CN105896533A - Static safety evaluation method of active distribution network - Google Patents

Abstract

The invention relates to a static safety evaluation method of an active distribution network. The method comprises the following steps of inputting a network parameter and wind power, solar energy and load data; carrying out static safety evaluation aiming at a fault of a certain branch at a certain moment; carrying out load transferring supply; judging whether a controllable power supply exists in an island or not, if yes, analyzing whether the power of the island is balanced or not; carrying out load translation and load shedding operation if the power of the island is not balanced; carrying out power flow calculation if the power of the island is balanced, analyzing whether out-of-limit exists or not, if yes, carrying out active management, otherwise recording the parameter; judging whether the fault is recovered or not, if not, entering a next fault period and returning the judgment step, and if yes, judging whether the fault calculation of all branch periods is completed or not; calculating a safety index according to the recorded parameter if the fault calculation is completed; and returning to continuously analyze a next expectation fault if the fault calculation is not completed. Compared with the prior art, the static safety evaluation method has the characteristics that the active performance and the initiative performance of the active distribution network are combined, the time sequence characteristic of network running is considered, and comprehensive analysis is achieved.

Description

A kind of active distribution network Static security assessment method

Technical field

The present invention relates to the static security analysis field of power distribution network, especially relate to a kind of master considering temporal characteristics Dynamic Security Analysis of Distribution Networks method.

Background technology

The sustainable growth of the size of population, the sustainable development of economic society, constantly consumption, the environment of traditional fossil energy The most seriously making of pollution problem is sustainable, green low-carbon develops into the new demand that contemporary mankind is developed.Working as Under the background of front ecodevelopment, the trend of sustainable development also must be complied with in electric power energy field.To this end, it is renewable Energy source utilizing electricity generating techn receives extensive concern and attention, distributed power source (Distributed Generation, DG) Accessed power distribution network in a large number.But due to the green distributed power source such as wind-driven generator, photovoltaic array possess intrinsic between Having a rest property and uncertainty so that DG is integrated widely will cause a series of impact to the operation of power distribution network.DG's A large amount of networkings will change trend and the voltage's distribiuting of network, make the complexity of relay protection strategy strengthen, cause power supply Power quality problem, increase planning and the difficulty of traffic control, affect distribution network reliability and safety etc..Though So energy storage technology and the introducing of Power Electronic Technique, can overcome caused the disappearing that DG networks to a certain extent Pole affect, but power distribution network still exist intermittent energy source is dissolved insufficient, compatible poor, the network optimization run Scarce capacity, scheduling mode falls behind, the problems such as source-interactive degree of net-lotus is low.Extensive to regenerative resource Make full use of, integrated and energy resource structure strategic the optimizing and revising of high permeability of DG still suffers from power distribution network Many difficulties.To this end, active distribution network (Active Distribution Network, ADN) technology is arisen at the historic moment, Aim to solve the problem that power distribution network compatibility and the large-scale application intermittent renewable energy, promote green energy resource utilization rate, optimization Adjust the problems such as primary energy structure.According to the definition be given in CIGRE C6.11 working group work report, main Dynamic power distribution network is can be with the distribution of Comprehensive Control distributed energy (Distributed Energy Resources, DER) Net, it is possible to use network technology realizes effective management of trend flexibly, and distributed energy reasonably supervises ring at it The supporting role certain to system is undertaken on the basis of border and access criterion.One as following intelligent distribution network is sent out Exhibition pattern, active distribution network be integrated with distributed power source, distributed energy storage (Electrical Energy Storage, ESS), controllable burden (Controllable Load, CL) the distributed energy, rely on advanced information communication skill Art and Power Electronic Technique, coordinate control and active management to controllable resources abundant in network, it is achieved to can The highly compatible of the renewable sources of energy and efficiently utilize, optimize network running status, promote distribution assets utilization ratio, The upgrading delaying power distribution network is invested, is improved power supply quality and security reliability.

Security Analysis of Distribution Networks is to be analyzed the steady-state operation situation after power distribution network generation forecast accident, right The accident causing the menace network safe operations such as apparatus overload, voltage out-of-limit, mistake load is warned, Jin Erping Estimate the level of security of power distribution network, and find out the weak link that system is run.For Security Analysis of Distribution Networks and peace Full assessment, existing many scholars have done relevant research, and have achieved certain achievement.Document " power distribution network safety The research of property index " and " power distribution network static security evaluation index based on Risk Theory research " establish distribution The index of security assessment of net static security analysis, and it is applied to example, document " fills based on alternate power autocast The power distribution network static security analysis put " consider the impact of alternate power autocast, based on N-1+M criterion Power distribution network is carried out static security analysis, but above-mentioned document is not the most counted and distributed power source.Document is " based on load The power distribution network N-1 security evaluation of recovery policy " utilize network reconfiguration to carry out fault after load service restoration, with The load proportion restored electricity is safety index, and power distribution network carries out N-1 security evaluation, but analysis result only pin Certain of network is determined running status, does not accounts for load and the timing of scene resource and undulatory property.Document 《Hierarchical Risk Assessment of Transmission System Considering the Influence of Active Distribution Network. " in power transmission network security evaluation, consider the impact of ADN, but have ignored The trend constraint of power distribution network, and only only account for the active property of ADN, initiative is considered deficiency, think simultaneously The isolated island only existing blower fan and photovoltaic can run, and actually intermittent power supply can not individually support island with power. Document " Security Assessment in Active Distribution Networks with Change in Weather Patterns " count and the Changes in weather impact on element fault, it is proposed that a kind of three condition synoptic model, with covering spy Monte Carlo Simulation of Ions Inside carrys out the uncertainty of processing system running status, assesses ADN's with load loss and electric quantity loss Safety, but not meter and energy storage in the power-balance of isolated island, do not account for the sustainability of island with power yet.

Summary of the invention

It is an object of the invention to provide a kind of active distribution network Static security assessment method for the problems referred to above.

