CN104734154A - Multilevel hierarchical control method of transmission congestion management based on multi-source active distribution network - Google Patents

Abstract

A multilevel hierarchical control method of transmission congestion management based on a multi-source active distribution network includes the steps of acquisition of operating data, active reconstruction operation, active islanding operation, demand response operation and the like. The method has the advantages that controllable resources in the multi-source active distribution network can be fully utilized, topological optimization and active isolating operation of the multi-source active distribution network is dynamically achieved, the power demand of the load end of an upstream transmission line can be effectively lowered, a brand-new idea is provided for the congestion control and management of the transmission line, auxiliary services can be provided for the transmission network congestion management at the premise of ensuring operational safety and stability of the distribution network, transmission line congestion can be partly relieved in emergency situations, power supply reliability of the distribution network can be guaranteed as far as possible, and the network has certain engineering application prospect.

Description

Based on the For Congestion management multilevel hierarchy control method of multi-source active distribution network

Technical field

The invention belongs to the management of power transmission network For Congestion and active distribution network coordination optimization control technology field, particularly relate to a kind of For Congestion based on multi-source active distribution network management multilevel hierarchy control method.

Background technology

For Congestion in electric power system refers to that system can not meet desired transmission of electricity requirement owing to being subject to self holding quantitative limitation.In order to ensure the safe and stable operation of electric power system, researching and developing effective For Congestion management strategy and having very important significance.Traditional For Congestion management study mainly concentrates on three aspects: adjustment generator output, load summate and system enhancement (such as, strengthening the thermally-stabilised or voltage stability limit of heavily loaded critical circuits or For Congestion district critical circuits).

But the research at present about For Congestion management mainly concentrates on adjustment generator output, self field of the power transmission network such as load summate and system enhancement.The shortcoming of three aspects below main existence:

1) no matter be by adjustment generator output or load summate carries out For Congestion management, is all that utilization is sent out, the adjusting control function of transmission side, have ignored a large amount of distributed resource of Demand-side and the ability of controllable burden.

2) have ignored the interaction between power transmission network and power distribution network.Under large-scale distributed power supply and the grid-connected environment of controllable burden, be difficult to realize power transmission and distribution coordination optimization and run and the requirement of integration planning.

3) traditional For Congestion control strategy based on load is to sacrifice users'comfort for cost.Being difficult to realize modern power systems for user provides flexible, reliable, safe, economical with can the requirement of mode.

Based on above discussion, comprehensive study considers that the power transmission network congestion management control strategy of large-scale distributed power supply and controllable burden access has very important significance.

Summary of the invention

In order to solve the problem, a kind of For Congestion based on multi-source active distribution network is the object of the present invention is to provide to manage multilevel hierarchy control method.

In order to achieve the above object, the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method provided by the invention comprises the following step carried out in order:

Step one, acquisition service data: obtain current power system core line operational data;

Step 2, judge whether satisfied first service conditions: judge whether to select power distribution network initiatively reconfiguration scheme according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 3, otherwise next step enters step 4;

Step 3, initiatively reconstruct operation: select power distribution network initiatively reconfiguration scheme, active distribution network management system (ADMS) is by initiatively reconstructing the network configuration optimizing and revising power distribution network, thus reduce transmission & distribution net dominant eigenvalues, the final For Congestion effectively reducing power transmission network; This flow process terminates;

Step 4, judge whether satisfied second service conditions: judge whether to select multiple source power distribution host to move islet operation scheme according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 5, otherwise next step enters step 6;

Step 5, initiatively islet operation: select multiple source power distribution host to move islet operation scheme, ADMS is exerted oneself by microgrid in MGCC control access power distribution network, form the active isolated island scheme considering power transmission network For Congestion demand and power distribution network ability, reduce the load of upstream power transmission network within a certain period of time, thus effectively reduce the For Congestion of power transmission network; This flow process terminates;

Step 6, judge whether satisfied 3rd service conditions: judge whether to select demand response scheme to carry out the management of power transmission network For Congestion according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 7, otherwise exits this process flow operation;

Step 7, demand response run: select demand response scheme, ADMS is by coordination optimization control MGCC and EVSCC, optimize and revise microgrid according to power transmission network For Congestion demand and power distribution network ability to exert oneself and charging electric vehicle load, on the basis of active isolated island scheme, further expansion isolated island scope, the load of further reduction upstream power transmission network, effectively reduces the For Congestion of power transmission network; This flow process terminates.

In step 2, the described concrete grammar of selection power distribution network active reconfiguration scheme that judges whether is: when the current operational mode of power transmission network meets formula (1), select power distribution network initiatively reconfiguration scheme;

△P _FR≥△P _LD(15)

Wherein, △ P _fRfor the power transmission and distribution dominant eigenvalues reduction by implementing the realization of power distribution network active reconfiguration scheme; △ P _lDthat crosses the thermally-stabilised limit for the out-of-limit critical circuits of current power transmission network has work value, specifically calculates by formula (2);

△P _LD＝P _ini,i-P _lim,i(16)

Wherein, P _{ini, i}for the trend of the out-of-limit critical circuits i of current power transmission network has work value, can be obtained by Load flow calculation; P _{lim, i}for current power transmission network out-of-limit critical circuits trend higher limit.

In step 3, described power distribution network initiatively reconfiguration scheme algorithm comprises the following steps:

Step 3.1) to read in initial data and algorithm parameter is set: initial data comprises load and branch switch state etc. under branch parameters, various load method; Algorithm parameter comprises population scale, inertia weight scope, accelerator coefficient and speed span etc.;

Step 3.2) initialization: iterations sets to 0, all particle positions of initialization and speed; Carry out the Load flow calculation under various mode according to initial data, the comprehensive network harm of network within this period obtained under each group on off state is its initial adaptive value and history adaptive optimal control value, and the particle position of loss minimization is global optimum's particle;

Step 3.3) speed and location updating: according to step 3.1) parameters carry out particle rapidity and location updating; Whether out-of-limitly check that particle position upgrades rear each variable, if a certain variable is out-of-limit, then get its corresponding limit value;

Step 3.4) radial verification: whether the network configuration under the Switch State Combination in Power Systems that the particle position after checksum update is corresponding meets radial constraint, if some particle does not meet, reinitializes this particle, until all satisfied;

Step 3.5) judge whether trend restrains: if convergence, then enter step 3.6), if do not restrain, iterations adds 1, forwards step 3.4 to) proceed;

Step 3.6) terminate to judge: as reached maximum permission iterations, then stop and Output rusults; Otherwise iterations adds 1, forward step 3.4 to) proceed.

