CN103700039A - Power grid real-time risk assessment and precontrol method - Google Patents

Abstract

The invention discloses a power grid real-time risk assessment and precontrol method and relates to a power grid risk precontrol method. At present, global extreme weather events are frequent, and meteorological disasters frequently occur, bringing great harm to an electric system, so that the risk of a power grid caused by weather change is urgently needed to be assessed, and the safety of the power grid is needed to be improved. The power grid real-time risk assessment and precontrol method comprises the following steps of 1, calculating the outage rate of an electric transmission line; 2, calculating the outage rate of equipment; 3, performing risk assessment of the electric system, wherein the risk assessment comprises the running risk assessment of loss loads and the running risk assessment of short-time overloading, and sorting the loss load risk and the short-time overloading rate risk; 4, automatically generating a fault set, calculating the fault set in real time according to the real-time topology information and a transfer ratio among equipment, dividing the fault set into a plurality of levels, and corresponding multiple levels of fault sets to multiple levels of limits. According to the technical scheme, two aspects of accident occurrence probability and accident consequence severity are comprehensively considered, and people can comprehensively and clearly know the encountered faults when the electric system runs.

Description

The real-time risk assessment of electrical network and pre-control method

The present invention relates to a kind of power grid risk pre-control method.

Rapid growth along with China's industrial development and electricity needs, electrical network scale constantly expands, structure is day by day complicated, the various new technologies such as the interconnected high pressure as object of the regional power grid of take, UHV transmission technology and Survey of Flexible AC Transmission System Technology are progressively applied to electric system, increased uncertainty and the randomness in operation of power networks, system disturbance is involved wider, consequence is also more serious.Traditional safety assessment and control method can not adapt to new power system environment.Repeatedly break out in recent years the accident of having a power failure on a large scale all over the world, in August, 2003, U.S.A adds electrical network large area blackout has occurred, and has fed through to the service area of more than 5,000 ten thousand populations, becomes power outage largest in American history.The Central China Power Grid power outage that on July 1st, 2006 occurs is also for we have beaten alarm bell.There is also occurring large area blackout in Shenzhen evening on April 10th, 2012.Have a power failure on a large scale and cause tremendous economic loss and social influence to country, make the research of power system security appraisal procedure seem very necessary.By to security analysis of electric power system, tender spots and the weakness zone of system be can find in time, all sidedly, and then defence and innovative approach proposed, effectively suppress and the generation of minimizing accident.

In electric power system dispatching, the risk level that conventional constant failure rate and fault collection carry out computing system, and constant failure rate cannot be described history run condition and the impact of following service condition on equipment stoppage in transit risk.In causing a plurality of factors of power system accident, the fault causing because of weather has occupied sizable proportion.Along with factor impacts such as global warmings, global Extreme Weather-climate Events is frequent, and meteorological disaster is multiple to take place frequently, and to electric system, brings very big harm.In the urgent need to the risk that Changes in weather is brought electrical network, assess, improve electric network security.

The technical assignment of the technical problem to be solved in the present invention and proposition is that prior art scheme is improved and improved, and provides the real-time risk assessment of electrical network and pre-control method, to reach forewarning function object.For this reason, the present invention takes following technical scheme.

The real-time risk assessment of electrical network and pre-control method, is characterized in that comprising the following steps:

1) outage rate of computing electric power line: λ i=λ _thunderi+ λ _windi+ λ _firei+ λ _icei+ λ _base;

In formula, λ _thunderifor the power transmission line outage rate that thunder and lightning causes, λ _fireifor the power transmission line outage rate that mountain fire causes, λ _windifor large wind-induced power transmission line outage rate, λ _iceifor the freezing power transmission line outage rate causing, λ _basebasic outage rate for power transmission line;

A) statistical basis outage rate: according to data formerly, according to different voltage, the basic outage rate of circuit is added up, line voltage distribution comprises 220KV, 500KV;

B) calculate the power transmission line outage rate that thunder and lightning causes: λ _thuderi=λ _aREAI* L _aREAI* M;

In formula: M is weather element, thunderstorm weather is 1, otherwise is 0, λ _aREAIfor the circuit lightning fault rate of thunder and lightning statistical regions, unit is inferior/(100km*1 Thunderstorm Day), L _aREAIfor being in the line length in this region, the km of unit; Circuit lightning fault rate causes that by the meteorological Thunderstorm Day in various places and thunder and lightning line failure rate calculates acquisition;

C) calculate large wind-induced power transmission line outage rate: λ _windi=λ _wind* L; ${\mathrm{\&lambda;}}_{\mathrm{wind}}=\left\{\begin{array}{c}0,\mathrm{\&omega;}\left(t\right)<{\mathrm{\&omega;}}_{\mathrm{cri}}\\ {\mathrm{\&lambda;}}_{\mathrm{base}}\&times;C_p\&times;(\frac{\mathrm{\&omega;}{\left(t\right)}^2}{{{\mathrm{\&omega;}}^2}_{\mathrm{cri}}}-1),\mathrm{\&omega;}\left(t\right)\&GreaterEqual;{\mathrm{\&omega;}}_{\mathrm{cri}}\end{array}\right.;$

In formula: L is the length of circuit in this climatic region, λ _basefor the crash rate under normal weather condition, ω _crifor critical wind velocity; C _pfor scale parameter; ω _crifor gale warning wind speed;

D) calculate the power transmission line outage rate that mountain fire causes: λ _firei=λ _fire* i*L _fire;

In formula, i is weather input quantity, and fine day cloudy day value is 1, and the rainy day is 0; L _firefor the length of circuit in mountain fire area, if circuit is not 0 in mountain fire region value; λ _firefor the line failure rate that mountain fire causes, unit is inferior/(100km* day), and its value changes according to Monthly changes,

E) calculate the freezing power transmission line outage rate causing: λ _icei=λ _ice* j*L _mountain; J, for freezing sleety weather sign occurs, represents freezing sleety weather during j=1, represent non-freezing weather during j=0; L _mountainfor circuit is in the length in mountain area; λ _icecan obtain according to historical statistics, computing formula is:

unit is inferior/(100km* day);

2) outage rate of computing equipment: the difference of the health status in the time of according to the operation of element, be divided into a plurality of state grades, the outage rate of different conditions grade element is separately added up; The outage rate of equipment is described with binary states synoptic model, $\mathrm{\&lambda;}(\mathrm{state},\mathrm{\&omega;},\mathrm{flawstate})=\left\{\begin{array}{c}\mathrm{\&lambda;}(\mathrm{state},\mathrm{flawstate})*\frac{N+S}{N}*(1-F),\mathrm{\&omega;}=0\\ \mathrm{\&lambda;}(\mathrm{state},\mathrm{flawstate})*\frac{N+S}{S}*F,\mathrm{\&omega;}=1\end{array}\right.;$ In formula, N is the normal weather duration, and S is the inclement weather duration, and F is the ratio that occurs in inclement weather fault, and ω is current device weather sign of living in, normal weather ω=0, inclement weather ω=1; λ (state, flawstate), represents the equipment outage rate under different conditions, supposes element obeys index distribution working time, and in time t, the failure probability of this element is:

