CN101349731B - Real time evaluating method of voltage stability - Google Patents

Abstract

The invention provides a circuit tidal current index for resolving the problems such as that the high circuit tidal current causes the voltage decrease at the bus of the receiving end and the failure about the real solution of the circuit tidal current equation. The circuit tidal current index is applied for real-time voltage stabilization detection to provide a voltage stability real-time evaluation method, based on the circuit tidal current index. The method can simply and quickly evaluate the voltage stability of a power network and can scan and calculate the circuit tidal current index of a full network line to fine the line of low voltage stability in the power network. Applied for the voltage stability real-time detection, the method can provide the change tread of the voltage stability of each line, to determine the initial point of the voltage stability problem.

Description

A kind of real time evaluating method of voltage stability

Technical field

The present invention relates to a kind of real time evaluating method of voltage stability, belong to Power System Analysis and control, power system voltage stabilization real-time analysis and control field.

Background technology

The collapse of voltage accident may occur in major network or some areas electrical network, have sudden and disguised, often be difficult to obviously perceive at the formation initial stage, this just need carry out the real-time continuous monitoring to operation states of electric power system, to have fast processing function and the stable quick arbitration functions of system voltage simultaneously, so that in time pinpoint the problems to data.Be subjected to WAMS (the Wide Area Measurements System of extensive concern in recent years; WAMS) system can capture the real-time stable state and the multidate information in each place of extensive interconnected electric power system under same reference time framework; and have higher accuracy, provide new visual angle and condition for realizing extensive interconnected electric power system running status real-time continuous monitoring.For preventing the collapse of voltage accident, the problem that the management and running personnel are concerned about the most is: the current power system running state from collapse point how far also have or stability margin much in addition.Therefore, determine that based on the voltage stability index of WAMS becoming voltage stablizes one of major function of dynamic real-time monitoring analysis.

To accurately assess voltage stability, just must have a well behaved voltage to stablize evaluation index.Have high accuracy, this is the basic demand of voltage being stablized evaluation index.Voltage as real-time monitoring is stablized evaluation index, also must calculate fast and has a favorable linearity.Lot of domestic and international work about electric power person stablizes evaluation index to voltage and studies, and the voltage of catching the different characteristic of voltage unstability to propose much to be in various forms is stablized evaluation index.

(1) sensitivity index: it utilizes the variation relation of some physical quantity in the system based on power flow equation, and promptly the differential relationship between them is studied the voltage stability of system.This index needs the whole network lot of data, even comprises the partial dynamic component parameters, therefore is difficult to use in the stable monitoring in real time of voltage.

(2) eigenwert/Singularity Value Index: this index judges by Jacobi matrix is whether unusual whether system voltage is stable.The formation of Jacobi matrix needs the network parameter of the whole network, and simultaneously, Jacobian matrix is carried out Eigenvalue Analysis/odd value analysis needs a large amount of calculating, and usually in critical point place, singular value and eigenwert have the process of very steep quick decline.As seen slow, the linear property of this index computing velocity is poor.

(3) nargin index: from the given running status of system, according to certain pattern, growth by load growth or through-put power progressively approaches the collapse of voltage point, and then the current operating point of system can be used as the index of voltage degree of stability to the distance of collapse of voltage point, is referred to as the nargin index.Nargin index major advantage has: measure intuitively current operating point voltage degree of stability, favorable linearity, can consider multiple limiting factor etc.But the calculated amount of this index is very big, is difficult to satisfy the requirement of monitoring in real time.

The present invention proposes a kind of voltage that can be used for monitoring in real time and stablize evaluation index---circuit trend index, whether this index has real solution to judge that whether voltage stablize according to the circuit trend, simultaneously simple in structure, explicit physical meaning, computing velocity is fast, the accuracy height, linearity is good, is applicable to the stable monitoring in real time of the considerable fully WAMS voltage of electric network state.On this basis, invented real time evaluating method of voltage stability based on circuit trend index.This method is calculated simply, the voltage stability of energy rapid evaluation electrical network.Increase the emulation testing under the multiple load growth mode in the growth of load constant power factor, the permanent active power growth of load, the permanent reactive power of load respectively by sending end busbar voltage constant system, sending end busbar voltage change system, IEEE9 node system, verified that this index has good computing velocity, accuracy and linearity, also verified feasibility and validity simultaneously based on the real time evaluating method of voltage stability of circuit trend index.

