CN105207200A - Development coordination analyzing method for power grid with load distribution unbalance - Google Patents

Abstract

The invention discloses a development coordination analyzing method for a power grid with load distribution unbalance. The method comprises the steps that 1, the load level of a system is given; 2, distribution coefficients of all load points are determined; 3, loads are distributed to all the load points according to the load distribution coefficient; 4, load flow calculation is carried out on the system; 5, whether overloads exist on a branch or not is judged, if yes, the step 6 is executed, or otherwise, the step 8 is executed; 6, output power of all the load points is adjusted; 7, it is ordered that K is equal to K+1, whether K<=N is supported or not is judged, if yes, the step 3 is executed, or otherwise, the step 10 is executed; 8, whether residual output power exists in the system or not is judged, if yes, the step 9 is executed, or otherwise, the step 10 is executed; 9, the system loads are increased, and the step 2 is executed; 10, the total load of the system is output; 11, the maximum power supply capacity of the system is determined; 12, the valley-to-peak difference of the system is obtained; 13, an evaluation report is formed; 14, the process is finished.

Description

A kind of power load distributing unbalanced power network development Coordination Analysis method

Technical field

The invention belongs to the technical field of distribution network planning, relate to a kind of power load distributing unbalanced power network development Coordination Analysis method particularly.

Background technology

The spatial distribution of load is relevant with factors such as the industrial structure, industrial nature, geographical environments.In general, the power load distributing of economy more developed regions is more concentrated, and load density is larger, and the load factor of equipment is higher, the lost of life; On the contrary, the utilization rate of equipment and installations in load district is smaller on the low side, can cause resources idle, affect the economy of electric grid investment.In the region that load proportion is very large, very high to the requirement of electric network composition, the serious accident in this region may cause whole mains breakdown.If load space distribution changes, just require that the operational mode of electrical network has stronger adaptability, need electrical network to have stronger adaptive capacity.

The unbalanced electrical network of this power load distributing, the ability to transmit electricity of restriction electrical network and Resource allocation and smoothing.Therefore, need the workload demand coordinating each region, improve the power supply capacity in each region, ensure that whole electric network coordination develops.The operational mode of spatial distribution to electrical network of load has material impact, and then affects the safe and stable operation of electrical network, and load equilibrium is spatially the important guarantee of the stabilization of power grids and economical operation.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, a kind of power load distributing unbalanced power network development Coordination Analysis method is provided, its can Efficient Evaluation electrical network to the adaptability of load, effectively can weigh the coordination degree between electrical network and load, thus improve the power supply capacity in each region, ensure that whole electric network coordination develops.

Technical solution of the present invention is: this power load distributing unbalanced power network development Coordination Analysis method, and the method comprises the following steps:

(1) to the load level of fixed system;

(2) distribution coefficient of each load point is determined;

(3) according to sharing of load coefficient by sharing of load to each load point;

(4) Load flow calculation is carried out to system;

(5) judge whether branch road exists overload, is, perform step (6), otherwise perform step (8);

(6) adjust each load point to exert oneself;

(7) make K=K+1, judge whether K≤N sets up, and is, perform step (3), otherwise perform step (10), wherein K represents cycle-index, and K is from 0; N is the maximum cycle of Operation system setting;

(8) judge whether have residue to exert oneself in system, to be, perform step (9), otherwise perform step (10);

(9) increase system loading, jump to step (2);

(10) output system total load;

(11) certainty annuity net capability;

(12) peak-valley difference of system is asked for;

(13) assessment report is formed;

(14) terminate.

This method is on Distribution Network Load Data model basis, by carrying out Load flow calculation to branch road, the adjustment of generator output and the change of different load is coordinated to ask for the net capability of system, the peak-valley difference of last certainty annuity, by analyzing the harmony of power network development to the evaluation of net capability and peak-valley difference, therefore, it is possible to Efficient Evaluation electrical network is to the adaptability of load, effectively can weigh the coordination degree between electrical network and load, thus improve the power supply capacity in each region, ensure that whole electric network coordination develops.

Accompanying drawing explanation

Fig. 1 shows the flow chart of power load distributing according to the present invention unbalanced power network development Coordination Analysis method;

Fig. 2 shows according to power flow algorithm of the present invention;

Fig. 3 shows the flow chart of process in accordance with the present invention (4).

