A method and system for fast estimation of the shape of the dynamic security region boundary of a power system

Abstract

The application discloses a kind of fast estimation method of power system dynamic security domain boundary shape, and disclosed with the fast estimation method of power system dynamic security domain boundary shape, wherein the fast estimation method of power system dynamic security domain boundary shape is based on practical DSR, the geometric property of DSR boundary is analyzed: for the same instability mode, different stability margin corresponds to a cluster of hyperplanes parallel to DSR boundary in security domain space. Based on this property, a method for quickly estimating the shape of DSR by increasing the stability margin (second fault clearance time) is designed. Finally, the correctness of the conclusion is verified by using IEEE 3-machine 9-node and IEEE 39-node systems.

Description

Technical Field

[0001] This invention relates to the field of dynamic security technology for power systems, and in particular to a method and system for rapidly predicting the boundary shape of the dynamic security domain of a power system. Background Technology

[0002] The power system security domain is one of the important methods for analyzing the safe and stable operation of the power grid. Developed from the "point-by-point method" (fixed operating mode), the power system security domain not only indicates whether the power grid's operating state is safe, but also provides safety margins and control directions.

[0003] The dynamic security region (DSR) is typically defined in the power injection space and consists of a set of operating points (on a fixed set of faults) that guarantee the transient stability of the system. Determining the DSR requires considering three time periods of the power system: before, during, and after a fault, and involves solving both algebraic and differential equations. Existing methods for determining the DSR based on simulation and fitting often require significant computational resources. Therefore, predicting the shape of the DSR using its physical and geometric properties is crucial for determining the final DSR and for the preventative control of the system. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a rapid prediction method for the dynamic safety domain boundary shape of a power system. The proposed method, which rapidly predicts the DSR shape by increasing the stability margin (second fault clearing time), can effectively reduce the exploration space of the DSR, reduce the computational requirements, and also enable preventive control of the power system based on the predicted DSR shape.

[0005] The present invention also proposes an apparatus for a rapid prediction method of the boundary shape of the dynamic security domain of a power system as described above.

[0006] A method for rapidly predicting the shape of the dynamic security domain boundary of a power system according to a first aspect embodiment of the present invention is characterized by comprising the following steps:

[0007] The geometric properties of the dynamic security domain are obtained based on the characteristic analysis of the dynamic security domain of the power system.

[0008] The geometric properties of the dynamic security domain are obtained based on the characteristic analysis of the dynamic security domain of the power system.

[0009] Establish a simulation environment for the system under study, and set the fault set and its initial fault clearing time;

[0010] Determine the initial running point;

[0011] Increase the fault clearing time of the fault set to the second fault clearing time;

[0012] Using the initial running point as the origin, explore the transient stability boundary of the second fault clearing time in the surrounding area, and obtain the shape of the transient stability boundary corresponding to the second fault clearing time.

[0013] Based on the geometric properties of the dynamic security domain, it can be deduced that the transient stable boundary shape corresponding to the second fault clearing time is similar to the transient stable boundary shape corresponding to the initial fault clearing time.

[0014] The method for rapidly predicting the dynamic safety domain boundary shape of a power system according to embodiments of the present invention has at least the following beneficial effects: by increasing the stability margin (second fault clearing time) to rapidly predict the DSR shape, the exploration space of the DSR can be effectively reduced, the computational requirements can be reduced, and the power system can be preventively controlled based on the predicted DSR shape.

[0015] According to some embodiments of the present invention, the geometric properties of the dynamic safety domain are as follows: for the same instability mode, different stability margins correspond to a set of hyperplanes parallel to the boundary of the dynamic safety domain in the safety domain space, and the greater the stability margin, the farther the operating point is from the boundary of the dynamic safety domain.

[0016] According to some embodiments of the present invention, the dynamic security domain of the power system consists of a set of stable operating points, which can be represented by the following formula:

[0017]

[0018] Where T0 and T1 represent the network structures of the system before and after the fault, respectively; F represents the fault under study; x β x is the run point in the defined DSR space. τ (x β ) indicates the state of the system at the moment of fault clearing.