3) Study of Risk Evaluation Analysis for Power System, comprises the operation risk assessment of loss load, the operation risk assessment of short-time overload, will lose load risk and short-time overload rate risk ranking; Set up the meteorological model on Operation of Electric Systems impact, by calculative determination risk class, and by risk indicator, show the extent of injury of fault; When the operation risk assessment of loss load, first hypothesis is cut-off target line and is caused fault, counting loss load, and simultaneously according to the outage rate of line length computational scheme, outage rate and the loss load value-at-risk that multiplies each other to obtain; When the operation risk assessment of short-time overload, select overload under static security as consequence, the short-time overload rate of usining is calculated again as severity, simultaneously according to the outage rate of line length computational scheme, according to outage rate and overload risk, obtains value-at-risk; Outage rate comprises power transmission line outage rate that power transmission line outage rate, large wind-induced power transmission line outage rate, mountain fire that basic outage rate, thunder and lightning cause cause, one or more in the freezing power transmission line outage rate causing;

4) fault collection generates automatically, according to real-time topology information and equipment room coefficient of migration, calculates in real time fault collection, fault collection is divided into multistage, and multistage fault set pair should multistage limit.

As the further of technique scheme improved and supplemented, the present invention also comprises following additional technical feature.

The state grade of element comprises kilter grade, alarm status grade, precarious position grade, and its corresponding element failure rate is: $\mathrm{\&lambda;}\left(\mathrm{state}\right)=\left\{\begin{array}{c}\frac{N_{\mathrm{good}}}{T_{\mathrm{good}}},\mathrm{state}=1\\ \frac{N_{\mathrm{warning}}}{T_{\mathrm{warning}}},\mathrm{state}=2\\ \frac{N_{\mathrm{danger}}}{T_{\mathrm{danger}}},\mathrm{state}=3\end{array}\right.;$

In formula, State represents state, and 1,2,3 represent respectively good, alarm and precarious position; Timing statistics T is divided into kilter duration T _good, alarm status duration T _warning, precarious position duration T _danger; N _good, N _warning, N _dangerfor the element fault number of times under corresponding states.

Timing statistics T interval is the moon,

$\mathrm{\&lambda;}\left(\mathrm{state}\right)=\begin{array}{c}\left\{\begin{array}{cc}\frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{good}}}{T_{i,\mathrm{good}}},\mathrm{state}=1\\ \frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{warning}}}{T_{i,\mathrm{warning}}},\mathrm{state}=2\\ \frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{danger}}}{T_{i,\mathrm{danger}}},\mathrm{state}=3\end{array};\right.\end{array}$

In formula: C represents statistics year number.

According to the data of real-time tour, provide the state grade of element, quantize the evaluation criterion of state grade, according to on-the-spot defect rank severity scale.

When risks and assumptions is larger, fault collection is larger, and limit is less.

Beneficial effect: use security risk assessment, the probability that accident is occurred and seriousness two aspects of damage sequence consider, the fault running in the time of can allowing people to Operation of Electric Systems has had understanding comprehensively and clearly.Power system security risk assessment based on meteorologic factor, set up the meteorological model on Operation of Electric Systems impact, by calculative determination risk class, and by risk indicator, show the extent of injury of fault, make operation personnel can carry out risk prevention, note emphatically the circuit that risk class is high, carry out plan, select optimized operation.Risk assessment is by accident probability and consequence considers and quantitative expression, some line fault consequence is serious but fault rate is low, just can as in the past, pay close attention to, but energy is placed on and takes precautions against the large circuit of some fault rates, thus the normal operation of assurance circuit.

Fig. 1 is process flow diagram of the present invention.

Fig. 2 is the outage rate Computing Principle schematic diagram of transmission line of electricity of the present invention.

Below technical scheme of the present invention is described in further detail.

As shown in Figure 1, the real-time risk assessment of electrical network and pre-control method, comprise the following steps:

1) outage rate of computing electric power line: λ i=λ _thunderi+ λ _windi+ λ _firei+ λ _icei+ λ _base;

In formula, λ _thunderifor the power transmission line outage rate that thunder and lightning causes, λ _fireifor the power transmission line outage rate that mountain fire causes, λ _windifor large wind-induced power transmission line outage rate, λ _iceifor the freezing power transmission line outage rate causing, λ _basebasic outage rate for power transmission line;

A) statistical basis outage rate: according to data formerly, according to different voltage, the basic outage rate of circuit is added up, line voltage distribution comprises 220KV, 500KV;

B) calculate the power transmission line outage rate that thunder and lightning causes: λ _thuderi=λ _aREAI* L _aREAI* M;

In formula: M is weather element, thunderstorm weather is 1, otherwise is 0, λ _aREAIfor the circuit lightning fault rate of thunder and lightning statistical regions, unit is inferior/(100km*1 Thunderstorm Day), L _aREAIfor being in the line length in this region, the km of unit; Circuit lightning fault rate causes that by the meteorological Thunderstorm Day in various places and thunder and lightning line failure rate calculates acquisition;

C) calculate large wind-induced power transmission line outage rate: λ _windi=λ _wind* L; ${\mathrm{\&lambda;}}_{\mathrm{wind}}=\left\{\begin{array}{c}0,\mathrm{\&omega;}\left(t\right)<{\mathrm{\&omega;}}_{\mathrm{cri}}\\ {\mathrm{\&lambda;}}_{\mathrm{base}}\&times;C_p\&times;(\frac{\mathrm{\&omega;}{\left(t\right)}^2}{{{\mathrm{\&omega;}}^2}_{\mathrm{cri}}}-1),\mathrm{\&omega;}\left(t\right)\&GreaterEqual;{\mathrm{\&omega;}}_{\mathrm{cri}}\end{array}\right.;$

In formula: L is the length of circuit in this climatic region, λ _basefor the crash rate under normal weather condition, ω _crifor critical wind velocity; C _pfor scale parameter; ω _crifor gale warning wind speed;

D) calculate the power transmission line outage rate that mountain fire causes: λ _firei=λ _fire* i*L _fire;

In formula, i is weather input quantity, and fine day cloudy day value is 1, and the rainy day is 0; L _firefor the length of circuit in mountain fire area, if circuit is not 0 in mountain fire region value; λ _firefor the line failure rate that mountain fire causes, unit is inferior/(100km* day), and its value changes according to Monthly changes,

E) calculate the freezing power transmission line outage rate causing: λ _icei=λ _ice* j*L _mountain; J, for freezing sleety weather sign occurs, represents freezing sleety weather during j=1, represent non-freezing weather during j=0; L _mountainfor circuit is in the length in mountain area; λ _icecan obtain according to historical statistics, computing formula is:

unit is inferior/(100km* day);

