Transient stability evaluation method and device for multi-machine power system

Abstract

The invention discloses a transient stability evaluation method and device for a multi-machine power system, and the method comprises the steps: obtaining a data set of a multi-machine power system model based on a dense channel fault condition, and the data set comprises a generator constant voltage node and a network node; constructing a transient stability index, and constructing a wave equation of each network node of the multi-machine power system model based on the transient stability index; and evaluating the transient stability of the multi-machine power system based on the wave equation and the transient stability index. The transient stability evaluation is prevented from depending on field data, the limitation is large, and the accuracy and the practicability of the transient stability evaluation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a transient stability assessment method and device for a multi-machine power system. Background Art

[0002] The instability of power systems can have significant economic consequences. The increasing load demand in power systems, but limited investment in facilities, forces the power network to carry more power than it is designed to bear, greatly reducing the transient stability margin of the power network. Transient stability refers to the ability of the system to maintain synchronization when a transmission line fails. Transient stability assessment (TSA) plays an important role in determining system operating limits and operating guidelines. During the planning stage, a transient stability assessment of the power system is required to determine whether additional equipment needs to be installed and where to install it to enhance transient stability.

[0003] The traditional transient stability assessment method uses an alternative TSA method with an energy function, called the direct method, which can determine transient stability without calculating the numerical integral of the power system after a fault. In addition to speed, the direct method also provides a quantitative measure of transient stability. A major disadvantage of the direct method is that the models it can handle are too simple. Moreover, current stability assessment methods ignore the situation where there are dense transmission channels in the power system. Existing TSA usually uses the rotor angle as a reference, such as the center of inertia (COI) angle. However, due to the possible errors in field data, such as time synchronization errors, transducer errors, phasor measurement unit algorithm errors, network attacks, etc.; the calculation of the center of inertia angle requires the connection status of all generators. Due to the open access to the power system network, offline analysis may not be fully correlated with online data. Traditional transient stability assessment methods rely on field data and have great limitations. They are prone to data leakage or inaccurate assessment due to errors or network attacks. Summary of the invention

[0004] The present invention provides a method and device for evaluating transient stability of a multi-machine power system, so as to improve the efficiency and accuracy of transient stability evaluation.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a transient stability assessment method for a multi-machine power system, comprising:

[0006] Acquire a data set of a multi-machine power system model based on a dense channel fault condition, the data set including generator constant voltage nodes and network nodes;

[0007] Constructing a transient stability index, and constructing a wave equation of each network node of the multi-machine power system model based on the transient stability index;

[0008] The transient stability of the multi-machine power system is evaluated based on the wave equation and the transient stability index.

[0009] In this embodiment, by obtaining a fault condition data set for dense transmission channels, including generator constant voltage nodes and network nodes, the dynamic behavior of the power system under various fault conditions can be more comprehensively reflected, thereby constructing a transient stability index based on voltage values ​​and voltage differential values, and by analyzing the time-varying voltage and current of each network node in the multi-machine power system model, the corresponding wave equation is constructed, which can more realistically capture the dynamic characteristics of the system. This method gets rid of the dependence on simple models, making the evaluation results more accurate and adaptable, avoiding the dependence of transient stability evaluation on field data, which has great limitations, and improving the accuracy and practicality of transient stability evaluation.

[0010] Furthermore, the transient stability index includes a voltage value and a voltage differential value. When the transient stability index changes over time, the value of the transient stability index is the first local maximum value.

[0011] Furthermore, the transient stability index is specifically:

[0012]

[0013] Among them, VdV is the transient stability index, V is the voltage value, dV is the voltage differential value, and t0 is the time.

[0014] Furthermore, the wave equations of each network node of the multi-machine power system model are constructed based on the transient stability index, including:

[0015] Obtaining the time-varying voltage and current of each network node in the multi-machine power system model, and constructing the voltage polar coordinates and current phasors of each network node;

[0016] constructing an admittance matrix based on time-varying voltages and currents of connections in the multi-machine power system model;

[0017] Acquire active power and reactive power of the multi-machine power system model based on the admittance matrix, voltage polar coordinates and current phasors;

[0018] A wave equation of the multi-machine power system model is constructed based on the active power, the reactive power and the transient stability index.