[0019] According to some embodiments of the present invention, this method takes the power injection space as the research object. For high-voltage transmission networks, it is assumed that the reactive power is sufficient to ensure the stability of the system voltage.

[0020] According to some embodiments of the present invention, in the step of exploring the transient stable boundary of the second fault clearing time with the initial running point as the origin and obtaining the transient stable boundary shape corresponding to the second fault clearing time, the method selected is the uniform point exploration method.

[0021] A method apparatus for rapidly predicting the shape of the dynamic security domain boundary of a power system according to a second aspect embodiment of the present invention, characterized in that it comprises:

[0022] The geometric analysis module can obtain the geometric properties of the dynamic security domain based on the characteristics of the dynamic security domain of the power system;

[0023] The simulation environment setup module can establish a simulation environment for the system under study and set the fault set and its initial fault clearing time.

[0024] Running the startup module can determine the initial running point;

[0025] The fault delay module is used to extend the fault clearance time of the fault set to a second fault clearance time;

[0026] The boundary exploration module can explore the transient stable boundary of the second fault clearing time with the initial running point as the origin, and obtain the shape of the transient stable boundary corresponding to the second fault clearing time.

[0027] Based on the geometric properties of the dynamic security domain, it can be deduced that the transient stable boundary shape corresponding to the second fault clearing time is similar to the transient stable boundary shape corresponding to the initial fault clearing time.

[0028] The method and apparatus for rapidly predicting the dynamic safety domain boundary shape of a power system according to an embodiment of the present invention has at least the following beneficial effects: the method of rapidly predicting the DSR shape by increasing the stability margin (second fault clearing time) can effectively reduce the exploration space of DSR, reduce the computational requirements, and can also perform preventive control of the power system based on the predicted DSR shape.

[0029] According to some embodiments of the present invention, the geometric properties of the dynamic safe domain obtained by the geometric analysis module are as follows: for the same instability mode, different stability margins correspond to a set of hyperplanes parallel to the boundary of the dynamic safe domain in the safe domain space, and the greater the stability margin, the farther the operating point is from the boundary of the dynamic safe domain.

[0030] According to some embodiments of the present invention, the dynamic security domain of the power system consists of a set of stable operating points, which can be represented by the following formula:

[0031]

[0032] Where T0 and T1 represent the network structures of the system before and after the fault, respectively; F represents the fault under study; x β x is the run point in the defined DSR space. τ (x β ) indicates the state of the system at the moment of fault clearing.

[0033] According to some embodiments of the present invention, the device takes the power injection space as the research object. For high-voltage transmission networks, it is assumed that the reactive power is sufficient to ensure the stability of the system voltage.

[0034] According to some embodiments of the present invention, the boundary exploration module uses a uniform point exploration method.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 This is a schematic diagram illustrating the steps of a method for rapidly predicting the boundary shape of a dynamic security domain in a power system according to an embodiment of the present invention.

[0038] Figure 2 A schematic diagram of simulation-based DSR boundary shape prediction provided for an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of an IEEE 3-machine, 9-node system provided in an embodiment of the present invention;

[0040] Figure 4 A schematic diagram of the second fault clearing time in the PG2 and PG3 spaces of a 3-machine 9-node system provided in an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of IEEE 39 nodes provided for an embodiment of the present invention;

[0042] Figure 6 A schematic diagram of the second fault clearing time in the PG33 and PG34 spaces of the IEEE 39-node system provided for an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of the structure of a device for rapidly predicting the boundary shape of the dynamic security domain of a power system, provided in an embodiment of the present invention. Detailed Implementation

[0044] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0045] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0046] In determining the dynamic security region (DSR) of a power system, traditional techniques often require extensive calculations through simulation, which consumes significant computing resources. As the scale of power systems continues to expand, the calculation process needs to be optimized to conserve computing resources and better coordinate the resource allocation of the entire power system.

[0047] To reduce the computational resources consumed in DSR calculation, this application proposes a fast prediction method for the boundary shape of the dynamic security domain of a power system, referring to... Figure 1 The method includes the following steps:

[0048] Step S100: Obtain the geometric properties of the dynamic security domain based on the characteristic analysis of the dynamic security domain of the power system.