In step 4, the described concrete grammar selecting multiple source power distribution host to move islet operation scheme that judges whether is: when the current operational mode of power transmission network meets formula (31), selects multiple source power distribution host to move islet operation scheme;

$\mathrm{\Δ}{P}_{\mathrm{FR}}\≤\mathrm{\Δ}{P}_{\mathrm{LD}}\≤\underset{i\∈V}{\mathrm{\Σ}}{P}_{L,i}---\left(17\right)$

Wherein, P _l,ifor the load of the circuit i within the scope of the maximum possible isolated island of power distribution network active isolated island has work value.

In step 5, the method for described active islet operation scheme comprises following four steps:

Step 5.1) build power distribution network rooted tree hierarchical mode

Power distribution network has rooted tree in radical model to be divided into five layers, wherein V={ ν ₁..., ν _nrepresenting the set of node, E represents the line set of feeder line, e _i,j(i<j) be the circuit between node i and node j;

Step 5.2) definition rooted tree node weights

The weights of described definition rooted tree node are the power summation being connected in load under this destination node and distributed power source, specifically calculate such as formula shown in (32):

w(v _i) _i∈V＝P _Gi-P _Li(18)

In formula, P _lifor being connected in node ν _ion total burden with power value; P _gifor being connected on node ν _ithe meritorious of upper microgrid is exerted oneself;

Step 5.3) carry out preliminary isolated island search, obtain maximum possible isolated island scope

First carry out preliminary isolated island search, be target to the maximum and carry out preliminary isolated island search, obtain the isolated island scope of maximum possible with isolated island scope, target function is such as formula shown in (33):

$\max \underset{i=1}{\overset{N_G}{\mathrm{\&Sigma;}}}{P}_{\mathrm{Li}}---\left(19\right)$

Demand fulfillment constraint equation (34) in isolated island search procedure ~ formula (38):

● power-balance constraint (Power balance constraint, PBC)

$F\left(T_S\right)=\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Gi}}-\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}>0---\left(20\right)$

In formula, F (T _s) be PBC valuation functions, consider that in isolated island, microgrid has certain regulating power to unbalanced power, PBC constraint is relaxed for meritorious exerting oneself total in isolated island is greater than total burden with power;

● transmission line security constraint

|P _eij| _eij∈V<α*P _{rated_eij}(21)

In formula, P _eijfor current operational mode line e _ijeffective power flow; P _{rate_eij}for circuit e _ijmaximum rated capacity; α is nargin coefficient;

● the radial operation constraint of isolated island

N＝M+1 (22)

In formula, N is the nodes within the scope of isolated island; M is the circuit number within the scope of isolated island;

● initiatively isolated island position constraint

$\mathrm{depth}(v_i,i\&Element;V)\&GreaterEqual;\mathrm{depth}(v_j,j\&NotElement;V)---\left(23\right)$

Depth (v in formula _i, i ∈ V) and represent node ν _ithe level at place in power distribution network rooted tree hierarchy structure model;

● For Congestion constraint of demand

$\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}\&le;k_D\mathrm{\&Delta;}{P}_{\mathrm{LD}}---\left(24\right)$

In formula, k _dfor power transmission network For Congestion demand nargin coefficient, its size can carry out dynamic conditioning according to the real-time net capability index of active distribution network;

Step 5.4) isolated island verification

For step 5.3) the initial isolated island that obtains, according to constraints, namely formula (7) ~ (10) verify one by one, if all constraints all can meet, then final isolated island scheme is determined; If there is a wherein item constraint condition not meet the demands, by isolated island range shorter one deck, turn back to step 5.3) proceed isolated island search; Finally, carry out static properties verification to the isolated island obtained, static performance index comprises islanded system voltage stability index and voltage fluctuate index, is specifically expressed as follows:

$L_{i,j}=4[{(P_j{X}_{i,j}-Q_j{R}_{i,j})}^2+(P_j{X}_{i,j}+Q_j{X}_{i,j})U_i^2]/U_i^4---\left(25\right)$

I＝max(L _i,j) (26)

In formula, R _i,jand X _i,jbe respectively resistance and the reactance of branch road i-j; P _jand Q _jbe respectively and flow into the meritorious of node j and reactive power; L _i,jfor the voltage stability index value of branch road i-j, the maximum of the voltage stability index of each branch road is the voltage stability index value of whole isolated island, shown in (13):

V＝max|U _j-U _b| (27)

In formula, U _jfor the voltage perunit value of node j; U _bfor node reference voltage value, be taken as 1.0; V is voltage fluctuate index, and V more mini system is more stable.

In step 6, the described selection demand response scheme that judges whether to carry out the concrete grammar of power transmission network For Congestion management is: when the current operation side of power transmission network meets formula (42), select demand response scheme to carry out the management of power transmission network For Congestion;

$\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}\&le;\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}+\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{\mathrm{EV}}_k---\left(28\right)$

In formula, p is according to step 4.3) in the quantity of electric automobile charging station initiatively within the scope of the isolated island that obtains of isolated island searching algorithm; ∑ EV _kfor according to step 4.3) in electric automobile charging station initiatively within the scope of the isolated island that obtains of isolated island searching algorithm can by the total amount of charging electric vehicle load.

In step 7, described demand response scheme comprises the following steps:

Step 7.1) calculate the load that need be transferred in isolated island: initial load transfer plan amount is the summation ∑ P of all burdens with power in isolated island V (i ∈ V) in active islet operation scheme in previous step _li, in workload demand scheme, successively increase in units of the node layer of load transfer plan amount in power distribution network rooted tree hierarchical mode, until meet the demand of power transmission network congestion management; Final load transfer plan amount computational methods are shown in formula (15);

$P_{\mathrm{trans}}=\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{Li}+\underset{i=n_l+1}{\overset{N_L}{\mathrm{\&Sigma;}}}{P}_i---\left(15\right)$

In formula, P _transfor load transfer plan amount final in demand response scheme; N _lfor being transferred to the sum of the node level in isolated island in units of the node layer in power distribution network rooted tree hierarchical mode; n _lfor the power distribution network level within the scope of the isolated island after active isolated island scheme;

Constraints is as follows:

${\stackrel{\&CenterDot;}{U}}_i\underset{j=1}{\overset{n_k}{\mathrm{\&Sigma;}}}{\stackrel{*}{Y}}_{\mathrm{ij}}{\stackrel{*}{U}}_j=P_i+Q_i,i\&Element;n_k---\left(16\right)$

V _k,min<V _k<V _k,maxk∈n _k(17)

I _l≤I _l,maxl∈n _l(18)

$\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{Li}\&GreaterEqual;\mathrm{\&Delta;}{P}_{\mathrm{LD}}---\left(19\right)$