2) outage rate of computing equipment: the difference of the health status in the time of according to the operation of element, be divided into a plurality of state grades, the outage rate of different conditions grade element is separately added up; The outage rate of equipment is described with binary states synoptic model, $\mathrm{\&lambda;}(\mathrm{state},\mathrm{\&omega;},\mathrm{flawstate})=\left\{\begin{array}{c}\mathrm{\&lambda;}(\mathrm{state},\mathrm{flawstate})*\frac{N+S}{N}*(1-F),\mathrm{\&omega;}=0\\ \mathrm{\&lambda;}(\mathrm{state},\mathrm{flawstate})*\frac{N+S}{S}*F,\mathrm{\&omega;}=1\end{array}\right.;$ In formula, N is the normal weather duration, and S is the inclement weather duration, and F is the ratio that occurs in inclement weather fault, and ω is current device weather sign of living in, normal weather ω=0, inclement weather ω=1; λ (state, flawstate), represents the equipment outage rate under different conditions, supposes element obeys index distribution working time, and in time t, the failure probability of this element is:

3) Study of Risk Evaluation Analysis for Power System, comprises the operation risk assessment of loss load, the operation risk assessment of short-time overload, will lose load risk and short-time overload rate risk ranking; Set up the meteorological model on Operation of Electric Systems impact, by calculative determination risk class, and by risk indicator, show the extent of injury of fault; When the operation risk assessment of loss load, first hypothesis is cut-off target line and is caused fault, counting loss load, and simultaneously according to the outage rate of line length computational scheme, outage rate and the loss load value-at-risk that multiplies each other to obtain; When the operation risk assessment of short-time overload, select overload under static security as consequence, the short-time overload rate of usining is calculated again as severity, simultaneously according to the outage rate of line length computational scheme, according to outage rate and overload risk, obtains value-at-risk; Outage rate comprises power transmission line outage rate that power transmission line outage rate, large wind-induced power transmission line outage rate, mountain fire that basic outage rate, thunder and lightning cause cause, one or more in the freezing power transmission line outage rate causing;

4) fault collection generates automatically, according to real-time topology information and equipment room coefficient of migration, calculates in real time fault collection, fault collection is divided into multistage, and multistage fault set pair should multistage limit; When risks and assumptions is larger, fault collection is larger, and limit is less.

Wherein the state grade of element comprises kilter grade, alarm status grade, precarious position grade, and its corresponding element failure rate is: $\mathrm{\&lambda;}\left(\mathrm{state}\right)=\left\{\begin{array}{c}\frac{N_{\mathrm{good}}}{T_{\mathrm{good}}},\mathrm{state}=1\\ \frac{N_{\mathrm{warning}}}{T_{\mathrm{warning}}},\mathrm{state}=2\\ \frac{N_{\mathrm{danger}}}{T_{\mathrm{danger}}},\mathrm{state}=3\end{array}\right.;$

In formula, State represents state, and 1,2,3 represent respectively good, alarm and precarious position; Timing statistics T is divided into kilter duration T _good, alarm status duration T _warning, precarious position duration T _danger; N _good, N _warning, N _dangerfor the element fault number of times under corresponding states.

Timing statistics T interval is the moon,

$\mathrm{\&lambda;}\left(\mathrm{state}\right)=\begin{array}{c}\left\{\begin{array}{cc}\frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{good}}}{T_{i,\mathrm{good}}},\mathrm{state}=1\\ \frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{wa\; rning}}}{T_{i,\mathrm{warning}}},\mathrm{state}=2\\ \frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{danger}}}{T_{i,\mathrm{danger}}},\mathrm{state}=3\end{array};\right.\end{array}$

In formula: C represents statistics year number.

According to the data of real-time tour, provide the state grade of element, quantize the evaluation criterion of state grade, according to on-the-spot defect rank severity scale.During concrete enforcement, consider the equipment such as transformer to carry out making an inspection tour in real time the transformer defect rank providing, provide the evaluation criterion of quantification, suppose to the scoring heavily providing, to be respectively 1,2 on the lenient side according to the on-the-spot defect rank order of severity 3,4,5 minutes.The transformer health status of take is example when good, considers that the failure rate of making an inspection tour in real time the transformer of status of equipment can be expressed as

$\mathrm{\&lambda;}(1,\mathrm{flawstate})=\mathrm{\&lambda;}\left(1\right)*{\left(\frac{\mathrm{flawstate}\left(i\right)}{\mathrm{flawstateav}}\right)}^r$

In formula, λ (1, the failure rate of equipment during flawstate) for the real-time defect rank of making an inspection tour of consideration equipment, the outage rate of λ (1) when not considering that defect rank transformer health status is good, flawstate (i) is equipment defect rank now, flawstateav is the residing average defect state of equipment, r>0, is weighting progression, can be calculated and be obtained by experience.Transformer, isolating switch, disconnector, bus and generator are divided into different brackets model to be added up, the result showing in real time according to equipment state on-line monitoring (well, alarm or danger, also can divide more state according to the situation of real system), can calculate the current outage rate λ of element _i.

Conventional risk indicator is as follows:

(1) load is cut down probability LOLP, explanation be that the possibility that load occurs to cut down during assessing has much;

$\mathrm{LOLP}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}\left(\underset{s\&Element;\mathrm{Fi}}{\mathrm{\&Sigma;}}{p}_{\left(s\right)}\right)\frac{T_i}{T}.$

(2) load is cut down frequency LOLF, explanation be that the average time that load occurs to cut down during assessing has how many;

$\mathrm{LOLF}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}\underset{s\&Element;\mathrm{Fi}}{\mathrm{\&Sigma;}}\left(P\left(s\right)\underset{j=1}{\overset{m\left(s\right)}{\mathrm{\&Sigma;}}}{\mathrm{\&lambda;}}_j\right)\frac{T_i}{T}.$

(3) expected loss of load EDNS, explanation be that the average load of cutting down during assessing is much;

$\mathrm{EDNS}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}\left(\underset{s\&Element;\mathrm{Fi}}{\mathrm{\&Sigma;}}P\left(s\right)C\left(s\right)\right)\frac{T_i}{T}.$

(4) expected loss of energy (expectation lack delivery) EENS (unit is megawatt hour), explanation be that the electric weight due to cutting load loss is much during assessment;

$\mathrm{EENS}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}(\underset{s\&Element;F_i}{\mathrm{\&Sigma;}}P\left(s\right)\&CenterDot;C\left(s\right))\&CenterDot;T_i$

(5) have a power failure and affect seriousness index S I, explanation be scarce delivery during assessment while changing into peak load power failure can continue how many minutes;

$\mathrm{SI}=60\&times;\frac{\mathrm{EENS}}{L}$

$.$

(6) grid disconnection probability P OGS, explanation be that the possibility that grid disconnection occurs during assessment has much;

$\mathrm{PGS}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}\left(\underset{s\&Element;G_i}{\mathrm{\&Sigma;}}P\left(s\right)\right)\frac{T_i}{T}.$

(7) transformer station's full cut-off probability P OSO, explanation be that the possibility that transformer station's full cut-off of a certain electric pressure occurs during assessment has much;

${\mathrm{POSO}}_k=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}\left(\underset{s\&Element;S_{\mathrm{ik}}}{\mathrm{\&Sigma;}}P\left(s\right)\right)\frac{T_i}{T}.$

(8) voltage out-of-limit risk ROVV(low-voltage or high voltage risk), explanation be that the risk of bus or system generation voltage out-of-limit has much during assessment;