Embodiment

As shown in Figure 1, this power load distributing unbalanced power network development Coordination Analysis method, the method comprises the following steps:

(1) to the load level of fixed system;

(2) distribution coefficient of each load point is determined;

(3) according to sharing of load coefficient by sharing of load to each load point;

(4) Load flow calculation is carried out to system;

(5) judge whether branch road exists overload, is, perform step (6), otherwise perform step (8);

(6) adjust each load point to exert oneself;

(7) make K=K+1, judge whether K≤N sets up, and is, perform step (3), otherwise perform step (10), wherein K represents cycle-index, and K is from 0; N is the maximum cycle of Operation system setting;

(8) judge whether have residue to exert oneself in system, to be, perform step (9), otherwise perform step (10);

(9) increase system loading, jump to step (2);

(10) output system total load;

(11) certainty annuity net capability;

(12) peak-valley difference of system is asked for;

(13) assessment report is formed;

(14) terminate.

This method is on Distribution Network Load Data model basis, by carrying out Load flow calculation to branch road, the adjustment of generator output and the change of different load is coordinated to ask for the net capability of system, the peak-valley difference of last certainty annuity, by analyzing the harmony of power network development to the evaluation of net capability and peak-valley difference, therefore, it is possible to Efficient Evaluation electrical network is to the adaptability of load, effectively can weigh the coordination degree between electrical network and load, thus improve the power supply capacity in each region, ensure that whole electric network coordination develops.

Preferably, as shown in Figure 3, described step (4) comprises step by step following:

(4.1) counter O reset k=0, reads in network parameter;

(4.2) each node voltage U of initialization _nk () is supply voltage;

(4.3) load equivalence branch admittance is tried to achieve according to load bus voltage:

Y _si=S ^* _si/ | U _ni(k) | ², i ∈ N _s*, N _sfor all load branch circuits number, form admittance matrix Y;

(4.4) the voltage vector U of each node is calculated according to formula (7) _n(k+1)

Un＝-(AYA ^T) ^-1AYU _S(7)；

(4.5) judge | U _n(k+1)-U _n(k) | _maxwhether < ε sets up, if set up, performs step (4.6);

Otherwise make k=k+1, return step (4.2);

(4.6) total load that this distribution district of comprising power that each load confesses and line loss power consumes is calculated $S_d=P_d+{\mathrm{jQ}}_d=\underset{i=1}{\overset{B}{\&Sigma;}}\left({{\left|A_T{U}_n\left(k+1\right)\right|}_i}^2{y}_{ii}\right),$ Wherein y _iifor the element that the i-th row i-th in Y arranges;

(4.7) calculation of tidal current U is returned _nand S (k+1) _d, terminate.

Preferably, when judging Line overload in described step (5), the maximum transmitted power of the power on each branch road under this load level obtained by Load flow calculation and branch road is compared, the maximum transmitted power being greater than branch road, for there is Line overload, is less than the maximum transmitted power of branch road for there is not Line overload.

Preferably, described step (12) comprises step by step following:

(12.1) determine that target function is peak-valley difference;

(12.2) under system normal operating mode, do not consider stoppage in transit and the maintenance of unit, set up corresponding maximum load Mathematical Modeling;

(12.3) under target function, constraints meets network power flow equation, and power supply is exerted oneself and do not got over line and circuit nonoverload, according to formula (1) founding mathematical models

$\left.\begin{array}{c}-B\mathrm{\&theta;}+g-k_{\max }d=0\\ g^{\&prime;}\&le;g\&le;g^{\&prime;\&prime;}\\ A^T\mathrm{\&theta;}\&le;\stackrel{\&OverBar;}{\mathrm{\&psi;}}\end{array}\right\}---\left(1\right)$

Wherein:

D-actual power load;

G', g, g "-be respectively power supply minimum output, actually to exert oneself and most high output;

B-node admittance matrix;

A ^tthe transposed matrix of-node branch road incidence matrices A;

θ-node voltage phase angle;

-branch road maximum permissible voltage phase angle;

K _maxthe ratio of-maximum supply load and actual power load, the peak load multiple normal system of electrical network meets k _max>=1, k _maxd represents the net capability of electrical network, k _maxmore can adapt to higher load level greatlyr, power supply capacity is stronger;

(12.4) under system normal operating mode, do not consider stoppage in transit and the maintenance of unit, set up corresponding minimum load Mathematical Modeling;