In formula, n _kit is the node total number of the power distribution network after load transfer plan; it is the voltage vector of node i; P _i, Q _ibe respectively active power and the reactive power of node i injection; the node admittance matrix element Y of the power distribution network after load transfer plan _ijconjugate complex number; V _kthe voltage of node k; V _{k, min}, V _{k, max}the minimum voltage that allows of node k and maximum voltage respectively; n _lit is the circuitry number in the power distribution network after load transfer plan; I _lit is the electric current of circuit l; I _{l, max}it is the lowest high-current value that circuit l allows;

Step 7.2) obtain isolated island scope and electric automobile excision load: the load total amount be transferred in isolated island in units of the node layer obtaining in power distribution network rooted tree hierarchical mode by sub-optimization problem I; The optimization aim of sub-optimization problem II is under the prerequisite ensureing isolated island safe and stable operation, based on the load transfer plan amount that sub-optimization problem I obtains, guarantee that the electric automobile cutting load amount of each electric automobile charging station is minimum, also namely ensure that user's uses energy comfort level to greatest extent, target function is shown in;

$\max \underset{i=1}{\overset{p}{\mathrm{\&Sigma;}}}{P}_{\mathrm{EV},i}---\left(20\right)$

In formula, p is the electric automobile charging station number in demand response scheme within the scope of isolated island; P _{eV, i}for the electric automobile cutting load amount in charging station i;

Constraints is as follows:

P _EV,i≤P _TR,ii∈V (21)

$P_{{\mathrm{MG}}_{j,\min }}\&le;P_{{\mathrm{MG}}_j}\&le;P_{{\mathrm{MG}}_{j,\max }},j=\mathrm{1,2},...,m---\left(22\right)$

$Q_{{\mathrm{MG}}_{j,\min }}\&le;Q_{{\mathrm{MG}}_j}\&le;Q_{{\mathrm{MG}}_{j,\max }},j=\mathrm{1,2},...,m---\left(23\right)$

In formula, P _mGjthe active power that microgrid j sends; P _{mGj, max}and P _{mGj, min}be respectively maximum and the minimum value of the active power that microgrid j sends; Q _mGjit is the reactive power that microgrid j sends; Q _{mGj, max}and Q _{mGj, min}be respectively maximum and the minimum value of the reactive power that microgrid j sends.

For Congestion based on multi-source active distribution network management multilevel hierarchy control method provided by the invention can make full use of the controllable resources in multi-source active distribution network, topological optimization and the active islet operation of dynamic implement multi-source active distribution network, effectively can reduce the power demand of upstream power line load end, for the obstructive root canal of transmission line provides brand-new thinking with management, can for power transmission network congestion management provides assistant service under the prerequisite ensureing power distribution network safe and stable operation, in emergency circumstances transmission line choking phenomenon can be alleviated to a certain extent, ensure the power supply reliability of power distribution network as far as possible simultaneously, there is certain future in engineering applications.

Accompanying drawing explanation

Fig. 1 is For Congestion management multilevel hierarchy control framework schematic diagram.

Fig. 2 is the For Congestion based on multi-source active distribution network provided by the invention management multilevel hierarchy control method flow chart.

Fig. 3 is that the power distribution network in the For Congestion based on multi-source active distribution network provided by the invention management multilevel hierarchy control method initiatively reconstructs flow chart.

Fig. 4 is the electrical network initiatively islet operation Scheme algorithm flow chart of the For Congestion based on multi-source active distribution network provided by the invention management multilevel hierarchy control method.

Fig. 5 is the demand response protocol procedures figure in the For Congestion based on multi-source active distribution network provided by the invention management multilevel hierarchy control method.

Fig. 6 is that power distribution network rooted tree hierarchical mode builds schematic diagram.

Fig. 7 is IEEE-30 node system figure.

Fig. 8 is the IEEE tri-feeder line distribution measurement system diagram improved.

Fig. 9 is initial isolated island search plan figure in isolated island active operating scheme.

Figure 10 is final isolated island search plan figure in isolated island active operating scheme.

Figure 11 is final isolated island search plan figure in demand response scheme.

Embodiment

As shown in Figure 1, this control program comprises moves islet operation scheme and demand response scheme with the minimum power distribution network quick reconfiguration scheme for target of transmission & distribution net dominant eigenvalues, multiple source power distribution host to the management of the For Congestion based on the multi-source active distribution network multilevel hierarchy control framework that this method adopts.When power transmission network break down cause critical circuits or trend section generation For Congestion cause thermally-stabilised out-of-limit time, the actual demand (gathered by real-time running data and Load flow calculation obtains) that first PSDC reduces For Congestion according to power transmission network assigns For Congestion control command to ADMS; Secondly, the operational mode that ADMS controls to change power distribution network by the coordination optimization of ADMS and MGCC and EVSCC responds For Congestion control command.

If select power distribution network initiatively reconfiguration scheme, ADMS by initiatively reconstructing the network configuration optimizing and revising power distribution network, thus reduces transmission & distribution net dominant eigenvalues, the final For Congestion effectively reducing power transmission network.

If select multiple source power distribution host to move islet operation scheme, ADMS is exerted oneself by microgrid in MGCC control access power distribution network, form the active isolated island scheme considering power transmission network For Congestion demand and power distribution network ability, reduce the load of upstream power transmission network within a certain period of time, thus effectively reduce the For Congestion of power transmission network.

If select demand response scheme, ADMS is by coordination optimization control MGCC and EVSCC, optimize and revise microgrid according to power transmission network For Congestion demand and power distribution network ability to exert oneself and charging electric vehicle load, on the basis of active isolated island scheme, further expansion isolated island scope, the load of further reduction upstream power transmission network, effectively reduces the For Congestion of power transmission network.

Below in conjunction with the drawings and specific embodiments, the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method provided by the invention is described in detail.

As shown in Figure 2, the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method provided by the invention comprises the following step performed in order:

Step one, acquisition service data: obtain current power system core line operational data;

Step 2, judge whether satisfied first service conditions: judge whether to select power distribution network initiatively reconfiguration scheme according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 3, otherwise next step enters step 4;

Step 3, initiatively reconstruct operation: select power distribution network initiatively reconfiguration scheme, ADMS optimizes and revises the network configuration of power distribution network by initiatively reconstruct, thus reduces transmission & distribution net dominant eigenvalues, the final For Congestion effectively reducing power transmission network; This flow process terminates;

Step 4, judge whether satisfied second service conditions: judge whether to select multiple source power distribution host to move islet operation scheme according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 5, otherwise next step enters step 6;

Step 5, initiatively islet operation: select multiple source power distribution host to move islet operation scheme, ADMS is exerted oneself by microgrid in MGCC control access power distribution network, form the active isolated island scheme considering power transmission network For Congestion demand and power distribution network ability, reduce the load of upstream power transmission network within a certain period of time, thus effectively reduce the For Congestion of power transmission network; This flow process terminates;

Step 6, judge whether satisfied 3rd service conditions: judge whether to select demand response scheme to carry out the management of power transmission network For Congestion according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 7, otherwise exits this process flow operation;

Step 7, demand response run: select demand response scheme, ADMS is by coordination optimization control MGCC and EVSCC, optimize and revise microgrid according to power transmission network For Congestion demand and power distribution network ability to exert oneself and charging electric vehicle load, on the basis of active isolated island scheme, further expansion isolated island scope, the load of further reduction upstream power transmission network, effectively reduces the For Congestion of power transmission network; This flow process terminates.