[0049] To simplify the DSR simulation process, the derivation is based on its geometric properties, thereby reducing the computational load of the simulation process and significantly reducing the computational resource consumption in determining the DSR.

[0050] Step S200: Establish the simulation environment of the system to be studied, and set the fault set and its initial fault clearing time.

[0051] Step S300: Determine the initial running point.

[0052] Step S400: Increase the fault clearing time of the fault set to the second fault clearing time.

[0053] Step S500: Using the initial running point as the origin, explore the transient stability boundary of the second fault clearing time in the surrounding area, and obtain the shape of the transient stability boundary corresponding to the second fault clearing time.

[0054] Furthermore, the derivation logic of step S100 is as follows:

[0055] The Dynamic Stability (DSR) of a power system consists of a set of operating points that guarantee the transient stability of the system (on a fixed set of faults), and can be expressed by the following formula:

[0056]

[0057] In the formula, T0 and T1 represent the network structure of the system before and after the fault, respectively; F represents the fault under study; and represents the operating point under the defined DSR space. This application takes the power injection space. For high-voltage transmission networks, assuming that reactive power is sufficient to ensure system voltage stability, can be taken as . n represents the number of nodes excluding the balancing machine node; x τ (x β S(x) represents the state of the system at the moment of fault clearing; β ) indicates the system's initial operating point x after the fault. β The stability region under Ω. d The points within are all x in the power injection space that can ensure transient stability before the accident. β A set of.

[0058] Equation (1) shows that the system Ω d The determination of S(x) β This relates to the relationship between the system's transient energy and critical energy in stability domain studies.

[0059] Since the DSR and the stability region have the mapping relationship described in equation (1), the energy function method also provides a theoretical basis for the analysis of DSR. If the system suffers a fault disturbance, the criterion for whether the system can remain stable is:

[0060]

[0061] Among them, V c KE and V c PE V represents the kinetic and potential energy of the system at the moment of fault clearing. cr V is the critical energy of the system. d =V cr -V c PE ΔV is called the stability margin. For a fixed set of faults, all operating points within the DSR satisfy the condition ΔV > 0.

[0062] Furthermore, ΔV has the following relationship with the distance S from the operating point to the DSR boundary:

[0063]

[0064] Where K represents the normal vector of the DSR boundary, and different instability modes correspond to different K; P and P' are the power injection vectors at the points on the DSR boundary and the operating point under the studied instability mode, respectively; P emax and P e They are respectively The power value after P is equal to infinite power for a single unit.

[0065] According to equation (3), the geometric properties obtained in step S100 are as follows:

[0066] For the same instability mode, different stability margins correspond to a set of hyperplanes parallel to the DSR boundary within the safe domain space, and the greater the stability margin, the farther the operating point is from the dynamic DSR boundary inside the DSR.

[0067] Furthermore, steps S200 to 500 constitute the DSR boundary shape prediction process.

[0068] Based on the geometric properties obtained in step S100, we understand that the shape of DSR can be predicted by increasing ΔV. However, the calculation of ΔV is usually complex and difficult to apply directly. But the second fault clearing time t... cc Simulation processes are widely used and readily available; therefore, this method uses a specific fault t. cc To represent the stability margin. For the same operating point, t cc The larger the value, the larger the ΔV for that fault.

[0069] Reference Figure 2 The estimation process in steps S200 to S500 can be described as follows:

[0070] 1. Establish a simulation environment for the system under study, given the fault set F, where the fault clearing time t is... c0 Given.

[0071] 2. Determine an initial running point, such as... Figure 2 The red running point x0 is shown in the middle.

[0072] 3. Increase the second fault clearing time t in fault set F. c1 , making t c1 >t c0 ;

[0073] 4. Explore the second fault clearance time t around x0 as the origin. cc =t c1 The boundary that guarantees transient stability is the DSR boundary.