For realizing purpose of the present invention, technical scheme is as follows:

A kind of active distribution network Static security assessment method, the method combines active property and the active of active distribution network Property, it is contemplated that the temporal characteristics of the network operation, initially set up the element sequence mould of active distribution network Static security assessment Type, arranges the safety evaluation index of active distribution network Static security assessment simultaneously, then considers according to above-mentioned data During fault period of right time and fault, of both network operation state, timing carries out Contingency analysis, it is achieved that Assessment to active distribution network static security, the method comprises the following steps:

(1) input network parameter and scene lotus data；

(2) for the nth bar branch trouble of t period, according to described network parameter and scene lotus data with And the element sequence model set up carries out Static security assessment, particularly as follows:

A () carries out load transfer: recover load by interconnection and power, the part that cannot recover is performed isolated island The method of operation；

Whether (b) isolated island to being formed after fault, exist stable controllable electric power as islet operation in analyzing isolated island Main power source, if then entering step (c), if otherwise entering step (e)；

C () analyzes whether the power of isolated island balances, if then entering step (d), if otherwise carrying out load translation Operate with cutting load, until isolated island power-balance, enter step (d)；

D () carries out the Load flow calculation of main distribution net and isolated island, it may be judged whether there is voltage out-of-limit or power is out-of-limit, If then carrying out active management, until eliminating out-of-limit, if otherwise entering step (e)；

(e) record power failure load, power off time and energy storage dump energy；

Whether (f) failure judgement repairs, if then entering step (3)；If otherwise entering the next fault period, Return step (b)；

Wherein, t=1,2.., T, n=1,2 ... N, T are period sum, and N is branch road sum；

(3) judge whether to have completed all branch roads, the calculation of fault of all periods, if then entering step (4)； If otherwise t or n to be progressively increased operation, returning step (2), continuing to analyze next forecast accident；

(4) index calculating and security evaluation are carried out according to the parameter of record and the safety evaluation index of setting.

The element sequence model of described active distribution network Static security assessment include blower fan and photovoltaic temporal model, meter and The sequential load model of translatable load and the temporal model of energy storage.

Described blower fan is with photovoltaic temporal model, and blower fan temporal model is:

$P_{WT}=\left\{\begin{array}{cc}0& v\≤v_{ci}\\ k_{1}v+k_2& v_{ci}\≤v\≤v_r\\ P_{WTr}& v_r\≤v\≤v_{co}\\ 0& v_{co}\≤v\end{array}\right.;$

Wherein: P_WTrSpecified active power for blower fan；Parameter k₁=P_WTr/(v_r-v_ci)；Parameter k₂=-k₁v_ci；V is Wind speed；v_ciFor incision wind speed；v_rFor rated wind speed；v_coFor cut-out wind speed；

Photovoltaic temporal model is:

P_PV=rA η

Wherein: P_PVActive power for photovoltaic array output；R is light intensity；A is the photovoltaic array gross area；η is Photoelectric transformation efficiency.

The sequential load model of described meter and translatable load is:

P_t=P_Forecast,t-P_Shiftout,t

Wherein: P_tFor t period load value after translation；P_Forecast,tPredicted load for the t period；P_Shiftout,tFor The translatable load that the t period removes:

$P_{Shiftout,t}=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{x}_{k,t,t}{P}_{k,1}+\underset{l=1}{\overset{L-1}{\mathrm{\Σ}}}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{x}_{k,t-l,t}{P}_{k,1+l}$

Wherein: M is translatable load equipment type sum；x_k,t,tThe t period removed for the t period should start power supply Kth class translatable load equipment number；P_k,1For the translatable load equipment of kth class in its continuous working period the 1st The power of individual period；L is the maximum continuous working period of all kinds of translatable load equipment；x_k,t-l,tRemove for the t period The t-l period should start power supply kth class translatable load equipment number；P_k,1+lFor the translatable load equipment of kth class The operating power of 1+l period in its continuous working period.

The temporal model of described energy storage is:

$P_{ESS,t}=\left\{\begin{array}{c}(P_{Load,t}-P_{DG,t})/{\mathrm{\η}}_{Dis}\\ (P_{Load,t}-P_{DG,t}){\mathrm{\η}}_{Cha}\end{array}\right.$

$S_{SOC,t+1}=S_{SOC,t}-\frac{P_{ESS,t}{\mathrm{\ΔD}}_t}{E_{ESS}}$

Wherein: P_ESS,tFor t period accumulator cell charging and discharging power, discharge for just, be charged as bearing；P_Load,tFor the t period Total load in isolated island；P_DG,tFor the gross output of other power supplys in t period isolated island；η_DisFor discharging efficiency；η_Cha For charge efficiency；S_SOC,tState-of-charge for t period accumulator；ΔD_tPersistent period for the t period；E_ESSFor storing The rated capacity of battery；Accumulator be enough to lower constraint at running fullness in the epigastrium and abdomen:

P_ESS,t≤P_ESS,max

S_SOC,min≤S_SOC,t≤S_SOC,max

Wherein: P_ESS,maxThe maximum charge-discharge electric power allowed for accumulator；S_SOC,max、S_SOC,minIt is respectively state-of-charge Bound.

In described step (a), carry out considering during load transfer the timing variations of interconnection active volume.

The safety evaluation index of described active distribution network Static security assessment includes electric quantity loss rate index, isolated island electricity Amount loss rate index, time safety index, branch road safety indexes and system synthesis safety indexes.

