CN104715144A - Power distribution network closed loop power flow simulation algorithm based on real-time running data - Google Patents

Abstract

The invention discloses a power distribution network closed loop power flow simulation algorithm based on real-time running data. The algorithm includes the following steps of firstly, reading in nodes, wherein branch files include main network models and distribution network models; secondly, arranging closed loop points a and b; thirdly, solving an admittance matrix to obtain loop equivalent impedance; fourthly, obtaining the voltage difference values of the nodes through the Newton Raphson method; fifthly, obtaining the stable-state current, the largest current and the time-domain current. The algorithm has the advantages that real-time simulation calculation can be conducted before closed loop operation through the combination of a current running data section, whether the current exceeds the limit after the loop is closed or not is judged according to the calculation result, a suggestion is given for deciding whether the loop can be closed or not, and therefore scheduling personnel are helped to make analysis and decisions.

Description

A kind of closed loop network Power flow simulation algorithm based on real-time running data

Technical field

The present invention relates to a kind of closed loop network Power flow simulation algorithm, be specifically related to a kind of closed loop network Power flow simulation algorithm based on real-time running data.

Background technology

According to the understanding at scene, in present urban power distribution network, Loop Closing Operation is very general, but but lack strong theory and analysis software to instruct this operation, scene is all rely on the experience of operations staff to judge whether to carry out Loop Closing Operation, not only easily there is judgment bias like this, and to the Alloy White Iron wantage fractional analysis that may occur, the result of practical operation has very large randomness.Existing technology Problems existing mainly contains: do not have the reliable network reduction method of complete set.Because Loop Closing Operation mainly carries out between power distribution network two buses or feeder line, relate to power transmission network and power distribution network, so, must simplify whole network.Retain involutive ring electric current and affect large node, circuit, load etc., and set up rational equivalent network.Also not too deep to the foundation research of computation model.Transformer divides the position of tap, the switching of capacitor, and feeder load distribution and character etc. all involutive ring result of calculation have a huge impact.How being connected with real-time system, obtaining distribution network operational factor accurately, set up rational computation model, is difficult point and the key that computational analysis meets actual conditions.The data of carrying out needs during Alloy White Iron are many, need good data and software support just can complete.There is no the computation model of the cyclization temporary impact electric current of Erecting and improving.When cyclization point both sides voltage difference is larger, even if steady-state current can escape the setting valve of overcurrent protection after cyclization, but the instantaneous cyclization dash current caused thus still likely causes the action of current quick.

Summary of the invention

The object of the invention is to, overcome the deficiencies in the prior art, there is provided one can in conjunction with current operating data section before Loop Closing Operation, carry out real-time simulated animation, judge that whether cyclization after-current is out-of-limit by result of calculation, can provide the suggestion of cyclization, thus helps dispatcher to carry out the closed loop network Power flow simulation algorithm based on real-time running data of analysing and decision.

Closed loop network Power flow simulation algorithm based on real-time running data of the present invention, comprises the steps:

1), read in node, branch road file, comprise major network and distribution network model;

2), cyclization point a, b are set;

3), solve admittance matrix and obtain loop equiva lent impedance;

4), by the voltage difference of Niu Lafa solution node;

5), steady-state current, maximum current, temporal current is obtained respectively.

As preferably: step 1) specifically comprise the steps: to read in node, branch road file (comprising major network and distribution network model) is for the topological structure of electric analysis in early stage; Model data derives CIM file by EMS system, then in conjunction with CIM analysis tool, generates the numbering of distinct device class, title, the information such as type; Finally call the algorithm generating node branch road, generate the network topology structure be made up of branch road and node of complete set.

As preferably: step 2) concrete steps be: by topological analysis in conjunction with PMS facility information, search out in distribution and for two circuits of cyclization and their interconnection switch, the circuit of appointment two concrete cyclizations during Loop Closing Operation, can be needed.

As preferably: step 3) concrete steps be: use Dai Weining method of equal effects, upwards searched for from cyclization point by topological analysis, the impedance of associated branch is added and obtains.

The invention has the beneficial effects as follows: usually distribution network line and equipment are overhauled or occur because of accident load cut time, need to carry out closing, Open Loop Operation, to reduce unnecessary power off time.But the circulation caused thus will have a great impact the safe operation of power distribution network.Generally, operating personnel can only carry out closing, unlinking by rule of thumb, there is larger security risk.The present invention in conjunction with current operating data section before Loop Closing Operation, can carry out real-time simulated animation, judges that whether cyclization after-current is out-of-limit by result of calculation, and can provide the suggestion of cyclization, thus helps dispatcher to carry out analysing and decision.

