CN111969661A - Method and system for improving dynamic voltage regulation capability of adjusting active power of generator - Google Patents
Method and system for improving dynamic voltage regulation capability of adjusting active power of generator Download PDFInfo
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- CN111969661A CN111969661A CN202010745487.1A CN202010745487A CN111969661A CN 111969661 A CN111969661 A CN 111969661A CN 202010745487 A CN202010745487 A CN 202010745487A CN 111969661 A CN111969661 A CN 111969661A
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Abstract
The invention discloses a method and a system for improving dynamic voltage regulation capability of adjusting the power of a generator, wherein the method comprises the following steps: determining weak nodes with dynamic voltage regulation capacity; searching generators effective to the voltage of the weak node, and establishing an effective generator set; calculating the track sensitivity of active power adjustment of each generator to the promotion of the dynamic voltage regulation capability of the weak node, and acquiring the track sensitivity of each generator to the voltage of the weak node; selecting a generator with high track sensitivity, and establishing a control generator set; determining active adjustment measures of the generators according to control target values of voltage drop areas predetermined by the generators in the generator set on weak nodes; and carrying out load flow adjustment on the generators of the control generator set, calculating an integral area of the weak node with the voltage lower than a set threshold, and when the integral area is smaller than or equal to a target value, determining an active adjustment measure to control the active power of the generators in the generator set to be adjusted to the minimum active output.
Description
Technical Field
The invention relates to the technical field of on-line safety and stability calculation analysis of a power system, in particular to a method and a system for improving dynamic voltage regulation capability of adjusting the active power of a generator.
Background
Along with the rapid increase of the direct current transmission scale and the rapid development of new energy sources such as wind power, photovoltaic and the like, the power supply and power grid pattern in China continuously and greatly change, and the safe operation of the power grid and the large-scale consumption of renewable energy sources face brand new challenges. On one hand, China is in the high-speed development period of an extra-high voltage power grid, the characteristics of the power grid continuously change, the current coupling of alternating current and direct current of the power grid and a transmitting and receiving end becomes tighter and tighter, the influence of faults on the operation of the power grid is changed from local to global, the dynamic voltage stability problem of the power grid is increasingly prominent due to the large-scale production of new energy and direct current transmission, the stability range of the power grid is further expanded, the electronic characteristics of power are prominent, and the voltage regulating capability of the power grid is continuously reduced. On the other hand, in recent years, new energy in China continuously and rapidly grows, the occupation ratio of the new energy in a power grid is gradually improved, the output of the new energy such as wind, light and the like has randomness and volatility, and the frequency and voltage regulation characteristics of the new energy are different from those of a conventional generator set, so that the voltage regulation capability and the disturbance resistance capability of a system are deteriorated to a certain extent, and the new energy consumption is influenced by the problem of insufficient voltage supporting capability of the power grid.
Under the background that the output components and the absorption mode of the whole network are deeply changed at present, the voltage characteristics of the power network are fundamentally changed, and the problems of reduced voltage regulation capability and insufficient disturbance resistance capability of a weak area are evolved from the quasi-static voltage balance problem. However, the existing scheduling control system module lacks functions and applications for accurately evaluating and optimizing the dynamic voltage regulation capability of the power grid, and needs to research a dynamic voltage regulation capability evaluation method based on online data and a layered and partitioned multi-objective coordinated optimization promotion technology urgently to finally form a scheme and functional software for online evaluation and optimized promotion of the dynamic voltage regulation capability of the power grid, and the scheme and the functional software are applied to a scheduling control center to provide decision support for power grid scheduling operators to promote the safety level and the voltage regulation capability of the power grid and continue to promote the consumption capability of new energy resources.
Therefore, a technique is needed to realize an improved technique for adjusting the active dynamic voltage regulation capability of the generator.
Disclosure of Invention
The technical scheme of the invention provides a method and a system for improving the dynamic voltage regulation capability of the active power of a generator, which are used for solving the problem of improving the dynamic voltage regulation capability of the active power of the generator.
In order to solve the above problem, the present invention provides a method for improving dynamic voltage regulation capability of adjusting the active power of a generator, wherein the method comprises:
determining weak nodes with dynamic voltage regulation capacity;
searching generators effective to the voltage of the weak node, and establishing an effective generator set;
calculating the track sensitivity of each generator in the effective generator set to the dynamic voltage regulation capability of the weak node, and acquiring the track sensitivity of each generator in the effective generator set to the voltage of the weak node;
selecting a generator with high track sensitivity, and establishing a control generator set;
determining active adjustment measures of the generators of the control generator set according to control target values of voltage drop areas predetermined by the generators of the control generator set on the weak nodes;
and carrying out load flow adjustment on the generators of the control generator set, calculating an integral area of which the voltage of the weak node is lower than a set threshold value in a simulation process, and determining an active adjustment measure to adjust the active power of the generators in the control generator set to the minimum active output when the integral area is smaller than or equal to a target value.