Summary of the invention

The condition whether the present invention has real solution whether to stablize as the receiving end busbar voltage with the single line trend, circuit trend index has been proposed first, grid simulation checking by a plurality of different qualities shows, this index has extensive applicability, good accuracy and linearity, is applicable to the real-time voltage stability monitoring.

For the real-time voltage stability monitoring, voltage is stablized evaluation index higher requirement.At first, require voltage to stablize evaluation index accurately and reliably, be unlikely to false assessment system voltage stability, cause serious consequence.Secondly, it is fast that computing velocity is wanted, because real-time system does not have the too many time to be used for data processing, requirement can provide the voltage stability assessment result fast.In addition, require voltage to stablize evaluation index and have favorable linearity,, avoid the generation of voltage stability accident so that after monitoring the system voltage stability problem, have time enough to take control measure.Therefore, this project is studied by analysis, has proposed a kind of voltage that can be used for monitoring in real time and has stablized evaluation index---circuit trend index.On this basis, invented real time evaluating method of voltage stability based on circuit trend index.

Therefore, the present invention proposes a kind of real time evaluating method of voltage stability, it is characterized in that may further comprise the steps:

(1) reading system state real time data and network parameter:

From real-time data base, read total bus number, each bus numbering, voltage magnitude, voltage phase angle, be kept in the predefined bus data structure; From real-time data base, read bus way, each circuit number, I side bus numbering, J side bus numbering, forward active power, forward reactive power, reverse active power, reverse reactive power, be kept in the predefined track data structure, simultaneously, number the associated circuitry numbering that is provided with in the corresponding bus data structure according to I side bus numbering and J side bus; From parameter database, read the line resistance, line reactance of respective lines and susceptance over the ground, be kept in the track data structure;

(2) read line circuit-switched data, computational scheme resistance value and angle of impedance:

By the resistance R of the circuit number k bar circuit in the read line circuit-switched data structure successively, reactance X, susceptance B, reverse meritorious P over the ground _j, reverse idle Q _J0, calculate line impedance Z and angle of impedance θ, wherein k is a positive integer

$Z=\sqrt{R^2+X^2}$

$\mathrm{\θ}=\arctan \left(\frac{X}{R}\right);$

(3) according to the first and last relation of positive and negative definite circuit two ends bus of circuit active power:

If the reverse active power P of circuit _jFor negative, illustrate that the I side bus is the circuit head end, the J side bus is a line end, reads circuit I side bus numbering so, searches this busbar voltage amplitude V in the bus data structure _iWith voltage phase angle δ _i, read circuit J side bus numbering, in the bus data structure, search this busbar voltage amplitude V _jWith voltage phase angle δ _jIf the reverse active power P of circuit _jFor non-negative, illustrate that the J side bus is the circuit head end, the I side bus is a line end, reads the meritorious P of forward so _jWith the idle Q of forward _J0, read circuit J side bus numbering, in the bus data structure, search this busbar voltage amplitude V _iWith voltage phase angle δ _i, read circuit I side bus numbering, in the bus data structure, search this busbar voltage amplitude V _jWith voltage phase angle δ _j

(4) partial data is done necessary the processing, calculates for index and prepare:

The data that read from track data structure and bus data structure can't directly apply to the calculating of circuit trend index, also need to do following necessary processing:

P _j＝-P _j

Q _j0＝-Q _j0

$Q_j=Q_{j0}-\frac{1}{2}B{V}_j^2$

δ＝δ _i-δ _j

(5) computational scheme trend index, the real-time judge voltage stability:

Through above-mentioned (1)-(4) preliminary work in step, directly bring each variable numerical value of front into following formula, can calculate circuit trend index:

$L_{\mathrm{PQ}}=\frac{4(\cos \mathrm{\θ}+\sin \mathrm{\θ})(P_j+Q_j)Z}{V_i^2[1+\sin 2(\mathrm{\θ}-\mathrm{\δ})]}$

If L _PQΔ l, wherein Δ l is given indicator threshold value, then provides warning message;

(6) the circuit trend index of each bar circuit of cycle calculations:

From the track data structure, read the data of k+1 bar circuit, calculate, entered for (7) step if k+1, then finishes epicycle greater than the bus way; Otherwise, according to the circuit trend index of (2)-(5) step calculating k+1 bar circuit;

(7) judge whether real-time data base upgrades:

If real-time data base has renewal, then entered for (1) step, read bus data and track data, upgrade bus data structure and track data structure; Otherwise, wait for, regularly inquire about, judge whether real-time data base upgrades.

