CN103595043B - A kind of power system dynamic stability appraisal procedure based on wide area measurement - Google Patents

Abstract

The present invention discloses a kind of power system dynamic stability appraisal procedure based on wide area measurement, comprises the following steps: set up voltage stability index; Monitoring main website, collects topologies change information, by WAN communication network, data is sent to monitoring sub-station; The monitoring sub-station of each node receives bus voltage and the source node voltage information of this node that power supply Administrative Unit is measured; Computing system voltage stability index; The present invention runs the operation area of point by prediction load node maximum transmission power and Monitoring systems, propose and a kind of monitor the stable local indexes method of voltage, and utilize wide area measurement system, it is applied to on-Line Voltage stability monitoring, and overcome the voltage magnitude of equivalent power supply when contact node can not be carried out Voltage Stability Evaluation and circuit index application on site by the index based on parameter identification has the defect of tight coupling relative to the voltage magnitude of monitored bus.

Description

A kind of power system dynamic stability appraisal procedure based on wide area measurement

Technical field

The present invention relates to electric energy efficiency management domain, particularly relate to a kind of power system dynamic stability appraisal procedure based on wide area measurement.

Background technology

During Operation of Electric Systems, when electric power workload demand exceedes the power limit that system can be transmitted, there will be system spread of voltage, and this unsteady state generally maintain several seconds to a few hours not etc. Unstable voltage can cause electric current, voltage waveform distortion, wherein only the harm of the current distortion that higher harmonic causes is just very huge: higher harmonic electric current passes through transformer, the core loss of transformer can be made obviously to increase, thus make transformer overheated, shorten work-ing life; Higher harmonic electric current, by alternating current motor, not only can make iron core of electric motor loss obviously increase, but also electric motor rotor will be made to vibrate, and seriously affects the quality product of mechanical workout; Higher harmonic is more outstanding on the impact of electrical condenser, and when the voltage containing higher harmonic is added in electrical condenser two ends, owing to the impedance of couple capacitors higher harmonic is very little, electrical condenser very easily burns out because of overload; In addition, higher harmonic electric current can make the energy consumption of electric power circuit increase, and makes the metering of the induction type watt-hour meter of the calculating electricity charge inaccurate; Also may make power system generation voltage resonance, cause superpotential to rise on the line, it is possible to puncture the insulation of circuit equipment. The existence of higher harmonic, it is also possible to make the relaying of system and automatic gear malfunction or tripping, and neighbouring signal equipment and circuit can be produced signal disturbing.

Wide area measurement system (wideareameasurementsystems, WAMS) by synchronous phasor measurement list (synchronizedphasormeasurementunit, PMU) and reliable high-speed communicating network form, it achieve the Real-Time Monitoring of generator's power and angle within the scope of the wide area of power system, frequency, bus voltage phasor and switch state etc., for on-Line Voltage safety and stability evaluation provides new measurement means.

Patent of invention (application number: 200610150055.6) disclose the wide area merit angle monitoring method in a kind of electrical network wide area measurement system (WAMS), this method is to the voltage phasor phase angle distribution priority of multiple equipment in the unified station of power train, all phase angles are according to priority arranged, composition phase angle group; If but the method is applied to whole power system, it is necessary to the voltage phasor phase angle of each equipment is carried out prioritization, and process is loaded down with trivial details, calculated amount is big, is unfavorable for large-scale promotion.

Summary of the invention

The object of the present invention is exactly to solve the problem, a kind of power system dynamic stability appraisal procedure based on wide area measurement is proposed, the method changes according to voltage magnitude in monitored area, to valve systems such as system loading node and junctor joint structure single power consumption transmission, it is achieved objective power system dynamic stability analyzed, evaluate.

In order to realize above-mentioned purpose, the present invention adopts following technical scheme:

Based on a power system dynamic stability appraisal procedure for wide area measurement, comprise the following steps:

(1) voltage stability index is set up;

(2) monitor main website, collect topologies change information, data are sent to monitoring sub-station by WAN communication network;

(3) monitoring sub-station of each node receives bus voltage and the source node voltage information of this node that power supply Administrative Unit is measured;

(4) computing system voltage stability index: the voltage stability index of calculating is passed to monitoring main website by WAN communication network by each monitoring sub-station, monitoring main website computing system voltage stability index.