In step 2, the described concrete grammar of selection power distribution network active reconfiguration scheme that judges whether is: when the current operational mode of power transmission network meets formula (1), select power distribution network initiatively reconfiguration scheme;

△P _FR≥△P _LD(29)

Wherein, △ P _fRfor the power transmission and distribution dominant eigenvalues reduction by implementing the realization of power distribution network active reconfiguration scheme; △ P _lDthat crosses the thermally-stabilised limit for the out-of-limit critical circuits of current power transmission network has work value, specifically calculates by formula (2);

△P _LD＝P _ini,i-P _lim,i(30)

Wherein, P _{ini, i}for the trend of the out-of-limit critical circuits i of current power transmission network has work value, can be obtained by Load flow calculation; P _{lim, i}for current power transmission network out-of-limit critical circuits trend higher limit.

As shown in Figure 3, in step 3, described power distribution network initiatively reconfiguration scheme algorithm comprises the following steps:

Step 3.1) to read in initial data and algorithm parameter is set: initial data comprises load and branch switch state etc. under branch parameters, various load method; Algorithm parameter comprises population scale, inertia weight scope, accelerator coefficient and speed span etc.;

Step 3.2) initialization: iterations sets to 0, all particle positions of initialization and speed; The Load flow calculation under various mode is carried out according to initial data, the comprehensive network harm of network within this period obtained under each group on off state by formula (1) is its initial adaptive value and history adaptive optimal control value, and the particle position of loss minimization is global optimum's particle;

Step 3.3) speed and location updating: according to step 3.1) parameters carry out particle rapidity and location updating; Whether out-of-limitly check that particle position upgrades rear each variable, if a certain variable is out-of-limit, then get its corresponding limit value;

Step 3.4) radial verification: whether the network configuration under the Switch State Combination in Power Systems that the particle position after checksum update is corresponding meets radial constraint, if some particle does not meet, reinitializes this particle, until all satisfied;

Step 3.5) judge whether trend restrains: if convergence, then enter step 3.6), if do not restrain, iterations adds 1, forwards step 3.4 to) proceed.

Step 3.6) terminate to judge: as reached maximum permission iterations, then stop and Output rusults; Otherwise iterations adds 1, forward step 3.4 to) proceed.

In step 4, the described concrete grammar selecting multiple source power distribution host to move islet operation scheme that judges whether is: when the current operational mode of power transmission network meets formula (31), selects multiple source power distribution host to move islet operation scheme;

$\mathrm{\&Delta;}{P}_{\mathrm{FR}}\&le;\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}---\left(31\right)$

Wherein, P _l,ifor the load of the circuit i within the scope of the maximum possible isolated island of power distribution network active isolated island has work value.

As shown in Figure 4, in step 5, the method for described active islet operation scheme comprises following four steps:

Step 5.1) build power distribution network rooted tree hierarchical mode

Power distribution network has radical model schematic as shown in Figure 6.Power distribution network adopts radial structure usually, even if adopt looped network or network, and also can open loop operation.Each approach of powering, can regard as with system-side power source point for root, the tree being leaf point with load and switch, and whole power distribution network is exactly set by this forest formed.The access of distributed power source only increases the node that part has power supply natures, does not change original tree structure.Therefore, what in Fig. 6, the distribution feeder F2 in left side can be reduced to right side take bus as rooted tree hierarchy T (V, E) of node, and whole rooted tree is divided into five layers, wherein V={ ν ₁..., ν _nrepresenting the set of node, E represents the line set of feeder line, e _i,j(i<j) be the circuit between node i and node j;

Step 5.2) definition rooted tree node weights

The weights (weight) of described definition rooted tree node, for being connected in the power summation of load under this destination node and distributed power source, specifically calculate such as formula shown in (32):

w(v _i) _i∈V＝P _Gi-P _Li(32)

In formula, P _lifor being connected in node ν _ion total burden with power value; P _gifor being connected on node ν _ithe meritorious of upper microgrid is exerted oneself;

Step 5.3) carry out preliminary isolated island search, obtain maximum possible isolated island scope

In order to simplify isolated island search procedure, the active isolated island search thinking that this step is taked " first search for and verify afterwards ", therefore preliminary isolated island search is first carried out, be target to the maximum with isolated island scope and carry out preliminary isolated island search, obtain the isolated island scope of maximum possible, target function is such as formula shown in (33):

$\max \underset{i=1}{\overset{N_G}{\mathrm{\&Sigma;}}}{P}_{\mathrm{Li}}---\left(33\right)$

Demand fulfillment constraint equation (34) in isolated island search procedure ~ formula (38):

● power-balance constraint (Power balance constraint, PBC)

$F\left(T_S\right)=\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Gi}}-\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}>0---\left(34\right)$

In formula, F (T _s) be PBC valuation functions, consider that in isolated island, microgrid has certain regulating power to unbalanced power, PBC constraint is relaxed for meritorious exerting oneself total in isolated island is greater than total burden with power;

● transmission line security constraint (rated value and limit constraint, RLC)

|P _eij| _eij∈V<α*P _{rated_eij}(35)

In formula, P _eijfor current operational mode line e _ijeffective power flow; P _{rate_eij}for circuit e _ijmaximum rated capacity; α is nargin coefficient;

● the radial operation constraint of isolated island

N＝M+1 (36)

In formula, N is the nodes within the scope of isolated island; M is the circuit number within the scope of isolated island;

● initiatively isolated island position constraint, this constraint is that power distribution network has part of nodes to have a power failure after active isolated island; Active isolated island scheme in this step is in order to the management of auxiliary bulk power grid For Congestion, be different from traditional power distribution network break down after isolated island restore electricity, therefore, should not be in and initiatively lose electric loading after isolated island scheme and exist;

$\mathrm{depth}(v_i,i\&Element;V)\&GreaterEqual;\mathrm{depth}(v_j,j\&NotElement;V)---\left(37\right)$

Depth (v in formula _i, i ∈ V) and represent node ν _ithe level at place in power distribution network rooted tree hierarchy structure model; Through type (37) can be seen, the level at the node place in power distribution network rooted tree hierarchy structure model initiatively within the scope of isolated island, higher than the extraneous node of active isolated island, does not exist dead electricity load after so just can ensureing isolated island scheme; This constraint is that power distribution network has part of nodes to have a power failure after active isolated island; Initiatively isolated island scheme is in order to auxiliary bulk power grid For Congestion management, be different from traditional power distribution network break down after isolated island restore electricity, therefore, should not be in and initiatively lose electric loading after isolated island scheme and exist;

● For Congestion constraint of demand

$\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}\&le;k_D\mathrm{\&Delta;}{P}_{\mathrm{LD}}---\left(38\right)$

In formula, k _dfor power transmission network For Congestion demand nargin coefficient, its size can carry out dynamic conditioning according to the real-time net capability index of active distribution network (Power Supply Capability Index, PSCI).