(1). the principle introduction

For simple circuit model as shown in Figure 1, its meritorious trend and reactive power flow can be used formula (1) and formula (2) expression:

$P_j=\frac{V_i{V}_j}{Z}\cos (\mathrm{\θ}-\mathrm{\δ})-\frac{V_j^2}{Z}\cos \mathrm{\θ}---\left(1\right)$

$Q_j=\frac{V_i{V}_j}{2}\sin (\mathrm{\θ}-\mathrm{\δ})-\frac{V_j^2}{Z}\sin \mathrm{\θ}---\left(2\right)$

Wherein, δ=δ _i-δ _jPut formula (1), formula (2) in order distortion a little

$V_j^2\cos \mathrm{\θ}-V_i\cos (\mathrm{\θ}-\mathrm{\δ})V_j+P_{j}Z=0---\left(3\right)$

$V_j^2\sin \mathrm{\θ}-V_i\sin (\mathrm{\θ}-\mathrm{\δ})V_j+Q_{j}Z=0---\left(4\right)$

With formula (3) and formula (4) addition

$V_j^2(\cos \mathrm{\θ}+\sin \mathrm{\θ})-V_i[\cos (\mathrm{\θ}-\mathrm{\δ})+\sin (\mathrm{\θ}-\mathrm{\δ})]V_j+(P_j+Q_j)Z=0---\left(5\right)$

Formula (5) be one about V _jQuadratic equation, according to quadratic equation the discriminant of real solution is arranged, can get

$V_i^2{[\cos (\mathrm{\θ}-\mathrm{\δ})+\sin (\mathrm{\θ}-\mathrm{\δ})]}^2-4(\cos \mathrm{\θ}+\sin \mathrm{\θ})(P_j+Q_j)Z\≥0---\left(6\right)$

Formula (6) is equivalent to formula (7)

$V_i^2[1+\sin 2(\mathrm{\θ}-\mathrm{\δ})]\≥4(\cos \mathrm{\θ}+\sin \mathrm{\θ})(P_j+Q_j)Z---\left(7\right)$

With formula (7) conversion, arrangement, can get formula (8)

$0\≤\frac{4(\cos \mathrm{\θ}+\sin \mathrm{\θ})(P_j+Q_j)Z}{V_i^2[1+\sin 2(\mathrm{\θ}-\mathrm{\δ})]}\≤1---\left(8\right)$

Expression formula shown in the title formula (8) is a circuit trend index, and note is made L _PQ, then

$L_{\mathrm{PQ}}=\frac{4(\cos \mathrm{\θ}+\sin \mathrm{\θ})(P_j+Q_j)Z}{V_i^2[1+\sin 2(\mathrm{\θ}-\mathrm{\δ})]}---\left(9\right)$

The span of circuit trend index of the present invention when the receiving end busbar voltage is stablized is [0,1], and in span along with applied power S _jIncrease be monotonically increasing trend.Work as L _PQ=1 o'clock, receiving end busbar voltage V _jTwo identical real solutions are arranged, receiving end busbar voltage neutrality; Work as L _PQ1 o'clock, receiving end busbar voltage V _jThere is not real solution, receiving end busbar voltage instability.By scanning to the circuit trend index on the whole network elder generation road, the circuit trend index of each bar circuit relatively, desired value the greater is the weak circuit of voltage stability in the electrical network.By real-time calculating monitoring, can understand each bar line voltage distribution change of stability trend, determine to cause the origin of voltage stability problem.

$S_j=\sqrt{P_j^2+Q_j^2}---\left(10\right)$

In actual engineering is used, the Π molded lines road models that use as shown in Figure 2 more, the power that provides also is the bus injecting power, therefore, carries out need carrying out certain conversion process to reactive power when circuit trend index is calculated in application formula (9).