Described step (1) sets up being specially of voltage stability index:

Set up power system through-put power model: the power transmission lines of every bar power system is simplified to simple power system through-put power model, wherein, U_s�� �� is power supply terminal voltage, and line impedance is Z_L=R+jX, load side voltage is U_r�� 0, load power isThen, wattful power is met and wattless power can be expressed as:

$P=U_r\[(U_{S}cos\mathrm{\θ}-U_r)\frac{R}{R^2+X^2}+U_{S}sin\mathrm{\θ}\frac{X}{R^2+X^2}\]---\left(1\right)$

$Q=U_r\[(U_{S}cos\mathrm{\θ}-U_r)\frac{X}{R^2+X^2}+U_{S}sin\mathrm{\θ}\frac{R}{R^2+X^2}\]---\left(2\right)$

Combine two formulas, eliminate cos �� and sin ��, it is possible to solve:

${U_r}^2=(\mathrm{\β}\±\sqrt{{\mathrm{\β}}^2-1})\sqrt{(P^2+Q^2)(R^2+X^2)}---\left(3\right)$

In formula, $\mathrm{\β}=\frac{{U_S}^2-2PR-2QX}{2\sqrt{(P^2+Q^2)(R^2+X^2)}}\≥1;$

Due toThen as ��>1 time, first dismemberent of the corresponding PV curve of high level solution in formula (3), low value separates second dismemberent of corresponding PV curve; And as ��,<when 1, system does not have trim point, and when ��=1, system is positioned at the flex point of PV curve;

Definition symbolic function sgnx is:

$\mathrm{sgn}x=\left\{\begin{array}{cc}1,& x>1\\ 0,& x=1\\ -1,& x<1\end{array}\right.---\left(4\right)$

In formula, $x=\frac{{U_r}^2}{\sqrt{P^2+Q^2}\&CenterDot;\sqrt{R^2+X^2}};$

Function sgnx gives and runs the information whether point is operated in PV curve first or second; Get load margin Pmargin, Qmargin and Smargin to be respectively

Pmargin=Pmax-P (5)

Qmargin=Qmax-Q (6)

Smargin=Smax-S (7)

Wherein:Pmax is that reactive power Q is fixed, when increasing active-power P, and the power of PV knee point; Qmax is that active-power P is fixed, when increasing reactive load power Q, and the performance number of QV knee point; Smax is firm power because of under said conditions, when increasing load S, and the load total amount of PV knee point;

Condition (��=1) and formula (5)��(7) of the power delivery limit are reached: at system power transmission limit point, load margin Pmargin, Qmargin and Smargin equal 0 simultaneously from system; Therefore, the available wherein minimum value of distance that tolerance runs some deviation system power transmission limit point provides, and definition voltage stability index (voltageinstabilityindex, VSI) is:

$I_{VSI}=\mathrm{sgn}x\&CenterDot;\min \left(\right|\frac{P_{m\arg in}}{P_{\max }}|,|\frac{Q_{m\arg in}}{Q_{\max }}|,|\frac{S_{m\arg in}}{S_{\max }}\left|\right)---\left(8\right)$

Described step (3) is specially: after the monitoring sub-station of node j receives the node j bus voltage and source node voltage information that power supply Administrative Unit measures, by the equivalent system model computing function sgnx of single power consumption transmission_j, power limit Pmax_j��Qmax_jAnd Smax_j, power margin Pmargin_j��Qmargin_jAnd Smargin_jAnd voltage stablizes power margin index.

In described step (4), monitoring main website computing system voltage stability index is according to following formula:

$I_{VSI,sys}=\underset{j\&Element;L}{\min }\left\{I_{VSIj}\right\}---\left(9\right)$

Above-mentioned appraisal procedure is applicable to electric power supervisory control system, this kind of electric power monitoring system comprises master station, WAN communication network, monitoring substation and monitoring equipment, wherein, monitoring substation accepts the change in topology value of monitoring device measuring, is transferred to master station by WAN communication network.

The useful effect of the present invention is: the operation area being run point by prediction load node maximum transmission power and Monitoring systems, propose and a kind of monitor the stable local indexes method of voltage, and utilize wide area measurement system, it is applied to on-Line Voltage stability monitoring, and overcome the voltage magnitude of equivalent power supply when contact node can not be carried out Voltage Stability Evaluation and circuit index application on site by the index based on parameter identification has the defect of tight coupling relative to the voltage magnitude of monitored bus.

Accompanying drawing explanation

Fig. 1 is the structural representation of the present invention.

Wherein, 1, monitoring substation; 2, master station; 3, equipment is monitored; 4, WAN communication network.

Embodiment:

Below in conjunction with accompanying drawing and embodiment, the invention will be further described.

Based on a power system dynamic stability appraisal procedure for wide area measurement, comprise the following steps:

(1) voltage stability index is set up;

(2) monitor main website, collect topologies change information, data are sent to monitoring sub-station by WAN communication network;

(3) monitoring sub-station of each node receives bus voltage and the source node voltage information of this node that power supply Administrative Unit is measured;

(4) computing system voltage stability index: the voltage stability index of calculating is passed to monitoring main website by WAN communication network by each monitoring sub-station, monitoring main website computing system voltage stability index.