Step 5.4) isolated island verification

For step 5.3) the initial isolated island that obtains, according to constraints, namely formula (7) ~ (10) verify one by one, if all constraints all can meet, then final isolated island scheme is determined; If there is a wherein item constraint condition not meet the demands, by isolated island range shorter one deck, turn back to step 5.3) proceed isolated island search; Finally, carry out static properties verification to the isolated island obtained, static performance index comprises islanded system voltage stability index and voltage fluctuate index, is specifically expressed as follows:

$L_{i,j}=4[{(P_j{X}_{i,j}-Q_j{R}_{i,j})}^2+(P_j{X}_{i,j}+Q_j{X}_{i,j})U_i^2]/U_i^4---\left(39\right)$

I＝max(L _i,j) (40)

In formula, R _i,jand X _i,jbe respectively resistance and the reactance of branch road i-j; P _jand Q _jbe respectively and flow into the meritorious of node j and reactive power; L _i,jfor the voltage stability index value of branch road i-j, the maximum of the voltage stability index of each branch road is the voltage stability index value of whole isolated island, shown in (13).

V＝max|U _j-U _b| (41)

In formula, U _jfor the voltage perunit value of node j; U _bfor node reference voltage value, be taken as 1.0; V is voltage fluctuate index, and V more mini system is more stable.

In step 6, the described selection demand response scheme that judges whether to carry out the concrete grammar of power transmission network For Congestion management is: when the current operation side of power transmission network meets formula (42), select demand response scheme to carry out the management of power transmission network For Congestion;

$\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}\&le;\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}+\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{\mathrm{EV}}_k---\left(42\right)$

In formula, p is according to step 4.3) in the quantity of electric automobile charging station initiatively within the scope of the isolated island that obtains of isolated island searching algorithm; ∑ EV _kfor according to step 4.3) in electric automobile charging station initiatively within the scope of the isolated island that obtains of isolated island searching algorithm can by the total amount of charging electric vehicle load.

As shown in Figure 5, in step 7, described demand response scheme comprises the following steps:

Step 7.1) calculate the load that need be transferred in isolated island: initial load transfer plan amount is the summation ∑ P of all burdens with power in isolated island V (i ∈ V) in active islet operation scheme in previous step _li, in workload demand scheme, successively increase in units of the node layer of load transfer plan amount in power distribution network rooted tree hierarchical mode, until meet the demand of power transmission network congestion management.Final load transfer plan amount computational methods are shown in formula (15);

$P_{\mathrm{trans}}=\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{Li}+\underset{i=n_l+1}{\overset{N_L}{\mathrm{\&Sigma;}}}{P}_i---\left(15\right)$

In formula, P _transfor load transfer plan amount final in demand response scheme; N _lfor being transferred to the sum of the node level in isolated island in units of the node layer in power distribution network rooted tree hierarchical mode; n _lfor the power distribution network level within the scope of the isolated island after active isolated island scheme.

Constraints is as follows:

${\stackrel{\&CenterDot;}{U}}_i\underset{j=1}{\overset{n_k}{\mathrm{\&Sigma;}}}{\stackrel{*}{Y}}_{\mathrm{ij}}{\stackrel{*}{U}}_j=P_i+Q_i,i\&Element;n_k---\left(16\right)$

V _k,min<V _k<V _k,maxk∈n _k(17)

I _l≤I _l,maxl∈n _l(18)

$\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{Li}\&GreaterEqual;\mathrm{\&Delta;}{P}_{\mathrm{LD}}---\left(19\right)$

In formula, n _kit is the node total number of the power distribution network after load transfer plan; it is the voltage vector of node i; P _i, Q _ibe respectively active power and the reactive power of node i injection; the node admittance matrix element Y of the power distribution network after load transfer plan _ijconjugate complex number.V _kthe voltage of node k; V _{k, min}, V _{k, max}the minimum voltage that allows of node k and maximum voltage respectively.N _lit is the circuitry number in the power distribution network after load transfer plan; I _lit is the electric current of circuit l; I _{l, max}it is the lowest high-current value that circuit l allows;

Step 7.2) obtain isolated island scope and electric automobile excision load: the load total amount be transferred in isolated island in units of the node layer obtaining in power distribution network rooted tree hierarchical mode by sub-optimization problem I, because microgrid in isolated island is exerted oneself limited, be difficult to support the burden with power newly proceeded to in isolated island, so need to utilize Demand Side Response resource, by controlling the charging electric vehicle load within the scope of isolated island, reach the object of isolated island optimizing operation.The optimization aim of sub-optimization problem II is under the prerequisite ensureing isolated island safe and stable operation, based on the load transfer plan amount that sub-optimization problem I obtains, guarantee that the electric automobile cutting load amount of each electric automobile charging station is minimum, also namely ensure that user's uses energy comfort level to greatest extent, target function is shown in;

$\max \underset{i=1}{\overset{p}{\mathrm{\&Sigma;}}}{P}_{\mathrm{EV},i}---\left(20\right)$

In formula, p is the electric automobile charging station number in demand response scheme within the scope of isolated island; P _{eV, i}for the electric automobile cutting load amount in charging station i;

Constraints is as follows:

P _EV,i≤P _TR,ii∈V (21)

$P_{{\mathrm{MG}}_{j,\min }}\&le;P_{{\mathrm{MG}}_j}\&le;P_{{\mathrm{MG}}_{j,\max }},j=\mathrm{1,2},...,m---\left(22\right)$

$Q_{{\mathrm{MG}}_{j,\min }}\&le;Q_{{\mathrm{MG}}_j}\&le;Q_{{\mathrm{MG}}_{j,\max }},j=\mathrm{1,2},...,m---\left(23\right)$

In formula, P _mGjthe active power that microgrid j sends; P _{mGj, max}and P _{mGj, min}be respectively maximum and the minimum value of the active power that microgrid j sends; Q _mGjit is the reactive power that microgrid j sends; Q _{mGj, max}and Q _{mGj, min}be respectively maximum and the minimum value of the reactive power that microgrid j sends.