$Q_j=Q_{j0}+{\mathrm{<figure-callout\; id="1"\; label="Q\; j"\; filenames="H2008101199248E00021.png"\; state="\{\{state\}\}">Q</figure-callout>}}_j=Q_{j0}-\frac{1}{2}{\mathrm{BV}}_j^2$

(2). specific implementation

As shown in Figure 3, be the process flow diagram of the implementation method of circuit trend index of the present invention in the real-time voltage stability monitoring is used, its specific implementation step is as follows:

1. initialization

(1) formation of bus array: read real-time data base, form the bus array, total bus number is N _b, each array element structure is as follows:

The bus numbering

Voltage magnitude

Voltage phase angle

Associated circuitry numbering pointer

(2) formation of circuit array: read parameter database and real-time data base, form the circuit array, the bus way is N _l, each array element structure is as follows:

2. cycle calculations

(1) from the circuit array, reads the resistance R, reactance X of k bar circuit, susceptance B, reverse meritorious P over the ground _j, reverse idle Q _J0, calculate Z and θ, wherein k is a positive integer

$Z=\sqrt{R^2+X^2}$

$\mathrm{\&theta;}=\arctan \left(\frac{X}{R}\right)$

(2) be negative if oppositely gain merit, read circuit I side bus numbering, in the bus array, search this busbar voltage amplitude V _iWith voltage phase angle δ _i, read circuit J side bus numbering, in the bus array, search this busbar voltage amplitude V _jWith voltage phase angle δ _j, entered for (4) step; If oppositely meritorious is nonnegative number, then entered for (3) step.

(3) read the meritorious P of forward _jWith the idle Q of forward _J0, read circuit J side bus numbering, in the bus array, search this busbar voltage amplitude V _iWith voltage phase angle δ _i, read circuit I side bus numbering, in the bus array, search this busbar voltage amplitude V _jWith voltage phase angle δ _j

(4) partial data is adjusted

P _j＝-P _j

Q _j0＝-Q _j0

$Q_j=Q_{j0}-\frac{1}{2}{\mathrm{BV}}_j^2$

δ＝δ _i-δ _j

(5) computational scheme trend index L _PQ

$L_{\mathrm{PQ}}=\frac{4(\cos \mathrm{\&theta;}+\sin \mathrm{\&theta;})(P_j+Q_j)Z}{V_i^2[1+\sin 2(\mathrm{\&theta;}-\mathrm{\&delta;})]}$

If L _PQΔ l, wherein Δ l is given indicator threshold value, then provides warning message.

(6) if k=k+1 is k〉N _l, then entered for (7) step; Otherwise, entered for (1) step.

Whether (7) detect real-time data base upgrades.If real-time data base upgrades, then entered for (8) step; Otherwise, wait for, regularly inquiry.

(8) read real-time bus information, real time line information, deposit bus array and circuit array in, entered for (1) step.

(3). the characteristics of circuit trend index

(1) calculates simply

The input data of this index are few, only relate to the voltage parameter of the physical parameter of circuit own, circuit operational factor and circuit two ends bus.

(2) explicit physical meaning

Along with the increase of circuit trend, the reduction of receiving end busbar voltage, will there be real solution in the circuit trend, and this has also just caused receiving end busbar voltage unstability.

(3) accuracy height

Simulation result shows, when the circuit trend is contiguous when not restraining, this index value all correspondingly levels off to critical value 1, has shown the stable case of voltage well.

(4) linearity is good

Simulation result shows that this index has good linearity, and along with the increase of circuit trend, this index is keeping well linearity.

(5) model applied widely

Because the derivation condition of this index is that the circuit trend does not have real solution, so, so long as owing to the overweight voltage unstability situation that causes of circuit trend can be shown by this index.

Advantage of the present invention is:

The circuit trend index that the present invention proposes, explicit physical meaning has than extensive applicability, calculates simply, and the accuracy height has better linearity.On this basis, the real time evaluating method of voltage stability based on circuit trend index of proposition calculates simple, the voltage stability of energy rapid evaluation electrical network, and the gained result has certain directive significance to the management and running of electrical network.