Described electric quantity loss rate index expression formula is:

$C_{ELR,t,n}={\mathrm{\λ}}_n\·L_n\·T_E\frac{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{F,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·(S_{d,i}-S_{SL,d,i})\·{\mathrm{\ΔD}}_{F,d,i}}{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{S,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·S_{d,i}\·{\mathrm{\ΔD}}_d}$

Wherein: C_ELR,t,nElectric quantity loss rate index for t period nth bar branch trouble；λ_nFor nth bar branch road Fault rate；L_nLength for nth bar branch road；T_EFor evaluation time；t_DFor last period that fault is lasting； φ_F,dPower failure load aggregation for the d period；γ_iThe important level factor for i-th load；S_d,iFor the d period i-th The capacity of individual load；S_SL,d,iThe capacity of extensible load is contained for d period i-th load；ΔD_F,d,iFor the d period The power off time of i-th load；φ_S,dSystem loading set for the d period；ΔD_dPersistent period for the d period；

Described isolated island electric quantity loss rate index, its expression formula is:

$C_{IELR,t,n}={\mathrm{\λ}}_n\·L_n\·T_E\frac{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{1F,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·(S_{d,i}-S_{SL,d,i})\·{\mathrm{\ΔD}}_{F,d,i}}{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{1,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·S_{d,i}\·{\mathrm{\ΔD}}_d}$

Wherein: C_IELR,t,nIsolated island rate of energy loss index for t period nth bar branch trouble；φ_IF,dFor the d period Isolated island power failure load aggregation；φ_I,dIsolated island load aggregation for the d period；

Described time safety index, its expression formula is:

$C_{S,t}=\frac{{\mathrm{\α}}_1}{2}(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{ELR,t,n}+\underset{n=1}{\overset{N}{max}}\{C_{ELR,t,n}\left\}\right)+\frac{{\mathrm{\α}}_2}{2}(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{IELR,t,n}+\underset{n=1}{\overset{N}{max}}\{C_{IELR,t,n}\left\}\right)$

Wherein: C_S,tIt it is the safety indexes of t period；α₁、α₂For weight coefficient；N is system branch number；

Described branch road safety indexes, its expression formula is:

$C_{S,n}=\frac{{\mathrm{\α}}_1}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{ELR,t,n}+\underset{t=1}{\overset{T}{max}}\{C_{ELR,t,n}\left\}\right)+\frac{{\mathrm{\α}}_2}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{IELR,t,n}+\underset{t=1}{\overset{T}{max}}\{C_{IELR,t,n}\left\}\right)$

Wherein: C_S,nSafety indexes for nth bar branch road；T is the time hop count of static security analysis；

Described system synthesis safety indexes, its expression formula is:

$C_{SCS}=\frac{{\mathrm{\β}}_1}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{S,t}+\underset{t=1}{\overset{T}{\max }}\{C_{S,t}\left\}\right)+\frac{{\mathrm{\β}}_2}{2}(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{S,n}+\underset{n=1}{\overset{N}{\max }}\{C_{S,n}\left\}\right)$

Wherein: C_SCSFor system synthesis safety indexes；β₁、β₂For weight coefficient.

Described active management includes meritorious reduction and idle control, the transformer tap of exerting oneself of exerting oneself of load translation, DG Head regulation, reactive-load compensation equipment control and cutting load.

Compared with prior art, the method have the advantages that

(1) combine ADN active property (containing the wind-light storage distributed energy, after fault can islet operation, Reduce power failure load) and initiative (there is active management ability, it is possible to elimination network out-of-limit danger) carry out quiet State security evaluation, assessment result is the most accurately and reliably.

(2) meter and the sequential undulatory property of scene lotus, carry out static security respectively in the different fault periods of right time and divide Analysis, assessment is more fully.

(3) consider the temporal characteristics of the network operation during fault, mainly include network trend dynamically change, The dynamically change of network cutting load and the sustainability of island with power.

Accompanying drawing explanation

Fig. 1 is the security evaluation flow chart of the present invention；

Fig. 2 is that 37 node AND test example figure；

Fig. 3 is the daily load curve figure of power distribution network；

Fig. 4 is that the translatable load of power distribution network accounts for total load ratio day curve chart；

Fig. 5 is that interconnection allows to turn the curve chart for peak load；

Fig. 6 is scene resource day curve chart；

Fig. 7 is time safety index；

Fig. 8 is branch road safety indexes；

Fig. 9 is the electric quantity loss rate index of period 19 each branch trouble；

Figure 10 is the electric quantity loss rate index of day part branch road 3 fault；

Figure 11 is the time safety index of different scene；

Figure 12 is the branch road safety indexes of different scene；

Figure 13 is the time safety index of different analysis method；

Figure 14 is the branch road safety indexes of different analysis method.

Detailed description of the invention

The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.The present embodiment is with the technology of the present invention side Implement premised on case, give detailed embodiment and concrete operating process, but the protection model of the present invention Enclose and be not limited to following embodiment.

The present embodiment provides a kind of active distribution network Static security assessment method, and the method combines active distribution network Active property and initiative, it is contemplated that the temporal characteristics of the network operation, initially set up active distribution network Static security assessment Element sequence model, the safety evaluation index of active distribution network Static security assessment, basis then are set simultaneously During above-mentioned data consideration fault period of right time and fault, timing of both network operation state carries out envisioning thing Therefore analyze, it is achieved that the assessment to active distribution network static security.

1, the element sequence model of active distribution network

ADN comprises abundant controllable resources, it is considered to the sequential undulatory property of scene lotus, sets up crucial unit in ADN The temporal model of part, is the basic work of static security analysis.

(1) blower fan and the temporal model of photovoltaic

The active-power P of wind-driven generator output_WTCan represent with following piecewise function with the relation of wind speed v:

$P_{WT}=\left\{\begin{array}{cc}0& v\≤v_{ci}\\ k_{1}v+k_2& v_{ci}\≤v\≤v_r\\ P_{WTr}& v_r\≤v\≤v_{co}\\ 0& v_{co}\≤v\end{array}\right.---\left(1\right)$

Wherein: P_WTrSpecified active power for blower fan；Parameter k₁=P_WTr/(v_r-v_ci)；Parameter k₂=-k₁v_ci；v_ciFor incision Wind speed；v_rFor rated wind speed；v_coFor cut-out wind speed.

The active-power P of photovoltaic array output_PVSimplified solution formulas be:

P_PV=rA η (2)

Wherein: r is light intensity；A is the photovoltaic array gross area；η is photoelectric transformation efficiency.

By scene resources, the sequential wind speed of time period to be analyzed (such as one day), light intensity data can be obtained, knot Box-like (1) (2), the sequential of blowing machine and photovoltaic goes out force data.