Preferably, the method further comprises the following steps: and when the integral area is larger than the target value, continuing to select the generator with high track sensitivity and adding the generator to the control generator set.
Preferably, the determining weak nodes with dynamic voltage regulation capability includes:
transient time domain simulation is carried out on the expected fault, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting preset criterion conditions are searched out based on the integral area Vdrop, the duration Tlow and the lowest voltage Vmin.
Preferably, the searching for the generator that is active for the voltage of the weak node, establishing an active generator set, further comprises:
and searching the generators with the voltage sensitivity greater than a preset voltage sensitivity threshold and the voltage drop greater than a voltage drop threshold, and establishing an effective generator set.
Preferably, the determining an active adjustment measure of the generator of the control generator set according to the control target value of the voltage drop area predetermined by the generator of the control generator set on the weak node further includes:
obtaining voltage drop area Vdrop of weak nodei 0According to a predetermined control target value Vdrop of the voltage drop areai tgvCalculating an accumulated contribution value of the voltage drop area of the weak node, stopping when the accumulated contribution value meets the following formula, and determining active adjustment measures of the generators of the control generator set;
UnSetCto control the generator set, k is the generator, dVdropi kThe reduced value of the voltage drop area of the weak node i.
Based on another aspect of the present invention, the present invention provides a system for improving dynamic voltage regulation capability of a generator, including:
the determining unit is used for determining weak nodes with dynamic voltage regulating capability;
the first establishing unit is used for searching generators effective to the voltage of the weak node and establishing an effective generator set;
the calculating unit is used for calculating the track sensitivity of each generator in the effective generator set to the active power adjustment for improving the dynamic voltage regulating capability of the weak node, and acquiring the track sensitivity of each generator in the effective generator set to the voltage of the weak node;
the second establishing unit is used for selecting the generator with high track sensitivity and establishing a control generator set;
a result unit, configured to determine an active adjustment measure of the generators in the control generator set according to a control target value of a voltage drop area predetermined by the generators in the control generator set for the weak node;
and the verification unit is used for carrying out power flow adjustment on the generators in the control generator set, calculating an integral area of which the voltage of the weak node is lower than a set threshold value in a simulation process, and determining an active adjustment measure to adjust the active power of the generators in the control generator set to the minimum active output when the integral area is smaller than or equal to a target value.
Preferably, the second establishing unit is further configured to: and when the integral area is larger than the target value, continuing to select the generator with high track sensitivity and adding the generator to the control generator set.
Preferably, the determining unit is configured to determine a weak node of the dynamic voltage regulation capability, and includes:
transient time domain simulation is carried out on the expected fault, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting preset criterion conditions are searched out based on the integral area Vdrop, the duration Tlow and the lowest voltage Vmin.
Preferably, the first establishing unit is configured to search for generators that are active on the voltage of the weak node, and establish an active generator set, including:
and searching the generators with the voltage sensitivity greater than a preset voltage sensitivity threshold and the voltage drop greater than a voltage drop threshold, and establishing an effective generator set.
Preferably, the result unit is configured to determine an active adjustment measure of the generators of the control generator set according to a control target value of a voltage drop area predetermined by the generators of the control generator set for the weak node, and includes:
obtaining voltage drop area Vdrop of weak nodei 0According to a predetermined control target value Vdrop of the voltage drop areai tgvCalculating an accumulated contribution value of the voltage drop area of the weak node, stopping when the accumulated contribution value meets the following formula, and determining active adjustment measures of the generators of the control generator set;
UnSetCto control the generator set, k is the generator, dVdropi kThe reduced value of the voltage drop area of the weak node i.