[0019] Furthermore, the evaluating the transient stability of the multi-machine power system based on the wave equation and the transient stability index includes:

[0020] Calculating the transient stability index value of each network node based on the Lambert function and the wave equation;

[0021] The transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold.

[0022] In a second aspect, the present invention provides a transient stability assessment device for a multi-machine power system, comprising: a node acquisition module, a wave equation construction module, and an assessment module;

[0023] The node acquisition module is used to acquire a data set of a multi-machine power system model based on a dense channel fault situation, wherein the data set includes a generator constant voltage node and a network node;

[0024] The wave equation construction module is used to construct a transient stability index and construct a wave equation of each network node of the multi-machine power system model based on the time-varying voltage and current of each network node in the multi-machine power system model;

[0025] The evaluation module is used to evaluate the transient stability of the multi-machine power system based on the wave equation and the transient stability index.

[0026] Furthermore, the transient stability index includes a voltage value and a voltage differential value. When the transient stability index changes over time, the value of the transient stability index is the first local maximum.

[0027] Furthermore, the transient stability index is specifically:

[0028]

[0029] Among them, VdV is the transient stability index, V is the voltage value, dV is the voltage differential value, and t0 is the time.

[0030] Furthermore, the wave equation building module includes:

[0031] Obtaining the time-varying voltage and current of each network node in the multi-machine power system model, and constructing the voltage polar coordinates and current phasors of each network node;

[0032] constructing an admittance matrix based on time-varying voltages and currents of connections in the multi-machine power system model;

[0033] Acquire active power and reactive power of the multi-machine power system model based on the admittance matrix, voltage polar coordinates and current phasors;

[0034] A wave equation of the multi-machine power system model is constructed based on the active power, the reactive power and the transient stability.

[0035] Furthermore, the evaluation module includes:

[0036] Calculating the transient stability index value of each network node based on the Lambert function and the wave equation;

[0037] The transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of a transient stability assessment method for a multi-machine power system provided in an embodiment of the present invention;

[0039] Figure 2 A structural schematic diagram of a multi-machine power system model provided by an embodiment of the present invention;

[0040] Figure 3 A transient stability assessment result diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0042] The terms "first" and "second" and the like in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] Example 1

[0045] See also Figure 1 , Figure 1 The flowchart of a transient stability assessment method for a multi-machine power system provided in an embodiment of the present invention is as follows. The embodiment of the present invention provides a transient stability assessment method for a multi-machine power system, including steps 101 to 103, which are as follows:

[0046] Step 101: acquiring a data set of a multi-machine power system model based on a dense channel fault condition, the data set including generator constant voltage nodes and network nodes;

[0047] Please refer to Figure 2 , Figure 2 A structural schematic diagram of a multi-machine power system model provided by an embodiment of the present invention.

[0048] In this embodiment, a multi-machine power system model is constructed based on the line parameters of the multi-machine power system, and system parameters of the multi-machine power system model are initialized. The system parameters include system frequency, fault type and load model.

[0049] In this embodiment, taking the 39-node system as an example, the line parameters of the 39 power system are obtained, a multi-machine power system model is constructed based on the line parameters, and the multi-machine power system model is initialized, and the system frequency is set to 60Hz, the fault type is a three-phase ground fault, and the fault duration is 0.001s. The power generation of the system generator is that the generator G6 outputs 100%, and the other generators output 80%. Among them, the active power of the load model is a constant current characteristic when the voltage is ~1.0pu, and it switches to a constant impedance characteristic when the voltage is less than 0.7V; the reactive power remains a constant impedance characteristic, and the multi-machine power system model and system parameters are simulated.

[0050] In this embodiment, a data set of a multi-machine power system model is obtained based on a dense channel fault situation, a generator constant voltage node and a network node of the multi-machine power system model are obtained, and the generator constant voltage node and the network node are marked.

[0051] In this embodiment, the generator constant voltage nodes are recorded as E1 to EN, and the network nodes are recorded as V1 to VN. The generators from E1 to EG are used as constant internal voltage sources E, and their terminal voltages V include V1 to V G , and the terminal voltage V varies with time. These constant voltage nodes are connected to the V G+1 To V N on the network node.

