, losing Load Probability is maximal value 1; Otherwise, ensureing that circuit not under the condition of overload, calculates the surplus turning for load circuit is provided, surplus is larger, and corresponding operation risk is less, and the index value calculating is the closer to 0; Surplus is less, and corresponding risk is larger, and numerical value is the closer to 1.The concrete mode of judging circuit surplus as, suppose that the design capacity of this circuit is " 1 " and operation value is " 0.6 ", provide that to turn for rear surplus be " 0.9 ",

Surplus is (1-0.9)/1=10%.And then, utilize membership function to obtain corresponding value-at-risk to 10% quantification, then all circuit value-at-risks that turn for branch road that provide are added, obtain the final loss load index about circuit i.

Specific formula for calculation is:

In above formula, footmark x represents specified critical circuits; Footmark i represents to provide the circuit that turns confession.Concrete, in programming process, in order to save operand, should consider effective " turning for circuit way of search ".Its concrete meaning is, because this index is that certain given line of assessment breaks down in situation, provide the adjacent lines turning for path whether overladen risk can occur, thereby, in specific implementation process, supply the node in path as root node to provide to turn, root node is searched for toward the circuit of upstream thus, until search changes and is less than 0.1p.u. (described 0.1p.u. can be set by user) to the transmission current of its upstream circuit, and this transmission current does not enter the region of overload risk, stop search, according to formula (1), the circuit of having searched for is turned for risk and added up.Further, while adopting multiple interconnection switches to carry out load transfer in order to solve, taking the common root node mutually that had as unit simultaneously, search for all line current situations of change in this region, when transmission current is less than 0.1p.u. ampere-hour, think and do not change, be not counted in to turn in index and go; Otherwise the circuit that curent change occurs is counted in final evaluation index.

4) according to 3) step, calculate successively in failure collection other substance fault indices, the summation that finally adds up, draws finish node average voltage risk indicator, other indexs are also carried out according to identical algorithms.

In the present invention, term " first ", " second ", " the 3rd " only object for describing, and can not be interpreted as instruction or hint relative importance.

More than be described with reference to the accompanying drawings technical scheme of the present invention, by technical scheme of the present invention, can be according to different power distribution networks or same power distribution network the actual needs in different working times, can revise flexibly the important level of each risk indicator, and can be respectively provide the risk level of system from entirety and/or single index, help dispatcher to integrate, analyze, refine a large amount of operation information in power distribution network, important directive function is played in safe early warning and stable operation for power distribution network, and in providing fast every risk assessment index, guarantee the degree of accuracy of risk assessment, strengthen the control to risk level.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims

1. a power distribution network operation risk assessment method, is characterized in that, comprising:

Determine the malfunction set in power distribution network;

According to default probability of malfunction assignment rule, calculate the probability that in described malfunction set, each fault occurs;

According to default computation rule, calculate in described malfunction set evaluation index value corresponding when each fault occurs, and according to the probability of evaluation index value corresponding to described each fault and described each fault generation, obtain the risk assessment desired value of described each fault, wherein, described evaluation index value comprises overall operation desired value and individual event operating index value, described overall operation desired value comprises node voltage mean value specification value, described individual event operating index value comprises the too high more line desired value of node voltage, the too low more line desired value of node voltage, circuit transmission overload desired value and equipment operating overload desired value and mistake load index value,

Determine the operation risk assessment desired value of described power distribution network according to the risk assessment desired value of described each fault.

2. power distribution network operation risk assessment method according to claim 1, is characterized in that, described default probability of malfunction assignment rule specifically comprises:

Described malfunction set is divided into line fault collection and other fault collection, the probability that described line fault collection occurs is set to the first probability, the probability that described other fault collection occur is set to the second probability, and wherein, described the first probability and described the second probability sum are 1;

First probability of answering according to described line fault set pair, and described line fault concentrates the first ratio between the corresponding length of arbitrary circuit and the total length of all circuits that described line fault set pair is answered of arbitrary line fault, calculate the probability that described arbitrary line fault occurs; And

Second probability of answering according to described other fault set pairs, and described other faults concentrate the second ratio between the total long-term operating statistic probability of the every other fault that long-time running statistical probability corresponding to arbitrary other faults and described other fault set pairs answer, calculate the probability of described arbitrary other faults generations.

3. power distribution network operation risk assessment method according to claim 1, is characterized in that, also comprises:

For described evaluation index value arranges important level, and

Be that described evaluation index value arranges corresponding weighted value according to described important level.

4. power distribution network operation risk assessment method according to claim 3, is characterized in that, also comprises:

By the weighted value of every operation risk index in power distribution network described in default disposal methods;

Described default disposal route comprises:

According to the first default formula and the second default formula, the weighted value of described every operation risk index is carried out to matching, wherein: the first default formula is:

The second default formula is:

In the time that operation risk index is circuit transmission overload index, a _maxfor upper critical value, a of circuit through-put power _minfor the lower critical value of described circuit through-put power, q (x) _rise, q (x) _fallfor the weighted value of described circuit through-put power, x is circuit transmission power value, and k is for adjusting coefficient, A _rise, A _fall, B _rise, B _fallbe setting value, wherein, A _rise, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _rise, B _fallbe used for setting tolerance size; In the time that operation risk index is equipment operating overload index, a _maxfor upper critical value, a of equipment operate power _minfor the lower critical value of described equipment operate power, q (x) _rise, q (x) _fallfor the weighted value of described equipment operate power, x is equipment operate power value, and k is for adjusting coefficient, A _rise, A _fall, B _rise, B _fallbe setting value, wherein, A _rise, A _fallfor magnification function value, make functional value in [0.005,1] interval, B _rise, B _fallbe used for setting tolerance size;

When operation risk index is while losing load index, a _maxfor the upper critical value of circuit through-put power, _q(x) _risefor the weighted value of described circuit through-put power, x is circuit transmission power value, and k is for adjusting coefficient, A _rise, B _risebe setting value, wherein, A _risefor magnification function value, make functional value in [0.005,1] interval, B _risebe used for setting tolerance size.