The technical scheme of the invention provides a method and a system for improving the dynamic voltage regulation capability of regulating the active power of a generator, wherein the method comprises the following steps: determining weak nodes with dynamic voltage regulation capacity; searching generators effective to the voltage of the weak node, and establishing an effective generator set; calculating the track sensitivity of each generator in the effective generator set to the dynamic voltage regulation capacity of the weak node, and acquiring the track sensitivity of each generator in the effective generator set to the voltage of the weak node; selecting a generator with high track sensitivity, and establishing a control generator set; determining active adjustment measures for controlling the generators of the generator set according to control target values of voltage drop areas predetermined by the generators in the generator set on weak nodes; and carrying out load flow adjustment on the generators controlling the generator set, calculating an integral area of which the voltage of a weak node is lower than a set threshold value in the simulation process, and determining an active adjustment measure to control the active power of the generators in the generator set to be adjusted to the minimum active output when the integral area is smaller than or equal to a target value. According to the technical scheme, the screening of the weak voltage area is realized by researching the evaluation index and method of the dynamic voltage regulation capacity of the power grid, the optimization scheme of the dynamic voltage regulation capacity of the weak area of the power grid is researched by combining the current real-time data of the power grid, the dynamic voltage regulation capacity is improved, the extra-high voltage direct-current voltage supporting capacity is improved, and a foundation is laid for improving the new energy consumption level on the basis of the safety of the power grid.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
FIG. 1 is a flow chart of a method for improving dynamic voltage regulation capability for regulating active power of a generator according to a preferred embodiment of the present invention;
FIG. 2 is a flow chart of a method for improving dynamic voltage regulation capability for adjusting the active power of a generator according to a preferred embodiment of the present invention; and
fig. 3 is a structural diagram of a lifting system for adjusting the dynamic voltage regulation capability of the generator according to the preferred embodiment of the 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 embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present 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, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those 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.
Fig. 1 is a flowchart of a method for improving dynamic voltage regulation capability of a generator according to an embodiment of the present invention. The invention aims to solve the technical problem of adjusting the active dynamic voltage regulation capability of a generator to improve the system. Specifically, weak nodes with dynamic voltage regulation capacity are determined, then a generator which is effective to the voltage of the weak nodes is searched, the track sensitivity of the active adjustment of the generator to the voltage of the weak nodes is calculated, then active adjustment measures of the generator are determined, the effect after the adjustment is verified, and the control measures are adjusted or the calculation is finished according to the verification result. Through the adjustment of the active power of the generator, the dynamic voltage regulation capability of the weak node is improved. As shown in fig. 1, the present invention provides a method for improving dynamic voltage regulation capability of adjusting the active power of a generator, the method comprising:
step 101: and determining weak nodes of the dynamic voltage regulation capacity. Preferably, the determining weak nodes of the dynamic voltage regulation capability includes: transient time domain simulation is carried out on the expected fault, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting preset criterion conditions are searched out based on the integral area Vdrop, the duration Tlow and the lowest voltage Vmin.
According to the invention, the dynamic voltage regulation capability improving system for adjusting the work of the generator comprises the following steps:
1) and determining the weak nodes of the dynamic voltage regulation capability.
And 1) determining the weak node with the dynamic voltage regulation capability. Transient time domain simulation is carried out on the expected faults, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration time Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting criterion conditions are searched.
For the node i, for the voltage Vj (the interval Δ t between two points in the present application is 0.01s) at each time in the simulation process (the simulation time duration in the present application may be 20s), the integral area Vdrop of which the voltage is lower than the set threshold (the voltage may be 0.9 per unit) is calculated according to the following formulaiDuration TlowiAnd minimum voltage Vmini。
Vmini＝min(Vij),t1≤j≤20
In the formula t1The voltage in the process of voltage recovery after the expected fault occurrence and the clearing is analyzed for the next moment after the fault is cleared, namely, the key point.
Setting the minimum voltage threshold value to 0.8 and setting the duration TlowiThe threshold value is 10s, and Vmin is searched outiLess than 0.8 and TlowiA set of nodes VSet that is greater than 10 s.
For nodes in set VSet, according to VdropiAnd sequencing to find out the node with the largest voltage drop area, namely the node with the weakest dynamic voltage regulation capability.
Step 102: and searching generators effective to the voltage of the weak node to establish an effective generator set. Preferably, searching for generators that are active for the voltage of the weak node, establishing an active generator set, further comprises: and searching the generators with the voltage sensitivity greater than a preset voltage sensitivity threshold and the voltage drop greater than a voltage drop threshold, and establishing an effective generator set.
2) The invention searches for a generator that is effective at weak node voltages.
Wherein the searching of step 2) is for a generator with a weak node voltage being effective. And calculating the sensitivity of each generator to reactive power adjustment on weak node voltage aiming at the weak nodes, calculating the generator node voltage drop caused by the short-circuit fault of the weak nodes, and screening out the generators with effective weak node voltage.
a) For weak nodes i, firstly, the sensitivity of reactive power adjustment of each generator m to the voltage of the nodes i is calculated one by one, and the calculation formula is as follows.