${\mathrm{ROVV}}_{\mathrm{Ni}}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}(\underset{s\&Element;V_i}{\mathrm{\&Sigma;}}P\left(s\right)\&CenterDot;{\left(\frac{\mathrm{\&Delta;U}\left(j\right)}{U\left(j\right)}\right)}^2)\frac{T_i}{T};$

${\mathrm{ROVV}}_s=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}(\underset{s\&Element;V_i}{\mathrm{\&Sigma;}}P\left(s\right)\&CenterDot;\left(\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left(\frac{\mathrm{\&Delta;U}\left(j\right)}{U\left(j\right)}\right)}^2\right))\frac{T_i}{T}.$

(9) element overload risk ROLV, explanation be that the risk of generating device or system overload has much during assessment;

${\mathrm{ROCV}}_{\mathrm{Ni}}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}(\underset{s\&Element;L_i}{\mathrm{\&Sigma;}}P\left(s\right)\&CenterDot;{\left(\frac{\mathrm{\&Delta;I}\left(j\right)}{I\left(j\right)}\right)}^2)\frac{T_i}{T};$

${\mathrm{ROCV}}_s=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}(\underset{s\&Element;L_i}{\mathrm{\&Sigma;}}P\left(s\right)\&CenterDot;\left(\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left(\frac{\mathrm{\&Delta;I}\left(j\right)}{I\left(j\right)}\right)}^2\right))\frac{T_i}{T}.$

During operation risk assessment based on EDNS, take EDNS as index, get loss load and calculate as severity.With design conditions be that the peak typical way in summer of the mode of getting is carried out forecast failure calculating, anticipation is cut-off target line and is caused fault, counting loss load.According to factors such as line lengths, calculate the basic outage rate of every circuit simultaneously.While calculating the value-at-risk under thunder and lightning weather, according to formula λ _thuderi=λ _aREAI* L _aREAI* M calculates the line failure rate in thunder and lightning situation, and failure rate is multiplied each other and obtains the value-at-risk in thunderbolt situation with loss load; While calculating the value-at-risk under strong wind (typhoon) weather, according to known wind speed substitution formula ${\mathrm{\&lambda;}}_{\mathrm{wind}}=\left\{\begin{array}{c}0,\mathrm{\&omega;}\left(t\right)<{\mathrm{\&omega;}}_{\mathrm{cri}}\\ {\mathrm{\&lambda;}}_{\mathrm{base}}\&times;C_p\&times;(\frac{\mathrm{\&omega;}{\left(t\right)}^2}{{{\mathrm{\&omega;}}^2}_{\mathrm{cri}}}-1),\mathrm{\&omega;}\left(t\right)\&GreaterEqual;{\mathrm{\&omega;}}_{\mathrm{cri}}\end{array}\right.;$

λ _windi=λ _wind* in L, obtain the line outage rate under high wind, according to formula, calculate total outage rate and lose the value-at-risk that arrives of loading and multiplying each other.

During Study of Risk Evaluation Analysis for Power System based on ROCV, select overload under static security as consequence, the short-time overload rate of usining is calculated again as severity, according to formula

${\mathrm{ROCV}}_{\mathrm{Ni}}=\underset{i=1}{\overset{\mathrm{NL}}{\mathrm{\&Sigma;}}}(\underset{s\&Element;L_i}{\mathrm{\&Sigma;}}P\left(s\right)\&CenterDot;{\left(\frac{\mathrm{\&Delta;I}\left(j\right)}{I\left(j\right)}\right)}^2)\frac{T_i}{T}$

Calculate Study of Risk Evaluation Analysis for Power System.With design conditions be that the peak typical way in summer of the mode of getting is carried out forecast failure calculating, anticipation is cut-off target line and is caused fault, calculates the short-time overload coefficient of hyperline road and main transformer.According to factors such as line lengths, calculate the basic outage rate of every circuit simultaneously.While calculating the value-at-risk under thunder and lightning weather, lightning parameter is constant, and failure rate does not change, again calculation risk value.

Value-at-risk under table 1 thunder and lightning weather

From table 1, see, new consequence calculates different value-at-risk.After each line disconnection, the sequence of value-at-risk is from previously to using the value-at-risk sequence that loss load calculates as severity different.Therefore, select different consequences can obtain different value-at-risks, specifically select which kind of consequence to calculate and can be determined by Operation of Electric Systems slip-stick artist's needs as severity.While calculating the value-at-risk under typhoon weather, example short-time weather forecasting Ningbo typhoon wind speed is 25m/s, Hangzhou is 15m/s, In Hangzhou Region of Zhe Jiang Province does not reach critical wind velocity, strong wind is negligible on the impact of line outage, calculate relevant outage rate, select short-time overload rate as severity, obtain new value-at-risk:

Value-at-risk under table 2 typhoon weather

At fault collection, automatically generate in step, carry out the fault collection of risk assessment except N-1 fault, also need to consider the situation of multiple failure, by Monte Carlo method, can consider the situation of multiple failure, but the speed of Monte Carlo method cannot reach practical degree, therefore, in actual EMS real-time system risk assessment, also need to carry out risk assessment by analytical method, we must obtain a fault collection that can cover all dangerous points before carrying out risk assessment so, and the risk evaluation result that makes us is useful.Multiple failure collection generates the main factor of considering two aspects automatically, and the one, electrical network is carried out to topological analysis, and electrical network is carried out to subregion, the one, the domain of influence of consideration fault.

Example is chosen 40 circuits (comprising same bar) and as basic fault collection, is carried out the automatic generation of fault collection

Table 3 basic circuit failure condition

Fault collection	Failure rate
		Blue instrument 5458 lines	0.0527
Blue rock 2459 lines	0.0233
		Blue rattan 2452 lines	0.0089
Blue blue or green 2451 lines	0.0089
		Blue phoenix 5457 lines	0.053
Orchid is spun 2455 lines	0.0347
		Orchid crosses 2461 lines	0.0244
Blue eastern 2462 lines	0.0244
		They new 4481 lines	0.1511
They salty 4485 lines	0.2115
		The world 4483 lines	0.0593
They field 4480 lines	0.1254
		They mulberry 4479 lines	0.1254
They peaceful 5475 lines	0.2411
		They nurse 5484 lines	0.2319
Daybreak 4474 lines	0.1669
		They blue 5455 lines	0.3273
The Milky Way 5483 lines	0.2319
		They Cai's 4471 lines	0.0388
They Bao 4475 lines	0.0664
		Gush and enclose 4424 lines	4.58E-05
Gush peaceful 4423 lines	4.58E-05
		Gush blue 5453 lines	0.000166
Gush phoenix 4420 lines	3.97E-05
		Gush phoenix 4419 lines	3.97E-05
Blue blue or green 2451 lines; Blue rattan 2452 lines	0.000688