[0052] In this embodiment, by constructing a multi-machine power system model for the fault conditions of dense transmission channels and obtaining the generator constant voltage nodes and network nodes of the multi-machine system model, the dynamic behavior of the power system under various fault conditions can be more comprehensively reflected. At the same time, simulation is performed using the multi-machine power system model to further improve the accuracy of the simulation, thereby improving the accuracy of the transient stability assessment.

[0053] Step 102: constructing a transient stability index, and constructing a wave equation of each network node of the multi-machine power system model based on the transient stability index;

[0054] In this embodiment, the transient stability indicator VdV is constructed based on the voltage value and the voltage differential value.

[0055] In this embodiment, the transient stability index includes a voltage value and a voltage differential value. When the transient stability index changes over time, the value of the transient stability index is the first local maximum. The transient stability index is specifically:

[0056]

[0057] Among them, VdV is the transient stability index, V is the voltage value, dV is the voltage differential value, and t0 is the time.

[0058] In this embodiment, in a multi-machine power system, the interaction between each generator and the load is complex, and the product of the voltage value and the voltage change rate can better adapt to this complexity. The product of the voltage value and the voltage differential value directly reflects the instantaneous change of the voltage in the power system and the stability state of the system, providing accurate stability evaluation results. The static level of voltage (voltage value) and the dynamic change rate (voltage differential value) are considered at the same time, which comprehensively reflects the transient stability of the power system. This comprehensiveness makes the evaluation results more comprehensive and reliable. Constructing a transient stability index based on the voltage value and the voltage differential value can clearly indicate the voltage stability of the power system at a specific moment; and the voltage differential value represents the voltage change rate, which can sensitively reflect the dynamic changes of the power system in a short period of time. When a disturbance or fault occurs, the change of this indicator can promptly identify possible stability problems of the system.

[0059] In this embodiment, the wave equations of each network node of the multi-machine power system model are constructed based on the transient stability index, including:

[0060] Obtaining the time-varying voltage and current of each network node in the multi-machine power system model, and constructing the voltage polar coordinates and current phasors of each network node;

[0061] constructing an admittance matrix based on time-varying voltages and currents of connections in the multi-machine power system model;

[0062] Acquire active power and reactive power of the multi-machine power system model based on the admittance matrix, voltage polar coordinates and current phasors;

[0063] A wave equation of the multi-machine power system model is constructed based on the active power, the reactive power and the transient stability index.

[0064] In this embodiment, each network node in the multi-machine power system model is obtained. The generator constant voltage nodes in the multi-machine power system model include E1 to EN, and the network nodes include V1 to VN. Generators E1 to EG are constant internal voltage sources E, and their terminal voltages V include V1 to V G , and the terminal voltage V varies with time. These constant voltage nodes are connected to the V G+1 To V N on the network node.

[0065] In this embodiment, based on the time-varying voltage and current of each network node in the multi-machine power system model, the voltage polar coordinates and current phasors of each network node are constructed. Specifically:

[0066]

[0067] I E1 (t),I E2 (t),…,I EG (t),I V1 (t),…,I VN (t) (4)

[0068] Among them, E i is the constant voltage node E i The voltage amplitude, θ Ei (t) is node E i The voltage phase angle at time t, j is an imaginary unit, t represents the time, V i (t) represents node E i The voltage at time t, Represents node E i Polar coordinates of voltage, I Ei (t) represents node E i The current vector.

[0069] In this embodiment, the wave equations of network nodes 1-n are calculated, specifically:

[0070] The equations for current and voltage are expressed based on the admittance matrix Y, namely:

[0071]

[0072] In this embodiment, since the line resistance and load in the multi-machine power system are not considered, the line admittance is:

[0073]

[0074] Among them, B ij represents the line susceptance between nodes i and j, X Represents a terminal node.

[0075] In this embodiment, the active power and reactive power of each network node are calculated by the line susceptance between the nodes, and the wave equation of each network node is constructed based on the active power, reactive power and transient stability index.

[0076] In this embodiment, a certain network node is selected as the generator terminal node, and the generator constant voltage node is connected to other nodes through the network node.