(2) meter and the sequential load model of translatable load

Translatable load (Shiftable Loads, SL) refers to that power-on time can move adjustment according to schedule Load.There is a large amount of friendly controlled translatable load in ADN, especially in resident load, its proportion is relatively Greatly.Load panning techniques is a kind of effective load management controls technology, falls into a trap and load is flat at static security analysis Move, be conducive to improving the safety of ADN.After accident occurs, in isolated island, power is not enough or network exists phase Close out-of-limit dangerous time, load translation can reduce the workload demand of network in trouble duration, so reduce cut negative Lotus and electric quantity loss, raising internet security.

For simplified model, being beneficial to analyze, present invention assumes that the power distribution automation degree of ADN is higher, fault is held The continuous time is shorter, and the maximum allowable delay power-on time (being typically taken as 6 hours) of translatable load is more than fault Persistent period, therefore the immigration to translatable load can be carried out after fault recovery, only need to consider within the fault period can The removal of translation load；Only after fault occurs, in isolated island, power is not enough or network exists relevant out-of-limit danger Time, just consider to carry out load translation；For the purpose of raising safety, once carry out load translation, the most to the greatest extent may be used The translatable load equipment of removal that can be many is until fault restoration.

In the fault period, the sequential load value formula of meter and translatable load is as follows:

P_t=P_Forecast,t-P_Shiftout,t (3)

Wherein: P_tFor t period load value after translation；P_Forecast,tPredicted load for the t period；P_Shiftout,tFor the t period The translatable load of removal.The translatable load that the t period removes includes two parts: the t period has just started putting down of removal Move load and had moved out before the t period but t the period still translatable load in its continuous working period, concrete table Reaching formula is:

$P_{Shiftout,t}=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{x}_{k,t,t}{P}_{k,1}+\underset{l=1}{\overset{L-1}{\mathrm{\Σ}}}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{x}_{k,t-l,t}{P}_{k,1+l}---\left(4\right)$

Wherein: M is translatable load equipment type sum；x_k,t,tThe t period removed for the t period should start the kth class of power supply Translatable load equipment number；P_k,1For the translatable load equipment of kth class the 1st period in its continuous working period Power；L is the maximum continuous working period of all kinds of translatable load equipment；x_k,t-l,tThe t-l period removed for the t period should Start the kth class translatable load equipment number of power supply；P_k,1+lFor the translatable load equipment of kth class when its continuous firing The operating power of interior 1+l period.

Sequential load data can be obtained by load prediction, in conjunction with the operation of network during translatable load prediction and fault Situation, can be drawn meter and the sequential load data of translatable load by formula (3) (4).

(3) temporal model of energy storage

In ADN static security analysis, energy storage is one of the core parts that must take into.As the most chargeable but also The flexible controllable electric power that can discharge, the introducing of energy storage substantially increases the initiative of ADN.

The present invention uses accumulator as energy storage device.Exert oneself in view of intermittent distributed power sources such as scene have with Machine, the stable operation of isolated island can not be supported, during fault, accumulator is considered as the main power source of isolated island, mainly Playing the effect maintaining isolated island power-balance, its access node is considered as the balance node of isolated island, and it is exerted oneself by isolated island Load and other power supplys are exerted oneself decision:

$P_{ESS,t}=\left\{\begin{array}{c}(P_{Load,t}-P_{DG,t})/{\mathrm{\η}}_{Dis}\\ (P_{Load,t}-P_{DG,t}){\mathrm{\η}}_{Cha}\end{array}\right.---\left(5\right)$

$S_{SOC,t+1}=S_{SOC,t}-\frac{P_{ESS,t}{\mathrm{\ΔD}}_t}{E_{ESS}}---\left(6\right)$

Wherein: P_ESS,tFor t period accumulator cell charging and discharging power (electric discharge is for just, being charged as bearing)；P_Load,tFor t period isolated island Interior total load；P_DG,tFor the gross output of other power supplys in t period isolated island；η_DisFor discharging efficiency；η_ChaFor filling Electrical efficiency；S_SOC,tState-of-charge for t period accumulator；ΔD_tPersistent period for the t period；E_ESSFor accumulator Rated capacity.For the protection life of storage battery and the purpose of operation safety, accumulator needs to meet in running Below constraint:

P_ESS,t≤P_ESS,max (7)

S_SOC,min≤S_SOC,t≤S_SOC,max (8)

Wherein: P_ESS,maxThe maximum charge-discharge electric power allowed for accumulator；S_SOC,max、S_SOC,minIt is respectively state-of-charge upper and lower Limit.

It addition, for ease of the analysis of problem, hypothesis below made by energy storage model by the present invention: many when existing in isolated island During individual energy storage, preferably of charge-discharge electric power maximum is as main power source, and remaining energy storage carries out merit to isolated island on demand Rate supports；If energy storage state-of-charge in electric discharge of balance node reaches lower limit, then isolated island is out of service.

2, the index of security assessment of active distribution network static security analysis

After static security analysis occurs with forecast accident, the voltage out-of-limit of network, power are out-of-limit and lose the situations such as load and come The safety of assessment system, carries out early warning, and finds out the weak link of system peril.At ADN environment Under, voltage out-of-limit and power is out-of-limit can be eliminated by active management, the therefore safety of the network operation after fault Rely primarily on mistake load condition to assess.Based on N-1 branch trouble, considering temporal characteristics, the present invention is with electricity Based on amount loss, establish the safety evaluation index of ADN.

(1) electric quantity loss rate index

Electric quantity loss rate index comprehensive considers fault rate and the order of severity of fault afterload power failure, and wherein load stops Electricity severity accounts for system with the electric quantity loss of system and answers the ratio of delivery to characterize, and index can go out certain by qualitative assessment The impact that security of system is powered by certain fault that the period occurs, desired value is the least, safety the best.This index is examined Consider change and the change of trouble duration internal loading of fault period of right time, there is timing.For the t period The fault of the nth bar branch road occurred, the expression formula of electric quantity loss rate index is:

$C_{ELR,t,n}={\mathrm{\λ}}_n\·L_n\·T_E\frac{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{F,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·(S_{d,i}-S_{SL,d,i})\·{\mathrm{\ΔD}}_{F,d,i}}{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{S,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·S_{d,i}\·{\mathrm{\ΔD}}_d}---\left(9\right)$

Wherein: C_ELR,t,nElectric quantity loss rate index for t period nth bar branch trouble；λ_nFault rate for nth bar branch road； L_nLength for nth bar branch road；T_EFor evaluation time；t_DFor last period that fault is lasting；φ_F,dDuring for d The power failure load aggregation of section；γ_iThe important level factor for i-th load；S_d,iCapacity for d period i-th load； S_SL,d,iThe capacity of extensible load is contained for d period i-th load；ΔD_F,d,iDuring for the power failure of d period i-th load Between；φ_S,dSystem loading set for the d period；ΔD_dPersistent period for the d period.