(12.5) exert oneself limited because power supply is adjustable, grid equipment has certain margin of safety, and the power supply capacity of electrical network is also by the restriction of low load levels, and the receptible minimum load of electrical network is formula (2):

$\left.\begin{array}{c}-B\mathrm{\&theta;}+g-k_{\min }d=0\\ g^{\&prime;}\&le;g\&le;g^{\&prime;\&prime;}\\ A^T\mathrm{\&theta;}\&le;\stackrel{\&OverBar;}{\mathrm{\&psi;}}\end{array}\right\}---\left(2\right)$

Wherein:

K _minthe ratio of-minimum supply load and actual power load, also referred to as minimum supply load multiple;

Normal system should meet k _min≤ 1, k _minless, electrical network more can adapt to lower load level;

K _mind is the minimum power supply capacity of electrical network;

(12.6) peak-valley difference k is calculated according to model _maxd-k _mind.

Preferably, described step (13) comprises step by step following:

(13.1) maximum supply load multiple k is solved _max, embody electrical network to the adaptability degree of high load capacity level, this value is larger, then the adaptability of electrical network to load growth is stronger;

(13.2) minimum supply load multiple k is solved _min, embody electrical network to the adaptedness of underload, this value is less, more can adapt to the great fluctuation process of load;

(13.3) peak-valley difference that can bear of system is larger, and the reliability of system is stronger, and this value power system dispatching department carries out operational mode arrangement and peak regulation provides reference, and its size embodies the coordination degree of electrical network and load.

Provide a specific embodiment below.

This analytical method mainly comprises the following aspects:

1, the processing method of power flow algorithm

Process step of the present invention (4) adopts and carries out Load flow calculation based on the branch impedance method in bus class calculating power system load flow, and the method convergence is good, and algorithm is simple, is applicable to weakly loops and radial distribution networks.Simplification Equivalent Calculation is carried out to distribution network line and load thereof, sets up Mathematical Modeling as shown in Figure 2.

One is had to the distribution network of N number of node, B bar branch road (comprising distribution branch road and equivalent load branch road), describe the matrix that its node associates character matrix A with branch road is N × B dimension, if node voltage column vector is U _n,branch voltage column vector U and branch current column vector I can be expressed as:

U＝A ^TU _n(3)

AI＝0(4)

For a distribution region, think do not have controlled current source in circuit, between inductance, coupling is smaller, can ignore, then have:

I＝Y(U+U _S)(5)

In formula, U _sbe power supply matrix, Y is that B × B ties up branch road diagonal angle admittance matrix, is by distribution network line admittance matrix Y _l, node load Equivalent Admittance Matrix Y _swith power branch admittance y _bbthree part compositions, that is:

$Y=\left[\begin{array}{ccc}{Y}_L& & \\ & Y_S& \\ & & y_{bb}\end{array}\right]---\left(6\right)$

Wherein, Y _land Y _sit is all diagonal matrix.The admittance y of i-th section of distribution line _li=1/ (R _i+ jX _i), R _i, X _ibe respectively resistance and the reactance of i-th section of distribution line; The admittance y of i-th equivalent load branch road _si=S ^*/ | U _ni(k) | ², S _sii-th equivalent load, U _nifor the node voltage of node i; y _bbit is power branch.

Thus, node voltage matrix equation can be obtained:

Un＝-(AYA ^T) ^-1AYU _S(7)

The concrete steps of Branch Power Flow algorithm are as follows:

(1) counter O reset k=0; Read in network parameter, each node voltage U of initialization _nk () is supply voltage;

(2) load equivalence branch admittance is tried to achieve according to load bus voltage:

Y _si=S ^* _si/ | U _ni(k) | ², i ∈ N _s*, N _sfor all load branch circuits number, form admittance matrix Y;

(3) the voltage vector U of each node is calculated according to formula (7) _n(k+1);

(4) judge | U _n(k+1)-U _n(k) | _max< ε, if set up, proceeds to (5) step; Otherwise k=k+1, returns (2) step;

(5) total load (comprising power and line loss power that each load confesses) that this distribution district consumes is calculated $S_d=P_d+{\mathrm{jQ}}_d=\underset{i=1}{\overset{B}{\&Sigma;}}\left({{\left|A_T{U}_n\left(k+1\right)\right|}_i}^2{y}_{ii}\right),$ Wherein y _iifor the element that the i-th row i-th in Y arranges;

(6) calculation of tidal current U is returned _nand S (k+1) _d, exit.