Described step (1) sets up being specially of voltage stability index:

Set up power system through-put power model: the power transmission lines of every bar power system is simplified to simple power system through-put power model, wherein, U_s�� �� is power supply terminal voltage, and line impedance is Z_L=R+jX, load side voltage is U_r�� 0, load power isThen, wattful power is met and wattless power can be expressed as:

$P=U_r\&lsqb;(U_{S}cos\mathrm{\&theta;}-U_r)\frac{R}{R^2+X^2}+U_{S}sin\mathrm{\&theta;}\frac{X}{R^2+X^2}\&rsqb;---\left(1\right)$

$Q=U_r\&lsqb;(U_{S}cos\mathrm{\&theta;}-U_r)\frac{X}{R^2+X^2}+U_{S}sin\mathrm{\&theta;}\frac{R}{R^2+X^2}\&rsqb;---\left(2\right)$

Combine two formulas, eliminate cos �� and sin ��, it is possible to solve:

${U_r}^2=(\mathrm{\&beta;}\&PlusMinus;\sqrt{{\mathrm{\&beta;}}^2-1})\sqrt{(P^2+Q^2)(R^2+X^2)}---\left(3\right)$

In formula, $\mathrm{\&beta;}=\frac{{U_S}^2-2PR-2QX}{2\sqrt{(P^2+Q^2)(R^2+X^2)}}\&GreaterEqual;1.$

Due toThen as ��>1 time, first dismemberent of the corresponding PV curve of high level solution in formula (3), low value separates second dismemberent of corresponding PV curve; And as ��,<when 1, system does not have trim point, and when ��=1, system is positioned at the flex point of PV curve;

Definition symbolic function sgnx is:

$\mathrm{sgn}x=\left\{\begin{array}{cc}1,& x>1\\ 0,& x=1\\ -1,& x<1\end{array}\right.---\left(4\right)$

In formula, $x=\frac{{U_r}^2}{\sqrt{P^2+Q^2}\&CenterDot;\sqrt{R^2+X^2}}$

Function sgnx gives and runs the information whether point is operated in PV curve first or second; Get load margin Pmargin, Qmargin and Smargin to be respectively

Pmargin=Pmax-P (5)

Qmargin=Qmax-Q (6)

Smargin=Smax-S (7)

Wherein:Pmax is that reactive power Q is fixed, when increasing active-power P, and the power of PV knee point; Qmax is that active-power P is fixed, when increasing reactive load power Q, and the performance number of QV knee point; Smax is firm power because of under said conditions, when increasing load S, and the load total amount of PV knee point.

Condition (��=1) and formula (5)��(7) of the power delivery limit are reached: at system power transmission limit point, load margin Pmargin, Qmargin and Smargin equal 0 simultaneously from system; Therefore, the available wherein minimum value of distance that tolerance runs some deviation system power transmission limit point provides, and definition voltage stability index (voltageinstabilityindex, VSI) is:

$I_{VSI}=\mathrm{sgn}x\&CenterDot;\min \left(\right|\frac{P_{m\arg in}}{P_{\max }}|,|\frac{Q_{m\arg in}}{Q_{\max }}|,|\frac{S_{m\arg in}}{S_{\max }}\left|\right)---\left(8\right)$

Step (3) is specially: after the monitoring sub-station of node j receives the node j bus voltage and source node voltage information that power supply Administrative Unit measures, by the equivalent system model computing function sgnx of single power consumption transmission_j, power limit Pmax_j��Qmax_jAnd Smax_j, power margin Pmargin_j��Qmargin_jAnd Smargin_jAnd voltage stablizes power margin index.

In step (4), monitoring main website computing system voltage stability index is according to following formula:

$I_{VSI,sys}=\underset{j\&Element;L}{\min }\left\{I_{VSIj}\right\}---\left(9\right)$

As shown in Figure 1: above-mentioned appraisal procedure is applicable to electric power supervisory control system, this kind of electric power monitoring system comprises master station 2, monitoring substation 1, WAN communication network 4 and monitoring equipment 3, monitoring substation 1 accepts the change in topology value that monitoring equipment 3 is measured, and is transferred to master station 2 by WAN communication network 4.

The present invention runs the operation area of point by prediction load node maximum transmission power and Monitoring systems, propose and a kind of monitor the stable local indexes method of voltage, and utilize wide area measurement system, it is applied to on-Line Voltage stability monitoring, and overcome the voltage magnitude of equivalent power supply when contact node can not be carried out Voltage Stability Evaluation and circuit index application on site by the index based on parameter identification has the defect of tight coupling relative to the voltage magnitude of monitored bus.