ΔUi＝RDGΔQm
In the formula, D is a weak voltage node, G is a generator node, an L matrix is a matrix established by an imaginary part of a load flow calculation admittance matrix, and RDG is a partial sub-matrix which enables the inverse of the L matrix to be related to the weak node i and the generator node.
b) Calculating voltage drop delta U of each generator node m caused by short-circuit fault of weak node imThe calculation formula is as follows:
in the formula of Ui(0)Is the voltage before the short-circuit fault of node i, Zeq iIs the Thevenin equivalent impedance, Z, looking into the system from node im-iIs the mutual impedance between node i and generator node m.
c) The threshold value of the reactive power of the generator for adjusting the voltage sensitivity of the weak node is set to be 0.05, the threshold value of the voltage drop of the generator node caused by the short-circuit fault of the weak node is set to be 0.2, the generator set UnSet with the voltage sensitivity larger than 0.05 and the voltage drop larger than 0.2 is screened out, namely, the generator which has supporting capacity for the voltage of the weak node and can sense the voltage drop caused by the fault of the weak node is found out and used as the generator which is effective for the voltage of the weak node.
Step 103: and calculating the track sensitivity of each generator in the effective generator set to the dynamic voltage regulation capacity of the weak node, and acquiring the track sensitivity of each generator in the effective generator set to the voltage of the weak node.
3) The method calculates the track sensitivity of the active power adjustment of the generator to the weak node voltage.
And 3) calculating the track sensitivity of the active power adjustment of the generator to the voltage of the weak node, and calculating the track sensitivity of the active power adjustment of each generator in the set to the dynamic voltage regulation capability of the weak node i one by one aiming at the weak node i and the effective generator set UnSet searched in the step 2.
a) Aiming at a generator n in a generator set UnSet, acquiring real-time active power Pu of the generator nnMinimum active technology output PminnReducing the active power of the generator n to a minimum active technical output, the active reduction Pminus ═ Pu-n-Pminn。
b) Acquiring a provincial power grid where a generator n is located or a certain subarea power grid of the provincial power grid, and searching a generator set UnSet of the provincial power grid or the subarea power grid except the generator n1. For generator set UnSet1The generator k in (1) obtains its real-time active power PukMaximum active power PmaxkCalculating the active upward adjustable capacity as Padjupk＝Pmaxk-Puk. Generator set UnSet1Total upward adjustable capacity Padjup1Is composed of
The generator set UnSet is calculated according to the following formula1Active up-regulation of each generator
Namely, the generator set UnSet1Each generator in (1) according to PunadjkActive power is adjusted up, and for a generator k, the adjusted active power is Puk+Punadjk。
c) Carrying out load flow calculation on the adjusted data, then carrying out transient time domain simulation of expected faults in the step 1), tracking the voltage condition of a weak node i in the simulation process, and calculating the integral area Vdrop of the node voltage i lower than a set threshold valuei 1And the voltage drop area Vdrop of the weak node i obtained in the step 1)i 0In comparison, the reduced value dVdrop of the voltage drop area of the weak node i is obtainedi kAnd the track sensitivity of the generator k to the weak node i voltage is adjusted as the active power.
Step 104: selecting a generator with high track sensitivity, and establishing a control generator set;
step 105: and determining active adjustment measures for controlling the generators of the generator set according to the control target value of the voltage drop area predetermined by the generators in the generator set on the weak node. Preferably, the active power adjustment measure for controlling the generators of the generator set is determined according to a control target value of a voltage drop area predetermined by the generator of the generator set to the weak node, and the active power adjustment measure further includes: obtaining voltage drop area Vdrop of weak nodei 0According to a predetermined control target value Vdrop of the voltage drop areai tgvCalculating an accumulated contribution value of the voltage drop area of the weak node, stopping when the following formula is met, and determining active adjustment measures for controlling the generators of the generator set;
UnSetCto control the generator set, k is the generator, dVdropi kThe reduced value of the voltage drop area of the weak node i.
4) The invention determines generator active power adjustment measures.
Wherein the active adjustment measure of the generator is determined in the step 4). Aiming at the weak node i, according to a control target value Vdrop of a predetermined voltage drop areai tgvAnd calculating and determining the active power adjusting measures of the generator.
Aiming at the generator set UnSet determined in the step 2), sorting the generator sets from large to small according to the track sensitivity determined in the step 3), preferentially adjusting the generator sets with large track sensitivity, and bringing the generator sets into the control set UnSetCAnd calculating the accumulated contribution value of the weak node i voltage drop area, and stopping when the following formula is satisfied.
Step 106: and carrying out load flow adjustment on the generators controlling the generator set, calculating an integral area of which the voltage of a weak node is lower than a set threshold value in the simulation process, and determining an active adjustment measure to control the active power of the generators in the generator set to be adjusted to the minimum active output when the integral area is smaller than or equal to a target value.