(2) isolated island electric quantity loss rate index

Being similar to, isolated island electric quantity loss rate index electric quantity loss in isolated island during fault accounts for isolated island and answers delivery Ratio describes the order of severity that isolated island internal loading has a power failure, and this index occurs for certain fault of qualitative assessment period The safe operation ability of rear ADN isolated island, desired value is the least, isolated island safety is the best.For the t period occur n-th The fault of bar branch road, the expression formula of its isolated island electric quantity loss rate index is:

$C_{IELR,t,n}={\mathrm{\λ}}_n\·L_n\·T_E\frac{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{1F,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·(S_{d,i}-S_{SL,d,i})\·{\mathrm{\ΔD}}_{F,d,i}}{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{1,d}}{\mathrm{\Σ}}{\mathrm{\γ}}_i\·S_{d,i}\·{\mathrm{\ΔD}}_d}---\left(10\right)$

Wherein: C_IELR,t,nIsolated island rate of energy loss index for t period nth bar branch trouble；φ_IF,dIsolated island for the d period stops Electric load set；φ_I,dIsolated island load aggregation for the d period.

(3) time safety index

The all branch troubles occurred for certain period, meter and average level and maximum horizontal, with rate of energy loss Based on isolated island rate of energy loss index, establish time safety index, it is possible to qualitative assessment goes out each period The safety of system power supply, finds out the weak period that system is run.The safety indexes that t period system is run is:

$C_{S,t}=\frac{{\mathrm{\α}}_1}{2}(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{ELR,t,n}+\underset{n=1}{\overset{N}{max}}\{C_{ELR,t,n}\left\}\right)+\frac{{\mathrm{\α}}_2}{2}(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{IELR,t,n}+\underset{n=1}{\overset{N}{max}}\{C_{IELR,t,n}\left\}\right)---\left(11\right)$

Wherein: C_S,tIt it is the safety indexes of t period；α₁、α₂For weight coefficient (present invention is taken as 0.7,0.3)； N is system branch number.

(4) branch road safety indexes

Certain branch trouble occurred for all periods, from meansigma methods and two angles of maximum, considers Rate of energy loss and isolated island rate of energy loss index, establish branch road safety indexes, and qualitative assessment goes out each bar branch road Safety, find out system run weak branch road.The safety indexes of nth bar branch road is:

$C_{S,n}=\frac{{\mathrm{\α}}_1}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{ELR,t,n}+\underset{t=1}{\overset{T}{max}}\{C_{ELR,t,n}\left\}\right)+\frac{{\mathrm{\α}}_2}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{IELR,t,n}+\underset{t=1}{\overset{T}{max}}\{C_{IELR,t,n}\left\}\right)---\left(12\right)$

Wherein: C_S,nSafety indexes for nth bar branch road；T is the time hop count of static security analysis.

(5) system synthesis safety indexes

System synthesis safety indexes combines time safety and branch road safety indexes, meter and average level and Big level, qualitative assessment goes out the general safety of whole distribution system, and its expression formula is:

$C_{SCS}=\frac{{\mathrm{\β}}_1}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{S,t}+\underset{t=1}{\overset{T}{\max }}\{C_{S,t}\left\}\right)+\frac{{\mathrm{\β}}_2}{2}(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{S,n}+\underset{n=1}{\overset{N}{\max }}\{C_{S,n}\left\}\right)---\left(13\right)$

Wherein: C_SCSFor system synthesis safety indexes；β₁、β₂For weight coefficient (present invention is taken as 0.5,0.5).

3, active distribution network Static security assessment method

Based on above-mentioned model and index, detailed process such as Fig. 1 of active distribution network Static security assessment method of the present invention Shown in, particularly as follows:

(1) input network parameter and scene lotus data；

(2) for the nth bar branch trouble of t period, according to described network parameter and scene lotus data with And the element sequence model set up carries out Static security assessment, particularly as follows:

A () carries out load transfer: recover load by interconnection and power, the part that cannot recover is performed isolated island The method of operation；

Whether (b) isolated island to being formed after fault, exist stable controllable electric power as islet operation in analyzing isolated island Main power source, if then entering step (c), if otherwise entering step (e)；

C () analyzes whether the power of isolated island balances, if then entering step (d), if otherwise carrying out load translation Operate with cutting load, until isolated island power-balance, enter step (d)；

D () carries out the Load flow calculation of main distribution net and isolated island, it may be judged whether there is voltage out-of-limit or power is out-of-limit, If then carrying out active management, until eliminating out-of-limit, if otherwise entering step (e)；

(e) record power failure load, power off time and energy storage dump energy；

Whether (f) failure judgement repairs, if then entering step (3)；If otherwise entering the next fault period, Return step (b)；

Wherein, t=1,2.., T, n=1,2 ... N, T are period sum, and N is branch road sum；

(3) judge whether to have completed all branch roads, the calculation of fault of all periods, if then entering step (4)； If otherwise t or n to be progressively increased operation, returning step (2), continuing to analyze next forecast accident；

(4) index calculating and security evaluation are carried out according to the parameter of record and the safety evaluation index of setting.

4, application example

The present invention establishes 37 node radiant type ADN test examples, as shown in Figure 2.The electric pressure of network For 10kV；0 node is transformer station's low-voltage bus bar node, and ULTC (110/10kV) tap is 17 grades, no-load voltage ratio adjustable extent is ± 8 × 1.25%；The SVG as reactive-load compensation equipment it is connected at 8 nodes, Idle adjustable extent-500kVar to+500kVar.