Power flow algorithm flow process is shown in Fig. 3.

2, the net capability of uncompensated load system is asked for

(1) to the given a certain load level of specific system, and according to certain sharing of load coefficient by sharing of load to each load point;

(2) carry out Load flow calculation, the power under obtaining this load level on each branch road, and compared by the maximum transmitted power of the rated output of branch road and branch road, whether inspection exists the situation of Line overload.If find do not have branch road generation overload after inspection, then, when needing solution load to reach much, branch road starts to occur overload;

(3) improve the total load of system, repeat step (1), step (2), until there is the situation of Line overload in system;

(4) after there is Line overload in system, should readjust power supply exert oneself alleviate overload;

(5) through step (4), after the overload disappearance of system, continue the total load of increase system, carry out Load flow calculation again, when occurring overload in system, and after adjustment several times, still cannot eliminate overload, or until do not have available exerting oneself, now the total load of system is the net capability of system.

3, the peak-valley difference of uncompensated load system is determined

Determine that the step of uncompensated load system peak-valley difference is as follows:

(1) target function and peak-valley difference is determined;

(2) under system normal operating mode, do not consider stoppage in transit and the maintenance of unit, set up corresponding maximum load Mathematical Modeling;

(3) under target function, constraints meets network power flow equation, and power supply is exerted oneself and do not got over line and circuit nonoverload, utilizes formula (1) to ask for the peak load multiple of electrical network, calculates k _maxd;

(4) under system normal operating mode, do not consider stoppage in transit and the maintenance of unit, set up corresponding minimum load Mathematical Modeling;

(5) exert oneself because power supply is adjustable limited, grid equipment has certain margin of safety, the power supply capacity of electrical network is also by the restriction of low load levels, the receptible minimum load of electrical network institute also can in order to upper model representation, utilize formula (2) to ask for the minimum load multiple of electrical network, calculate k _mind;

(6) peak-valley difference, i.e. k is calculated according to (4), (5) _maxd-k _mind.

4, in action 2 with the basis of content 3, show that the unbalanced power network development harmony of power load distributing is assessed.

The assessment of power load distributing unbalanced power network development Coordination Analysis mainly comprises following content:

(1) the maximum supply load multiple k solved _max, embody electrical network to the adaptability degree of high load capacity level, this value is larger, then the adaptability of electrical network to load growth is stronger;

(2) minimum supply load multiple k _min, embody electrical network to the adaptedness of underload, this value is less, more can adapt to the great fluctuation process of load;

(3) peak-valley difference that can bear of system is larger, and the reliability of system is stronger, and this value power system dispatching department carries out operational mode arrangement and peak regulation provides reference, and its size embodies the coordination degree of electrical network and load.

The above; it is only preferred embodiment of the present invention; not any pro forma restriction is done to the present invention, every above embodiment is done according to technical spirit of the present invention any simple modification, equivalent variations and modification, all still belong to the protection range of technical solution of the present invention.

Claims (5)

1. a power load distributing unbalanced power network development Coordination Analysis method, is characterized in that: the method comprises the following steps:

(1) to the load level of fixed system;

(2) distribution coefficient of each load point is determined;

(3) according to sharing of load coefficient by sharing of load to each load point;

(4) Load flow calculation is carried out to system;

(5) judge whether branch road exists overload, is, perform step (6), otherwise perform step (8);

(6) adjust each load point to exert oneself;

(7) make K=K+1, judge whether K≤N sets up, and is, perform step (3), otherwise perform step (10), wherein K represents cycle-index, and K is from 0; N is the maximum cycle of Operation system setting;

(8) judge whether have residue to exert oneself in system, to be, perform step (9), otherwise perform step (10);

(9) increase system loading, jump to step (2);

(10) output system total load;

(11) certainty annuity net capability;

(12) peak-valley difference of system is asked for;

(13) assessment report is formed;

(14) terminate.