Preferably, the method further comprises the following steps: when the integral area is larger than the target value, the generator with high track sensitivity is continuously selected and added to the control generator set.
5) The invention checks the effect after adjustment, adjusts the control measures or ends the calculation.
And 5) verifying the adjusted effect, adjusting control measures or finishing calculation. And (4) carrying out load flow adjustment on the generator adjustment set determined in the step 4), and finishing calculation or readjusting control measures according to a verification result through transient time domain simulation verification. As shown in fig. 2.
a) For generator set UnSetCThe generator in (1) calculates the active power of the generator and adjusts the total sum Punadj downwardsC。
b) Obtaining UnSetCSearching for the UnSet of the provincial power grid or the subarea power gridCSet of generators other than UnSet1. For generator set UnSet1The generator k in (1) obtains its real-time active power PukMaximum active power PmaxkCalculating the active upward adjustable capacity as Padjupk＝Pmaxk-Puk. Generator set UnSet1Total upward adjustable capacity Padjup1Comprises the following steps:
the generator set UnSet is calculated according to the following formula1Active power up-regulation quantity of each generator:
namely, the generator set UnSet1Each generator in (1) according to PunadjkActive power is adjusted up, and for a generator k, the adjusted active power is Puk+Punadjk。
c) Carrying out load flow calculation on the adjusted data, then carrying out transient time domain simulation of expected faults in the step 1), tracking the voltage condition of a weak node i in the simulation process, and calculating the integral area Vdrop of the node voltage i lower than a set threshold valuei 1If Vdrop is usedi 1Is less than or equal to the target value Vdropi tgvIf so, the control target is reached, the calculation is stopped, UnSetCNamely, the generator set is controlled by the UnSetCThe generator active power in (1) is adjusted to its minimum active technology output.
If Vdropi 1Is greater than the target value Vdropi tgvReturning to the step 4), continuing to add generator control measures, namely adding a new generator to the generator set UnSetCAnd 5) judging that the control target is reached.
Aiming at weak nodes with voltage drop amplitude reaching the duration after expected faults, the generator set with the effect of improving the dynamic voltage regulation capability of the weak nodes can be searched through reactive voltage sensitivity calculation and interactive influence calculation of short-circuit faults on the voltage of the nodes. According to the method, the track sensitivity of the active power adjustment of the generator to the voltage drop area of the weak node is calculated, the active adjustment control sequence of the generator is determined according to the sensitivity, and the control set is finally determined, so that the dynamic voltage capability of the weak node is improved through the active power adjustment of the generator.
Fig. 3 is a structural diagram of a lifting system for adjusting the dynamic voltage regulation capability of the generator according to the preferred embodiment of the invention. As shown in fig. 3, the present invention provides a system for improving dynamic voltage regulation capability of a generator, which comprises:
and the determining unit 301 is configured to determine a weak node of the dynamic voltage regulation capability. Preferably, the determining unit is configured to determine a weak node of the dynamic voltage regulation capability, and includes: transient time domain simulation is carried out on the expected fault, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting preset criterion conditions are searched out based on the integral area Vdrop, the duration Tlow and the lowest voltage Vmin.
According to the invention, the dynamic voltage regulation capability improving system for adjusting the work of the generator comprises the following steps:
1) and determining the weak nodes of the dynamic voltage regulation capability.
And 1) determining the weak node with the dynamic voltage regulation capability. Transient time domain simulation is carried out on the expected faults, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration time Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting criterion conditions are searched.
For the node i, for the voltage Vj (the interval Δ t between two points in the present application is 0.01s) at each time in the simulation process (the simulation time duration in the present application may be 20s), the integral area Vdrop of which the voltage is lower than the set threshold (the voltage may be 0.9 per unit) is calculated according to the following formulaiDuration TlowiAnd minimum voltage Vmini。
Vmini＝min(Vij),t1≤j≤20
In the formula t1Predict the occurrence of the fault for the next moment after the fault is cleared, i.e. the key analysisVoltage in the voltage recovery process after clearing.
Setting the minimum voltage threshold value to 0.8 and setting the duration TlowiThe threshold value is 10s, and Vmin is searched outiLess than 0.8 and TlowiA set of nodes VSet that is greater than 10 s.
For nodes in set VSet, according to VdropiAnd sequencing to find out the node with the largest voltage drop area, namely the node with the weakest dynamic voltage regulation capability.
A first establishing unit 302, configured to search for a generator that is effective for the voltage of the weak node, and establish an effective generator set; preferably, the first establishing unit is configured to search for generators that are active for the voltage of the weak node, and establish an active generator set, including: and searching the generators with the voltage sensitivity greater than a preset voltage sensitivity threshold and the voltage drop greater than a voltage drop threshold, and establishing an effective generator set.
2) The invention searches for a generator that is effective at weak node voltages.
Wherein the searching of step 2) is for a generator with a weak node voltage being effective. And calculating the sensitivity of each generator to reactive power adjustment on weak node voltage aiming at the weak nodes, calculating the generator node voltage drop caused by the short-circuit fault of the weak nodes, and screening out the generators with effective weak node voltage.
a) For weak nodes i, firstly, the sensitivity of reactive power adjustment of each generator m to the voltage of the nodes i is calculated one by one, and the calculation formula is as follows.
ΔUi＝RDGΔQm
In the formula, D is a weak voltage node, G is a generator node, an L matrix is a matrix established by an imaginary part of a load flow calculation admittance matrix, and RDG is a partial sub-matrix which enables the inverse of the L matrix to be related to the weak node i and the generator node.
b) Calculating each generator caused by weak node i short-circuit faultVoltage drop Δ U at node mmThe calculation formula is as follows:
in the formula of Ui(0)Is the voltage before the short-circuit fault of node i, Zeq iIs the Thevenin equivalent impedance, Z, looking into the system from node im-iIs the mutual impedance between node i and generator node m.
c) The threshold value of the reactive power of the generator for adjusting the voltage sensitivity of the weak node is set to be 0.05, the threshold value of the voltage drop of the generator node caused by the short-circuit fault of the weak node is set to be 0.2, the generator set UnSet with the voltage sensitivity larger than 0.05 and the voltage drop larger than 0.2 is screened out, namely, the generator which has supporting capacity for the voltage of the weak node and can sense the voltage drop caused by the fault of the weak node is found out and used as the generator which is effective for the voltage of the weak node.
And the calculating unit 303 is configured to calculate the trajectory sensitivity of the active power adjustment of each generator in the effective generator set to the promotion of the dynamic voltage regulation capability of the weak node, and obtain the trajectory sensitivity of each generator in the effective generator set to the voltage of the weak node.
3) The method calculates the track sensitivity of the active power adjustment of the generator to the weak node voltage.
And 3) calculating the track sensitivity of the active power adjustment of the generator to the voltage of the weak node, and calculating the track sensitivity of the active power adjustment of each generator in the set to the dynamic voltage regulation capability of the weak node i one by one aiming at the weak node i and the effective generator set UnSet searched in the step 2.
a) Aiming at a generator n in a generator set UnSet, acquiring real-time active power Pu of the generator nnMinimum active technology output PminnReducing the active power of the generator n to a minimum active technical output, the active reduction Pminus ═ Pu-n-Pminn。
b) Obtaining the provincial electric network where the generator n is located or a certain subarea electricity of the provincial electric networkNetwork, search for generator sets UnSet other than generators n of provincial or partitioned grids1. For generator set UnSet1The generator k in (1) obtains its real-time active power PukMaximum active power PmaxkCalculating the active upward adjustable capacity as Padjupk＝Pmaxk-Puk. Generator set UnSet1Total upward adjustable capacity Padjup1Is composed of
The generator set UnSet is calculated according to the following formula1Active up-regulation of each generator
Namely, the generator set UnSet1Each generator in (1) according to PunadjkActive power is adjusted up, and for a generator k, the adjusted active power is Puk+Punadjk。
c) Carrying out load flow calculation on the adjusted data, then carrying out transient time domain simulation of expected faults in the step 1), tracking the voltage condition of a weak node i in the simulation process, and calculating the integral area Vdrop of the node voltage i lower than a set threshold valuei 1And the voltage drop area Vdrop of the weak node i obtained in the step 1)i 0In comparison, the reduced value dVdrop of the voltage drop area of the weak node i is obtainedi kAnd the track sensitivity of the generator k to the weak node i voltage is adjusted as the active power.
And a second establishing unit 304, configured to select a generator with high trajectory sensitivity, and establish a control generator set.
A result unit 305, configured to determine an active adjustment measure for controlling the generators of the generator set according to the control target value of the voltage sag area predetermined for the weak node by controlling the generators of the generator set. Preferably, the result unit 305 is configured to determine an active adjustment measure for controlling the generators of the generator set according to the control target value of the voltage sag area predetermined for the weak node by controlling the generators of the generator set, and includes:
obtaining voltage drop area Vdrop of weak nodei 0According to a predetermined control target value Vdrop of the voltage drop areai tgvCalculating an accumulated contribution value of the voltage drop area of the weak node, stopping when the following formula is met, and determining active adjustment measures for controlling the generators of the generator set;
UnSetCto control the generator set, k is the generator, dVdropi kThe reduced value of the voltage drop area of the weak node i.
4) The invention determines generator active power adjustment measures.
Wherein the active adjustment measure of the generator is determined in the step 4). Aiming at the weak node i, according to a control target value Vdrop of a predetermined voltage drop areai tgvAnd calculating and determining the active power adjusting measures of the generator.
Aiming at the generator set UnSet determined in the step 2), sorting the generator sets from large to small according to the track sensitivity determined in the step 3), preferentially adjusting the generator sets with large track sensitivity, and bringing the generator sets into the control set UnSetCAnd calculating the accumulated contribution value of the weak node i voltage drop area, and stopping when the following formula is satisfied.
The checking unit 306 is configured to perform power flow adjustment on the generators controlling the generator set, calculate an integral area where the voltage of the weak node is lower than a set threshold in the simulation process, and determine an active adjustment measure to control active power of the generators in the generator set to be adjusted to minimum active output when the integral area is smaller than or equal to a target value.
Preferably, the second establishing unit is further configured to: when the integral area is larger than the target value, the generator with high track sensitivity is continuously selected and added to the control generator set.
5) The invention checks the effect after adjustment, adjusts the control measures or ends the calculation.
And 5) verifying the adjusted effect, adjusting control measures or finishing calculation. And (4) carrying out load flow adjustment on the generator adjustment set determined in the step 4), and finishing calculation or readjusting control measures according to a verification result through transient time domain simulation verification. As shown in fig. 2.
a) For generator set UnSetCThe generator in (1) calculates the active power of the generator and adjusts the total sum Punadj downwardsC。
b) Obtaining UnSetCSearching for the UnSet of the provincial power grid or the subarea power gridCSet of generators other than UnSet1. For generator set UnSet1The generator k in (1) obtains its real-time active power PukMaximum active power PmaxkCalculating the active upward adjustable capacity as Padjupk＝Pmaxk-Puk. Generator set UnSet1Total upward adjustable capacity Padjup1Comprises the following steps:
the generator set UnSet is calculated according to the following formula1Active power up-regulation quantity of each generator:
namely, the generator set UnSet1Each generator in (1) according to PunadjkActive power is adjusted up, and for a generator k, the adjusted active power is Puk+Punadjk。
c) Carrying out load flow calculation on the adjusted data, then carrying out transient time domain simulation of expected faults in the step 1), tracking the voltage condition of a weak node i in the simulation process, and calculating the integral area Vdrop of the node voltage i lower than a set threshold valuei 1If Vdrop is usedi 1Is less than or equal to the target value Vdropi tgvIf so, the control target is reached, the calculation is stopped, UnSetCNamely, the generator set is controlled by the UnSetCThe generator active power in (1) is adjusted to its minimum active technology output.
If Vdropi 1Is greater than the target value Vdropi tgvReturning to the step 4), continuing to add generator control measures, namely adding a new generator to the generator set UnSetCAnd 5) judging that the control target is reached.
Aiming at weak nodes with voltage drop amplitude reaching the duration after expected faults, the generator set with the effect of improving the dynamic voltage regulation capability of the weak nodes can be searched through reactive voltage sensitivity calculation and interactive influence calculation of short-circuit faults on the voltage of the nodes. According to the method, the track sensitivity of the active power adjustment of the generator to the voltage drop area of the weak node is calculated, the active adjustment control sequence of the generator is determined according to the sensitivity, and the control set is finally determined, so that the dynamic voltage capability of the weak node is improved through the active power adjustment of the generator.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
Claims (10)
1. A method for improving dynamic voltage regulation capability for regulating active power of a generator, the method comprising:
determining weak nodes with dynamic voltage regulation capacity;
searching generators effective to the voltage of the weak node, and establishing an effective generator set;
calculating the track sensitivity of each generator in the effective generator set to the dynamic voltage regulation capability of the weak node, and acquiring the track sensitivity of each generator in the effective generator set to the voltage of the weak node;
selecting a generator with high track sensitivity, and establishing a control generator set;
determining active adjustment measures of the generators of the control generator set according to control target values of voltage drop areas predetermined by the generators of the control generator set on the weak nodes;
and carrying out load flow adjustment on the generators of the control generator set, calculating an integral area of which the voltage of the weak node is lower than a set threshold value in a simulation process, and determining an active adjustment measure to adjust the active power of the generators in the control generator set to the minimum active output when the integral area is smaller than or equal to a target value.
2. The method of claim 1, further comprising: and when the integral area is larger than the target value, continuing to select the generator with high track sensitivity and adding the generator to the control generator set.
3. The method of claim 1, wherein the determining weak nodes of dynamic voltage regulation capability comprises:
transient time domain simulation is carried out on the expected fault, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting preset criterion conditions are searched out based on the integral area Vdrop, the duration Tlow and the lowest voltage Vmin.
4. The method of claim 1, the searching for generators active on the voltage of the weak node, establishing an active set of generators, further comprising:
and searching the generators with the voltage sensitivity greater than a preset voltage sensitivity threshold and the voltage drop greater than a voltage drop threshold, and establishing an effective generator set.
5. The method of claim 1, wherein determining the active adjustment measure of the generator of the set of control generators according to the control target value of the voltage sag area predetermined by the generator of the set of control generators for the weak node, further comprises:
obtaining voltage drop area Vdrop of weak nodei 0According to a predetermined control target value Vdrop of the voltage drop areai tgvCalculating an accumulated contribution value of the voltage drop area of the weak node, stopping when the accumulated contribution value meets the following formula, and determining active adjustment measures of the generators of the control generator set;
UnSetCto control the generator set, k is the generator, dVdropi kThe reduced value of the voltage drop area of the weak node i.
6. A boost system to adjust the dynamic voltage regulation capability of a generator active, the system comprising:
the determining unit is used for determining weak nodes with dynamic voltage regulating capability;
the first establishing unit is used for searching generators effective to the voltage of the weak node and establishing an effective generator set;
the calculating unit is used for calculating the track sensitivity of each generator in the effective generator set to the active power adjustment for improving the dynamic voltage regulating capability of the weak node, and acquiring the track sensitivity of each generator in the effective generator set to the voltage of the weak node;
the second establishing unit is used for selecting the generator with high track sensitivity and establishing a control generator set;
a result unit, configured to determine an active adjustment measure of the generators in the control generator set according to a control target value of a voltage drop area predetermined by the generators in the control generator set for the weak node;
and the verification unit is used for carrying out power flow adjustment on the generators in the control generator set, calculating an integral area of which the voltage of the weak node is lower than a set threshold value in a simulation process, and determining an active adjustment measure to adjust the active power of the generators in the control generator set to the minimum active output when the integral area is smaller than or equal to a target value.
7. The system of claim 6, the second establishing unit further to: and when the integral area is larger than the target value, continuing to select the generator with high track sensitivity and adding the generator to the control generator set.
8. The system of claim 6, wherein the determining unit is configured to determine weak nodes of dynamic voltage regulation capability, and comprises:
transient time domain simulation is carried out on the expected fault, the voltage condition of each node in the simulation process is tracked, the integral area Vdrop, the duration Tlow and the lowest voltage Vmin of each node voltage lower than a set threshold value are calculated, and weak nodes with dynamic voltage regulation capability meeting preset criterion conditions are searched out based on the integral area Vdrop, the duration Tlow and the lowest voltage Vmin.
9. The system of claim 6, the first establishing unit for searching for generators active on the voltage of the weak node, establishing an active set of generators, comprising:
and searching the generators with the voltage sensitivity greater than a preset voltage sensitivity threshold and the voltage drop greater than a voltage drop threshold, and establishing an effective generator set.
10. The system of claim 6, wherein the result unit is configured to determine an active adjustment measure of the generators of the control generator set according to the control target value of the voltage sag area predetermined by the generators of the control generator set for the weak node, and comprises:
obtaining voltage drop area Vdrop of weak nodei 0According to a predetermined control target value Vdrop of the voltage drop areai tgvCalculating an accumulated contribution value of the voltage drop area of the weak node, stopping when the accumulated contribution value meets the following formula, and determining active adjustment measures of the generators of the control generator set;
UnSetCto control the generator set, k is the generator, dVdropi kThe reduced value of the voltage drop area of the weak node i.
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| CN105098763A (en) * | 2014-05-16 | 2015-11-25 | 国家电网公司 | Transient voltage stable on-line assessment method based on WAMS and EMS |
| CN106684855A (en) * | 2015-11-10 | 2017-05-17 | 中国电力科学研究院 | Transient stability emergency control method based on key branch identification |
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| CN105098763A (en) * | 2014-05-16 | 2015-11-25 | 国家电网公司 | Transient voltage stable on-line assessment method based on WAMS and EMS |
| CN106684855A (en) * | 2015-11-10 | 2017-05-17 | 中国电力科学研究院 | Transient stability emergency control method based on key branch identification |
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