[0077] As a specific example of the embodiment of the present invention, the network node V1 is selected as the generator terminal node, and the generator constant voltage node E1 is connected to other nodes through V1. ij Convert to B′ ij To eliminate the node voltage and current of the next node from V1 to VN, we get:

[0078]

[0079] Further we get:

[0080]

[0081] Among them, E i is the constant voltage node E i The voltage amplitude, θ Ei (t) is node E i The voltage phase angle at time t, j is an imaginary unit, t represents the time, V i (t) represents node E i The voltage at time t, Represents node E i Polar coordinates of voltage, I Ei (t) represents node E i The current vector, B ij represents the line susceptance between nodes i and j.

[0082] Multiplying the above equation by the voltage at the generator terminal node V1 yields:

[0083]

[0084] Among them, E i is the constant voltage node E i The voltage amplitude, θ Ei (t) is node E i The voltage phase angle at time t, j is an imaginary unit, t represents the time, V i (t) represents node E i The voltage at time t, Represents node E i Polar coordinates of voltage, I Ei (t) represents node Ei The current vector, B ij represents the line susceptance between nodes i and j.

[0085] Since the generator terminal node V1 is not a current source node, I1(t)=0.

[0086] Therefore, the active power of the system is:

[0087] B E1V1 V1(t)E1sin(θ V1 (t)-θ E1 (t))+B E2V1 V1(t)E2sin(θ V1 (t)-θ E2 (t))+…+B EGV1 V1(t)E G sin(θ V1 (t)-θ EG (t))=0 (10)

[0088] Among them, E i is the constant voltage node E i The voltage amplitude, θ Ei (t) is node E i The voltage phase angle at time t, j is an imaginary unit, t represents the time, V i (t) represents node E i The voltage at time t, Represents node E i Polar coordinates of voltage, I Ei (t) represents node E i The current vector, B ij represents the line susceptance between nodes i and j.

[0089] The total reactive power of the system is:

[0090] -B E1V1 V1(t)E1cos(θ V1 (t)-θ E1 (t))-B E2V1 V1(t)E2cos(θ V1 (t)-θ E2 (t))-…-B EGV1 V1(t)E G cos(θ V1 (t)-θ EG (t))-B V1V1 V1(t)V1(t)=0 (11)

[0091] Among them, E i is the constant voltage node Ei The voltage amplitude, θ Ei (t) is node E i The voltage phase angle at time t, j is an imaginary unit, t represents the time, V i (t) represents node E i The voltage at time t, Represents node E i Polar coordinates of voltage, I Ei (t) represents node E i The current vector, B ij represents the line susceptance between nodes i and j.

[0092] Derivative both sides of the reactive power formula with respect to time t:

[0093] B V1V1 dV1(t) / dt=B E1V1 E1(ω V1 (t)-ω E1 (t))sin(θ V1 (t)-θ E1 (t))+B E2V1 E2(ω V1 (t)-ω E2 (t))sin(θ V1 (t)-θ E2 (t))+…+B EGV1 E G (ω V1 (t)-ω EG (t))sin(θ V1 (t)-θ EG (t)) (12)

[0094] Multiplying both sides of the above equation by V1(t) yields:

[0095] B V1V1 V1(t)dV1(t) / dt=ω V1 (t)((B E1V1 V1(t)E1sin(θ V1 (t)-θ E1 (t)))+B E2V1 V1(t)E2sin(θ V1 (t)-θ E2 (t))+…+B EGV1 V1(t)E G sin(θ V1 (t)-θ EG (t)))-ω E1 (t)B E1V1 V1(t)E1sin(θ V1 (t)-θE1 (t))-ω E2 (t)B E2V1 V1(t)E2sin(θ V1 (t)-θ E2 (t))-ω EG (t)B EGV1 V1(t)E G sin(θ V1 (t)-θ EG (t)) (13)

[0096] Substituting the system's active power formula into the above formula yields:

[0097] B V1V1 V1(t)dV1(t) / dt=-ω E1 (t)B E1V1 V1(t)E1sin(θ V1 (t)-θ E1 (t))-ω E2 (t)B E2V1 V1(t)E2sin(θ V1 (t)-θ E2 (t))-ω EG (t)B EGV1 V1(t)E G sin(θ V1 (t)-θ EG (t)) (13) The active power output from E1 to EG of each generator connected to the generator terminal node V1 is expressed as follows:

[0098] P e1 (t) = B E1V1 V1(t)E1sin(θ V1 (t)-θ E1 (t)) (14)

[0099]

[0100] After finishing, we get:

[0101]

[0102] Among them, E i is the constant voltage node E i The voltage amplitude, θ Ei (t) is node E i The voltage phase angle at time t, j is an imaginary unit, t represents the time, V i (t) represents node E i The voltage at time t, Represents node E iPolar coordinates of voltage, I Ei (t) represents node E i The current vector, B ij represents the line susceptance between nodes i and j.

[0103] Next, decompose it into the following two formulas:

[0104] -k i V1(t)dV1(t) / dt=ω Ei (t)P ei (t),i∈1,…,G (18)

[0105] -k ij V1(t)dV1(t) / dt=ω EiEj (t)B EiEj E i E j sinθ EiEj (t)i,j∈{1,…,G},{i,j≠1},{i≠j},{i<j} (19)

[0106] In the formula, θ EiEj (t) = θ Ei (t)-θ Ej (t),ω EiEj (t) = ω Ei (t)-ω Ej (t), k i and k ij is the positive coefficient corresponding to the decomposition of equations (18) and (19).

[0107] In this embodiment, V1(t)dV1(t) / dt is a constant, which is usually taken in the range near the first local maximum of V1(t)dV1(t) / dt and V1dV1. Solving the angle differential equation yields:

[0108]

[0109] ω EiEj (0) = ω EiEj0 (twenty one)

[0110] therefore,

[0111] Since the right side of the above formula Being a constant, the local maximum of V1dV1 can be used as a transient stability indicator, and its right side is calculated from the simulation and used as the stability threshold.

[0112] Based on the above active power and reactive power, i.e. transient stability index, the wave equation of nodes 1-n is obtained:

[0113]

[0114] Among them, M i is the inertia coefficient, P ei and P mi is the mechanical power. Then the wave equation is obtained as:

[0115]

[0116] In this embodiment, by analyzing the time-varying voltage and current of each network node in the multi-machine power system model and constructing the corresponding wave equation, the dynamic characteristics of the system can be captured more realistically. This method gets rid of the dependence on simple models and makes the evaluation results more accurate and adaptable.

[0117] Step 103: Evaluate the transient stability of the multi-machine power system based on the wave equation and the transient stability index.

[0118] The evaluating the transient stability of the multi-machine power system based on the wave equation and the transient stability index includes:

[0119] Calculating the transient stability index value of each network node based on the Lambert function and the wave equation;

[0120] The transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold.

[0121] In this embodiment, the wave equation is solved using the Lambert function, the coefficients of the wave equation are calculated based on the Lambert function, and the transient stability index is separated from the wave equation to calculate the transient stability index value of each network node.

[0122] In this embodiment, the Lambert function expression is:

[0123] W -1 (x) = xe x (twenty four)

[0124]

[0125] Assumptions are made on the wave equation expression:

[0126]

[0127] Where: C1, C2 and C3 are constants. Further we get:

[0128]

[0129] The contrast coefficient is:

[0130]

[0131] Among them, W(x) has only one real solution when the domain constraint x>0. Therefore, the above formula also has only one real solution, so its stability condition is V1dV1>-P mi ω i0 / k i , since the right side is a constant, the local maximum value of V1dV1 can be used as the transient stability index.

[0132] In this embodiment, the transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold.

[0133] In this embodiment, the transient stability of the power system is evaluated based on the existence of a solution to the wave equation.

[0134] As a specific example of the embodiment of the present invention, please refer to Figure 3 , Figure 3 A transient stability assessment result diagram provided by an embodiment of the present invention.