Blue rock 2459 lines; Booth Ke 2460 lines	0.000688
		Orchid is spun 2455 lines; Booth spins 2458 lines	0.000688
Orchid crosses 2461 lines; Blue eastern 2462 lines	0.000688
		Gush phoenix 4419 lines; Gush phoenix 4420 lines	3.97E-05
Gush peaceful 4423 lines; Gush and enclose 4424 lines	4.58E-05
		They peaceful 5475 lines; One peaceful 5476 lines	0.000416
The Milky Way 5483 lines; They nurse 5484 lines	0.000416
		They Cai's 4471 lines; They youth's 4472 lines	0.000688
They favour 4473 lines; Daybreak 4474 lines	0.000688
		They Bao 4475 lines; They family's 4476 lines	0.000688
They mulberry 4479 lines; They field 4480 lines	0.000688
		They new 4481 lines; They happy 4482 lines	0.000688
The world 4483 lines; It answers 4484 lines	0.000688
		They salty 4485 lines; Tianxiang 4486 lines	0.000688

The short-term outage rate that carries out N-x for 40 circuits above calculates, and usings 0.0002 and 0.0004 as constraint condition, to carry out the calculating of short-term outage rate, and the result of calculating, has 1586 fault collection 0.0002 time, has 1051 fault collection 0.0004 time.Fault collection (an intercepting part) as shown in table 4 below:

Table 4 partial fault collection

They are new 4481 years old; The world 4483; It mulberry 4479; They are peaceful 5475 years old
	They are new 4481 years old; The world 4483; It mulberry 4479; It nurse 5484
They are new 4481 years old; The world 4483; It mulberry 4479; They are blue 5455 years old
	They are new 4481 years old; The world 4483; It mulberry 4479; The Milky Way 5483
They are new 4481 years old; The world 4483; They are peaceful 5475 years old; It nurse 5484
	They are new 4481 years old; The world 4483; They are peaceful 5475 years old; Daybreak 4474
They are new 4481 years old; The world 4483; They are peaceful 5475 years old; They are blue 5455 years old
	They are new 4481 years old; The world 4483; They are peaceful 5475 years old; The Milky Way 5483
They are new 4481 years old; The world 4483; It nurse 5484; Daybreak 4474
	They are new 4481 years old; The world 4483; It nurse 5484; They are blue 5455 years old
They are new 4481 years old; The world 4483; It nurse 5484; The Milky Way 5483
	They are new 4481 years old; The world 4483; Daybreak 4474; They are blue 5455 years old
They are new 4481 years old; The world 4483; Daybreak 4474; The Milky Way 5483
	They are new 4481 years old; The world 4483; They are blue 5455 years old; The Milky Way 5483
They are new 4481 years old; It field 4480; It mulberry 4479; They are peaceful 5475 years old
	They are new 4481 years old; It field 4480; It mulberry 4479; It nurse 5484
They are new 4481 years old; It field 4480; It mulberry 4479; Daybreak 4474
	They are new 4481 years old; It field 4480; It mulberry 4479; They are blue 5455 years old

They are new 4481 years old; It field 4480; It mulberry 4479; The Milky Way 5483
	They are new 4481 years old; It field 4480; They are peaceful 5475 years old; It nurse 5484
They are new 4481 years old; It field 4480; They are peaceful 5475 years old; Daybreak 4474
	They are new 4481 years old; It field 4480; They are peaceful 5475 years old; They are blue 5455 years old

While carrying out analysis of failure collection with topological analysis and fault effects territory, on the basis of upper step, carry out partition analysis, provide the partition information of each equipment, and according to the sensitivity between equipment, carry out the analysis of failure domain of influence on the basis of these subregions, it is as follows that in 40 circuits, some have the circuit of larger sensitivity each other:

The sensitivity of table 5 equipment room

Equipment 1	Equipment 2	Sensitivity
			Orchid crosses 2461	Blue east 2462	-1.00615
Blue blue or green 2451	Blue rattan 2452	-1.00313
			It Bao 4475	It family 4476	-1.00112
The world 4483	It answers 4484	-1.00099
			It Cai 4471	It youth 4472	-0.918741
It favour 4473	Daybreak 4474	-0.827512
			Blue rock 2459	Booth Ke 2460	-0.697272
One peaceful 5476	They are peaceful 5475 years old	-0.674115
			It nurse 5484	The Milky Way 5483	-0.66159
Blue instrument 5458	Blue phoenix 5457	-0.604169
			They are salty 4485 years old	Tianxiang 4486	-0.569012
Orchid spins 2455	Booth spins 2458	-0.562823
			They are new 4481 years old	They are happy 4482 years old	-0.505266
They are blue 5455 years old	It nurse 5484	-0.19033
			They are blue 5455 years old	The Milky Way 5483	-0.190327
They are new 4481 years old	It mulberry 4479	-0.16851
			They are happy 4482 years old	It field 4480	-0.162917
They are happy 4482 years old	It mulberry 4479	-0.161726
			Orchid spins 2455	Blue rock 2459	-0.159375
Booth spins 2458	Booth Ke 2460	-0.159125
			They are new 4481 years old	It field 4480	-0.158503
Booth spins 2458	Blue rock 2459	-0.152205
			They are peaceful 5475 years old	They are blue 5455 years old	-0.148642
Orchid spins 2455	Booth Ke 2460	-0.147499
			One peaceful 5476	They are blue 5455 years old	-0.146393
They are salty 4485 years old	It mulberry 4479	-0.124709

Tianxiang 4486	It field 4480	-0.12371
			They are salty 4485 years old	They are happy 4482 years old	-0.122542
They are new 4481 years old	They are salty 4485 years old	-0.119929
			Tianxiang 4486	It mulberry 4479	-0.119877
They are happy 4482 years old	Tianxiang 4486	-0.11785
			They are salty 4485 years old	It field 4480	-0.116825
They are new 4481 years old	Tianxiang 4486	-0.112567
			They are peaceful 5475 years old	Blue instrument 5458	-0.0841828
One peaceful 5476	Blue instrument 5458	-0.082895
			They are peaceful 5475 years old	Blue phoenix 5457	-0.0825561
One peaceful 5476	Blue phoenix 5457	-0.0812927
			They are peaceful 5475 years old	The Milky Way 5483	-0.0710806
They are peaceful 5475 years old	It nurse 5484	-0.0710802
			One peaceful 5476	The Milky Way 5483	-0.0699978
One peaceful 5476	It nurse 5484	-0.0699975

As above table 5, can find out from sensitivity, the circuit in a subregion not substantially, and its sensitivity also can be less,, in further work, is therefore mainly the fault collection that how to reduce by 500,000 equipment.According to this sensitivity, can be given in a fault and concentrate sensitivity all more than-0.1 fault collection (definition that sensitivity is-0.1 is: suppose ground state trend A100MW, B50MW, after A fault, the trend of B is 60MW).The above fault collection of N-2 providing is as follows:

