CN103001219A - Optimal coordination control method of multiple flexible alternative current transmission systems (FACTSs) based on trend entropy - Google Patents

Abstract

The invention discloses an optimal coordination control method of multiple flexible alternative current transmission systems (FACTSs) based on trend entropy. The trend entropy is used as an optimizing index of system trend distribution, trend change is coordinated and controlled through control parameters of an FACTS device, and simultaneously too small use rate or overload of circuits is avoided during optimization of a target function trend entropy. First, the trend entropy is obtained through trend calculation and used for judging a trend distribution condition, circuit information affecting system trend distribution is obtained, then the FACTS device is coordinated and controlled, restrain of FACTS device quantity, generator unit output, circuit level, node voltage amplitudes, FACTS positions and the like are considered, and the trend of the system is optimized. Therefore, optimized index trend entropy is adjusted, effective use rate of the circuits is guaranteed, and even trend distribution of the system is reflected on the whole.

Description

A kind of many FACTS optimization control method for coordinating based on the trend entropy

Technical field

The invention belongs to the control technology field of electrical power trans mission/distribution system in the electric power system, particularly a kind of many FACTS optimization control method for coordinating based on the trend entropy.

Background technology

Along with the continuous expansion of power system network scale, one of interconnected Main Trends of The Development that has become modern power systems of high voltage, large capacity, long distance power transmission and large electrical network.Yet, in its fast development, also having exposed the one side of electric power transmission network fragility, a series of new contradiction and problems highlight day by day.In recent years, at home so that in the world wide, the serious accident of electric power transmission network happens occasionally.For example India's 7.30 large-area power-cuts impacts exceedes 300,000,000 people, 7.31 anotherly take turns more massive blackout, 6.7 hundred million people are affected, and involve almost half India.When electric power transmission network improved quality of voltage and the stability of a system in the urgent need to new control measures, a kind of new technology that changes traditional ability to transmit electricity---flexible AC transmitting system (FACTS) technology was arisen at the historic moment.

So-called " flexible AC transmitting system " technology claims again " flexible ac transmission system " technology, be called for short FACTS, a kind of the new and high technologies such as MICROCOMPUTER PROCESSING technology, control technology, power electronic technology to be applied to high voltage power transmisson system, to improve system reliability, controllability, operational efficiency and the quality of power supply, and can obtain the Novel integrated technology of a large amount of energy-saving efficiencies, to come load disturbance to distribute by the major parameter that changes electric power system, make the transmission of electricity process more reliable, have larger controllability and better efficient.

The use of FACTS has broken through in the past local action and the impact of Single Controller, improves on the whole AC power line and power transmission network operation control ability and level.FACTS has the effect of the control electric power transmission network trend flow direction and conveying capacity, is that electricity market is created the directed transport condition of electric power, helps to improve the stability of existing power transmission network, reliability and power supply quality etc.One of most important application facet of FACTS is trend control, and the research of therefore carrying out the control of FACTS trend has important theory value and practical significance, and is very critical and urgent, to satisfy the under the new situation operation needs of electric power system.

The trend entropy proposed based on entropy theory in the law of thermodynamics in recent years, and entropy is chaotic to system and a kind of of disordered state measures, and the order degree of system is lower, and then its entropy is larger; Otherwise the order degree of system is higher, and its entropy is just less.The character of entropy have additive property, nonnegativity, extremum property, with the status number independence.Entropy is implanted in the electric power system and can mates with the trend distribution of circuit, and the meaning of entropy and character are given new implication in electric power system.

Summary of the invention

The present invention lays particular emphasis on the FACTS device to the raising of line load rate mostly in view of research in the past, do not weigh the trend distribution optimization effect of bringing after the FACTS device increases from whole system comprehensively, a kind of many FACTS optimization control method for coordinating based on the trend entropy has been proposed, the power changes in distribution problem that the method causes because of load variations in can the corresponding electrical network of quick adjustment, the input of FACTS device is regulated control can suppress the transient stability that shakes and improve system, the voltage stability that control can improve system is regulated in putting into operation of FACTS, increase load margin, the trend of improving control circuit distributes, and has also improved simultaneously the ability to transmit electricity of electric power system.The position of FACTS device can be reasonably selected in this invention, avoids causing the reduction of voltage stability and ability to transmit electricity, and the selection capacity that can be fit to, and avoids the waste of cost.