For Congestion based on multi-source active distribution network management multilevel hierarchy control method preferred forms provided by the invention:

1 scene introduction

This chapter is the correctness that example verifies the management of the For Congestion based on the multi-source active distribution network multilevel hierarchy control strategy of proposition by IEEE-30 node transmission system (as shown in Figure 7) and the distribution system that is connected to node 19 place.In example, suppose power grids circuits L _18-19break down, thus cause critical circuits L _19-20effective power flow is crossed thermally-stabilised out-of-limit, and For Congestion occurs; This power distribution network example adopts IEEE typical case three feeder systems improved shown in Fig. 8, and wherein, node 17 accesses microgrid, and node 8 and node 12 are provided with electric automobile charging station.In simulation process, the maximum output of setting microgrid is 13+j10MVA, and the thermally-stabilised limit data of circuit of transmission system is in table 1, and the related data of distribution system is in table 2;

The thermally-stabilised limit of table 1IEEE-30 node system circuit

Table 2 example initial data

2 simulation results

2.1 active reconfiguration scheme simulation results

As power grids circuits L _18-19break down, thus cause critical circuits L _19-20effective power flow is 32.02MW, crosses thermally-stabilised out-of-limit (32MW) and For Congestion occurs.△ P can be calculated by carrying out active reconstruct to power distribution network _fRfor 0.0242MW, and △ P _lDfor 0.02MW, meet formula (1), select power distribution network initiatively reconfiguration scheme.

Power distribution network active reconstruction result is in table 3.Can see according to active reconstruction calculations result, be reconstructed by the active of power distribution network, effectively can reduce the active power loss of power distribution network, also namely reduce the active power on power transmission and distribution interconnection, thus slow down For Congestion.Critical circuits L can be obtained by the power transmission network trend after calculating power distribution network active reconstruct _19-20effective power flow is 31.98MW, lower than the thermally-stabilised limit of this circuit, realizes the target slowing down For Congestion.

Table 3 power distribution network is reconstruction calculations result initiatively

2.2 active islet operation scheme simulation results

Suppose critical circuits L under this scene _19-20the thermally-stabilised limit be 85% of original thermally-stabilised limiting figure.Under this suppositive scenario, if select power distribution network initiatively reconfiguration scheme, critical circuits L _19-20effective power flow is 31.98MW, higher than the thermally-stabilised limit of this circuit.Therefore, under this scene, power distribution network active reconfiguration scheme is difficult to the demand meeting For Congestion management, now, and △ P _fRfor 0.0242MW, and △ P _lDfor 4.82MW, meet the condition of formula (31), therefore, select initiatively islet operation scheme.In isolated island search procedure, take the thinking of " first search for and verify afterwards ", introduce example isolated island search procedure below.First in power distribution network, carry out preliminary isolated island search, meet the preliminary isolated island Search Results of PBC as shown in Figure 9.

Isolated island verification is carried out to the preliminary isolated island Search Results obtained below, first the constraints represented by check formula (10), avoids occurring that initiatively isolated island reduction plans amount is being greater than power transmission network congestion management reduction plans demand thus is causing sacrificing the problem of user by energy comfort level.The present invention is after the division of initial initiatively isolated island, and power distribution network originally becomes 12 nodes from 16 nodes, and block switch becomes 11 from 15, and interconnection switch becomes 2 from 4.Critical circuits L is obtained through Load flow calculation _19-20effective power flow is 20.18MW, lower than the thermally-stabilised limit under this scene.But, △ P now _lDfor 4.82MW, for 11.1MW, power transmission network For Congestion demand nargin coefficient k in example _dvalue is 1.2, obviously do not meet the constraints represented by formula (10), therefore stop the verification to other constraintss, re-start isolated island search, and constantly carry out isolated island verification after obtaining isolated island search plan, until meet all isolated island constraints; The final isolated island search plan obtained under this scene as shown in Figure 10.

After carrying out the active islet operation scheme of Figure 10, after the plan of active isolated island, power distribution network originally becomes 14 nodes from 16 nodes, and block switch becomes 13 from 15, and interconnection switch becomes 3 from 4.Critical circuits L is obtained through Load flow calculation _19-20effective power flow is 26.06MW, lower than the thermally-stabilised limit under this scene.Meanwhile, △ P now _lDfor 4.82MW, for 5.5MW, power transmission network For Congestion demand nargin coefficient k in example _dvalue is 1.2, obviously meets the constraints represented by formula (10), and, isolated island plan reduction plans amount does not exceed the demand for security amount of power transmission network yet, is also greater than power transmission network reduction plans demand simultaneously.Meanwhile, other constraintss are verified also meet the demands.Finally, the static properties of isolated island is verified, obtain the static properties contrast of initial isolated island and final isolated island as shown in Figure 10, as we can see from the figure, no matter final isolated island scheme is all better than initial isolated island in the static properties such as voltage stability index or voltage fluctuate index., can see from the isolated island search plan of Figure 10, final isolated island scheme compares initial isolated island search plan range shorter meanwhile, can ensure that using of user can comfort level to greatest extent while ensureing to exchange power transmission network For Congestion.The isolated island searching method that visible the present invention carries can carry out interaction with the actual motion demand of power transmission network, ensures the safe operation of active distribution network to greatest extent, be adapted to the power transmission network congestion management under active distribution network background while supporting power transmission network to run.Multi-source active distribution network active islet operation scheme result of calculation is in table 4.

Table 4 multi-source active distribution network is islet operation scheme result of calculation initiatively

2.3 demand response scheme simulation results

Suppose critical circuits L under this scene _19-20the thermally-stabilised limit be 60% of original thermally-stabilised limiting figure.Under this suppositive scenario, if select power distribution network initiatively islet operation scheme, critical circuits L _19-20effective power flow is 26.06MW, higher than the thermally-stabilised limit (19.2MW) of this circuit.Therefore, under this scene, power distribution network active islet operation scheme is difficult to the demand meeting For Congestion management.Set the maximum available charging electric vehicle load of EVCS1 and EVCS2 under this scene and be respectively 4MW and 4.5MW.Now, △ P _lDfor 6.86MW, ∑ P _lifor 5.5MW, and ∑ EV _kfor 4MW, meet the condition of formula (42), therefore, select demand response scheme.

Isolated island division result under demand response scheme as shown in figure 11, can see on the basis of active islet operation scheme, be transferred in isolated island in units of the node layer of node 9,11,8,10 in power distribution network rooted tree hierarchical mode, therefore, the optimum transfer load amount that sub-optimization problem I obtains is the load summation (10.6MW) of node 9,11,8,10.In order to ensure isolated island safe and reliable operation, need Demand-side electric automobile to participate in running, islet operation scheme result of calculation is in table 5.

Table 5 demand response scheme islet operation result of calculation

By the enforcement of demand response scheme, obtain critical circuits L through Load flow calculation _19-20effective power flow is 18.53MW, lower than the thermally-stabilised limit under this scene.The optimization result of calculation of table 5 shows, although displaced a large amount of burdens with power in demand response scheme in isolated island, but by controlling the charging process of electric automobile, ensureing that user is with excision part charging load under the prerequisite of energy comfort level, can ensure the safe and stable operation of isolated island.