The fault collection screening of table 6 based on sensitivity > 0.1

Fault set name claims	Fault collection equipment
		Blue instrument 5458: Lan Feng 5457	Blue instrument 5458: Lan Feng 5457
They are peaceful 5475: days blue 5455 years old	They are peaceful 5475: days blue 5455 years old
		It new 4481: days salty 4485: day field 4480	It new 4481: days salty 4485: day field 4480
It new 4481: days salty 4485: day mulberry 4479	It new 4481: days salty 4485: day mulberry 4479
		It nurse 5484: day orchid 5455: the Milky Way 5483	It nurse 5484: day orchid 5455: the Milky Way 5483
Blue rock 2459: orchid spins 2455	Blue rock 2459: orchid spins 2455
		Blue blue or green 2451: blue rattan 2452	Blue blue or green 2451: blue rattan 2452
Blue rock 2459: booth Ke 2460	Blue rock 2459: booth Ke 2460
		Orchid spins 2455: booth spins 2458	Orchid spins 2455: booth spins 2458
Orchid crosses 2461: blue east 2462	Orchid crosses 2461: blue east 2462
		It Cai 4471: day youth 4472	It Cai 4471: day youth 4472
It favour 4473: daybreak 4474	It favour 4473: daybreak 4474
		It Bao 4475: day family 4476	It Bao 4475: day family 4476
They are new 4481: days happy 4482 years old	They are new 4481: days happy 4482 years old
		The world 4483: sky answers 4484	The world 4483: sky answers 4484
It salty 4485: Tianxiang 4486	It salty 4485: Tianxiang 4486

They peaceful 5475: one peaceful 5476

They peaceful 5475: one peaceful 5476

Also can be given in a fault concentrates sensitivity all at more than-0.01 fault collection:

The fault collection screening of table 7 based on sensitivity > 0.01

Fault set name claims	Fault collection equipment
		Blue instrument 5458: Lan Feng 5457: sky peaceful 5475	Blue instrument 5458: Lan Feng 5457: sky peaceful 5475
It new 4481: days salty 4485: day field 4480	It new 4481: days salty 4485: day field 4480
		It new 4481: days salty 4485: day mulberry 4479	It new 4481: days salty 4485: day mulberry 4479
It peaceful 5475: day nurse 5484: days blue 5455: the Milky Way 5483	It peaceful 5475: day nurse 5484: days blue 5455: the Milky Way 5483
		It Cai 4471: day Bao 4475	It Cai 4471: day Bao 4475
Blue rock 2459: orchid spins 2455	Blue rock 2459: orchid spins 2455
		Blue rattan 2452: blue east 2462	Blue rattan 2452: blue east 2462
Blue blue or green 2451: orchid crosses 2461	Blue blue or green 2451: orchid crosses 2461
		Blue blue or green 2451: blue rattan 2452	Blue blue or green 2451: blue rattan 2452
Blue rock 2459: booth Ke 2460	Blue rock 2459: booth Ke 2460
		Orchid spins 2455: booth spins 2458	Orchid spins 2455: booth spins 2458
Orchid crosses 2461: blue east 2462	Orchid crosses 2461: blue east 2462
		It Cai 4471: day youth 4472	It Cai 4471: day youth 4472
It favour 4473: daybreak 4474	It favour 4473: daybreak 4474
		It Bao 4475: day family 4476	It Bao 4475: day family 4476
They are new 4481: days happy 4482 years old	They are new 4481: days happy 4482 years old
		The world 4483: sky answers 4484	The world 4483: sky answers 4484
It salty 4485: Tianxiang 4486	It salty 4485: Tianxiang 4486
		They peaceful 5475: one peaceful 5476	They peaceful 5475: one peaceful 5476

If use Monte Carlo method to consider the situation of multiple failure during risk assessment, computing time is longer, often cannot reach practical degree, therefore will carry out risk assessment by analytical method.The automatic generation of multiple failure collection will be considered topological analysis and fault effects region.Subregion should guarantee that the fault in Yi Ge district is almost negligible on the impact of district's external equipment, to improve the efficiency of algorithm.For large subregion, the scale of its N-2 fault collection may be still larger, therefore will further decompose, with the fault collection of fast filtering safety.By the research of this chapter, think based on risks and assumptions in the situation that, the fault collection that provides N-x is feasible, and its main cause is that risks and assumptions can make N-3 and later fault collection scale become very little, rather than in the expansion of the inferior level of the situation that there is no risks and assumptions.Meanwhile, can not be used in a fault and concentrate appearance between the different subregion equipment of the mode of use sensitivity, be also to have reduced greatly calculated amount.

When limit is calculated, when electrical network normally moves, should meet thermally-stabilised constraint, the trend of any one Branch Type power equipment should be no more than the long-term permission current-carrying capacity of equipment, to guarantee the safe operation of power equipment.The reliability constraint of electrical network requires electrical network can bear certain forecast failure (N-1 fault and partial multi fault) safe operation, be that electrical network is after the believable anticipation of generation is cut-off, in electrical network, the trend of any one power equipment all should not surpass the short-term current-carrying capacity of equipment, set apart to dispatching of power netwoks personnel processing accident, guarantee the safe operation of electrical equipment and electrical network.Because the reliability constraint of electrical network is relevant with the electric network state after forecast failure, and and the relation between dispatching of power netwoks personnel's main regulating measure (exerting oneself as unit is meritorious) is comparatively complicated, very not directly perceived, monitor with control electrical network to dispatching of power netwoks personnel and bring difficulty, this just requires to pass through to the supervision of electrical network normal operating condition and control, to guarantee the reliability constraint of electrical network.The object that the thermally-stabilised limit of section is provided is exactly in fact to wish by the supervision of electrical network normal operating condition is realized to the supervision to electric network reliability constraint, as long as guarantee that the trend of each section under electrical network normal operating condition is no more than section limit, the reliability constraint of electrical network just can be guaranteed.In high pressure, UHV (ultra-high voltage) and extra-high voltage grid, each power plant and transformer station all have certain idle regulating power, for reducing the active loss of electrical network, in actual motion, the power rate of Line Flow and main transformer trend is generally all higher, by given conservative coefficient (as 0.9), as long as guarantee that the meritorious trend of circuit or section is not out-of-limit, corresponding electric current should can be not out-of-limit yet.In general, in high pressure, UHV (ultra-high voltage) and extra-high voltage grid, between meritorious trend, generally there is good linear relationship, therefore can be by the relation between meritorious trend before and after linearization approximate representation electrical network forecast failure.When anticipation, cut-off while occurring, in electrical network, the meritorious trend of each equipment will redistribute, the power flow changing that front and back are cut-off in anticipation with envision the position of cut-offfing and cut-off front trend relevant.When anticipation, cut-off while betiding a certain section, some will transmit the meritorious trend of this section by the surplus equipment in section, and another part will be transferred to other section.Anticipation cut-off the residue trend of place section with cut-off before meritorious trend between ratio be called residual coefficient, the meritorious power flow increment of other section anticipation before and after cut-offfing and envisioning cut-offs the ratio that section cut-offs between front trend and is called coefficient of migration.Suppose that, for a certain forecast failure k, if this forecast failure only cut-offs the equipment in i section, the definition according to residual coefficient and coefficient of migration, has:

$R_{\mathrm{ii}}=\frac{{P_i}^c}{{P_i}^0}---(5-1)$

$R_{\mathrm{ij}}=\frac{P_j^c-P_j^0}{{P_i}^0},j\&Element;S_T-\left\{i\right\}---(5-2)$

In formula: R represents residual coefficient or coefficient of migration; Subscript i represents to envision the numbering of the section that cut-offs element place; Subscript j represents the numbering of affected section; S _trepresent section set; P represents the meritorious trend of section; Subscript 0 represents the electric network state before anticipation is cut-off; Subscript c represents the electric network state after anticipation is cut-off.