The present invention is based on the concept of trend entropy, analyze from the overall situation of system, utilize the FACTS device that the trend in the electric power system is optimized control, reach the optimum behaviour in service of system line etc.

The present invention distributes the trend entropy as system load flow optimization index, trend entropy more trend towards zero show trend in the system distribute more even, the Systems balanth degree is higher.Utilize the coordination control of many FACTS device in the optimizing process, avoid causing the too small or overload of line efficiency, therefore, asking for of trend entropy will be satisfied certain circuit constraints, final goal is by the coordination control of FACTS device so that the trend entropy of system is optimum, and the load state of circuit also reaches perfect condition simultaneously.

The present invention introduces the FACTS device in electric power system, control the optimization system trend so that the optimization of trend entropy by the coordination of FACTS device, the FACTS device has can be in harmonious proportion the model of the various ways such as grouping switching continuously, the FACTS element that has so far trend control mainly contains ASVG, TCPS, TCSC, UPFC, SPFC etc., although its control variables is different, but its model can be expressed as with the form of admittance of series and parallel connections general FACTS model (such as Fig. 1), can simplify calculating, design process thus, the convenient coordination controlled.

1 target setting function:

min H(X _n,Y _n) （1）

Wherein: X _n=[X ₁, X ₂..., X _n] ^T, Y _n=[Y ₁, Y ₂..., Y _n] ^TExpression FACTS device control variables;

N represents the FACTS device number of installing;

Below be the factor of analyzing influence trend entropy, Main Factors is the active power of circuit, finally can sum up in the point that by the FACTS device and coordinate control.

The line load rate:

${\mathrm{\α}}_i=\frac{p_i}{P_i^{\max }}---\left(2\right)$

In the formula: P _iBe the actual trend power of circuit i, Be the maximum meritorious transmission capacity of circuit, i=1,2 ..., M, M are the circuit number.

Given constant sequence U={U _1,U _{2, ,}U _{K, ,}U _n, with α _iCarrying out the by stages is α _i∈ (U _k, U _K+1), U value 1.5 will have behind the number of lines randomization in the different load rate interval

$P\left(k\right)=\frac{l_k}{\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}{l}_k}---\left(3\right)$

In the formula: P (k) is load factor α _i∈ (U _k, U _K+1) the ratio of circuit number the line is busy road sum, l _kBe load factor α _i∈ (U _k, U _K+1) number;

By the above trend entropy that can get electrical network be

$H=-C\underset{K=1}{\overset{N-1}{\mathrm{\Σ}}}P\left(k\right)\ln P\left(k\right)---\left(4\right)$

In the formula: N represents the nodes of system

2 constraintss:

(1) equality constraint:

Equality constraint is the system load flow equation behind the introducing FACTS device

$P_{\mathrm{Gi}}-P_{\mathrm{Li}}-V_i\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}})=0---\left(5\right)$

$Q_{\mathrm{Gi}}-Q_{\mathrm{Li}}-V_i\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}})=0---\left(6\right)$

In the formula:

P _Gi, Q _GiBe respectively the meritorious and reactive power of generator i; P _Li, Q _LiBe respectively the meritorious and reactive power on each branch road i;

V _i, θ _iBe respectively voltage magnitude and the phase angle of node i; G _Ij, B _IjCorresponding element for system node admittance matrix Y behind the introducing FACTS device; N is the node sum.

(2) inequality constraints condition

The inequality constraints condition has the constraint of generating set units limits, circuit horizontal restraint, node voltage Filters with Magnitude Constraints, FACTS position and the load factor constraint of the constraint of number constraint, configuration capacity, circuit and the relation constraint of considering FACTS plant investment and income is installed.

$\left\{\begin{array}{c}{P}_{\mathrm{Gi}}^{\min }\&le;P_{\mathrm{Gi}}\&le;P_{\mathrm{Gi}}^{\max }---\left(7\right)\\ Q_{\mathrm{Gi}}^{\min }\&le;Q_{\mathrm{Gi}}\&le;Q_{\mathrm{Gi}}^{\max }---\left(8\right)\\ P_{\mathrm{Li}}^{\min }\&le;P_{\mathrm{Li}}\&le;P_{\mathrm{Li}}^{\max }---\left(9\right)\\ Q_{\mathrm{Li}}^{\min }\&le;Q_{\mathrm{Li}}\&le;Q_{\mathrm{Li}}^{\max }---\left(10\right)\\ V_i^{\min }\&le;V_i\&le;V_i^{\max }---\left(11\right)\\ 0<L_i\&le;n---\left(12\right)\\ 0<n\&le;N/2---\left(13\right)\\ C_i^{\min }\&le;C_i\&le;C_i^{\max }---\left(14\right)\\ 0<\mathrm{\&alpha;}\&le;1.5---\left(15\right)\\ 0<W<D---\left(16\right)\end{array}\right.$