Description of drawings

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

Fig. 1 is simple circuit model;

Fig. 2 is a Π molded lines road model;

Fig. 3 is the real-time applicating flow chart of circuit trend index.

Embodiment

Below be an embodiment of the inventive method, carry out l-G simulation test with the IEEE9 node system and make embodiment, further specify as follows:

Simulate the real-time power network image data by the following method: under the basic load condition, slowly increase load, use PSD-BPA trend program repeat and calculate trend, thereby obtain a series of system states (being that each busbar voltage phasor, each circuit are meritorious and idle) time series; These system state time serieses are write file, in following application, system state amount is deposited into real-time data base, simulate process of real-time data acquisition with this by reading these files.

The concrete enforcement of the real time evaluating method of voltage stability that the present invention proposes may further comprise the steps:

(1) reading system state real time data and network parameter:

From real-time data base, read total bus number, each bus numbering, voltage magnitude, voltage phase angle, be kept in the predefined bus data structure; From real-time data base, read bus way, each circuit number, I side bus numbering, J side bus numbering, forward active power, forward reactive power, reverse active power, reverse reactive power, be kept in the predefined track data structure, simultaneously, number the associated circuitry numbering that is provided with in the corresponding bus data structure according to I side bus numbering and J side bus; From parameter database, read the line resistance, line reactance of respective lines and susceptance over the ground, be kept in the track data structure;

(2) read line circuit-switched data, computational scheme resistance value and angle of impedance:

By the resistance R of the circuit number k bar circuit in the read line circuit-switched data structure successively, reactance X, susceptance B, reverse meritorious P over the ground _j, reverse idle Q _J0, calculate line impedance Z and angle of impedance θ, wherein k is a positive integer

$Z=\sqrt{R^2+X^2}$

$\mathrm{\&theta;}=\arctan \left(\frac{X}{R}\right)$

(3) according to the first and last relation of positive and negative definite circuit two ends bus of circuit active power:

If the reverse active power P of circuit _jFor negative, illustrate that the I side bus is the circuit head end, the J side bus is a line end, reads circuit I side bus numbering so, searches this busbar voltage amplitude V in the bus data structure _iWith voltage phase angle δ _i, read circuit J side bus numbering, in the bus data structure, search this busbar voltage amplitude V _jWith voltage phase angle δ _jIf the reverse active power P of circuit _jFor non-negative, illustrate that the J side bus is the circuit head end, the I side bus is a line end, reads the meritorious P of forward so _jWith the idle Q of forward _J0, read circuit J side bus numbering, in the bus data structure, search this busbar voltage amplitude V _iWith voltage phase angle δ _i, read circuit I side bus numbering, in the bus data structure, search this busbar voltage amplitude V _jWith voltage phase angle δ _j

(4) partial data is done necessary the processing, calculates for index and prepare:

The data that read from track data structure and bus data structure can't directly apply to the calculating of circuit trend index, also need to do following necessary processing:

P _j＝-P _j

Q _j0＝-Q _j0

$Q_j=Q_{j0}-\frac{1}{2}{\mathrm{BV}}_j^2$

δ＝δ _i-δ _j

(5) computational scheme trend index, the real-time judge voltage stability:

Through above-mentioned (1)-(4) preliminary work in step, directly bring each variable numerical value of front into following formula, can calculate circuit trend index:

$L_{\mathrm{PQ}}=\frac{4(\cos \mathrm{\&theta;}+\sin \mathrm{\&theta;})(P_j+Q_j)Z}{V_i^2[1+\sin 2(\mathrm{\&theta;}-\mathrm{\&delta;})]}$

If L _PQΔ l, wherein Δ l is given indicator threshold value, then provides warning message;

(6) the circuit trend index of each bar circuit of cycle calculations:

From the track data structure, read the data of k+1 bar circuit, calculate, entered for (7) step if k+1, then finishes epicycle greater than the bus way; Otherwise, according to the circuit trend index of (2)-(5) step calculating k+1 bar circuit;

(7) judge whether real-time data base upgrades:

If real-time data base has renewal, then entered for (1) step, read bus data and track data, upgrade bus data structure and track data structure; Otherwise, wait for, regularly inquire about, judge whether real-time data base upgrades.