[0135] A CCT fault is created for all generator terminal voltage buses, the fault is set between nodes 3 and 4, and the calculated VdV maximum value is used as the threshold for each node. Since the value of the node in the figure represents the difference between the threshold of the compared fault and VdV. The transient stability evaluation result diagram includes the difference between the transient stability index value of the network node and the stability threshold of each network node. The larger the negative value, the stronger the transient stability, the closer it is to zero and the darker the color in the figure.

[0136]

[0137] Table 1

[0138] Please refer to Table 1, which is a comparative time table of fault clearing using angle index and transient stability index provided by an embodiment of the present invention. It lists the local maximum values ​​and predicted required time of the angle index and VdV index at different clearing times. In this embodiment, in this power system model, the fault clearing time ranges from 32ms to 52ms, and the CCT is 42ms. The fault is set between nodes 21 and 22. Compared with the angle index, the VdV index predicts transient stability in a shorter time. In addition, even in the case of unstable power system, the VdV index will have a local maximum value. For example, in the case of fluctuations when the clearing time is 52ms, VdV is 0.42.

[0139] In this embodiment, the results show that the transient stability indicator VdV shows an unstable interval and evaluates the transient stability by comparing the thresholds. Although the model is stable due to CCT fault, the transient stability is mistakenly predicted as unstable because nodes 7 and 8 are positive. However, these positive values ​​are almost zero and are regarded as errors in the VdV indicator. In addition, this error is caused by incomplete threshold adjustment. If both the terminal voltage CCT fault and the branch CCT fault are considered when setting the threshold, the error is zero.

[0140] In this embodiment, by obtaining a fault condition data set for dense transmission channels, including generator constant voltage nodes and network nodes, the dynamic behavior of the power system under various fault conditions can be more comprehensively reflected, thereby constructing a transient stability index based on voltage values ​​and voltage differential values, and by analyzing the time-varying voltage and current of each network node in the multi-machine power system model, the corresponding wave equation is constructed, which can more realistically capture the dynamic characteristics of the system. It gets rid of the dependence on simple models, making the evaluation results more accurate and adaptable, avoiding the dependence of transient stability evaluation on field data, which has great limitations, and improving the accuracy and practicality of transient stability evaluation.

[0141] The embodiment of the present invention also provides a transient stability assessment device for a multi-machine power system, comprising: a node acquisition module, a wave equation construction module and an assessment module;

[0142] The node acquisition module is used to acquire a data set of a multi-machine power system model based on a dense channel fault situation, wherein the data set includes a generator constant voltage node and a network node;

[0143] The wave equation construction module is used to construct a transient stability index and construct a wave equation of each network node of the multi-machine power system model based on the time-varying voltage and current of each network node in the multi-machine power system model;

[0144] The evaluation module is used to evaluate the transient stability of the multi-machine power system based on the wave equation and the transient stability index.

[0145] In this embodiment, the transient stability index includes a voltage value and a voltage differential value. When the transient stability index changes over time, the value of the transient stability index is the first local maximum.

[0146] In this embodiment, the transient stability index is specifically:

[0147]

[0148] Among them, VdV is the transient stability index, V is the voltage value, dV is the voltage differential value, and t0 is the time.

[0149] In this embodiment, the wave equation building module includes:

[0150] Obtaining the time-varying voltage and current of each network node in the multi-machine power system model, and constructing the voltage polar coordinates and current phasors of each network node;

[0151] constructing an admittance matrix based on time-varying voltages and currents of connections in the multi-machine power system model;

[0152] Acquire active power and reactive power of the multi-machine power system model based on the admittance matrix, voltage polar coordinates and current phasors;

[0153] A wave equation of the multi-machine power system model is constructed based on the active power, the reactive power and the transient stability index.

[0154] In this embodiment, the evaluation module includes:

[0155] Calculating the transient stability index value of each network node based on the Lambert function and the wave equation;

[0156] The transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold.

[0157] In an embodiment of the present invention, a terminal device is also provided, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the above-mentioned transient stability assessment method of a multi-machine power system is implemented.

[0158] In an embodiment of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the above-mentioned multi-device access platform processing method.

[0159] Exemplarily, the computer program may be divided into one or more modules, one or more modules are stored in a memory and executed by a processor to implement the present invention. One or more modules may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program in a terminal device.