Accompanying drawing explanation

Fig. 1 is overall flow schematic diagram of the present invention;

Fig. 2 is Single-ring network breakpoint schematic diagram;

Fig. 3 position Dai Weinan equivalent schematic;

Fig. 4 is distribution network closed loop network diagram;

Fig. 5 is cyclization network equivalent figure;

Fig. 6 is simple closed loop network sketch map;

Fig. 7 is the computation model after simplifying;

Fig. 8 is cyclization simulation calculation surface chart;

Fig. 9 is cyclization simulation calculation surface chart.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described further.Although the present invention will be described in conjunction with preferred embodiment, should know, and not represent and limit the invention in described embodiment.On the contrary, the present invention will contain can be included in attached claims limit scope of the present invention in alternative, modified and equivalent.

The present invention needs network structure, device parameter and the operational factor of High-Voltage Network (10kV bus and above network interface) and 10kV distribution.

Wherein the service data of High-Voltage Network, obtains from SCADA.Model data, can by manual modeling or from EMS system introducing.For High-Voltage Network, need to select certain bus to be balance node, the standard of selection is

(1) bus of highest voltage level

(2) bus that capacity is maximum

Complete for model parameter, measurement of correlation gathers complete loop, by the information of major network, can calculate each node voltage, phase angle difference on major network.There is the equivalent impedance of transformer in the loop of cyclization, also systematic equivalent impedance, by these voltage sources and impedance, just can calculate cyclization steady-state current value, Alloy White Iron time domain specification, maximum impact electric current etc.The implementation of program as shown in Figure 1.

1, invention in read in node, branch road file (comprising major network and distribution network model) for early stage topological structure of electric analysis.

Idiographic flow is: model data can derive CIM file by EMS system, then in conjunction with CIM analysis tool, generates the numbering of distinct device class, title, the information such as type.Finally call the algorithm generating node branch road, generate the network topology structure be made up of branch road and node of complete set.

Node file definition (Node.txt format description):

Branch road document definition: (branch.txt format description):

2, cyclization point a, b in invention are two line names of cyclization.

In the present invention, by topological analysis in conjunction with PMS facility information, search out in distribution and for two circuits of cyclization and their interconnection switch, the circuit of appointment two concrete cyclizations during Loop Closing Operation, can be needed.

3, the loop equivalent impedance method that solves in invention uses Dai Weining method of equal effects, upwards searched for from cyclization point by topological analysis, the impedance of associated branch is added and obtains.

Idiographic flow is as follows: first, is opened by looped network at cyclization point, with the electric current before open loop or power, and the state before simulation open loop.As shown in Figure 2.

In figure A, M, N are the first and last node waiting to close interconnection switch, and before cyclization, its on-load is respectively S _l1, S _l2; Figure B is schematic diagram after cyclization, and the power flowing through cyclization point after M, N point merges in network is S _lOOP, corresponding electric current is I _lOOP.Figure C is schematic diagram after open loop, if U before cyclization _m>U _n, for state during analog closed-loop adds a current source at a M, a current source, for flowing out, is added at a N in direction, and direction is for flowing into, and size is I _lOOPfor the ease of Load flow calculation, offset current can be converted to load, namely M point load becomes S _l1+ S _lOOP, N point load is S _l2-S _lOOP.If U before cyclization _m<U _n, to add the symbol of current source contrary.

After above-mentioned process, the weakly loops after cyclization becomes radial, and its topological structure is consistent with network before cyclization, but node load have passed through correction.

This based on Thevenin theorem to S _lOOPsolve.An ideal voltage source and a series resistance can be equivalent to for figure B Central Plains Radial network, as shown in Figure 3:

Voltage source U in figure _oCvalue be the open-circuit voltage of this active two terminal circuit, i.e. the voltage difference U of M and N point before cyclization _m-U _n, obtain by trend before calculating cyclization.

Dai Weinan equiva lent impedance Z in figure tri-, during for all independent sources and load zero setting, adds a unit current source between two-terminal, at the voltage that opening part is formed.If calculate Z from circuit network analysis angle merely, comparatively complicated, need to calculate open-circuit voltage and short-circuit current.In fact, after power supply and load zero setting, added unitary current only flows through the branch road on loop, therefore opening voltage should equal all loop branch impedance sums, be Z, when having multiple loop in network and each loop is interrelated, opening voltage is just not equal to loop circuit impedance).Therefore, the radial structure of network can be made full use of here, to calculate from M, N point to joint or slack bus process all branch roads impedance and as Dai Weinan equiva lent impedance, greatly can accelerate computing velocity like this.For cyclization in feeder line, upwards can search for a certain common node by cyclization point, this common node may be a certain joint in the root node of network or network, can form a loop like this, Z be all branch roads in this loop impedance and.For cyclization between feeder line, upwards search two source points by cyclization point, at this moment Z be all main line branch roads between this two source point impedance and.Loop equiva lent impedance calculates as shown in Figure 4.