Load includes resident load, industrial load and Commercial Load, based on resident load, and its interior joint 1-29 For resident load, node 30-33 is industrial load, and node 34-36 is Commercial Load.Load design parameter is shown in Table 1, wherein load important factor is the biggest, load is the most important.The daily load curve of power distribution network entirety is as shown in Figure 3.

Table 1 node load parameter

This example is only counted and translatable load in resident load, translatable load consider dehydrator, dish-washing machine, Washing machine three types, its concrete use electrical characteristics and day part access the number of devices such as table 2 of electrical network, table 3 institute Showing, the translatable load of power distribution network day part accounts for the curve of total load ratio and sees Fig. 4.

The translatable load equipment of table 2 use electrical characteristics

Table 3 day part accesses the translatable load equipment quantity (unit: platform) of electrical network

Each branch road circuit is cable, every kilometer of impedance 0.18+j0.09 Ω, and maximum carrying capacity is 509A, and fault is repaiied The multiple time takes 4h, and fault rate is 0.04 time/a km, and the line length of each branch road of main feeder takes 0.6km, node 16, Each branch road line length of 26 place branches takes 0.4km, each branch road circuit of node 23,30,34 place branch Length takes 0.3km.Interconnection switch is mainly used in the load transfer of node 26 place branch, and it allows to turn for maximum The curve of cyclical fluctuations of load as it is shown in figure 5, the 18-21 period interconnection load that can turn confession is relatively limited, remaining period All loads in the most transferable branch.

Select wind speed and the intensity of illumination data in somewhere summer day, generate scene resource day curve such as Fig. 6.Net Network comprises some blower fans, photovoltaic and energy storage, and total permeability of scene is about 48%.The incision wind speed of blower fan is 2.5m/s, rated wind speed is 12m/s, and cut-out wind speed is 25m/s, the volume of 14,20,35 access blower fans of node Constant volume is respectively 300kW, 400kW, 300kW.The photoelectric transformation efficiency of photovoltaic is 16%, node 14, 22, the gross area of 24 accessed photovoltaics is respectively 1875m²、2500m²、2500m², rated capacity is respectively 300kW、400kW、400kW.The charge efficiency of accumulator and discharging efficiency are respectively 80% and 85%, lotus The electricity condition upper limit and lower limit are respectively 100% and 20%, and the maximum of the accessed accumulator of node 15,22,33 is filled Discharge power is respectively 750kW, 600kW, 400kW, and rated capacity is respectively 1500kW h, 1200kW ·h、800kW·h。

For above-mentioned example, it is considered to temporal characteristics, meter and the islet operation of ADN and active management ability, carry out ADN static security analysis, to find the weak period and weak branch road that system runs.With isolated island power-balance and Network trend is constrained to criterion, carries out translating the operation of the active management such as load, cutting load, obtains each period each bar Electric quantity loss rate during branch trouble and isolated island electric quantity loss rate index, then when the statistical computation carrying out being correlated with can draw Section safety indexes (such as Fig. 7), branch road safety indexes (such as Fig. 8) and system synthesis safety indexes.

General safety index C of system_SCS=0.0069.

As shown in Figure 7: period 5-11, the safety of network is preferable, and its reason is these periods Fault, in trouble duration internal loading is not up to peak value, network, available translatable load is more, blower fan Exert oneself relatively big with photovoltaic, make in isolated island that power supply is relatively sufficient, cutting load amount is less；Period 18-21, the peace of network Full property is poor, and the system the weakest period is the period 19, and its reason is the fault that these periods occur, age at failure Between the workload demand of network is very big, controllable burden equipment is less, photovoltaic is not exerted oneself, interconnection active volume Limited, there is bigger power shortage in isolated island after fault is occurred in these factors, causes substantial amounts of cutting load, Cause security of system more weak.For the period 19 that system is the weakest, make this period each bar branch trouble Electric quantity loss rate index, as shown in Figure 9, it is seen that operations staff should be specifically noted that period 19 main feeder upstream occurs Fault.

Analysis chart 8 can obtain: the safety of branch road 12-15,19-22,28-29 and 32-33 is optimal, Qi Zhongzhi The high security of road 28-29 is due to the load transfer of interconnection during fault, remaining branch road safety preferably because The isolated island scale that these branch roads break down formed is less, the internal distributed power source having again abundance and energy storage, can Support the operation of isolated island with security and stability, tend to avoid the generation of cutting load；The safety of main feeder upstream branch Property poor, the weakest branch road of system is branch road 3, owing to network presents radial structure, once upstream branch occur Fault, will form larger isolated island, distributed power source permeability and the highest when, isolated island is often A period of time is run, it is difficult in maintaining whole trouble duration, the reliable of isolated island supplies only with limited resource Electricity, after isolated island energy storage electricity exhausts, will occur substantial amounts of cutting load, cause the decline of safety.For system Branch road 3 the weakest, makes the electric quantity loss rate index of each this branch trouble of period, as shown in Figure 10, It can be seen that, occur branch road 3 fault in night (17-21 period) the most dangerous, should cause operations staff's Special concern.

The distributed energy of ADN includes: distributed power source, distributed energy storage, controllable burden etc., for embodying this A little element impacts on ADN static security analysis, construct following four scene (being shown in Table 4) and carry out quiet respectively State safety analysis, result is as shown in Figure 11, Figure 12, table 5.

The different scenes of table 4 static security analysis

The system synthesis safety indexes of the different scene of table 5

Relatively Figure 11, Figure 12 Scene 1 and scene 2, scene 3 and the curve of scene 4, it is known that to Demand-side The control of translatable load can be effectively improved the safety of system, and this raising effect is at translatable load equipment More upper, the period at noon is the most notable.Compare translatable load, distributed power source and energy storage to security of system Lifting effect the most considerable, compare the curve of scene 1 and scene 3, scene 2 and scene 4, it is seen that distributed The access of power supply and energy storage makes network be provided with islet operation ability, and after fault generation, the dead electricity load of system is significantly Reducing, safety is greatly improved.By table 5 it will also be appreciated that, along with the networking of distributed energy, system are available main The increase of dynamic resource, after accident generation, the dead electricity load of system gradually decreases, and power distribution network overall security gradually strengthens. Analysis method and the assessment of the ADN static security analysis that the present invention proposes also proved by above-mentioned chart with analyzing discussion The effectiveness of index, on the other hand illustrates that distributed energy accesses power distribution network the most effectively, negative for having a power failure after fault The minimizing of lotus, internet security reliability raising of great advantage.