2. power load distributing according to claim 1 unbalanced power network development Coordination Analysis method, is characterized in that: described step (4) comprises step by step following:

(4.1) counter O reset k=0, reads in network parameter;

(4.2) each node voltage U of initialization _nk () is supply voltage;

(4.3) load equivalence branch admittance is tried to achieve according to load bus voltage:

Y _si=S ^* _si/ U _ni(k) ², n _sfor all load branch circuits number, form admittance matrix Y;

(4.4) the voltage vector U of each node is calculated according to formula (7) _n(k+1)

Un＝-(AYA ^T) ^-1AYU _S(7)；

(4.5) judge | U _n(k+1)-U _n(k) | _maxwhether < ε sets up, if set up, performs step (4.6);

Otherwise make k=k+1, return step (4.2);

(4.6) total load that this distribution district of comprising power that each load confesses and line loss power consumes is calculated $S_d=P_d+{\mathrm{jQ}}_d=\underset{i=1}{\overset{B}{\&Sigma;}}\left({{\left|A_T{U}_n\left(k+1\right)\right|}_i}^2{y}_{ii}\right),$ Wherein y _iifor the element that the i-th row i-th in Y arranges;

(4.7) calculation of tidal current U is returned _nand S (k+1) _d, terminate.

3. power load distributing according to claim 2 unbalanced power network development Coordination Analysis method, it is characterized in that: when judging Line overload in described step (5), the maximum transmitted power of the power on each branch road under this load level obtained by Load flow calculation and branch road is compared, the maximum transmitted power being greater than branch road, for there is Line overload, is less than the maximum transmitted power of branch road for there is not Line overload.

4. power load distributing according to claim 3 unbalanced power network development Coordination Analysis method, is characterized in that: described step (12) comprises step by step following:

(12.1) determine that target function is peak-valley difference;

(12.2) under system normal operating mode, do not consider stoppage in transit and the maintenance of unit, set up corresponding maximum load Mathematical Modeling;

(12.3) under target function, constraints meets network power flow equation, and power supply is exerted oneself and do not got over line and circuit nonoverload, according to formula (1) founding mathematical models

$\left.\begin{array}{c}-B\mathrm{\&theta;}+g-k_{\max }d=0\\ g^{\&prime;}\&le;g\&le;g^{\&prime;\&prime;}\\ A^T\mathrm{\&theta;}\&le;\stackrel{\&OverBar;}{\mathrm{\&psi;}}\end{array}\right\}---\left(1\right)$ Wherein:

D-actual power load;

G', g, g "-be respectively power supply minimum output, actually to exert oneself and most high output;

B-node admittance matrix;

A ^tthe transposed matrix of-node branch road incidence matrices A;

θ-node voltage phase angle;

-branch road maximum permissible voltage phase angle;

K _maxthe ratio of-maximum supply load and actual power load, the peak load multiple normal system of electrical network meets k _max>=1, k _maxd represents the net capability of electrical network, k _maxmore can adapt to higher load level greatlyr, power supply capacity is stronger;

(12.4) under system normal operating mode, do not consider stoppage in transit and the maintenance of unit, set up corresponding minimum load Mathematical Modeling;

(12.5) exert oneself limited because power supply is adjustable, grid equipment has certain margin of safety, and the power supply capacity of electrical network is also by the restriction of low load levels, and the receptible minimum load of electrical network is formula (2):

$\left.\begin{array}{c}-B\mathrm{\&theta;}+g-k_{\min }d=0\\ g^{\&prime;}\&le;g\&le;g^{\&prime;\&prime;}\\ A^T\mathrm{\&theta;}\&le;\stackrel{\&OverBar;}{\mathrm{\&psi;}}\end{array}\right\}---\left(2\right)$

Wherein:

K _minthe ratio of-minimum supply load and actual power load, also referred to as minimum supply load multiple; Normal system should meet k _min≤ 1, k _minless, electrical network more can adapt to lower load level; k _mind is the minimum power supply capacity of electrical network;

(12.6) peak-valley difference k is calculated according to model _maxd-k _mind.

5. power load distributing according to claim 4 unbalanced power network development Coordination Analysis method, is characterized in that: described step (13) comprises step by step following:

(13.1) maximum supply load multiple k is solved _max, embody electrical network to the adaptability degree of high load capacity level, this value is larger, then the adaptability of electrical network to load growth is stronger;

(13.2) minimum supply load multiple k is solved _min, embody electrical network to the adaptedness of underload, this value is less, more can adapt to the great fluctuation process of load;

(13.3) peak-valley difference that can bear of system is larger, and the reliability of system is stronger, and this value power system dispatching department carries out operational mode arrangement and peak regulation provides reference, and its size embodies the coordination degree of electrical network and load.