Formula (7), formula (8) are the constraint of electric power networks generator output, wherein P _Gi, Q _GiBe respectively the meritorious and reactive power of generator;

Formula (9), formula (10) are the constraint of power circuit, wherein P _Li, Q _LiBe respectively the meritorious and reactive power of circuit

Formula (11) is the constraint of system node voltage magnitude, wherein V _iBe the node voltage amplitude;

Formula (12) is the installation position constraint of FACTS device, wherein L _iInstallation site for the FACTS device;

Formula (13) is the arrangement constraint number constraint of FACTS device, and wherein n is the installation number of FACTS device;

Formula (14) is self constrained, wherein C of circuit FACTS device _iThe compensation capacity that provides for the FACTS device;

Formula (15) is the line load rate requirement of FACTS device coordination control, and wherein α is the load factor of circuit;

Formula (16) is the constraint of the benefits of FACTS device, and wherein D is the proportionality coefficient of benefits.

Description of drawings

Fig. 1 is based on the general admittance illustraton of model of FACTS device of many FACTS optimization coordination control of trend entropy;

Fig. 2 is based on the FACTS device control structure figure of many FACTS optimization coordination control of trend entropy;

Fig. 3 is based on the FACTS device control flow chart of many FACTS optimization coordination control of trend entropy.

Embodiment

The present invention is further illustrated below in conjunction with accompanying drawing.

As shown in Figure 1, structure for the FACTS device among the present invention has been carried out unified naturalization, form a general FACTS mounted cast, in coordinating control, can simplify unnecessary state variable and control variables, control variables with the FACTS device converts two form of admittance that can change to thus, namely control parameter [X, Y], from model, can comparatively simply annotate the effect of FACTS device.

As shown in Figure 2, coordination control optimization of the present invention is operated by the FACTS device, variation by the control variables of FACTS device is controlled coordination to the trend entropy, satisfies simultaneously the constraint of grid power balance, line load constraint, node voltage Filters with Magnitude Constraints, FACTS position and the constraint of number constraint, configuration capacity, the load factor constraint of circuit and the relation constraint of considering FACTS plant investment and income are installed.

As shown in Figure 3, coordinate control procedure and be divided into following 9 steps:

1) trend is calculated, and original system is carried out a trend calculate, and can obtain thus the trend cardinal principle distribution situation information of each bar branch road, and the active-power P of each branch road _i

2) ask for line load rate α _i, by the trend of the circuit active-power P of each branch road as can be known _i, the meritorious transmission capacity of the maximum of each circuit again

As can be known, therefore, can be in the hope of the load factor α of each branch road _i, further reflected the trend distribution situation of circuit;

3) to sorting out between the load factor partition, by 2) the load factor α of each bar circuit as can be known _i, given constant sequence U={U _1,U _{2, ,}U _{K, ,}U _n, with α _iCarrying out the by stages is α _i∈ (U _k, U _K+1), U value 1.5, this has just simplified a large amount of computational process;

4) circuit that belongs to same interval, different load rate is carried out randomization, can obtain P (k), be load factor α _i∈ (U _k, U _K+1) the ratio of circuit number the line is busy road sum, can change into thus one about the problem of circuit probability;

5) trend entropy H is about to 4) the trend entropy formula of P (k) the substitution definition that obtains

, can obtain entropy, can reflect thus the trend distribution situation of whole system;

6) by 5) obtain trend entropy H, can judge the load factor α that affects entropy H _iThe interval, just can draw thus is the information of circuit of impact;

7) utilize the FACTS universal model, adopt the GSO algorithm, the position of FACTS device is installed in screening, by regulating the controlled quentity controlled variable control changes of entropy of FACTS device, then reflects the system load flow distribution situation;

8) coordination of FACTS device control is by 7) as can be known, the optimization of entropy is exactly the optimization of trend, by FACTS device control variables X _n, Y _nAdjusting, system is regulated control;

9) after the control of the coordination by FACTS system is carried out the one-time continuous trend again and calculates, as step 1) to 7) so that the entropy of system, trend distribution optimization, realize the coordination control ability of FACTS device.