In the present embodiment, the data of each real-time section of application system state are calculated the circuit trend index of each bar circuit fast, when desired value during greater than certain threshold value, provide warning message.Result of calculation shows that simple, the linear property of circuit trend index calculating proposed by the invention is good, accuracy is high; Real time evaluating method of voltage stability based on circuit trend index proposed by the invention calculates simple, the voltage stability of energy rapid evaluation electrical network.

Invention has been described according to specific exemplary embodiment herein.It will be conspicuous carrying out suitable replacement to one skilled in the art or revise under not departing from the scope of the present invention.Exemplary embodiment only is illustrative, rather than to the restriction of scope of the present invention, scope of the present invention is by appended claim definition.

Claims (1)

1. real time evaluating method of voltage stability is characterized in that may further comprise the steps:

(1) reading system state real time data and network parameter:

From real-time data base, read total bus number, each bus numbering, voltage magnitude and voltage phase angle, be kept in the predefined bus data structure; From real-time data base, read bus way, each circuit number, I side bus numbering, J side bus numbering, forward active power, forward reactive power, reverse active power, reverse reactive power, be kept in the predefined track data structure, simultaneously, number the associated circuitry numbering that is provided with in the corresponding bus data structure according to I side bus numbering and J side bus; From parameter database, read the line resistance, line reactance of respective lines and susceptance over the ground, be kept in the track data structure;

(2) read line circuit-switched data, computational scheme resistance value and angle of impedance:

By the resistance R of the circuit number k bar circuit in the read line circuit-switched data structure successively, reactance X, susceptance B, reverse active power P over the ground _j, reverse idle Q _J0, calculate line impedance Z and angle of impedance θ, wherein k is a positive integer

$Z=\sqrt{R^2+X^2}$

$\mathrm{\&theta;}=\arctan \left(\frac{X}{R}\right);$

(3) according to the first and last relation of positive and negative definite circuit two ends bus of circuit active power:

If the reverse active power P of circuit _jFor negative, illustrate that the I side bus is the circuit head end, the J side bus is a line end, reads circuit I side bus numbering so, searches this busbar voltage amplitude V in the bus data structure _iWith voltage phase angle δ _i, read circuit J side bus numbering, in the bus data structure, search this busbar voltage amplitude V _jWith voltage phase angle δ _jIf the reverse active power P of circuit _jFor non-negative, illustrate that the J side bus is the circuit head end, the I side bus is a line end, reads the meritorious P of forward so _jWith the idle Q of forward _J0, read circuit J side bus numbering, in the bus data structure, search this busbar voltage amplitude V _iWith voltage phase angle δ _i, read circuit I side bus numbering, in the bus data structure, search this busbar voltage amplitude V _jWith voltage phase angle δ _j

(4) partial data is done necessary the processing, calculates for circuit trend index and prepare:

The data that read from track data structure and bus data structure can't directly apply to the calculating of circuit trend index, also need to do following necessary processing:

P _j＝-P _j

Q _j0＝-Q _j0

$Q_j=Q_{j0}-\frac{1}{2}{\mathrm{BV}}_j^2$

δ＝δ _i-δ _j

(5) computational scheme trend index, the real-time judge voltage stability:

Through above-mentioned (1)-(4) preliminary work in step, directly bring each variable numerical value of front into following formula, can calculate circuit trend index:

$L_{\mathrm{PQ}}=\frac{4(\cos \mathrm{\&theta;}+\sin \mathrm{\&theta;})(P_j+Q_j)Z}{V_i^2\&lsqb;1+\sin 2(\mathrm{\&theta;}-\mathrm{\&delta;})\&rsqb;}$

If L _PQ＞Δ l, wherein Δ l is given circuit trend indicator threshold value, then provides warning message;

(6) the circuit trend index of each bar circuit of cycle calculations:

From the track data structure, read the data of k+1 bar circuit, calculate, entered for (7) step if k+1, then finishes epicycle greater than the bus way; Otherwise, according to the circuit trend index of (2)-(5) step calculating k+1 bar circuit;

(7) judge whether real-time data base upgrades:

If real-time data base has renewal, then entered for (1) step, read bus data and track data, upgrade bus data structure and track data structure; Otherwise, wait for, regularly inquire about, judge whether real-time data base upgrades.

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