Claims (7)

1. based on a For Congestion management multilevel hierarchy control method for multi-source active distribution network, it is characterized in that: the described management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method comprises the following step carried out in order:

Step one, acquisition service data: obtain current power system core line operational data;

Step 2, judge whether satisfied first service conditions: judge whether to select power distribution network initiatively reconfiguration scheme according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 3, otherwise next step enters step 4;

Step 3, initiatively reconstruct operation: select power distribution network initiatively reconfiguration scheme, active distribution network management system (ADMS) is by initiatively reconstructing the network configuration optimizing and revising power distribution network, thus reduce transmission & distribution net dominant eigenvalues, the final For Congestion effectively reducing power transmission network; This flow process terminates;

Step 4, judge whether satisfied second service conditions: judge whether to select multiple source power distribution host to move islet operation scheme according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 5, otherwise next step enters step 6;

Step 5, initiatively islet operation: select multiple source power distribution host to move islet operation scheme, ADMS is exerted oneself by microgrid in microgrid control centre (MGCC) control access power distribution network, form the active isolated island scheme considering power transmission network For Congestion demand and power distribution network ability, reduce the load of upstream power transmission network within a certain period of time, thus effectively reduce the For Congestion of power transmission network; This flow process terminates;

Step 6, judge whether satisfied 3rd service conditions: judge whether to select demand response scheme to carry out the management of power transmission network For Congestion according to the current operational mode of power transmission network, if judged result is ' being ', then next step enters step 7, otherwise exits this process flow operation;

Step 7, demand response run: select demand response scheme, ADMS is by coordination optimization control MGCC and electric automobile charging station (EVSCC), optimize and revise microgrid according to power transmission network For Congestion demand and power distribution network ability to exert oneself and charging electric vehicle load, on the basis of active isolated island scheme, further expansion isolated island scope, the load of further reduction upstream power transmission network, effectively reduces the For Congestion of power transmission network; This flow process terminates.

2. the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method according to claim 1, it is characterized in that: in step 2, the described concrete grammar of selection power distribution network active reconfiguration scheme that judges whether is: when the current operational mode of power transmission network meets formula (1), select power distribution network initiatively reconfiguration scheme;

△P _FR≥△P _LD(1)

Wherein, △ P _fRfor the power transmission and distribution dominant eigenvalues reduction by implementing the realization of power distribution network active reconfiguration scheme; △ P _lDthat crosses the thermally-stabilised limit for the out-of-limit critical circuits of current power transmission network has work value, specifically calculates by formula (2);

△P _LD＝P _ini,i-P _lim,i(2)

Wherein, P _{ini, i}for the trend of the out-of-limit critical circuits i of current power transmission network has work value, can be obtained by Load flow calculation; P _{lim, i}for current power transmission network out-of-limit critical circuits trend higher limit.

3. the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method according to claim 1, it is characterized in that: in step 3, described power distribution network initiatively reconfiguration scheme algorithm comprises the following steps:

Step 3.1) to read in initial data and algorithm parameter is set: initial data comprises load and branch switch state etc. under branch parameters, various load method; Algorithm parameter comprises population scale, inertia weight scope, accelerator coefficient and speed span etc.;

Step 3.2) initialization: iterations sets to 0, all particle positions of initialization and speed; Carry out the Load flow calculation under various mode according to initial data, the comprehensive network harm of network within this period obtained under each group on off state is its initial adaptive value and history adaptive optimal control value, and the particle position of loss minimization is global optimum's particle;

Step 3.3) speed and location updating: according to step 3.1) parameters carry out particle rapidity and location updating; Whether out-of-limitly check that particle position upgrades rear each variable, if a certain variable is out-of-limit, then get its corresponding limit value;

Step 3.4) radial verification: whether the network configuration under the Switch State Combination in Power Systems that the particle position after checksum update is corresponding meets radial constraint, if some particle does not meet, reinitializes this particle, until all satisfied;

Step 3.5) judge whether trend restrains: if convergence, then enter step 3.6), if do not restrain, iterations adds 1, forwards step 3.4 to) proceed;

Step 3.6) terminate to judge: as reached maximum permission iterations, then stop and Output rusults; Otherwise iterations adds 1, forward step 3.4 to) proceed.

4. the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method according to claim 1, it is characterized in that: in step 4, the described concrete grammar selecting multiple source power distribution host to move islet operation scheme that judges whether is: when the current operational mode of power transmission network meets formula (31), selects multiple source power distribution host to move islet operation scheme;

$\mathrm{\&Delta;}{P}_{\mathrm{FR}}\&le;\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}---\left(3\right)$

Wherein, P _l,ifor the load of the circuit i within the scope of the maximum possible isolated island of power distribution network active isolated island has work value.

5. the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method according to claim 1, it is characterized in that: in step 5, the method for described active islet operation scheme comprises following four steps:

Step 5.1) build power distribution network rooted tree hierarchical mode

Power distribution network has rooted tree in radical model to be divided into five layers, wherein V={ ν ₁..., ν _nrepresenting the set of node, E represents the line set of feeder line, e _i,j(i<j) be the circuit between node i and node j;

Step 5.2) definition rooted tree node weights

The weights of described definition rooted tree node are the power summation being connected in load under this destination node and distributed power source, specifically calculate such as formula shown in (32):

w(v _i) _i∈V＝P _Gi-P _Li(4)

In formula, P _lifor being connected in node ν _ion total burden with power value; P _gifor being connected on node ν _ithe meritorious of upper microgrid is exerted oneself;

Step 5.3) carry out preliminary isolated island search, obtain maximum possible isolated island scope

First carry out preliminary isolated island search, be target to the maximum and carry out preliminary isolated island search, obtain the isolated island scope of maximum possible with isolated island scope, target function is such as formula shown in (33):

$\max \underset{i=1}{\overset{N_G}{\mathrm{\&Sigma;}}}{P}_{\mathrm{Li}}---\left(5\right)$

Demand fulfillment constraint equation (34) in isolated island search procedure ~ formula (38):

● power-balance constraint (Power balance constraint, PBC)

$F\left(T_S\right)=\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Gi}}-\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}>0---\left(6\right)$

In formula, F (T _s) be PBC valuation functions, consider that in isolated island, microgrid has certain regulating power to unbalanced power, PBC constraint is relaxed for meritorious exerting oneself total in isolated island is greater than total burden with power;

● transmission line security constraint

|P _eij| _eij∈V<α*P _{rated_eij}(7)

In formula, P _eijfor current operational mode line e _ijeffective power flow; P _{rate_eij}for circuit e _ijmaximum rated capacity; α is nargin coefficient;