Upper figure cyclization point K and J place are added respectively the electric current that a current value is 1 and-1.Then Fig. 5 can be equivalent to.As seen from Figure 5, the equivalent impedance of cyclization point K, J 2 is exactly U _kJvalue.

$\left[\begin{array}{c}0\\ .\\ .\\ 1\left(K\right)\\ .\\ .\\ -1\left(J\right)\\ .\\ .\\ 0\end{array}\right]=\left[\begin{array}{ccc}{Y}_{11}& .........& Y_{1N}\\ .& & \\ .& & \\ Y_{K1}& .........& Y_{\mathrm{KN}}\\ .& & \\ .& & \\ Y_{J1}& .........& Y_{\mathrm{JN}}\\ .& & \\ .& & \\ Y_{N1}& .........& Y_{\mathrm{NN}}\end{array}\right]\left[\begin{array}{c}{U}_1\\ .\\ .\\ U_K\\ .\\ .\\ U_J\\ .\\ .\\ U_N\end{array}\right]$

U _kJvalue be U _k-U _j.Equiva lent impedance then between K and J is Z _kJ=U _kJ

The Load flow calculation of the voltage difference by Niu Lafa solution node 4, in invention has fast convergence rate, and iterations and electric network model are substantially irrelevant, the feature that convergence is good.

The calculating of cyclization dash current:

Figure 6 shows that a simple closed loop network system, normal when running cyclization point interconnection switch disconnect, network keeps radial, when overhaul of the equipments or the time of falling load close interconnection switch.Due to the existence of cyclization point both sides voltage difference, dash current certainly will be produced in loop network system, system be done and suitably simplifies to facilitate the computation and analysis to dash current.Because Three-phase Power Systems is symmetrical, so only study a phase wherein, as A phase, calculate the single-phase equivalent circuit of cyclization transient state dash current as shown in Figure 7.

In computation model, system is simplified as follows:

Omit load in figure;

For the overhead transmission line of lOkV and following voltage level, disregard line admittance;

For cyclization switch place interconnector part, use lumped parameter model, do not consider cyclization switch position distribution in the line and effect.

Closing the ring circuit other part use outer waits duty value process, owing to waiting duty value and line impedance than very large, therefore can ignore when calculating dash current.

In Fig. 7, L and R is inductance and the impedance sum of all electrical equipments in looped network, and the voltage difference of cyclization point both sides is equivalent to a voltage source and is present in computation model.

Calculate Alloy White Iron time-domain value:

Because circuit is in perception, cyclization is oscillatory extinction to the whole process of stable state, therefore sets up the differential equation and calculates dash current, obtain real-time response.

A phase phase voltage is actuated in computation model, for

Wherein for cyclization point both sides voltage difference, namely

The non-secondly differential equation of circuit is

$E_{\max }\sin (\mathrm{\&omega;t}+\mathrm{\&alpha;})=\mathrm{Ri}+L\frac{\mathrm{di}}{\mathrm{dt}},$

The initial phase angle of E when α is cyclization moment t=0, it is determined by the phase angle difference of this moment cyclization point both sides voltage.

The particular solution of equation is the periodic component benevolence of Alloy White Iron or claims AC compounent:

$i_p\left(t\right)=\frac{E_{\max }}{\sqrt{R^2+{\mathrm{\&omega;}}^2{L}^2}}\sin [\mathrm{\&omega;t}+\mathrm{\&alpha;}-{\tan }^{-1}\left(\frac{\mathrm{\&omega;L}}{R}\right)];$

Above formula i.e. steady-state current I _m, i.e. I _m=i _p(t);

The general solution of equation is the DC component benevolence of Alloy White Iron or claims free component, and it is ever-reduced DC current, and its value is:

i _k(t)＝C ₁e ^-(R/L)t

C in formula ₁value be the initial value of DC component.