[0074] Increasing the fault clearing time will decrease DSR1, but it will still have a similar shape to the original DSR0 (corresponding to the same instability mode, with parallel boundaries), thus effectively reducing the number of points that need to be explored. For example... Figure 2 As shown, when t cc =t c0 The DSR obtained at that time is the outer circle region in the figure, t cc =t c1The time is the inner circle area in the diagram, which obviously reduces the exploration range of the initial point.

[0075] It is understandable that Figure 2 The exploration point method shown in this paper is the uniform exploration point method, which is a commonly used method in this field. However, it does not mean that this method must be used. Any other exploration method that can reduce the amount of computation can be used in the method of this application. This is only an example.

[0076] To verify the effectiveness of the method proposed in this application, simulation experiments are now conducted for different systems.

[0077] 1) Taking the IEEE 3-machine 9-node system as an example

[0078] Assume the fault under study is a three-phase short circuit in line 5-7, such as Figure 3 As shown, since this study focuses on DSR, the limits of the static safety domain (such as generator upper and lower limits, line thermal stability limits, etc.) are not considered; only the power angle stability constraints of the system after a short-circuit fault are considered. The load in the fixed system is adjusted by changing the power of generators G2 and G3 to obtain different operating modes (G1 is the balancing machine).

[0079] In actual systems, the safety control action time is typically 0.1s. Through simulation calculations, the DSR boundary of the 3-machine 9-node system in the power injection space is obtained as follows: Figure 4 Chinese cc =0.1s boundary. Gradually increasing the fault duration to 0.4s, calculations showed that t cc =0.2s,t cc =0.3s,t cc At 0.4s, the boundary gradually contracts inwards, while maintaining the same position as t. cc The shapes are similar (i.e., parallel) at 0.1s. Because DSR shrinks to a smaller area, the number of sample points required to explore DSR can be effectively reduced.

[0080] 2) Taking the IEEE 39-node system as an example

[0081] The structure of the IEEE 39-node system is as follows: Figure 5 As shown, a three-phase short circuit is set to occur on line 17-18, with a fault duration of 0.1s (the safety control action time is generally 0.1s). Different operating modes are obtained by changing the generator output. For ease of visualization, Figure 5 The diagram illustrates the second fault clearing time for different operating modes of generators Gen 33 and Gen 34 under the power injection space. Under the studied fault (set), the DSR boundary is as follows: Figure 6 The (t) shown cc=0.10s). Gradually increasing the fault duration to 0.14s, calculations showed that t cc =0.11s,t cc =0.12s,t cc =0.13s,t cc At 0.14s, the boundary gradually contracts inwards, while maintaining the same position as t. cc The shapes are similar at 0.1s. Because DSR shrinks to a smaller area, the number of sample points required to explore DSR can be effectively reduced.

[0082] Furthermore, embodiments of this application provide a method apparatus 70 for rapid prediction of the boundary shape of the dynamic security domain of a power system, such as... Figure 7 As shown, it includes: geometric analysis module 701, simulation environment setup module 702, operation startup module 703, fault delay module 704, and boundary exploration module 705.

[0083] The geometric analysis module 701 is capable of obtaining the geometric properties of the dynamic security domain based on the characteristic analysis of the dynamic security domain of the power system;

[0084] The simulation environment building module 702 can establish a simulation environment for the system under study and set the fault set and its initial fault clearing time.

[0085] Running startup module 703 can determine the initial running point;

[0086] The fault delay module 704 is used to extend the fault clearance time of the fault set to a second fault clearance time;

[0087] The boundary exploration module 705 is able to explore the transient stable boundary of the second fault clearing time around the origin, with the initial running point as the origin, and obtain the shape of the transient stable boundary corresponding to the second fault clearing time.

[0088] Furthermore, the geometric properties of the dynamic safe domain obtained by the geometric analysis module 701 are as follows: for the same instability mode, different stability margins correspond to a set of hyperplanes parallel to the boundary of the dynamic safe domain in the safe domain space, and the greater the stability margin, the farther the operating point is from the boundary of the dynamic safe domain.