The trend operation constraint of electrical network can be described as:

${P_i}^0\&le;{\stackrel{\&OverBar;}{P_i}}^0,i\&Element;S_T---(5-3)$

The reliability constraint of electrical network can be described as:

${P_i}^c\&le;{\stackrel{\&OverBar;}{P_i}}^k---(5-4)$

$P_j^c\&le;{\stackrel{\&OverBar;}{P}}_j^{\&prime;},j\&Element;S_T-\left\{i\right\}---(5-5)$

In formula:

for anticipation cut-off k and occur after the current-carrying capacity of the permission in short-term upper limit of section i surplus equipment, can cut-off in rear section the current-carrying capacity in short-term of the trend ratio between surplus equipment and key equipment by anticipation and calculate;

for section j allows the upper limit of current-carrying capacity in short-term.

By formula (5-1) and formula (5-4), can be obtained:

$R_{\mathrm{ii}}{P_i}^0\&le;{\stackrel{\&OverBar;}{P_i}}^c,i\&Element;S_T---(5-6)$

By formula (5-2) and formula (5-5), can be obtained:

$P_j^0+R_{\mathrm{ij}}{P_i}^0\&le;{\stackrel{\&OverBar;}{P}}_j^{\&prime;},j\&Element;S_T-\left\{i\right\}---(5-7)$

For bus-bar fault or multiple failure, forecast failure will cut-off a plurality of equipment, and these equipment may be positioned at a plurality of different sections.Suppose that forecast failure k will cut-off section collection S _kin equipment, due to trend after forecast failure distribute will with section collection S _kin before the fault of each section trend all have relation.For calculating the relation between the meritorious trend of forecast failure front and back section, forecast failure k can be regarded as and cut-off one by one the S with section i ∈ _kthe result of relevant equipment.If forecast failure k s step is cut-off the equipment relevant to section f,

$R_{\mathrm{ff}}^s=\frac{{P_i}^s}{P_f^{s-1}}---(5-8)$

${R^s}_{\mathrm{ft}}=\frac{{P_t}^s-{P_t}^{s-1}}{P_f^{s-1}},t\&Element;S_T-\left\{f\right\}---(5-9)$

By formula (5-8) and formula (5-9), comprehensively can be obtained:

$P_j^s=\underset{i\&Element;S_T}{\mathrm{\&Sigma;}}{R}_{\mathrm{ij}}^s{P}_i^{s-1},j\&Element;S_T---(5-10)$

By formula (5-10) recursion, can be obtained:

$P_j^c=\underset{i\&Element;S_T}{\mathrm{\&Sigma;}}{R}_{\mathrm{ij}}^c{P}_{i_t}^0,j\&Element;S_T---(5-12)$

The trend operation constraint of electrical network can be described as:

$P_j^0\&le;{\stackrel{\&OverBar;}{L}}_j,j\&Element;S_T---(5-13)$

In formula:

for envisioning the meritorious trend of cut-offfing front section j,

long-term permission current-carrying capacity for section j.

The reliability constraint of electrical network can be described as:

$P_j^k\&le;{\stackrel{\&OverBar;}{E}}_j^k,j\&Element;S_T---(5-14)$

In formula:

for anticipation cut-off k and occur after the current-carrying capacity of permission in short-term of section j surplus equipment, can cut-off in rear section the current-carrying capacity in short-term of the trend ratio between surplus equipment and key equipment by anticipation and calculate.

By formula (5-10) and formula (5-14), can be obtained:

$\underset{i\&Element;S_T}{\mathrm{\&Sigma;}}{R}_{\mathrm{ij}}^k{P_i}^0\&le;{\stackrel{\&OverBar;}{E}}_j^k,j\&Element;S_T---(5-15)$

Formula (5-13) and formula (5-15) have provided the restriction relation between the meritorious trend of section, have described the feasible zone space of the meritorious trend of section.As long as the initial meritorious trend of each section meets the constraint condition of formula (5-13) and formula (5-15), can guarantee the thermally-stabilised safety of electrical network.

The thermally-stabilised limit of section is defined as to the initially permission upper control limit of meritorious trend of section, as long as the initial power flow control that each is moved to section is within this limit, just can guarantees the safe operation of electrical network.Obviously, the thermally-stabilised limit of section should be a special normal safe operation state, can obtain thus:

${\stackrel{\&OverBar;}{P}}_j\&le;{\stackrel{\&OverBar;}{L}}_j,j\&Element;S_T---(5-16)$

$\underset{i\&Element;S_T}{\mathrm{\&Sigma;}}{R}_{\mathrm{ij}}^k{\stackrel{\&OverBar;}{P}}_i\&le;{\stackrel{\&OverBar;}{E}}_j^k,j\&Element;S_T---(5-17)$

In formula:

thermally-stabilised control limit for section j.

Obviously, from the angle of operation of power networks, keeping, under the condition of the normal operation of electrical network, wishing that the thermally-stabilised control limit of section is large as much as possible.Due to the existence of formula (5-17) constraint, between the thermally-stabilised control limit of section, there is the relation of coordinating.Consider that the initial trend running status of electrical network roughly described the meritorious flow state of electrical network, the target of coordination may be defined as and makes the steady limit of section heat maximum with the minimum ratio of initial meritorious trend.The steady limit computational problem of section heat can be described as thus:

maxs (5-18)

${\stackrel{\&OverBar;}{P}}_j\&GreaterEqual;s{P}_j^0,j\&Element;S_T---(5-19)$

${\stackrel{\&OverBar;}{P}}_j\&le;{\stackrel{\&OverBar;}{L}}_j,j\&Element;S_T---(5-20)$

$\underset{i\&Element;S_T}{\mathrm{\&Sigma;}}{R}_{\mathrm{ij}}^k{\stackrel{\&OverBar;}{P}}_i\&le;{\stackrel{\&OverBar;}{E}}_j^k,j\&Element;S_T,k\&Element;S_k---(5-21)$

The impact of the fault set pair stability limitation that different short-term outage rates produces, gives yardman more abundant reference limit.

Example, utilize short duration failure rate <0.0002 and the short duration failure rate <0.0004 fault collection of chapter 5, and the fault of using sensitivity > 1% is assembled the comparison of fruit and N-1 fault collection, can provide the steady limit of heat of three ladders, be the result changing below:

The multipole section limit of table 8

In the situation that risks and assumptions is larger, the possibility of fault collection N-X is larger, limit will become less so, because a lot of N-1 limit great majority of 2 line sections are to produce because the line in 2 lines breaks down, the fault of N-X is that all the other two lines or three line faults are caused mostly, therefore for the degree of impact between the different section of research, also has good reference.Providing of multipole limit also has good directive significance for yardman, makes yardman can instruct scheduling by different limits under different weather conditions.

