CN103997049A - Real-time emergency control method of power grid - Google Patents

Abstract

The invention provides a real-time emergency control method of a power grid, and belongs to the field of electric power systems. According to the real-time emergency control method of the power grid, influences, caused due to the fact that an initial rotor angle is too large, on critical cluster recognition are overcome, and critical clusters can be recognized more accurately; the defect that in former steady state analysis, equivalent calculation must be conducted is overcome, stability judgment of a whole system is conducted through several generator units in the critical clusters, therefore, the calculation amount is saved, and system stability judgment can be completed more rapidly. According to the real-time emergency control method of the power grid, derivation of the generator tripping amount is conducted through equivalent calculation of the critical clusters and residue clusters; on the basis of a synchronous phasor measuring unit (PMU), the method can supplement a traditional transient stability method, and a large real-time blackout defense system can be built easily.

Description

A kind of electrical network real time emergency control method

Technical field

The invention belongs to field of power, be specifically related to a kind of electrical network real time emergency control method.

Background technology

One main trend of power system development is Power System Interconnection, and along with the continuous rising of electric pressure and the expansion gradually of electrical network scale, the transient stability problem of electric power system becomes most important one of study a question; After electrical network breaks down, if do not take appropriate measures in time and may develop into cascade failure, finally cause having a power failure on a large scale, this just has higher requirement maintaining aspect power system safety and stability operation to second defence line (emergency control) of having a power failure on a large scale of defence.

At present, the development of the synchronous phasor measuring device based on global positioning system (GPS) (PMU), for the monitoring field of electric power system provides new research direction.Utilize PMU to carry out synchro measure to voltage, current signal, comprise amplitude, frequency and phase information, by high-speed transfer network, voltage, current signal are close to and are sent in real time control centre, and by the renewal speed of the information such as the voltage in grid control centre, electric current and merit angle by second level bring up to Millisecond, this is just for the transition operation control of electric power system provides new research visual angle.Therefore, the research of the transient stability Real-time Emergency Control based on synchronized phasor measurement technology, in theory and practice, all tool is of great significance.

Traditional transient stability analysis of power system often carries out group of planes equivalence based on expansion equal-area method (EEAC) and single machine equal area criterion method, on the basis of integration, the amount of calculation of an equivalent group of planes is larger, calculation procedure is more loaded down with trivial details, than the impact that is easier to be subject to internal system destabilizing factor, sometimes cannot meet the requirement of real-time.

Summary of the invention

Shortcoming for prior art, the present invention proposes a kind of electrical network real time emergency control method, to reach, overcome the excessive impact for critical machine identification of initial rotor angle, overcome the drawback that must carry out equivalent calculation in transient analysis in the past, the object of only carrying out the judgement of whole system stability by several generating sets in critical machine.

An electrical network real time emergency control method, comprises the following steps:

Step 1, after electrical network produces fault, by rotor angle, rotating speed and the active power of every generator in phasor measurement unit Real-time Collection electrical network;

Step 2, according to the moment of inertia of generator speed variable quantity, power variation, the time interval and generator, determine every generator amature angle variable quantity;

Step 3, by descending sequence of rotor angle variable quantity of every generator, determine adjacent rotor angle variable quantity difference maximum, using this place the place ahead all generators as critical unit, using this place rear all generators as residue unit;

Step 4, judge whether electrical network meets transient stability, if meet, return to step 1, otherwise, execution step 5;

Be specially:

Step 4-1, according to the mechanical output of each generator, the angular acceleration of each generator under the output electromagnetic power of each sampling instant, the rotor inertia constant of generator and center of inertia referential, obtain the imbalance power of each generator under the center of inertia of each sampling instant referential;

Computing formula is as follows:

${P_{\mathrm{ci}}}^{\mathrm{k\Δt}}=P_{\mathrm{mi}}-{P_{\mathrm{ei}}}^{\mathrm{k\Δt}}-M_i\frac{{\mathrm{d\ω}}_o}{\mathrm{dt}}---\left(1\right)$

Wherein, P _ci ^{k Δ t}represent the imbalance power under the center of inertia referential of k Δ t generator i constantly; P _mithe mechanical output that represents generator i; P _ei ^{k Δ t}the output electromagnetic power that represents k Δ t generator i constantly; M _ithe rotor inertia constant of generator i; ω _orepresent the angular acceleration under electric power system center of inertia referential; T represents the time; Δ t represents the sampling period;

Step 4-2, the imbalance power according to each generator under the center of inertia of each sampling instant referential, determine the generator amature angle value of current time;

Computing formula is as follows:

${{\widetilde{\mathrm{\δ}}}_i}^{\mathrm{K\Δt}}=[\underset{k=1}{\overset{1}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}+\underset{k=1}{\overset{2}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}+...+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}]{\left(\mathrm{\Δt}\right)}^2---\left(2\right)$

Wherein, the rotor angle that represents K Δ t generator i constantly, K Δ t represents current time, P _ci ^{(k-1) Δ t}the output electromagnetic power that represents k-1 Δ t generator i constantly; K represents current employing number of cycles;

Step 4-3, judge whether the generator amature angle value of current time is 0, if so, stablize and return to execution step 1, otherwise unstable, execution step 5;

Step 5, according to the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, the mechanical output of generator in the failure removal angle of critical unit and critical unit, calculate the Critical Stability rotor angle that obtains critical unit, and then obtain the required power excision amount of critical unit;

Step 6, according to the required power excision amount of critical unit obtaining, in excision electrical network, the generator of corresponding power, makes electrical network reach stable state.

Described in step 2 according to the moment of inertia of generator speed variable quantity, power variation, sampling period and the generator measured, determine every generator amature angle variable quantity, formula is as follows:

$\mathrm{\Δ\δ}=k^{\′}\mathrm{\Δ\ω}+k^{\′2}\frac{\mathrm{\Δp}}{2M}---\left(3\right)$

Wherein, the rotor angle variable quantity that Δ δ is generator; Δ ω is the rotation speed change amount of generator; M is the moment of inertia of generator; Δ P is the active power variable quantity of generator; In time interval when setting value k ' is screening critical machine, span is [0,0.5].

Calculating described in step 5 obtains the Critical Stability rotor angle of critical unit, and then obtains the required power excision amount of critical unit, specific as follows:

Build the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, in the failure removal angle of critical unit, critical unit the mechanical output of generator, the relation between the required power excision amount of the Critical Stability rotor angle of critical unit and critical unit, as shown in formula (4) and formula (5):

$\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{P}_{\mathrm{mi}}-(a_0+a_1{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}+a_2{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^2){\mathrm{\ΔP}}_A=0---\left(4\right)$

$\begin{array}{c}\frac{1}{2}{M}_A{\left({\widetilde{\mathrm{\ω}}}_A^{\mathrm{cl}}\right)}^2=-(\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{P}_{\mathrm{mi}}-a_0-{\mathrm{\ΔP}}_A)({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}-{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}})\\ +\frac{1}{2}{a}_1\left[{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^2{-\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}\right)}^2\right]+\frac{1}{3}{a}_2[{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^3-{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}\right)}^3]\end{array}---\left(5\right)$

Wherein, M _afor the equivalent rotor inertia constant of critical machine A, be the rotor inertia constant sum of generating set in critical machine A; equivalent angular speed for critical machine A; failure removal angle for critical machine A; p _mimechanical output for generator i in critical machine; J represents the sum of generator in critical machine A; a ₀, a ₁and a ₂for polynomial coefficient, Δ P _athe quantity of power that need to excise for the equivalent machine of critical machine; critical Stability angle for critical machine A;

Formula (4) and formula (5) are carried out to simultaneous, substitution known quantity: build the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, the mechanical output of generator in the failure removal angle of critical unit and critical unit, obtain Critical Stability rotor angle and the required power excision amount of critical unit of critical unit.

Advantage of the present invention:

The present invention proposes a kind of electrical network real time emergency control method, overcome the excessive impact for critical machine identification of initial rotor angle, identify more exactly critical machine; Overcome the drawback that must carry out equivalent calculation in steady-state analysis in the past, but only by several generating sets in critical machine, carried out the judgement of whole system stability, so just saved amount of calculation, more quickly completion system judgement of stability; The present invention has carried out cutting the derivation of machine amount by critical machine and residue group of planes equivalent calculation; Based on synchronous phasor measurement unit (PMU), the method that the present invention proposes can be supplemented with traditional transient stability method, is conducive to build the Real-time defence system of having a power failure on a large scale.

Accompanying drawing explanation

Fig. 1 is New England's 10 machine 39 node system schematic diagrames of an embodiment of the present invention;

Fig. 2 is the electrical network real time emergency control method flow chart of an embodiment of the present invention;

Fig. 3 is the power-angle curve schematic diagram of generator in center of inertia referential (COI) after the disturbance of an embodiment of the present invention;

Fig. 4 is the merit angle simulation curve schematic diagram of each generating set before the emergency control of an embodiment of the present invention;

Fig. 5 is the machine of the cutting control decision schematic diagram of an embodiment of the present invention;

Fig. 6 is the merit angle simulation curve schematic diagram of each generating set after the emergency control of an embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, an embodiment of the present invention is described further.

In the embodiment of the present invention, as shown in Figure 1, the system of New England's 10 machine 39 nodes of take is research object; in figure, G represents generator, and when three-phase shortcircuit occurs at No. 19 circuit 30% places, the protective relaying device of both sides is at 0.05s tripping circuit; after fault is cut, system loses stable.

An electrical network real time emergency control method, method flow diagram as shown in Figure 2, comprises the following steps:

Step 1, after electrical network produces fault, by rotor angle, rotating speed and the active power of every generator in phasor measurement unit (PMU) Real-time Collection electrical network;

In the embodiment of the present invention, utilize the advantage of phasor measurement unit (PMU) aspect data measurement in real time, in conjunction with the transmission performance of optical fiber communication, the data volume in Real-time Collection electric power system;

Under conventional coordinate system, before and after fault the rotor angle running of generator as shown in Figure 3, in figure, P _afor the generator's power and angle curve of generating set before fault, P _bfor the generator's power and angle curve of generating set in fault, P _cfor the generator's power and angle curve of generating set after fault, P _m(suppose in perturbation process, this value remains unchanged) is the mechanical output of prime mover output, A ₁for accelerating area, A ₂for retardation area, δ ₁for the merit angle of normal operation (before being fault) generator, δ ₂for the merit angle of failure removal moment generator, δ _maxthe merit angle of generator during for energy balance.

Step 2, according to the moment of inertia of generator speed variable quantity, power variation, the time interval and the generator measured, determine every generator amature angle variable quantity;

Formula is as follows:

$\mathrm{\Δ\δ}=k^{\′}\mathrm{\Δ\ω}+k^{\′2}\frac{\mathrm{\Δp}}{2M}---\left(3\right)$

Wherein, the rotor angle variable quantity that Δ δ is generator; Δ ω is the rotation speed change amount of generator; M is the moment of inertia of generator; Δ P is the active power variable quantity of generator;

Step 3, by descending sequence of rotor angle variation delta δ of every generator, determine adjacent rotor angle variable quantity difference maximum, using all generators in this place ahead, place as critical unit, using all generators at this rear, place as residue unit;

In the embodiment of the present invention, the merit angle running status of Real-Time Monitoring electric power system, after failure removal, from 0.56s, there is increase tendency at the merit angle of generator, illustrates that the disequilibrium of the machinery power of generator now and electromagnetic power produces, and should start emergency control measure.The critical machine diagnostic method of utilization based on rotor angle variable quantity, calculates No. 15 and No. 18 generating sets form critical cluster, utilizes the single machine equal area criterion method based on rotor angle, and as can be seen here, system loses stable.As can drawing the merit angle of critical machine, Fig. 4 has the trend increasing gradually.

Step 4, judge whether electrical network meets transient stability, if meet, return to step 1, otherwise, execution step 5;

Be specially:

Concrete grammar is as follows:

The equation of motion under step a, structure center of inertia referential;

Formula is as follows:

$\left\{\begin{array}{c}{\mathrm{\δ}}_0=\frac{1}{M_T}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{M}_i{\mathrm{\δ}}_i\\ M_T=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{M}_i\\ \frac{{\mathrm{d\δ}}_0}{\mathrm{dt}}={\mathrm{\ω}}_0-{\mathrm{\ω}}_n\\ M_T\frac{{\mathrm{d\ω}}_0}{\mathrm{dt}}=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(P_{\mathrm{mi}}-P_{\mathrm{ei}})\end{array}---\left(6\right)\right.$

In formula, δ ₀for the rotor angle under electric power system center of inertia referential, ω ₀for the angular acceleration under electric power system center of inertia referential; M _trotor inertia constant sum for all generating sets; N is total number of units of generator unit; M _ifor the rotor inertia constant of generator i, i=1 ..., N; δ _ifor the rotor angle of generator i, ω _irotor angle acceleration for generator i; ω _nspecified synchro angle acceleration for generator; P _mifor the mechanical output of generator i, P _eioutput electromagnetic power for generator i; T represents the time;

Relation under step b, the rotor angle of determining generator i under rotor angle under electric power system center of inertia referential, the angular acceleration under electric power system center of inertia referential, center of inertia referential and center of inertia referential between the rotor angle acceleration of generator i;

Formula is as follows:

$\left\{\begin{array}{c}{\widetilde{\mathrm{\δ}}}_i={\mathrm{\δ}}_i-{\mathrm{\δ}}_0\\ {\widetilde{\mathrm{\ω}}}_i={\mathrm{\ω}}_i-{\mathrm{\ω}}_0\\ \frac{d{\widetilde{\mathrm{\δ}}}_i}{\mathrm{dt}}={\widetilde{\mathrm{\ω}}}_i\end{array}\right.---\left(7\right)$

Wherein, for the rotor angle of generator i under center of inertia referential, rotor angle acceleration for generator i under center of inertia referential;

Step c (4-1), the generator building under electric power system center of inertia referential according to formula (6) and formula (7) wave equation:

Formula is as follows:

${P_{\mathrm{ci}}}^{\mathrm{k\Δt}}=P_{\mathrm{mi}}-{P_{\mathrm{ei}}}^{\mathrm{k\Δt}}-M_i\frac{{\mathrm{d\ω}}_o}{\mathrm{dt}}=M_i\frac{{d\widetilde{\mathrm{\ω}}}_i}{\mathrm{dt}}---\left(8\right)$

Wherein, P _cithe imbalance power that represents generator i under center of inertia referential;

The generator of differential form is waved to equation and be converted to difference equation form;

Formula is as follows:

${\mathrm{\Δ}\widetilde{\mathrm{\ω}}}_i=\frac{P_{\mathrm{ci}}\mathrm{\Δt}}{M_i}---\left(9\right)$

Steps d, determine that generating set i is at the variable quantity of (k+1) period internal rotor angular speed for:

$\mathrm{\Δ}{\widetilde{\mathrm{\ω}}}_i^{(k+1)}={\widetilde{\mathrm{\ω}}}_i^{(k-1)}-{\widetilde{\mathrm{\ω}}}_i^k=\frac{{P_{\mathrm{ci}}}^{\left(k\right)\mathrm{\Δt}}\mathrm{\Δt}}{M_i}---\left(10\right)$

Wherein, under electric power system center of inertia COI referential, for generating set i is at (k+1) Δ t rotor velocity constantly; for generating set i is at k Δ t rotor velocity constantly; for generating set i is at k Δ t moment P _civalue; Δ t is the length of each integration period; M _irotor inertia constant for generating set i;

Step e, determine that generating set i at the variable quantity of (k+1) period internal rotor angular speed is:

$\mathrm{\Δ}{\widetilde{\mathrm{\ω}}}_i^k={\widetilde{\mathrm{\ω}}}_i^k-{\widetilde{\mathrm{\ω}}}_i^{(k-1)}=\frac{{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}\mathrm{\Δt}}{M_i}---\left(11\right)$

Wherein, wherein, under electric power system center of inertia COI referential, for generating set i is at (k-1) Δ t rotor velocity constantly; for generating set i is at (k-1) Δ t moment P _civalue;

Step f, formula (10) and formula (11) are added, obtain formula as follows:

$\mathrm{\Δ}{\widetilde{\mathrm{\ω}}}_i^k=\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}\mathrm{\Δt}---\left(12\right)$

In the embodiment of the present invention because generator angular velocity varies is very slow, so think adjacent two the time of integration section angular velocity varies amount identical, therefore formula (10) and formula (11) are added to processing;

The angular velocity varies amount of step g, each integration period of accumulative total is carried out summation operation, until failure removal constantly, cut to fault at random after, the integration period, while reaching K, now the angular speed of (K Δ t is constantly) generating set i was:

${\widetilde{\mathrm{\ω}}}_i^k=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^k+{P_{\mathrm{ci}}}^{(k-1)}}{{2M}_i}\mathrm{\Δt}---\left(13\right)$

Step h, in formula (7), the rotor angle of generating set i and the relational expression of rotor velocity can obtain:

${\widetilde{\mathrm{\δ}}}_i^k-{\widetilde{\mathrm{\δ}}}_i^{(k-1)}={\widetilde{\mathrm{\ω}}}_i^k\mathrm{\Δt}---\left(14\right)$

Wherein, under electric power system center of inertia COI referential, for generating set i is at k Δ t rotor angle constantly, for generating set i is at (k-1) Δ t rotor angle constantly;

Utilize mathematical induction to solve formula (14), can obtain:

${\widetilde{\mathrm{\δ}}}_i^k=({\widetilde{\mathrm{\ω}}}_i^1+{\widetilde{\mathrm{\ω}}}_i^2+...+{\widetilde{\mathrm{\ω}}}_i^k)\mathrm{\Δt}---\left(15\right)$

Step I (4-2), the imbalance power according to each generator under the center of inertia of each sampling instant referential, determine the generator amature angle value of current time;

By formula (13) and formula (15), can obtain formula as follows:

${{\widetilde{\mathrm{\δ}}}_i}^{\mathrm{K\Δt}}=[\underset{k=1}{\overset{1}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}+\underset{k=1}{\overset{2}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}+...+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}]{\left(\mathrm{\Δt}\right)}^2---\left(2\right)$

Wherein, the rotor angle that represents k Δ t generator i constantly, K Δ t represents current time, P _ci ^{(k-1) Δ t}the output electromagnetic power that represents k-1 Δ t generator i constantly; K represents current employing number of cycles;

Step 4-3, judge whether the generator amature angle value of current time is 0, if so, stablize and return to execution step 1, otherwise unstable, execution step 5;

In the embodiment of the present invention, judgement according to as follows: at a time, when time, it is stable that the first forward of generating set i waves.Due to the rotor angle of initial time generating set under electric power system center of inertia COI referential is 0, and when electric power system is broken down, some generating set in critical machine can accelerate, and the rotor angle of generator increases; After fault is cut, generating set reduces speed now, and after the rotor velocity of generating set is reduced to center of inertia angular speed, due to effect of inertia, generating set continues to slow down, and after this rotor angle of generating set starts to reduce.If system stability after failure removal, can be in some moment, the rotor angle of generating set is reduced to initial rotor angle (under center of inertia COI referential, the initial rotor angle of generating set is 0), when a certain moment be 0 o'clock, generating set i is stable under center of inertia COI referential.Now, to wave be stable to the first forward of generating set i.If all generating sets in system are carried out to judgement of stability, can not meet the requirement of rapidity.In fact, can be only by several generating sets in critical machine, just can judge whether unstability of whole system, judgement object can be elected several generating sets of critical machine screening criterion rotor angle variable quantity maximum as.

Step 5, according to the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, the mechanical output of generator in the failure removal angle of critical unit and critical unit, calculate the Critical Stability rotor angle that obtains critical unit, and then obtain the required power excision amount of critical unit;

Specific as follows:

Build the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, in the failure removal angle of critical unit, critical unit the mechanical output of generator, the relation between the required power excision amount of the Critical Stability rotor angle of critical unit and critical unit, as shown in formula (4) and formula (5):

$\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{P}_{\mathrm{mj}}-(a_0+a_1{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}+a_2{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^2){\mathrm{\ΔP}}_A=0---\left(4\right)$

In the unsettled situation of system, for critical machine A, there is following formula, the generating set that critical machine A comprises is j=1 ..., k,

$\frac{1}{2}{M}_A{\left({\widetilde{\mathrm{\ω}}}_A^{\mathrm{cl}}\right)}^2=-{\∫}_{{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}}^{{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}}[\underset{J=1}{\overset{k}{\mathrm{\Σ}}}{P}_{\mathrm{mj}}-(a_0+a_1{\widetilde{\mathrm{\δ}}}_A+a_2{\left({\widetilde{\mathrm{\δ}}}_A\right)}^2){\mathrm{\ΔP}}_A]d{\widetilde{\mathrm{\δ}}}_A---\left(15\right)$

According to formula (15), can obtain:

$\begin{array}{c}\frac{1}{2}{M}_A{\left({\widetilde{\mathrm{\ω}}}_A^{\mathrm{cl}}\right)}^2=-(\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{P}_{\mathrm{mi}}-a_0-{\mathrm{\ΔP}}_A)({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}-{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}})\\ +\frac{1}{2}{a}_1\left[{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^2{-\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}\right)}^2\right]+\frac{1}{3}{a}_2[{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^3-{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}\right)}^3]\end{array}---\left(5\right)$

Wherein, M _afor the equivalent rotor inertia constant of critical machine A, be the rotor inertia constant sum of generating set in critical machine A; equivalent angular speed for critical machine A; failure removal angle for critical machine A; P _mimechanical output for generator i in critical machine; J represents the sum of generator in critical machine A; a ₀, a ₁and a ₂for polynomial coefficient, by critical machine electromagnetic power and center of inertia angle, carry out matching acquisition; Δ P _athe quantity of power that need to excise for the equivalent machine of critical machine; critical Stability angle for critical machine A;

Formula (4) and formula (5) are carried out to simultaneous, substitution known quantity: build the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, the mechanical output of generator in the failure removal angle of critical unit and critical unit, obtain Critical Stability rotor angle and the required power excision amount of critical unit of critical unit.

Utilize PMU to measure in real time each discrete data of generating set constantly, according to least square method, carry out data fitting, cut machine amount and calculate.

Least square fitting curve as shown in Figure 5, A ₃, A ₄be respectively acceleration area and the retardation area of the equivalent machine of critical machine, and δ _maxbe respectively normal operation (before being fault), failure removal constantly the equivalent machine of critical machine merit angle; total electromagnetic power for critical machine; δ _arotor angle for the equivalent machine of a center of inertia COI referential lower critical group of planes.

In the embodiment of the present invention, after failure removal, matching obtains the power-angle curve of the equivalent machine of critical machine,, calculate Δ P=505.4MW.Cutting machine amount is 505.4MW.

Step 6, according to the required power excision amount of critical unit obtaining, in excision electrical network, the generator of corresponding power, makes electrical network reach stable state.

In the embodiment of the present invention, cut machine amount and distribute: according to the situation of exerting oneself of No. 5 and No. 8 generating sets, through calculating, the machine of the cutting amount of No. 5 units is 326.4MW, and the machine of the cutting amount of No. 8 units is 179MW.Cut the merit angle simulation curve of rear each generating set of machine control as shown in Figure 6, as seen from the figure, the power-angle curve of generating set trend steadily, recover to stablize by system.

The present invention can be used for the dispatching control center of electrical networks at different levels.The present invention can the electrical network for configuration synchronization phasor measuring set (PMU) in, build the Real-time defence system of having a power failure on a large scale, realize the emergency control to electrical network, guarantee power network safety operation, the generation that defence electrical network is had a power failure on a large scale.

Claims (3)

1. an electrical network real time emergency control method, is characterized in that, comprises the following steps:

Step 1, after electrical network produces fault, by rotor angle, rotating speed and the active power of every generator in phasor measurement unit Real-time Collection electrical network;

Step 2, according to the moment of inertia of generator speed variable quantity, power variation, the time interval and generator, determine every generator amature angle variable quantity;

Step 3, by descending sequence of rotor angle variable quantity of every generator, determine adjacent rotor angle variable quantity difference maximum, using this place the place ahead all generators as critical unit, using this place rear all generators as residue unit;

Step 4, judge whether electrical network meets transient stability, if meet, return to step 1, otherwise, execution step 5;

Be specially:

Step 4-1, according to the mechanical output of each generator, the angular acceleration of each generator under the output electromagnetic power of each sampling instant, the rotor inertia constant of generator and center of inertia referential, obtain the imbalance power of each generator under the center of inertia of each sampling instant referential;

Computing formula is as follows:

${P_{\mathrm{ci}}}^{\mathrm{k\Δt}}=P_{\mathrm{mi}}-{P_{\mathrm{ei}}}^{\mathrm{k\Δt}}-M_i\frac{{\mathrm{d\ω}}_o}{\mathrm{dt}}---\left(1\right)$

Wherein, P _ci ^{k Δ t}represent the imbalance power under the center of inertia referential of k Δ t generator i constantly; p _mithe mechanical output that represents generator i; P _ei ^{k Δ t}the output electromagnetic power that represents k Δ t generator i constantly; M _ithe rotor inertia constant of generator i; ω _orepresent the angular acceleration under electric power system center of inertia referential; T represents the time; Δ t represents the sampling period;

Step 4-2, the imbalance power according to each generator under the center of inertia of each sampling instant referential, determine the generator amature angle value of current time;

Computing formula is as follows:

${{\widetilde{\mathrm{\δ}}}_i}^{\mathrm{K\Δt}}=[\underset{k=1}{\overset{1}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}+\underset{k=1}{\overset{2}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}+...+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\frac{{P_{\mathrm{ci}}}^{\mathrm{k\Δt}}+{P_{\mathrm{ci}}}^{(k-1)\mathrm{\Δt}}}{{2M}_i}]{\left(\mathrm{\Δt}\right)}^2---\left(2\right)$

Wherein, the rotor angle that represents K Δ t generator i constantly, K Δ t represents current time, the output electromagnetic power that represents k-1 Δ t generator i constantly; K represents current employing number of cycles;

Step 4-3, judge whether the generator amature angle value of current time is 0, if so, stablize and return to execution step 1, otherwise unstable, execution step 5;

Step 5, according to the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, the mechanical output of generator in the failure removal angle of critical unit and critical unit, calculate the Critical Stability rotor angle that obtains critical unit, and then obtain the required power excision amount of critical unit;

Step 6, according to the required power excision amount of critical unit obtaining, in excision electrical network, the generator of corresponding power, makes electrical network reach stable state.

2. electrical network real time emergency control method according to claim 1, it is characterized in that, described in step 2 according to the moment of inertia of generator speed variable quantity, power variation, sampling period and the generator measured, determine every generator amature angle variable quantity, formula is as follows:

$\mathrm{\Δ\δ}=k^{\′}\mathrm{\Δ\ω}+k^{\′2}\frac{\mathrm{\Δp}}{2M}---\left(3\right)$

Wherein, the rotor angle variable quantity that Δ δ is generator; Δ ω is the rotation speed change amount of generator; M is the moment of inertia of generator; Δ P is the active power variable quantity of generator; In time interval when setting value k ' is screening critical machine, span is [0,0.5].

3. electrical network real time emergency control method according to claim 1, is characterized in that, the calculating described in step 5 obtains the Critical Stability rotor angle of critical unit, and then obtains the required power excision amount of critical unit, specific as follows:

Build the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, in the failure removal angle of critical unit, critical unit the mechanical output of generator, the relation between the required power excision amount of the Critical Stability rotor angle of critical unit and critical unit, as shown in formula (4) and formula (5):

$\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{P}_{\mathrm{mi}}-(a_0+a_1{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}+a_2{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^2){\mathrm{\ΔP}}_A=0---\left(4\right)$

$\begin{array}{c}\frac{1}{2}{M}_A{\left({\widetilde{\mathrm{\ω}}}_A^{\mathrm{cl}}\right)}^2=-(\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{P}_{\mathrm{mi}}-a_0-{\mathrm{\ΔP}}_A)({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}-{\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}})\\ +\frac{1}{2}{a}_1\left[{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^2{-\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}\right)}^2\right]+\frac{1}{3}{a}_2[{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cr}}\right)}^3-{\left({\widetilde{\mathrm{\δ}}}_A^{\mathrm{cl}}\right)}^3]\end{array}---\left(5\right)$

Wherein, M _afor the equivalent rotor inertia constant of critical machine A, be the rotor inertia constant sum of generating set in critical machine A; equivalent angular speed for critical machine A; failure removal angle for critical machine A; p _mimechanical output for generator i in critical machine; J represents the sum of generator in critical machine A; a ₀, a ₁and a ₂for polynomial coefficient, Δ P _athe quantity of power that need to excise for the equivalent machine of critical machine; critical Stability angle for critical machine A;

Formula (4) and formula (5) are carried out to simultaneous, substitution known quantity: build the equivalent angular speed of all generators in the equivalent rotor inertia constant of all generators in critical unit, critical unit, the mechanical output of generator in the failure removal angle of critical unit and critical unit, obtain Critical Stability rotor angle and the required power excision amount of critical unit of critical unit.