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of the technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (3)

1., based on a power system dynamic stability appraisal procedure for wide area measurement, it is characterized in that: comprise the following steps:

(1) voltage stability index is set up;

(2) monitor main website, collect topologies change information, data are sent to monitoring sub-station by WAN communication network;

(3) monitoring sub-station of each node receives bus voltage and the source node voltage information of this node that power supply Administrative Unit is measured;

(4) computing system voltage stability index: the voltage stability index of calculating is passed to monitoring main website by WAN communication network by each monitoring sub-station, monitoring main website computing system voltage stability index;

Described step (3) is specially: after the monitoring sub-station of node j receives the node j bus voltage and source node voltage information that power supply Administrative Unit measures, by the equivalent system model computing function sgnx of single power consumption transmission_j, power limit Pmax_j��Qmax_jAnd Smax_j, power margin Pmargin_j��Qmargin_jAnd Smargin_jAnd voltage stablizes power margin index;

Described step (1) sets up being specially of voltage stability index:

Set up power system through-put power model: the power transmission lines of every bar power system is simplified to simple power system through-put power model, wherein, U_s�� �� is power supply terminal voltage, and line impedance is Z_L=R+jX, load side voltage is U_r�� 0, load power isThen, wattful power is met and wattless power can be expressed as:

$P=U_r\&lsqb;(U_{S}cos\mathrm{\&theta;}-U_r)\frac{R}{R^2+X^2}+U_{S}sin\mathrm{\&theta;}\frac{X}{R^2+X^2}\&rsqb;---\left(1\right)$

$Q=U_r\&lsqb;(U_{S}cos\mathrm{\&theta;}-U_r)\frac{X}{R^2+X^2}+U_{S}sin\mathrm{\&theta;}\frac{R}{R^2+X^2}\&rsqb;---\left(2\right)$

Combine two formulas, eliminate cos �� and sin ��, it is possible to solve:

${U_r}^2=(\mathrm{\&beta;}\&PlusMinus;\sqrt{{\mathrm{\&beta;}}^2-1})\sqrt{(P^2+Q^2)(R^2+X^2)}---\left(3\right)$

In formula, $\mathrm{\&beta;}=\frac{{U_S}^2-2PR-2QX}{2\sqrt{(P^2+Q^2)(R^2+X^2)}}\&GreaterEqual;1,$

Due toThen as ��>1 time, first dismemberent of the corresponding PV curve of high level solution in formula (3), low value separates second dismemberent of corresponding PV curve; And as ��,<when 1, system does not have trim point, and when ��=1, system is positioned at the flex point of PV curve;

Definition symbolic function sgnx is:

$\mathrm{sgn}x=\left\{\begin{array}{cc}1,& x>1\\ 0,& x=1\\ -1,& x<1\end{array}\right.---\left(4\right)$

In formula, $x=\frac{{U_r}^2}{\sqrt{P^2+Q^2}\&CenterDot;\sqrt{R^2+X^2}}$

Function sgnx gives and runs the information whether point is operated in PV curve first or second; Get load margin Pmargin, Qmargin and Smargin to be respectively

Pmargin=Pmax-P (5)

Qmargin=Qmax-Q (6)

Smargin=Smax-S (7)

Wherein:Pmax is that reactive power Q is fixed, when increasing active-power P, and the power of PV knee point; Qmax is that active-power P is fixed, when increasing reactive load power Q, and the performance number of QV knee point;Smax is firm power because of under said conditions, when increasing load S, and the load total amount of PV knee point;

Condition (��=1) and formula (5)��(7) of the power delivery limit are reached: at system power transmission limit point, load margin Pmargin, Qmargin and Smargin equal 0 simultaneously from system; Therefore, the distance that tolerance runs some deviation system power transmission limit point provides by wherein minimum value, defines voltage stability index voltageinstabilityindex, VSI and is:

$I_{VSI}=\mathrm{sgn}x\&CenterDot;\min \left(\left|\frac{P_{m\arg in}}{P_{\max }}\right|,\left|\frac{Q_{m\arg in}}{Q_{\max }}\right|,\left|\frac{S_{m\arg in}}{S_{\max }}\right|\right)---\left(8\right).$

2. a kind of power system dynamic stability appraisal procedure based on wide area measurement as claimed in claim 1, is characterized in that: in described step (4), and monitoring main website computing system voltage stability index is according to following formula:

$I_{VSI,sys}=\underset{j\&Element;L}{\min }\left\{I_{VSIj}\right\}---\left(9\right).$

3. apply the electric power supervisory control system of the appraisal procedure as according to any one of claim 1-2 for one kind, it is characterized in that: electric power monitoring system comprises master station, WAN communication network, monitoring substation and monitoring equipment, wherein, monitoring substation accepts the change in topology value of monitoring device measuring, is transferred to master station by WAN communication network.