● the radial operation constraint of isolated island

N＝M+1 (8)

In formula, N is the nodes within the scope of isolated island; M is the circuit number within the scope of isolated island;

● initiatively isolated island position constraint

Depth (v in formula _i, i ∈ V) and represent node ν _ithe level at place in power distribution network rooted tree hierarchy structure model;

● For Congestion constraint of demand

$\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}\&le;k_D\mathrm{\&Delta;}{P}_{\mathrm{LD}}---\left(10\right)$

In formula, k _dfor power transmission network For Congestion demand nargin coefficient, its size can carry out dynamic conditioning according to the real-time net capability index of active distribution network;

Step 5.4) isolated island verification

For step 5.3) the initial isolated island that obtains, according to constraints, namely formula (7) ~ (10) verify one by one, if all constraints all can meet, then final isolated island scheme is determined; If there is a wherein item constraint condition not meet the demands, by isolated island range shorter one deck, turn back to step 5.3) proceed isolated island search; Finally, carry out static properties verification to the isolated island obtained, static performance index comprises islanded system voltage stability index and voltage fluctuate index, is specifically expressed as follows:

$L_{i,j}=4[{(P_j{X}_{i,j}-Q_j{R}_{i,j})}^2+(P_j{X}_{i,j}+Q_j{X}_{i,j})U_i^2]/U_i^4---\left(11\right)$

I＝max(L _i,j) (12)

In formula, R _i,jand X _i,jbe respectively resistance and the reactance of branch road i-j; P _jand Q _jbe respectively and flow into the meritorious of node j and reactive power; L _i,jfor the voltage stability index value of branch road i-j, the maximum of the voltage stability index of each branch road is the voltage stability index value of whole isolated island, shown in (13):

V＝max|U _j-U _b| (13)

In formula, U _jfor the voltage perunit value of node j; U _bfor node reference voltage value, be taken as 1.0; V is voltage fluctuate index, and V more mini system is more stable.

6. the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method according to claim 1, it is characterized in that: in step 6, the described selection demand response scheme that judges whether to carry out the concrete grammar of power transmission network For Congestion management is: when the current operation side of power transmission network meets formula (42), select demand response scheme to carry out the management of power transmission network For Congestion;

$\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}\&le;\mathrm{\&Delta;}{P}_{\mathrm{LD}}\&le;\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{L,i}+\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{\mathrm{EV}}_k---\left(14\right)$

In formula, p is according to step 4.3) in the quantity of electric automobile charging station initiatively within the scope of the isolated island that obtains of isolated island searching algorithm; ∑ EV _kfor according to step 4.3) in electric automobile charging station initiatively within the scope of the isolated island that obtains of isolated island searching algorithm can by the total amount of charging electric vehicle load.

7. the management of the For Congestion based on multi-source active distribution network multilevel hierarchy control method according to claim 1, it is characterized in that: in step 7, described demand response scheme comprises the following steps:

Step 7.1) calculate the load that need be transferred in isolated island: initial load transfer plan amount is the summation ∑ P of all burdens with power in isolated island V (i ∈ V) in active islet operation scheme in previous step _li, in workload demand scheme, successively increase in units of the node layer of load transfer plan amount in power distribution network rooted tree hierarchical mode, until meet the demand of power transmission network congestion management; Final load transfer plan amount computational methods are shown in formula (15);

$P_{\mathrm{trans}}=\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}+\underset{i=n_l+1}{\overset{N_L}{\mathrm{\&Sigma;}}}{P}_i---\left(15\right)$

In formula, P _transfor load transfer plan amount final in demand response scheme; N _lfor being transferred to the sum of the node level in isolated island in units of the node layer in power distribution network rooted tree hierarchical mode; n _lfor the power distribution network level within the scope of the isolated island after active isolated island scheme;

Constraints is as follows:

${\stackrel{\&CenterDot;}{U}}_i\underset{j=1}{\overset{n_k}{\mathrm{\&Sigma;}}}\stackrel{*}{Y_{\mathrm{ij}}}\stackrel{*}{U_j}=P_i+Q_i,i\&Element;n_k---\left(16\right)$

V _k,min<V _k<V _k,maxk∈n _k(17)

I _l≤I _l,maxl∈n _l(18)

$\underset{i\&Element;V}{\mathrm{\&Sigma;}}{P}_{\mathrm{Li}}\&GreaterEqual;\mathrm{\&Delta;}{P}_{\mathrm{LD}}---\left(19\right)$

In formula, n _kit is the node total number of the power distribution network after load transfer plan; it is the voltage vector of node i; P _i, Q _ibe respectively active power and the reactive power of node i injection; the node admittance matrix element Y of the power distribution network after load transfer plan _ijconjugate complex number; V _kthe voltage of node k; V _{k, min}, V _{k, max}the minimum voltage that allows of node k and maximum voltage respectively; n _lit is the circuitry number in the power distribution network after load transfer plan; I _lit is the electric current of circuit l; I _{l, max}it is the lowest high-current value that circuit l allows;

Step 7.2) obtain isolated island scope and electric automobile excision load: the load total amount be transferred in isolated island in units of the node layer obtaining in power distribution network rooted tree hierarchical mode by sub-optimization problem I; The optimization aim of sub-optimization problem II is under the prerequisite ensureing isolated island safe and stable operation, based on the load transfer plan amount that sub-optimization problem I obtains, guarantee that the electric automobile cutting load amount of each electric automobile charging station is minimum, also namely ensure that user's uses energy comfort level to greatest extent, target function is shown in;

$\min \underset{i=1}{\overset{p}{\mathrm{\&Sigma;}}}{P}_{\mathrm{EV},i}---\left(20\right)$

In formula, p is the electric automobile charging station number in demand response scheme within the scope of isolated island; P _{eV, i}for the electric automobile cutting load amount in charging station i;

Constraints is as follows:

P _EV,i≤P _TR,ii∈V (21)

$P_{{\mathrm{MG}}_{j,\min }}\&le;P_{{\mathrm{MG}}_j}\&le;P_{{\mathrm{MG}}_{j,\max }},j=\mathrm{1,2},...,m---\left(22\right)$

$Q_{{\mathrm{MG}}_{j,\min }}\&le;Q_{{\mathrm{MG}}_j}\&le;Q_{{\mathrm{MG}}_{j,\max }},j=\mathrm{1,2},...,m---\left(23\right)$

In formula, P _mGjthe active power that microgrid j sends; P _{mGj, max}and P _{mGj, min}be respectively maximum and the minimum value of the active power that microgrid j sends; Q _mGjit is the reactive power that microgrid j sends; Q _{mGj, max}and Q _{mGj, min}be respectively maximum and the minimum value of the reactive power that microgrid j sends.