For checking ADN static security analysis considering the necessity of network operation temporal characteristics during fault, with two Planting distinct methods and carry out safety analysis, result is as shown in Figure 13, Figure 14.Wherein the time method of section is traditional method, I.e. only consider the power-balance of discontinuity surface during the fault generation moment and out-of-limit situation, draw cutting load quiescent value and safety Index；All the period of time method is the inventive method, considers that fault occurs to repair the power-balance in the whole period the most comprehensively With out-of-limit situation, draw cutting load method and safety index；Analyze scene and be all scene 4.

For system synthesis safety indexes, the result of calculation of the time method of section is 0.0036, the meter of all the period of time method Calculating result is 0.0069.

As seen from Figure 13, if discontinuity surface when only focusing on the fault generation moment according to the time method of section, at net load relatively Little morning and daytime period, security of system is fabulous, and its main cause is not count and network operation state in analysis The sustainability dynamically changing, have ignored energy storage for power supply；On the other hand, the weakest period of system becomes clean negative 21 periods that lotus is maximum, it is clear that this analysis result is the most unilateral.Refer in conjunction with Figure 13, Figure 14 and comprehensive safety Mark understands, and compared to all the period of time method, the desired value that the time method of section is drawn is lower, security of system more preferable, point Analysis result is the most optimistic, and its traditional method that has its source in does not accounts for what scene lotus fluctuation in trouble duration caused Network trend and the dynamic change of cutting load, do not count yet and energy storage electricity exhausts brought isolated island and has a power failure.Above-mentioned point Analysis result and compare discussion, indicates the analysis method only considering discontinuity surface when fault occurs the moment, ignoring timing Deficiency, fully prove in ADN static security analysis network operation temporal characteristics during consideration fault must simultaneously The property wanted, also demonstrates the present invention and analyzes the science of method.

Claims (9)

1. an active distribution network Static security assessment method, it is characterised in that the method combines actively distribution The active property of net and initiative, it is contemplated that the temporal characteristics of the network operation, initially set up active distribution network static security The element sequence model of assessment, arranges the safety evaluation index of active distribution network Static security assessment, then simultaneously During considering fault period of right time and fault according to above-mentioned data, timing of both network operation state carries out pre- Thinking accident analysis, it is achieved that the assessment to active distribution network static security, the method comprises the following steps:

(1) input network parameter and scene lotus data；

(2) for the nth bar branch trouble of t period, according to described network parameter and scene lotus data with And the element sequence model set up carries out Static security assessment, particularly as follows:

A () carries out load transfer: recover load by interconnection and power, the part that cannot recover is performed isolated island The method of operation；

Whether (b) isolated island to being formed after fault, exist stable controllable electric power as islet operation in analyzing isolated island Main power source, if then entering step (c), if otherwise entering step (e)；

C () analyzes whether the power of isolated island balances, if then entering step (d), if otherwise carrying out load translation Operate with cutting load, until isolated island power-balance, enter step (d)；

D () carries out the Load flow calculation of main distribution net and isolated island, it may be judged whether there is voltage out-of-limit or power is out-of-limit, If then carrying out active management, until eliminating out-of-limit, if otherwise entering step (e)；

(e) record power failure load, power off time and energy storage dump energy；

Whether (f) failure judgement repairs, if then entering step (3)；If otherwise entering the next fault period, Return step (b)；

Wherein, t=1,2.., T, n=1,2 ... N, T are period sum, and N is branch road sum；

(3) judge whether to have completed all branch roads, the calculation of fault of all periods, if then entering step (4)； If otherwise t or n to be progressively increased operation, returning step (2), continuing to analyze next forecast accident；

(4) index calculating and security evaluation are carried out according to the parameter of record and the safety evaluation index of setting.

2. active distribution network Static security assessment method as claimed in claim 1, it is characterised in that described master The element sequence model of dynamic power distribution network Static security assessment includes blower fan and photovoltaic temporal model, meter and translatable load The temporal model of sequential load model and energy storage.

3. active distribution network Static security assessment method as claimed in claim 2, it is characterised in that described wind Machine is with photovoltaic temporal model, and blower fan temporal model is:

$P_{WT}=\left\{\begin{array}{cc}0& v\≤v_{ci}\\ k_{1}v+k_2& v_{ci}\≤v\≤v_r\\ P_{WTr}& v_r\≤v\≤v_{co}\\ 0& v_{co}\≤v\end{array}\right.;$

Wherein: P_WTrSpecified active power for blower fan；Parameter k₁=P_WTr/(v_r-v_ci)；Parameter k₂=-k₁v_ci；V is Wind speed；v_ciFor incision wind speed；v_rFor rated wind speed；v_coFor cut-out wind speed；

Photovoltaic temporal model is:

P_PV=rA η

Wherein: P_PVActive power for photovoltaic array output；R is light intensity；A is the photovoltaic array gross area；η is Photoelectric transformation efficiency.

4. active distribution network Static security assessment method as claimed in claim 2, it is characterised in that described meter And the sequential load model of translatable load is:

P_t=P_Forecast,t-P_Shiftout,t

Wherein: P_tFor t period load value after translation；P_Forecast,tPredicted load for the t period；P_Shiftout,tFor The translatable load that the t period removes:

$P_{Shiftout,t}=\underset{k=1}{\overset{M}{\Σ}}{x}_{k,t,t}{P}_{k,1}+\underset{l=1}{\overset{L-1}{\Σ}}\underset{k=1}{\overset{M}{\Σ}}{x}_{k,t-l,t}{P}_{k,1+l}$

Wherein: M is translatable load equipment type sum；x_k,t,tThe t period removed for the t period should start power supply Kth class translatable load equipment number；P_k,1For the translatable load equipment of kth class in its continuous working period the 1st The power of individual period；L is the maximum continuous working period of all kinds of translatable load equipment；x_k,t-l,tRemove for the t period The t-l period should start power supply kth class translatable load equipment number；P_k,1+lFor the translatable load equipment of kth class The operating power of 1+l period in its continuous working period.