[0089] Furthermore, the dynamic security domain of the power system consists of a set of stable operating points, which can be expressed by the following formula:

[0090]

[0091] Where T0 and T1 represent the network structures of the system before and after the fault, respectively; F represents the fault under study; x β x is the run point in the defined DSR space.τ (x β ) indicates the state of the system at the moment of fault clearing.

[0092] Furthermore, the device takes the power injection space as the research object. For high-voltage transmission networks, it is assumed that reactive power is sufficient to ensure system voltage stability.

[0093] Furthermore, the boundary exploration module 705 uses a uniform point exploration method.

[0094] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for fast estimation of the shape of the dynamic security region boundary of a power system, characterized in that, Includes the following steps: The geometric properties of the dynamic security domain are obtained based on the characteristic analysis of the dynamic security domain of the power system. Establish a simulation environment for the system under study, and set the fault set and its initial fault clearing time; Determine the initial running point; Increase the fault clearing time of the fault set to the second fault clearing time; Using the initial running point as the origin, explore the transient stability boundary of the second fault clearing time in the surrounding area to obtain the shape of the transient stability boundary corresponding to the second fault clearing time. Based on the geometric properties of the dynamic security domain, it can be deduced that the transient stable boundary shape corresponding to the second fault clearing time is similar to the transient stable boundary shape corresponding to the initial fault clearing time.

2. The method of claim 1, wherein, Specifically, the geometric properties of the dynamic safety domain are as follows: for the same instability mode, different stability margins correspond to a set of hyperplanes parallel to the boundary of the dynamic safety domain within the safety domain space, and the greater the stability margin, the farther the operating point is from the boundary of the dynamic safety domain.

3. The method of claim 1, wherein, The dynamic security domain of the power system consists of a set of stable operating points, which can be represented by the following formula: where T0, T1denote the network structure of the system before and after the fault respectively; F denotes the fault under study; x β is the operating point in the defined DSR space, x τ (x β ) denotes the state of the system at the moment of fault clearing.

4. The method of claim 3, wherein, This method takes the power injection space as the research object. For high-voltage transmission networks, it is assumed that reactive power is sufficient to ensure system voltage stability.

5. The method of claim 1, wherein, In the step of exploring the transient stable boundary of the second fault clearing time with the initial running point as the origin and obtaining the shape of the transient stable boundary corresponding to the second fault clearing time, the method used is the uniform point exploration method.

6. A method apparatus for fast estimation of power system dynamic security region boundary shape, characterized in that, include: The geometric analysis module can obtain the geometric properties of the dynamic security domain based on the characteristics of the dynamic security domain of the power system; The simulation environment setup module can establish a simulation environment for the system under study and set the fault set and its initial fault clearing time. Running the startup module can determine the initial running point; The fault delay module is used to extend the fault clearance time of the fault set to a second fault clearance time; The boundary exploration module can explore the transient stable boundary of the second fault clearing time with the initial running point as the origin, and obtain the shape of the transient stable boundary corresponding to the second fault clearing time. Based on the geometric properties of the dynamic security domain, it can be deduced that the transient stable boundary shape corresponding to the second fault clearing time is similar to the transient stable boundary shape corresponding to the initial fault clearing time.

7. The apparatus of claim 6, wherein, The geometric properties of the dynamic safe domain obtained by the geometric analysis module are as follows: for the same instability mode, different stability margins correspond to a set of hyperplanes parallel to the boundary of the dynamic safe domain in the safe domain space, and the greater the stability margin, the farther the operating point is from the boundary of the dynamic safe domain.

8. The apparatus of claim 6, wherein, The dynamic security domain of the power system consists of a set of stable operating points, which can be represented by the following formula: Where T0 and T1 represent the network structures of the system before and after the fault, respectively; F represents the fault under study; x β x is the run point in the defined DSR space. τ (x β ) indicates the state of the system at the moment of fault clearing.

9. The apparatus of claim 8, wherein, This device takes the power injection space as the research object. For high-voltage transmission networks, it is assumed that the reactive power is sufficient to ensure the stability of the system voltage.

10. The apparatus of claim 6, wherein, The boundary exploration module uses a uniform point exploration method.

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