Separate completely as particular solution and general solution sum

$i\left(t\right)=i_k\left(t\right)+i_p\left(t\right)=C_1{e}^{-(R/L)t}+\frac{E_{\max }}{\sqrt{R^2+{\mathrm{\&omega;}}^2{L}^2}}\sin [\mathrm{\&omega;t}+\mathrm{\&alpha;}-{\tan }^{-1}\left(\frac{\mathrm{\&omega;L}}{R}\right)];$

Cyclization inductance of front moment does not have electric current to pass through, can C be obtained ₁, can obtain

$i\left(t\right)=e^{-(R/L)t}\frac{-E_{\max }}{\sqrt{R^2+{\mathrm{\&omega;}}^2{L}^2}}\sin [\mathrm{\&alpha;}-{\tan }^{-1}\left(\frac{\mathrm{\&omega;L}}{R}\right)]+\frac{E_{\max }}{\sqrt{R^2+{\mathrm{\&omega;}}^2{L}^2}}\sin [\mathrm{\&omega;t}+\mathrm{\&alpha;}-{\tan }^{-1}\left(\frac{\mathrm{\&omega;L}}{R}\right)];$

Order

M is the amplitude of Alloy White Iron periodic component, for the phase angle between periodic component and Emax bis-.

Thus have the complete expression formula of dash current

Can be found out by derivation of equation result, the size of cyclization temporary impact electric current and the difference in magnitude of cyclization point both sides voltage are approximated to direct ratio, are approximated to inverse ratio with looped network resulting impedance.In addition, the phase angle difference of voltage is also the key factor affecting its size, when or during the integral multiple of π, DC component is 0, namely enters stable state immediately after cyclization; When during left and right, DC component initial value is equal with periodic component amplitude, and dash current is maximum.Therefore, for ensureing safe cyclization, adjustable system operation mode reduces difference in magnitude and the phase angle difference of cyclization point both sides voltage as far as possible.

Under most serious conditions, maximum instantaneous electric current appears at half period after cyclization, has

i _m＝[1+exp(-0.01/T _a)M

T in formula _a=L/R

Because current setting in fast tripping protection is the effective value of electric current, so consider the root-mean-square value of momentary current in one-period centered by the instantaneous T of cyclization, namely

$I_t=\sqrt{\frac{1}{T}{\&Integral;}_{t-\frac{T}{2}}^{t+\frac{T}{2}}{i}^2\mathrm{dt}}=\sqrt{\frac{1}{T}{\&Integral;}_{t-\frac{T}{2}}^{t+\frac{T}{2}}{(i_{\mathrm{pt}}+i_{\mathrm{at}})}^2}=\sqrt{{(I_m/\sqrt{2})}^2+{i_{\mathrm{at}}}^2}$

I in the cycle is supposed before and after T in formula _at(DC component) is constant.Due to maximum effective value electric current occur in cyclization after half period time (supposing cyclization in the worst case), its value is (as Km=l.9):

$\begin{array}{c}{I}_M=\sqrt{{(I_m/\sqrt{2})}^2+{i_{\mathrm{at}}}^2(t=0.01s)}\\ =\sqrt{{(I_m/\sqrt{2})}^2+{(i_m-I_m)}^2}\\ =\sqrt{{(I_m/\sqrt{2})}^2+{I_C}^2{(K_M-1)}^2}\\ =1.62\frac{\left|I_m\right|}{\sqrt{2}}\end{array}$

I in above formula _mfor the modulus value of steady-state current.

Claims (4)

1., based on a closed loop network Power flow simulation algorithm for real-time running data, it is characterized in that, comprise the steps:

1), read in node, branch road file, comprise major network and distribution network model;

2), cyclization point a, b are set;

3), solve admittance matrix and obtain loop equiva lent impedance;

4), by the voltage difference of Niu Lafa solution node;

5), steady-state current, maximum current, temporal current is obtained respectively.

2. the closed loop network Power flow simulation algorithm based on real-time running data according to claim 1, it is characterized in that, step 1) specifically comprise the steps: to read in node, branch road file (comprising major network and distribution network model) is for the topological structure of electric analysis in early stage; Model data derives CIM file by EMS system, then in conjunction with CIM analysis tool, generates the numbering of distinct device class, title, type information; Finally call the algorithm generating node branch road, generate the network topology structure be made up of branch road and node of complete set.

3. the closed loop network Power flow simulation algorithm based on real-time running data according to claim 1, it is characterized in that: step 2) concrete steps be: by topological analysis in conjunction with PMS facility information, search out in distribution and for two circuits of cyclization and their interconnection switch, the circuit of appointment two concrete cyclizations during Loop Closing Operation, can be needed.

4. the closed loop network Power flow simulation algorithm based on real-time running data according to claim 1, it is characterized in that: step 3) concrete steps be: use Dai Weining method of equal effects, upwards searched for from cyclization point by topological analysis, the impedance of associated branch is added and obtains.