Claims (3)

1. the many FACTS optimization control method for coordinating based on the trend entropy is characterized in that, has set up a function take trend moisture in the soil minimum as target, the control method of coordinating to control by many FACTS device.Consider the variation of present FACTS device, it has been carried out standardization, simplified the control analysis to the trend entropy, reduced simultaneously unnecessary state variable.

2. a kind of many FACTS optimization control method for coordinating based on the trend entropy according to claim 1, it is characterized in that, described trend entropy H is as the judge index of trend distribution consistency degree, is applied in the coordination control procedure of FACTS device so that the trend optimization of system.When the network analysis trend is distributed, set up trend entropy minH (X _n, Y _n) Mathematical Modeling, X wherein _n=[X ₁, X ₂..., X _n] ^T, Y _n=[Y ₁, Y ₂..., Y _n] ^TExpression FACTS device control variables; N represents the FACTS device number of installing.

Constraints comprises equality constraint and inequality constraints;

(1) equality constraint

$\left\{\begin{array}{c}{P}_{\mathrm{Gi}}-P_{\mathrm{Li}}-V_i\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{V}_j(G_{\mathrm{ij}}\cos {\mathrm{\&theta;}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\&theta;}}_{\mathrm{ij}})=0\\ Q_{\mathrm{Gi}}-Q_{\mathrm{Li}}-V_i\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{V}_j(G_{\mathrm{ij}}\sin {\mathrm{\&theta;}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\&theta;}}_{\mathrm{ij}})=0\end{array}\right.---\left(1\right)$

In the formula:

P _Gi, Q _GiBe respectively the meritorious and reactive power of generator i; P _Li, Q _LiBe respectively the meritorious and reactive power on each branch road i;

V _i, θ _iBe respectively voltage magnitude and the phase angle of node i; G _Ij, B _IjCorresponding element for system node admittance matrix Y behind the introducing FACTS device; N is the node sum.

(2) inequality constraints condition

The inequality constraints condition has the constraint of generating set units limits, circuit horizontal restraint, node voltage Filters with Magnitude Constraints, FACTS position and the load factor constraint of the constraint of number constraint, configuration capacity, circuit and the relation constraint of considering FACTS plant investment and income is installed.

$\left\{\begin{array}{c}{P}_{\mathrm{Gi}}^{\min }\&le;P_{\mathrm{Gi}}\&le;P_{\mathrm{Gi}}^{\max }\\ Q_{\mathrm{Gi}}^{\min }\&le;Q_{\mathrm{Gi}}\&le;Q_{\mathrm{Gi}}^{\max }\\ P_{\mathrm{Li}}^{\min }\&le;P_{\mathrm{Li}}\&le;P_{\mathrm{Li}}^{\max }\\ Q_{\mathrm{Li}}^{\min }\&le;Q_{\mathrm{Li}}\&le;Q_{\mathrm{Li}}^{\max }\\ V_i^{\min }\&le;V_i\&le;V_i^{\max }\\ 0<L_i\&le;n\\ 0<n\&le;N/2\\ C_i^{\min }\&le;C_i\&le;C_i^{\max }\\ 0<\mathrm{\&alpha;}\&le;1.5\\ 0<W<D\end{array}\right.---\left(2\right)$

P wherein _Gi, Q _GiBe respectively the meritorious and reactive power of generator; P _Li, Q _LiBe respectively the meritorious and reactive power of circuit; V _iBe the node voltage amplitude; L _iInstallation site for the FACTS device; N is the installation number of FACTS device; C _iThe compensation capacity that provides for the FACTS device; α is the load factor of circuit, and D is the proportionality coefficient of benefits.

3. a kind of many FACTS optimization control method for coordinating based on the trend entropy according to claim 2 is characterized in that, in the process that obtains concrete trend entropy, about to each line load rate α _iSort out between partition, given constant sequence U={U1, U2 ..., Uk ..., Un} gets final product to get α _i∈ (U _k, U _K+1), then U value 1.5 carries out randomization to the circuit that belongs to same interval, different load rate, converts probability problem to, forms the crucial basis of judging of trend entropy.

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