[0160] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The terminal device may include, but is not limited to, a processor, a memory, and a display. Those skilled in the art will appreciate that the above components are merely examples of the terminal device and do not constitute a limitation on the terminal device. The terminal device may include more or fewer components than the components, or may combine certain components, or different components. For example, the terminal device may also include input and output devices, network access devices, buses, etc.

[0161] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal device, and uses various interfaces and lines to connect various parts of the entire terminal device.

[0162] The memory can be used to store computer programs and / or modules. The processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function (such as a sound playback function, a text conversion function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, text message data, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0163] Among them, if the module based on the processing of the multi-device access platform is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0164] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A transient stability assessment method for a multi-machine power system, characterized in that: include: Acquire a data set of a multi-machine power system model based on a dense channel fault condition, the data set including generator constant voltage nodes and network nodes; Constructing a transient stability index, and constructing a wave equation of each network node of the multi-machine power system model based on the transient stability index; The transient stability of the multi-machine power system is evaluated based on the wave equation and the transient stability index.

2. A method for evaluating transient stability of a multi-machine power system according to claim 1, characterized in that: The transient stability index includes a voltage value and a voltage differential value. When the transient stability index changes over time, the value of the transient stability index is the first local maximum value.

3. A method for transient stability assessment of a multi-machine power system as claimed in claim 2, characterized in that: The transient stability index is specifically: Among them, VdV is the transient stability index, V is the voltage value, dV is the voltage differential value, and t0 is the time.

4. A method for evaluating transient stability of a multi-machine power system according to claim 3, characterized in that: The wave equations of each network node of the multi-machine power system model are constructed based on the transient stability index, including: Obtaining the time-varying voltage and current of each network node in the multi-machine power system model, and constructing the voltage polar coordinates and current phasors of each network node; constructing an admittance matrix based on time-varying voltages and currents of connections in the multi-machine power system model; Acquire active power and reactive power of the multi-machine power system model based on the admittance matrix, voltage polar coordinates and current phasors; A wave equation of the multi-machine power system model is constructed based on the active power, the reactive power and the transient stability index.

5. A method for evaluating transient stability of a multi-machine power system according to claim 4, characterized in that: The evaluating the transient stability of the multi-machine power system based on the wave equation and the transient stability index includes: Calculating the transient stability index value of each network node based on the Lambert function and the wave equation; The transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold.

6. A transient stability assessment device for a multi-machine power system, characterized in that: include: Node acquisition module, wave equation construction module and evaluation module; The node acquisition module is used to acquire a data set of a multi-machine power system model based on a dense channel fault situation, wherein the data set includes a generator constant voltage node and a network node; The wave equation construction module is used to construct a transient stability index and construct a wave equation of each network node of the multi-machine power system model based on the time-varying voltage and current of each network node in the multi-machine power system model; The evaluation module is used to evaluate the transient stability of the multi-machine power system based on the wave equation and the transient stability index.

7. A transient stability assessment device for a multi-machine power system according to claim 6, characterized in that: The transient stability index includes a voltage value and a voltage differential value. When the transient stability index changes over time, the value of the transient stability index is the first local maximum.

8. A transient stability assessment device for a multi-machine power system according to claim 7, characterized in that: The transient stability index is specifically: Among them, VdV is the transient stability index, V is the voltage value, dV is the voltage differential value, and t0 is the time.

9. A transient stability assessment device for a multi-machine power system according to claim 8, characterized in that: The wave equation building block comprises: Obtaining the time-varying voltage and current of each network node in the multi-machine power system model, and constructing the voltage polar coordinates and current phasors of each network node; constructing an admittance matrix based on time-varying voltages and currents of connections in the multi-machine power system model; Acquire active power and reactive power of the multi-machine power system model based on the admittance matrix, voltage polar coordinates and current phasors; A wave equation of the multi-machine power system model is constructed based on the active power, the reactive power and the transient stability.

10. A transient stability assessment device for a multi-machine power system according to claim 9, characterized in that: The evaluation module comprises: Calculating the transient stability index value of each network node based on the Lambert function and the wave equation; The transient stability of the multi-machine power system is evaluated based on the transient stability index value of each network node and a preset stability threshold.

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