Claims (5)

1. the real-time risk assessment of electrical network and pre-control method, is characterized in that comprising the following steps:

1) outage rate of computing electric power line: λ i=λ _thunderi+ λ _windi+ λ _firei+ λ _icei+ λ _base;

In formula, λ _thunderifor the power transmission line outage rate that thunder and lightning causes, λ _fireifor the power transmission line outage rate that mountain fire causes, λ _windifor large wind-induced power transmission line outage rate, λ _iceifor the freezing power transmission line outage rate causing, λ _basebasic outage rate for power transmission line;

A) statistical basis outage rate: according to data formerly, according to different voltage, the basic outage rate of circuit is added up, line voltage distribution comprises 220KV, 500KV;

B) calculate the power transmission line outage rate that thunder and lightning causes: λ _thuderi=λ _aREAI* L _aREAI* M;

In formula: M is weather element, thunderstorm weather is 1, otherwise is 0, λ _aREAIfor the circuit lightning fault rate of thunder and lightning statistical regions, unit is inferior/(100km*1 Thunderstorm Day), L _aREAIfor being in the line length in this region, the km of unit; Circuit lightning fault rate causes that by the meteorological Thunderstorm Day in various places and thunder and lightning line failure rate calculates acquisition;

C) calculate large wind-induced power transmission line outage rate: λ _windi=λ _wind* L; ${\mathrm{\&lambda;}}_{\mathrm{wind}}=\left\{\begin{array}{c}0,\mathrm{\&omega;}\left(t\right)<{\mathrm{\&omega;}}_{\mathrm{cri}}\\ {\mathrm{\&lambda;}}_{\mathrm{base}}\&times;C_p\&times;(\frac{\mathrm{\&omega;}{\left(t\right)}^2}{{{\mathrm{\&omega;}}^2}_{\mathrm{cri}}}-1),\mathrm{\&omega;}\left(t\right)\&GreaterEqual;{\mathrm{\&omega;}}_{\mathrm{cri}}\end{array}\right.;$

In formula: L is the length of circuit in this climatic region, λ _basefor the crash rate under normal weather condition, ω _crifor critical wind velocity; C _pfor scale parameter; ω _crifor gale warning wind speed;

D) calculate the power transmission line outage rate that mountain fire causes: λ _firei=λ _fire* i*L _fire;

In formula, i is weather input quantity, and fine day cloudy day value is 1, and the rainy day is 0; L _firefor the length of circuit in mountain fire area, if circuit is not 0 in mountain fire region value; λ _firefor the line failure rate that mountain fire causes, unit is inferior/(100km* day), and its value changes according to Monthly changes,

E) calculate the freezing power transmission line outage rate causing: λ _icei=λ _ice* j*L _mountain; J, for freezing sleety weather sign occurs, represents freezing sleety weather during j=1, represent non-freezing weather during j=0; L _mountainfor circuit is in the length in mountain area; λ _icecan obtain according to historical statistics, computing formula is:

unit is inferior/(100km* day);

2) outage rate of computing equipment: the difference of the health status in the time of according to the operation of element, be divided into a plurality of state grades, the outage rate of different conditions grade element is separately added up; The outage rate of equipment is described with binary states synoptic model, $\mathrm{\&lambda;}(\mathrm{state},\mathrm{\&omega;},\mathrm{flawstate})=\left\{\begin{array}{c}\mathrm{\&lambda;}(\mathrm{state},\mathrm{flawstate})*\frac{N+S}{N}*(1-F),\mathrm{\&omega;}=0\\ \mathrm{\&lambda;}(\mathrm{state},\mathrm{flawstate})*\frac{N+S}{S}*F,\mathrm{\&omega;}=1\end{array}\right.;$ In formula, N is the normal weather duration, and S is the inclement weather duration, and F is the ratio that occurs in inclement weather fault, and ω is current device weather sign of living in, normal weather ω=0, inclement weather ω=1; λ (state, flawstate), represents the equipment outage rate under different conditions, supposes element obeys index distribution working time, and in time t, the failure probability of this element is:

3) Study of Risk Evaluation Analysis for Power System, comprises the operation risk assessment of loss load, the operation risk assessment of short-time overload, will lose load risk and short-time overload rate risk ranking; Set up the meteorological model on Operation of Electric Systems impact, by calculative determination risk class, and by risk indicator, show the extent of injury of fault; When the operation risk assessment of loss load, first hypothesis is cut-off target line and is caused fault, counting loss load, and simultaneously according to the outage rate of line length computational scheme, outage rate and the loss load value-at-risk that multiplies each other to obtain; When the operation risk assessment of short-time overload, select overload under static security as consequence, the short-time overload rate of usining is calculated again as severity, simultaneously according to the outage rate of line length computational scheme, according to outage rate and overload risk, obtains value-at-risk; Outage rate comprises power transmission line outage rate that power transmission line outage rate, large wind-induced power transmission line outage rate, mountain fire that basic outage rate, thunder and lightning cause cause, one or more in the freezing power transmission line outage rate causing;

4) fault collection generates automatically, according to real-time topology information and equipment room coefficient of migration, calculates in real time fault collection, fault collection is divided into multistage, and multistage fault set pair should multistage limit.

2. the real-time risk assessment of electrical network according to claim 1 and pre-control method, is characterized in that: the state grade of element comprises kilter grade, alarm status grade, precarious position grade, and its corresponding element failure rate is: $\mathrm{\&lambda;}\left(\mathrm{state}\right)=\left\{\begin{array}{c}\frac{N_{\mathrm{good}}}{T_{\mathrm{good}}},\mathrm{state}=1\\ \frac{N_{\mathrm{warning}}}{T_{\mathrm{warning}}},\mathrm{state}=2\\ \frac{N_{\mathrm{danger}}}{T_{\mathrm{danger}}},\mathrm{state}=3\end{array}\right.;$

In formula, State represents state, and 1,2,3 represent respectively good, alarm and precarious position; Timing statistics T is divided into kilter duration T _good, alarm status duration T _warning, precarious position duration T _danger; N _good, N _warning, N _dangerfor the element fault number of times under corresponding states.

3. the real-time risk assessment of electrical network according to claim 2 and pre-control method, is characterized in that: timing statistics T is interval is the moon,

$\mathrm{\&lambda;}\left(\mathrm{state}\right)=\begin{array}{c}\left\{\begin{array}{cc}\frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{good}}}{T_{i,\mathrm{good}}},\mathrm{state}=1\\ \frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{warning}}}{T_{i,\mathrm{warning}}},\mathrm{state}=2\\ \frac{1}{C}\underset{i=1}{\overset{C}{\mathrm{\&Sigma;}}}& \frac{N_{i,\mathrm{danger}}}{T_{i,\mathrm{danger}}},\mathrm{state}=3\end{array};\right.\end{array}$

In formula: C represents statistics year number.

4. the real-time risk assessment of electrical network according to claim 3 and pre-control method, is characterized in that: according to the data of real-time tour, provide the state grade of element, quantize the evaluation criterion of state grade, according to on-the-spot defect rank severity scale.

5. the real-time risk assessment of electrical network according to claim 1 and pre-control method, is characterized in that: when risks and assumptions is larger, fault collection is larger, and limit is less.

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