5. active distribution network Static security assessment method as claimed in claim 2, it is characterised in that described storage The temporal model of energy is:

$P_{ESS,t}=\left\{\begin{array}{c}(P_{Load,t}-P_{DG,t})/{\mathrm{\η}}_{Dis}\\ (P_{Load,t}-P_{DG,t}){\mathrm{\η}}_{Cha}\end{array}\right.$

$S_{SOC,t+1}=S_{SOC,t}-\frac{P_{ESS,t}{\mathrm{\ΔD}}_t}{E_{ESS}}$

Wherein: P_ESS,tFor t period accumulator cell charging and discharging power, discharge for just, be charged as bearing；P_Load,tFor the t period Total load in isolated island；P_DG,tFor the gross output of other power supplys in t period isolated island；η_DisFor discharging efficiency；η_Cha For charge efficiency；S_SOC,tState-of-charge for t period accumulator；ΔD_tPersistent period for the t period；E_ESSFor storing The rated capacity of battery；Accumulator be enough to lower constraint at running fullness in the epigastrium and abdomen:

P_ESS,t≤P_ESS,max

S_SOC,min≤S_SOC,t≤S_SOC,max

Wherein: P_ESS,maxThe maximum charge-discharge electric power allowed for accumulator；S_SOC,max、S_SOC,minIt is respectively state-of-charge Bound.

6. active distribution network Static security assessment method as claimed in claim 1, it is characterised in that described step Suddenly, in (a), carry out considering during load transfer the timing variations of interconnection active volume.

7. active distribution network Static security assessment method as claimed in claim 1, it is characterised in that described master The safety evaluation index of dynamic power distribution network Static security assessment includes that electric quantity loss rate index, isolated island electric quantity loss rate refer to Mark, time safety index, branch road safety indexes and system synthesis safety indexes.

8. active distribution network Static security assessment method as claimed in claim 7, it is characterised in that described electricity Amount loss rate index expression formula is:

$C_{ELR,t,n}={\mathrm{\λ}}_n\·L_n\·T_E\frac{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{F,d}}{\Σ}{\mathrm{\γ}}_i\·(S_{d,i}-S_{SL,d,i})\·{\mathrm{\ΔD}}_{F,d,i}}{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{S,d}}{\Σ}{\mathrm{\γ}}_i\·S_{d,i}\·{\mathrm{\ΔD}}_d}$

Wherein: C_ELR,t,nElectric quantity loss rate index for t period nth bar branch trouble；λ_nFor nth bar branch road Fault rate；L_nLength for nth bar branch road；T_EFor evaluation time；t_DFor last period that fault is lasting； φ_F,dPower failure load aggregation for the d period；γ_iThe important level factor for i-th load；S_d,iFor the d period i-th The capacity of individual load；S_SL,d,iThe capacity of extensible load is contained for d period i-th load；ΔD_F,d,iFor the d period The power off time of i-th load；φ_S,dSystem loading set for the d period；ΔD_dPersistent period for the d period；

Described isolated island electric quantity loss rate index, its expression formula is:

$C_{IELR,t,n}={\mathrm{\λ}}_n\·L_n\·T_E\frac{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{1F,d}}{\Σ}{\mathrm{\γ}}_i\·(S_{d,i}-S_{SL,d,i})\·{\mathrm{\ΔD}}_{F,d,i}}{\underset{d=t}{\overset{t_D}{\mathrm{\Σ}}}\underset{i\∈{\mathrm{\φ}}_{1,d}}{\Σ}{\mathrm{\γ}}_i\·S_{d,i}\·{\mathrm{\ΔD}}_d}$

Wherein: C_IELR,t,nIsolated island rate of energy loss index for t period nth bar branch trouble；φ_IF,dFor the d period Isolated island power failure load aggregation；φ_I,dIsolated island load aggregation for the d period；

Described time safety index, its expression formula is:

$C_{S,t}=\frac{{\mathrm{\α}}_1}{2}\left(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{ELR,t,n}+\underset{n=1}{\overset{N}{\max }}\left\{C_{ELR,t,n}\right\}\right)+\frac{{\mathrm{\α}}_2}{2}\left(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{IELR,t,n}+\underset{n=1}{\overset{N}{\max }}\left\{C_{IELR,t,n}\right\}\right)$

Wherein: C_S,tIt it is the safety indexes of t period；α₁、α₂For weight coefficient；N is system branch number；

Described branch road safety indexes, its expression formula is:

$C_{S,n}=\frac{{\mathrm{\α}}_1}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\Σ}}{C}_{ELR,t,n}+\underset{t=1}{\overset{T}{max}}\{C_{ELR,t,n}\left\}\right)+\frac{{\mathrm{\α}}_2}{2}(\frac{1}{T}\underset{t=1}{\overset{T}{\Σ}}{C}_{IELR,t,n}+\underset{t=1}{\overset{T}{max}}\{C_{IELR,t,n}\left\}\right)$

Wherein: C_S,nSafety indexes for nth bar branch road；T is the time hop count of static security analysis；

Described system synthesis safety indexes, its expression formula is:

$C_{SCS}=\frac{{\mathrm{\β}}_1}{2}\left(\frac{1}{T}\underset{t=1}{\overset{T}{\mathrm{\Σ}}}{C}_{S,t}+\underset{t=1}{\overset{T}{\max }}\left\{C_{S,t}\right\}\right)+\frac{{\mathrm{\β}}_2}{2}\left(\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{C}_{S,n}+\underset{n=1}{\overset{N}{\max }}\left\{C_{S,n}\right\}\right)$

Wherein: C_SCSFor system synthesis safety indexes；β₁、β₂For weight coefficient.

9. active distribution network Static security assessment method as claimed in claim 1, it is characterised in that described master Dynamic management includes meritorious reduction and idle control of exerting oneself, load tap changer regulation, the nothing of exerting oneself of load translation, DG Merit compensates equipment and controls and cutting load.