5. power distribution network operation risk assessment method according to claim 4, is characterized in that, the computing formula of described node voltage mean value specification value is:

Wherein, U _avgfor the mean value of described node voltage, U _overvoltage for described node voltage during higher than described critical value, U _lowervoltage for described node voltage during lower than described critical value, q (x) _{rise θ}, q (x) _{θ falls}for the weighted value of described node voltage, p _ifor the probability that in described malfunction set, arbitrary circuit or equipment i break down, W _ifor the important level of described arbitrary circuit or equipment i, θ is numbering corresponding to all described nodes under described arbitrary circuit or equipment i malfunction, U _{superpotential node θ calculated value}for the magnitude of voltage higher than standard voltage value in all described node voltages, U _{lower voltage node θ calculated value}for the magnitude of voltage lower than standard voltage value in all described node voltages, U _{superpotential critical value}for default overtension critical value, U _{low-voltage critical value}for default brownout critical value,

Wherein, L _overfor exceeding the through-put power of through-put power ratings in circuit transmitting procedure, q (x) _{rise θ}for the weighted value of circuit through-put power, p _ifor the probability that circuit described in described malfunction set or equipment i break down, W _ifor the important level of circuit or equipment i, θ is numbering corresponding to all described circuits under described arbitrary circuit or equipment i malfunction, I _{overload circuit θ calculated value}for through-put power is greater than the through-put power of the circuit of the described through-put power ratings of described circuit; I _{the effective limit of circuit θ}for the described through-put power ratings of described circuit,

Wherein, E _overfor exceeding the operate power of operate power ratings in equipment running process, q (x) _{rise θ}for the weighted value of equipment operate power, p _ifor the probability that in described malfunction set, arbitrary circuit or equipment i break down, W _ifor the important level of described arbitrary circuit or equipment i, θ is numbering corresponding to all described equipment under described arbitrary circuit or equipment i malfunction, S _{overload equipment θ calculated value}for operate power is greater than the operate power of the equipment of the described operate power ratings of described equipment; S _{the effective limit of equipment θ}refer to the described operate power ratings of described equipment;

The computing formula of described mistake load index value is:

6. a power distribution network operation risk assessment system, is characterized in that, comprising:

Determining unit, for determining the malfunction set of power distribution network;

The first computing unit, according to default probability of malfunction assignment rule, calculates the probability that in described malfunction set, each fault occurs;

The second computing unit, according to default computation rule, corresponding evaluation index value while calculating each fault in described malfunction set, the probability occurring by evaluation index value corresponding to described each fault and described each fault, obtain the risk assessment desired value of described each fault, wherein, described evaluation index value comprises overall operation desired value and individual event operating index value, wherein, described overall operation desired value comprises node voltage mean value specification value, described individual event operating index value comprises the too high more line desired value of node voltage, the too low more line desired value of node voltage, circuit transmission overload desired value and equipment operating overload desired value,

The 3rd computing unit, determines the operation risk assessment desired value of described power distribution network according to the risk assessment desired value of described each fault.

7. power distribution network operation risk assessment system according to claim 6, is characterized in that, described the first computing unit specifically for:

8. power distribution network operation risk assessment system according to claim 6, is characterized in that, also comprises:

The second setting unit, for described evaluation index value arranges important level, and

The 3rd setting unit is that described evaluation index value arranges corresponding weighted value according to described important level.

9. power distribution network operation risk assessment system according to claim 8, is characterized in that, also comprises:

Critical numerical value processing unit, by the weighted value of every operation risk index in power distribution network described in default disposal methods;

The second default formula is:

10. power distribution network operation risk assessment system according to claim 9, is characterized in that,

The computing formula of described node voltage mean value specification value is:

Wherein, U _avgfor the mean value of described node voltage, U _overvoltage for described node voltage during higher than described critical value, U _lowervoltage for described node voltage during lower than described critical value, q (x) _{rise θ}, q (x) _{θ falls}for the described weighted value of described node voltage, p _ifor the probability that in described malfunction set, arbitrary circuit or equipment i break down, Wi is the important level of described arbitrary circuit or equipment i, and θ is numbering corresponding to all described nodes under described arbitrary circuit or equipment i malfunction, U _{superpotential node θ calculated value}for the magnitude of voltage higher than standard voltage value in all described node voltages, U _{lower voltage node θ calculated value}for the magnitude of voltage lower than standard voltage value in all described node voltages, U _{superpotential critical value}for default overtension critical value, U _{low-voltage critical value}for default brownout critical value,

Wherein, L _overfor exceeding the through-put power of through-put power ratings in circuit transmitting procedure, q (x) _{rise θ}for the weighted value of circuit through-put power, p _ifor the probability that arbitrary circuit described in described malfunction set or equipment i break down, W _ifor the important level of described arbitrary circuit or equipment i, θ is numbering corresponding to all described circuits under described arbitrary circuit or equipment i malfunction, I _{overload circuit θ calculated value}for through-put power is greater than the through-put power of the circuit of the described through-put power ratings of described circuit; I _{the effective limit of circuit θ}for the described through-put power ratings of described circuit,

The computing formula of described mistake load index value is: