CN113824094B - Active disconnection control method and system for voltage instability of power system - Google Patents
Active disconnection control method and system for voltage instability of power system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
Abstract
The invention discloses a kind ofAn active disconnection control method and system for voltage instability of a power system belong to the technical field of safety and stability analysis of the power system. The method of the invention comprises the following steps: setting control parameters of the power system according to the voltage instability condition of the power system; positioning a key branch according to the sBTTC index; flag bit F for judging key branch k tsc Is a value of (2); and executing splitting control on the key branch k according to the active splitting cutting set. The method can implement active disconnection control on the disconnection cut set branch obtained by searching when the voltage of the power system is unstable, and quickly disconnect the out-of-step power grid, thereby avoiding cascading failure caused by local voltage instability and reducing the influence range of instability.
Description
Technical Field
The invention relates to the technical field of safety and stability analysis of power systems, and in particular relates to an active disconnection control method and system for voltage instability of a power system.
Background
The voltage instability is one of three instability forms in the electromechanical transient domain of the alternating current-direct current hybrid power grid, and is an extreme expression form that the voltage of the power grid is continuously and greatly lower than the rated running state. For many years, the problem related to voltage stabilization has been a focus of attention in the field of power systems, and voltage stabilization problems on a time scale can be classified into static voltage stabilization, transient voltage stabilization, and medium-long term voltage stabilization. In the aspect of transient voltage stabilization, when the voltage of a power grid is continuously lower, cascading faults of power electronic equipment are easily caused, so that the fault coverage range is enlarged, and the fault loss is increased.
Disclosure of Invention
In view of the above problems, the present invention provides an active disconnection control method for voltage instability of an electric power system, including:
setting control parameters of the power system aiming at the voltage instability condition of the power system, wherein the control parameters comprise: delay time T set for avoiding influence of electric quantity fluctuation in initial stage after fault clearing of power system voltage instability FS Threshold value epsilon for determining whether voltage stability of system has deteriorated asth ；
After the voltage instability of the power system occurs, judging whether the delay time after fault clearing is greater than T FS If the value is larger than the preset value, measuring branch parameters in the power system, determining an sBTTC index of each branch in the power system according to the branch parameters, and positioning a key branch according to the sBTTC index;
if the sBTTC index value of the critical branch k is smaller than the set threshold value epsilon Lth And duration Deltat Lk Greater than the set required duration T Ld When determining the flag bit F of the key branch k tsc Is a value of (2);
if F tsc The value of sBTTC index of the critical branch k is less than ε asth If the voltage stability of the power system is less than the determined voltage stability, the critical branch k is subjected to splitting control according to the active splitting cutting set.
Optionally, measuring a branch parameter in the power system, determining an sBTTC index of each branch in the power system according to the branch parameter, and positioning a critical branch according to the sBTTC index, including:
measuring the voltage amplitude U of the nodes at the two ends of each branch of the power system mi And U ni And voltage phase delta theta i I is the total number of branches in the power system, and the sBTTC index of each branch is calculated according to the following formula;
according to the following formula:
wherein, delta theta i ＝|Δθ mi -Δθ ni I, m and n are the positions of two measuring points taken on one line, and i is the ith branch;
the sBTTC index of each branch is ordered from small to large, the branch with the smallest sBTTC index value is defined as a key branch, and the branch number of the key branch is marked as k.
Optionally, after locating the critical branches according to the sBTTC index, defining several branches with the next smallest sBTTC index value as potential quasi-critical branch clusters capable of forming a cut set with the critical branches.
Optionally, if the delay time after fault clearing is smaller than T FS Duration Δt Lk If it is smaller than the set required duration T Ld If the sBTTC index value of the key branch k is larger than epsilon asth After the delay time after the fault is cleared is added with delta T time, judging whether the delay time after the fault is cleared is larger than T again FS The delay time after fault clearing is greater than T FS 。
Alternatively, F tsc If the value is 0, an active splitting cutting set is not determined, cluster analysis of the active splitting cutting set is performed, a cluster set value Kc=3 is set, and a branch cluster B of the power system for connecting a high-voltage area and a low-voltage area is identified M The method comprises the steps of carrying out a first treatment on the surface of the If in branch cluster B M Find the active splitting cutting set, judge the total branch number L in the active splitting cutting set sc Whether or not it is smaller than the maximum value N of the number of the optional splitting cut sets max If less, according to the following formula:
wherein, the vsTSC voltage instability target cutset, P scl0 For steady state active power of branch l, N sc The number of the cutting sets is selected;
determining a preferable splitting cutting set and judging the continuous judging time T for continuously guaranteeing the searching reliability of the splitting cutting set ct If so, let F tsc After adding Δt to the delay time after fault clearing, determine again whether the delay time after fault clearing is greater than T FS ；
If the time delay after fault clearing is not consistent with the delta T time, judging whether the time delay after fault clearing is greater than T again FS ；
If actively splitting the total branch number L in the cut set sc A maximum value N greater than the number of the optional splitting cutting sets max Judging whether Kc=4, if yes, adding delta T time to the delay time after fault clearing, and judging whether the delay time after fault clearing is greater than T again FS The method comprises the steps of carrying out a first treatment on the surface of the If the clustering analysis of the clustering set value Kc=4 of the active splitting cut set is not satisfied.
Optionally, the sBTTC index value of the critical branch k is greater than a set threshold value epsilon Lth At, or for a duration of Δt Lk Less than a set required duration T Ld When the time delay time after fault clearing is added with delta T time, judging whether the time delay time after fault clearing is larger than T again FS The delay time after fault clearing is greater than T FS 。
The invention also provides an active disconnection control system for voltage instability of the power system, which comprises:
the parameter determining module is used for setting control parameters of the power system according to the voltage instability condition of the power system, wherein the control parameters comprise: delay time T set for avoiding influence of electric quantity fluctuation in initial stage after fault clearing of power system voltage instability FS Threshold value epsilon for determining whether voltage stability of system has deteriorated asth ；
Positioning module, in electric power systemAfter voltage instability occurs, judging whether the delay time after fault clearing is greater than T FS If the value is larger than the preset value, measuring branch parameters in the power system, determining an sBTTC index of each branch in the power system according to the branch parameters, and positioning a key branch according to the sBTTC index;
the judging module is used for judging whether the sBTTC index value of the key branch k is smaller than the set threshold value epsilon Lth At the same time and for a duration of Δt Lk Greater than the set required duration T Ld When determining the flag bit F of the key branch k tsc Is a value of (2);
control module, when F tsc When=1, the determined active splitting cut set is judged, and whether the sBTTC index value of the key branch k is smaller than epsilon or not is judged asth If the voltage stability of the power system is less than the determined voltage stability, the critical branch k is subjected to splitting control according to the active splitting cutting set.
Optionally, measuring a branch parameter in the power system, determining an sBTTC index of each branch in the power system according to the branch parameter, and positioning a critical branch according to the sBTTC index, including:
measuring the voltage amplitude U of the nodes at the two ends of each branch of the power system mi And U ni And voltage phase delta theta i I is the total number of branches in the power system, and the sBTTC index of each branch is calculated according to the following formula;
according to the following formula:
wherein, delta theta i ＝|Δθ mi -Δθ ni I, m and n are the positions of two measuring points taken on one line, and i is the ith branch;
the sBTTC index of each branch is ordered from small to large, the branch with the smallest sBTTC index value is defined as a key branch, and the branch number of the key branch is marked as k.
Optionally, after locating the critical branches according to the sBTTC index, defining several branches with the next smallest sBTTC index value as potential quasi-critical branch clusters capable of forming a cut set with the critical branches.
Optionally, if the delay time after fault clearing is smaller than T FS Duration Δt Lk If it is smaller than the set required duration T Ld If the sBTTC index value of the key branch k is larger than epsilon asth After the delay time after the fault is cleared is added with delta T time, judging whether the delay time after the fault is cleared is larger than T again FS The delay time after fault clearing is greater than T FS 。
Alternatively, F tsc If the value is 0, an active splitting cutting set is not determined, cluster analysis of the active splitting cutting set is performed, a cluster set value Kc=3 is set, and a branch cluster B of the power system for connecting the high-voltage area and the low-voltage area is identified M The method comprises the steps of carrying out a first treatment on the surface of the If in branch cluster B M Find the active splitting cutting set, judge the total branch number L in the active splitting cutting set sc Whether or not it is smaller than the maximum value N of the number of the optional splitting cut sets max If less, according to the following formula:
wherein, the vsTSC voltage instability target cutset, P scl0 For steady state active power of branch l, N sc The number of the cutting sets is selected;
determining a preferable splitting cutting set and judging the continuous judging time T for continuously guaranteeing the searching reliability of the splitting cutting set ct If so, let F tsc After adding Δt to the delay time after fault clearing, determine again whether the delay time after fault clearing is greater than T FS ；
If the time delay after fault clearing is not consistent with the delta T time, judging whether the time delay after fault clearing is greater than T again FS ；
If actively splitting the total branch number L in the cut set sc A maximum value N greater than the number of the optional splitting cutting sets max Judging whether Kc=4, if yes, adding delta T time to the delay time after fault clearing, and judging whether the delay time after fault clearing is greater than T again FS The method comprises the steps of carrying out a first treatment on the surface of the If the clustering analysis of the clustering set value Kc=4 of the active splitting cut set is not satisfied.
Optionally, the sBTTC index value of the critical branch k is greater than a set threshold value epsilon Lth At, or for a duration of Δt Lk Less than a set required duration T Ld When the time delay time after fault clearing is added with delta T time, judging whether the time delay time after fault clearing is larger than T again FS The delay time after fault clearing is greater than T FS 。
The method can implement active disconnection control on the disconnection cut set branch obtained by searching when the voltage of the power system is unstable, and quickly disconnect the out-of-step power grid, thereby avoiding cascading failure caused by local voltage instability and reducing the influence range of instability.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a representative system model of the voltage stabilization analysis of the present invention;
FIG. 3 is a schematic diagram of an active splitting control flow scheme in accordance with the present invention;
fig. 4 is a block diagram of the system of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the examples described herein, which are provided to fully and completely disclose the present invention and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like elements/components are referred to by like reference numerals.
Unless otherwise indicated, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, it will be understood that terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The invention provides an active disconnection control method for voltage instability of an electric power system, which is shown in fig. 1 and comprises the following steps:
setting control parameters of the power system aiming at the voltage instability condition of the power system, wherein the control parameters comprise: delay time T set for avoiding influence of electric quantity fluctuation in initial stage after fault clearing of power system voltage instability FS Threshold value epsilon for determining whether voltage stability of system has deteriorated asth ；
After the voltage instability of the power system occurs, judging whether the delay time after fault clearing is greater than T FS If the value is larger than the preset value, measuring branch parameters in the power system, determining an sBTTC index of each branch in the power system according to the branch parameters, and positioning a key branch according to the sBTTC index;
if the sBTTC index value of the critical branch k is smaller than the set threshold value epsilon Lth And duration Deltat Lk Greater than the set required duration T Ld When determining the flag bit F of the key branch k tsc Is a value of (2);
if F tsc The value of sBTTC index of the critical branch k is less than ε asth If the voltage stability of the power system is less than the determined voltage stability, the critical branch k is subjected to splitting control according to the active splitting cutting set.
The method for determining the sBTTC index of each branch in the power system comprises the steps of measuring the branch parameters in the power system, determining the sBTTC index of each branch in the power system, and positioning a key branch according to the sBTTC index, wherein the method specifically comprises the following steps:
measuring each branch of the power systemVoltage amplitude U of two end nodes mi And U ni And voltage phase delta theta i I is the total number of branches in the power system, and the sBTTC index of each branch is calculated according to the following formula;
according to the following formula:
wherein, delta theta i ＝|Δθ mi -Δθ ni I, m and n are the positions of two measuring points taken on one line, and i is the ith branch;
the sBTTC index of each branch is ordered from small to large, the branch with the smallest sBTTC index value is defined as a key branch, and the branch number of the key branch is marked as k.
After positioning the critical branches according to the sBTTC index, defining a plurality of branches with the second smallest sBTTC index value as potential quasi-critical branch clusters capable of forming a cut set with the critical branches.
Wherein if the delay time after fault clearing is smaller than T FS Duration Δt Lk If it is smaller than the set required duration T Ld If the sBTTC index value of the key branch k is larger than epsilon asth After the delay time after the fault is cleared is added with delta T time, judging whether the delay time after the fault is cleared is larger than T again FS The delay time after fault clearing is greater than T FS 。
Wherein F is tsc If the value is 0, an active splitting cutting set is not determined, cluster analysis of the active splitting cutting set is performed, a cluster set value Kc=3 is set, and a branch cluster B of the power system for connecting a high-voltage area and a low-voltage area is identified M The method comprises the steps of carrying out a first treatment on the surface of the If in branch cluster B M Find the active splitting cutting set, judge the total branch number L in the active splitting cutting set sc Whether or not it is smaller than the maximum value of the number of optional splitting cutsetsN max If less, according to the following formula:
wherein, the vsTSC voltage instability target cutset, P scl0 For steady state active power of branch l, N sc The number of the cutting sets is selected;
determining a preferable splitting cutting set and judging the continuous judging time T for continuously guaranteeing the searching reliability of the splitting cutting set ct If so, let F tsc After adding Δt to the delay time after fault clearing, determine again whether the delay time after fault clearing is greater than T FS ；
If the time delay after fault clearing is not consistent with the delta T time, judging whether the time delay after fault clearing is greater than T again FS ；
If actively splitting the total branch number L in the cut set sc A maximum value N greater than the number of the optional splitting cutting sets max Judging whether Kc=4, if yes, adding delta T time to the delay time after fault clearing, and judging whether the delay time after fault clearing is greater than T again FS The method comprises the steps of carrying out a first treatment on the surface of the If the clustering analysis of the clustering set value Kc=4 of the active splitting cut set is not satisfied.
Wherein the sBTTC index value of the key branch k is larger than a set threshold value epsilon Lth At, or for a duration of Δt Lk Less than a set required duration T Ld When the time delay time after fault clearing is added with delta T time, judging whether the time delay time after fault clearing is larger than T again FS The delay time after fault clearing is greater than T FS 。
The following description is made in connection with specific embodiments:
the invention analyzes according to a typical system model of voltage stability analysis, the model is shown in fig. 2, the flow principle is shown in fig. 3, and the method comprises the following steps:
step one: setting control related parameter T FS 、ε asth 、N b 、U vth 。
T FS Delay time manually set for avoiding influence of fluctuation of electric quantity in an initial stage after fault clearing;
ε asth a threshold value is set for judging whether the voltage stability of the test system has deteriorated;
N b for the total number of branches to be examined, counting all branches in the test system to obtain the parameter for different test systems;
U vth is a threshold value set for determining the severity of the test system instability.
Step two: determining whether the duration after fault clearing is greater than T FS 。
T FS Delay time is set for avoiding influence of fluctuation of electric quantity in initial stage after fault clearing.
If the duration after fault clearing is greater than T FS Step three is entered;
if the duration after fault clearing is less than T FS Let t=t+Δt and return to step two.
Step three: measuring the voltage amplitude U of the two end nodes of each branch mi 、U ni And voltage phase delta theta i (i=1, 2 … N, N is the total number of branches in the system) and calculating the sBTTC index for each branch according to equation (1). The critical branches are ordered and located according to equation (2).
Δθ i ＝|Δθ mi -Δθ ni And I, the voltage phase difference of the two end nodes of the branch i is shown. U (U) mi 、U ni 、Δθ mi 、Δθ ni In fig. 2, the subscripts m and n denote the positions of two measurement points taken on a line, typically taken at both ends of the line. U (U) mi Is the voltage amplitude of node m on branch i, U ni Is the voltage amplitude, delta theta, of node n on branch i mi Is the voltage phase of node m on branch i, Δθ ni Is the voltage phase at node n on branch i.
And (3) sequencing the sBTTC indexes of each branch from small to large according to the formula (2), defining the branch with the smallest sBTTC index value as a key branch, marking the branch number as k, and defining a plurality of branches with the secondary small sBTTC index value as potential quasi-key branch clusters capable of forming a cutting set with the key branch.
Step four: it is determined whether the critical branch k satisfies both equations (3) and (4).
Since the sBTTC index has the characteristic of monotonically decreasing with the deterioration of the voltage stability, when the value of the sBTTC index of the key branch k is smaller than the set threshold value epsilon Lth At this time, it is indicated that the voltage stability of the system has significantly deteriorated and that the voltage instability of the system has occurred. This criterion is described by formula (3) as follows:
sBTTC i <ε Lth (3)
at the same time, duration Δt Lk Required to be greater than the set required duration T Ld This criterion is described by formula (4):
Δt Lk ≥T Ld (4)
if the formulas (3) and (4) are simultaneously satisfied, the step five is entered;
if equations (3) and (4) are not satisfied at the same time, let t=t+Δt, and return to step two.
Step five: determining whether critical leg k satisfies F tsc ＝1。
F tsc Is defined bit zone, F when active splitting cutting set is searched tsc Get 1, F when no cutset is searched tsc Taking 0.
If yes, entering a step six;
if not, the step seven is entered.
Step six: determining whether the critical branch k satisfies (5)
sBTTC k <ε asth (5)
Wherein ε asth A threshold value set for human beings.
If yes, implementing disconnection control on the branch, and ending the flow;
if not, let t=t+Δt, and return to step two.
Step seven: cluster analysis with kc=3 was performed.
The clustering algorithm divides the study into a number of classes (clusters) according to some similarity measure, where samples belonging to the same cluster have the greatest similarity, while samples belonging to different clusters have less similarity. In order to realize automatic decision of the active splitting cut set of the voltage instability, the method adopts the minimum sBTTC index difference value to measure the similarity among branch clusters, and utilizes a condensation hierarchical clustering algorithm (agglomerative nesting, AGNES) to identify the branch clusters BM connecting the high-voltage area and the low-voltage area.
Assuming that N is a positive integer set between 1 and N, and assuming that N branches in the system are finally clustered into a set KC (KC is less than or equal to N) cluster, an algorithm for realizing clustering by using the AGNES is as follows:
(1) Each branch is taken as a branch cluster C i Resulting in cluster set p= { C containing n clusters i }(i∈N)。
(2) Calculated according to (6), n× (n-1)/2 inter-branch cluster distances d are obtained ij Wherein x and y are respectively the belonging branch clusters C i And branches in Cj.
(3) Two branch clusters C with the smallest inter-cluster distance in the set P p 、C q Merging into a new cluster C n+1 And generates a new set of branch clusters p= { C 1 ,…,C p-1 ,C p+1 ,…,C q-1 ,C q+1 ,…,C n+1 }。
(4) Recalculating C using (6) n+1 Distance d from other clusters in P (n+1)j (j=1, …, p-1, p+1, …, q-1, q+1, …, n); let n=n+1.
(5) Repeating the steps (3) and (4) until the clustering number in the set P reaches the set value K c 。
Step eight: in branch cluster B M A matching split cut set.
If the cut set is found, entering a step nine;
if no cutset is found, step ten is entered.
Step nine: determining whether or not L is satisfied sc <N max 。
Branch cluster B in which a connection voltage instability region is detected M On the basis of the method, whether branches in the cluster form a splitting cut set is analyzed and judged through a network topology structure, and the branches can be matched with the splitting cut set which is set off line for inquiring so as to improve the rapidity of cut set searching. If the searched cleavable cut set is a single cut set, the voltage instability target cut set (voltage stability target splitting cutset, vsTSC) is the cut set; if a plurality of optional splitting cutsets exist, the principle of optimal selection with the minimum active power exchanged in a stable state of the cutsets is shown as a formula (7), or the principle of minimum branch number in the cutsets is shown as a formula (8), and the vsTSC is determined.
Wherein L is sc For the total branch number, P, contained in the cut set SC scl0 For steady state active power, N, of branch l in SC sc The number of cutsets is optionally split. In addition, when discriminating or matching cut sets, the branch clusters B should be M And removing fault breaking branches and non-separable branches with high-voltage electromagnetic ring networks.
If satisfied, the cut set is preferably split by using the formula (7) or (8), and the continuous T is judged ct If the results are consistent, if so, let F tsc =1, let t=t+Δt, and return to step two; if the two values are inconsistent, directly enabling t=t+deltat, and returning to the step two;
if not, go to step ten.
Step ten: it is determined whether kc=4 is satisfied.
If yes, let t=t+Δt, and return to step two;
if not, performing the clustering analysis of kc=4 on the branch, and returning to the step eight.
The present invention also proposes an active disconnection control system 200 for voltage instability of an electric power system, as shown in fig. 4, comprising:
the parameter determining module 201 sets control parameters of the power system for the voltage instability condition of the power system, where the control parameters include: delay time T set for avoiding influence of electric quantity fluctuation in initial stage after fault clearing of power system voltage instability FS Threshold value epsilon for determining whether voltage stability of system has deteriorated asth ；
The positioning module 202 determines whether the delay time after fault clearing is greater than T after voltage instability occurs in the power system FS If the value is larger than the preset value, measuring branch parameters in the power system, determining an sBTTC index of each branch in the power system according to the branch parameters, and positioning a key branch according to the sBTTC index;
the decision module 203 determines that when the sBTTC index value of the key branch k is smaller than the set threshold value ε Lth At the same time and for a duration of Δt Lk Greater than the set required duration T Ld When determining the flag bit F of the key branch k tsc Is a value of (2);
control module 204, when F tsc When=1, the determined active splitting cut set is judged, and whether the sBTTC index value of the key branch k is smaller than epsilon or not is judged asth If the voltage stability of the power system is less than the determined voltage stability, the critical branch k is subjected to splitting control according to the active splitting cutting set.
The method for determining the sBTTC index of each branch in the power system comprises the steps of measuring the branch parameters in the power system, determining the sBTTC index of each branch in the power system, and positioning a key branch according to the sBTTC index, wherein the method specifically comprises the following steps:
measuring the voltage amplitude U of the nodes at the two ends of each branch of the power system mi And U ni And voltage phase delta theta i I is the total number of branches in the power system, and the sBTTC index of each branch is calculated according to the following formula;
according to the following formula:
wherein, delta theta i ＝|Δθ mi -Δθ ni I, m and n are the positions of two measuring points taken on one line, and i is the ith branch;
the sBTTC index of each branch is ordered from small to large, the branch with the smallest sBTTC index value is defined as a key branch, and the branch number of the key branch is marked as k.
After positioning the critical branches according to the sBTTC index, defining a plurality of branches with the second smallest sBTTC index value as potential quasi-critical branch clusters capable of forming a cut set with the critical branches.
Wherein if the delay time after fault clearing is smaller than T FS Duration Δt Lk If it is smaller than the set required duration T Ld If the sBTTC index value of the key branch k is larger than epsilon asth After the delay time after the fault is cleared is added with delta T time, judging whether the delay time after the fault is cleared is larger than T again FS The delay time after fault clearing is greater than T FS 。
Wherein F is tsc If the value is 0, the active splitting cutting set is not determined, cluster analysis of the active splitting cutting set is performed, a cluster set value Kc=3 is set, and electric power is identifiedBranch cluster B for systematically connecting high-voltage region and low-voltage region M The method comprises the steps of carrying out a first treatment on the surface of the If in branch cluster B M Find the active splitting cutting set, judge the total branch number L in the active splitting cutting set sc Whether or not it is smaller than the maximum value N of the number of the optional splitting cut sets max If less, according to the following formula:
wherein, the vsTSC voltage instability target cutset, P scl0 For steady state active power of branch 1, N sc The number of the cutting sets is selected;
determining a preferable splitting cutting set and judging the continuous judging time T for continuously guaranteeing the searching reliability of the splitting cutting set ct If so, let F tsc After adding Δt to the delay time after fault clearing, determine again whether the delay time after fault clearing is greater than T FS ；
If the time delay after fault clearing is not consistent with the delta T time, judging whether the time delay after fault clearing is greater than T again FS ；
If actively splitting the total branch number L in the cut set sc A maximum value N greater than the number of the optional splitting cutting sets max Judging whether Kc=4, if yes, adding delta T time to the delay time after fault clearing, and judging whether the delay time after fault clearing is greater than T again FS The method comprises the steps of carrying out a first treatment on the surface of the If the clustering analysis of the clustering set value Kc=4 of the active splitting cut set is not satisfied.
Wherein the sBTTC index value of the key branch k is larger than a set threshold value epsilon Lth At, or for a duration of Δt Lk Less than a set required duration T Ld When the time delay time after fault clearing is added with delta T time, judging whether the time delay time after fault clearing is larger than T again FS Until after the fault is clearedIs greater than T FS 。
The method can implement active disconnection control on the disconnection cut set branch obtained by searching when the voltage of the power system is unstable, and quickly disconnect the out-of-step power grid, thereby avoiding cascading failure caused by local voltage instability and reducing the influence range of instability.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the invention can be realized by adopting various computer languages, such as object-oriented programming language Java, an transliteration script language JavaScript and the like.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (8)
1. An active disconnect control method for power system voltage instability, the method comprising:
setting control parameters of the power system aiming at the voltage instability condition of the power system, wherein the control parameters comprise: delay time T set for avoiding influence of electric quantity fluctuation in initial stage after fault clearing of power system voltage instability FS Threshold value epsilon for determining whether voltage stability of system has deteriorated asth ；
After the voltage instability of the power system occurs, judging whether the delay time after fault clearing is greater than T FS If the value is larger than the preset value, measuring branch parameters in the power system, determining an sBTTC index of each branch in the power system according to the branch parameters, and positioning a key branch according to the sBTTC index;
if the value of the sBTTC index of the key branch k is smaller than the set valueThreshold epsilon Lth And duration Deltat Lk Greater than the set required duration T Ld When determining the flag bit F of the key branch k tsc Is a value of (2);
if F tsc The value of sBTTC index of the critical branch k is less than ε asth If the voltage stability of the power system is less than the determined voltage stability, performing splitting control on the key branch k according to the active splitting cutting set;
the method for measuring the branch parameters in the power system comprises the steps of determining the sBTTC index of each branch in the power system according to the branch parameters, and positioning the key branch according to the sBTTC index, wherein the method specifically comprises the following steps:
measuring the voltage amplitude U of the nodes at the two ends of each branch of the power system mi And U ni And voltage phase delta theta i I is the total number of branches in the power system, and the sBTTC index of each branch is calculated according to the following formula;
according to the following formula:
wherein, delta theta i ＝|Δθ mi -Δθ ni The I, m and n are the positions of two measuring points taken on each line, and i is the ith branch;
sequencing the sBTTC index of each branch from small to large, defining the branch with the smallest sBTTC index value as a key branch, and marking the branch number of the key branch as k;
the F is tsc If the value is 0, an active splitting cutting set is not determined, cluster analysis of the active splitting cutting set is performed, a cluster set value Kc=3 is set, and a branch cluster B of the power system for connecting the high-voltage area and the low-voltage area is identified M The method comprises the steps of carrying out a first treatment on the surface of the If in branch cluster B M Find active splitting cutsetsJudging the total branch number L of the active splitting cutting set sc Whether or not it is smaller than the maximum value N of the number of the optional splitting cut sets max If less, according to the following formula:
wherein vsTSC is a target cut set of voltage instability, P scl0 For steady state active power of branch l, N sc The number of the cutting sets is selected;
determining a preferable splitting cutting set and judging the continuous judging time T for continuously guaranteeing the searching reliability of the splitting cutting set ct If so, let F tsc After adding Δt to the delay time after fault clearing, determine again whether the delay time after fault clearing is greater than T FS ；
If the time delay after fault clearing is not consistent with the delta T time, judging whether the time delay after fault clearing is greater than T again FS ；
If actively splitting the total branch number L in the cut set sc A maximum value N greater than the number of the optional splitting cutting sets max Judging whether Kc=4, if yes, adding delta T time to the delay time after fault clearing, and judging whether the delay time after fault clearing is greater than T again FS The method comprises the steps of carrying out a first treatment on the surface of the If the clustering analysis of the clustering set value Kc=4 of the active splitting cut set is not satisfied.
2. The method of claim 1, wherein after locating the critical branches according to the sBTTC index, defining a plurality of branches with the next smallest sBTTC index value as potential quasi-critical branch clusters capable of forming a cut set with the critical branches.
3. The method of claim 1, the post-fault-clearing delayIf the time is less than T FS Duration Δt Lk If it is smaller than the set required duration T Ld If the sBTTC index value of the key branch k is larger than epsilon asth After the delay time after the fault is cleared is added with delta T time, judging whether the delay time after the fault is cleared is larger than T again FS The delay time after fault clearing is greater than T FS 。
4. The method of claim 1, wherein the sBTTC index value of the critical leg k is greater than a set threshold value ε Lth At, or for a duration of Δt Lk Less than a set required duration T Ld When the time delay time after fault clearing is added with delta T time, judging whether the time delay time after fault clearing is larger than T again FS The delay time after fault clearing is greater than T FS 。
5. An active disconnect control system for power system voltage instability, the system comprising:
the parameter determining module is used for setting control parameters of the power system according to the voltage instability condition of the power system, wherein the control parameters comprise: delay time T set for avoiding influence of electric quantity fluctuation in initial stage after fault clearing of power system voltage instability FS Threshold value epsilon for determining whether voltage stability of system has deteriorated asth ；
The positioning module is used for judging whether the delay time after fault clearing is greater than T after voltage instability occurs in the power system FS If the value is larger than the preset value, measuring branch parameters in the power system, determining an sBTTC index of each branch in the power system according to the branch parameters, and positioning a key branch according to the sBTTC index;
the judging module is used for judging whether the sBTTC index value of the key branch k is smaller than the set threshold value epsilon Lth At the same time and for a duration of Δt Lk Greater than the set required duration T Ld When determining the flag bit T of the key branch k tsc Is a value of (2);
control module, when F tsc Determination when=1An active splitting cut set has been determined and a determination is made as to whether the sBTTC index value of the critical leg k is less than epsilon asth If the voltage stability of the power system is less than the determined voltage stability, performing splitting control on the key branch k according to the active splitting cutting set;
the method for measuring the branch parameters in the power system comprises the steps of determining the sBTTC index of each branch in the power system according to the branch parameters, and positioning the key branch according to the sBTTC index, wherein the method specifically comprises the following steps:
measuring the voltage amplitude U of the nodes at the two ends of each branch of the power system mi And U ni And voltage phase delta theta i I is the total number of branches in the power system, and the sBTTC index of each branch is calculated according to the following formula;
according to the following formula:
wherein, delta theta i ＝|Δθ mi -Δθ ni I, m and n are the positions of two measuring points taken on one line, and i is the ith branch;
sequencing the sBTTC index of each branch from small to large, defining the branch with the smallest sBTTC index value as a key branch, and marking the branch number of the key branch as k;
the F is tsc If the value is 0, an active splitting cutting set is not determined, cluster analysis of the active splitting cutting set is performed, a cluster set value Kc=3 is set, and a branch cluster B of the power system for connecting the high-voltage area and the low-voltage area is identified M The method comprises the steps of carrying out a first treatment on the surface of the If in branch cluster B M Find the active splitting cutting set, judge the total branch number L in the active splitting cutting set sc Whether or not it is smaller than the maximum value N of the number of the optional splitting cut sets max If less, according to the following formula:
wherein, the vsTSC voltage instability target cutset, P scl0 For steady state active power of branch l, N sc The number of the cutting sets is selected;
determining a preferable splitting cutting set and judging the continuous judging time T for continuously guaranteeing the searching reliability of the splitting cutting set ct If so, let F tsc After adding Δt to the delay time after fault clearing, determine again whether the delay time after fault clearing is greater than T FS ；
If the time delay after fault clearing is not consistent with the delta T time, judging whether the time delay after fault clearing is greater than T again FS ；
If actively splitting the total branch number L in the cut set sc A maximum value N greater than the number of the optional splitting cutting sets max Judging whether Kc=4, if yes, adding delta T time to the delay time after fault clearing, and judging whether the delay time after fault clearing is greater than T again FS The method comprises the steps of carrying out a first treatment on the surface of the If the clustering analysis of the clustering set value Kc=4 of the active splitting cut set is not satisfied.
6. The system of claim 5, wherein after locating the critical branches according to the sBTTC index, defining a plurality of branches with the next smallest sBTTC index value as potential quasi-critical branch clusters that can form cutsets with the critical branches.
7. The system of claim 5, wherein the post-fault-clearing delay time is less than T FS Duration Δt Lk If it is smaller than the set required duration T Ld If the sBTTC index value of the key branch k is larger than epsilon asth The delay time after the fault is cleared is added with delta t timeJudging whether the delay time after fault clearing is greater than T FS The delay time after fault clearing is greater than T FS 。
8. The system of claim 5, wherein the sBTTC index value of the critical leg k is greater than a set threshold value ε Lth At, or for a duration of Δt Lk Less than a set required duration T Ld When the time delay time after fault clearing is added with delta T time, judging whether the time delay time after fault clearing is larger than T again FS The delay time after fault clearing is greater than T FS 。
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| CN109428327A (en) * | 2017-09-01 | 2019-03-05 | 中国电力科学研究院 | Power grid key branch and leading stable mode recognition methods and system based on response |
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| CN112234627A (en) * | 2020-08-31 | 2021-01-15 | 国网浙江省电力有限公司温州供电公司 | Active splitting control method integrating off-line simulation and real-time information monitoring |
| CN112332417A (en) * | 2021-01-07 | 2021-02-05 | 中国电力科学研究院有限公司 | Wide-area cooperative out-of-step separation method and device based on correction of oscillation center voltage |
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| CN109428327A (en) * | 2017-09-01 | 2019-03-05 | 中国电力科学研究院 | Power grid key branch and leading stable mode recognition methods and system based on response |
| CN110932291A (en) * | 2019-11-29 | 2020-03-27 | 国网浙江省电力有限公司温州供电公司 | Active splitting method for preserving stability of local power grid |
| CN112234627A (en) * | 2020-08-31 | 2021-01-15 | 国网浙江省电力有限公司温州供电公司 | Active splitting control method integrating off-line simulation and real-time information monitoring |
| CN112332417A (en) * | 2021-01-07 | 2021-02-05 | 中国电力科学研究院有限公司 | Wide-area cooperative out-of-step separation method and device based on correction of oscillation center voltage |
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