CN106100003A - The voltage security assessments method and system of power system - Google Patents

Abstract

The present invention relates to a method and system for evaluating voltage safety of a power system. The method includes: acquiring a plurality of preset operation modes satisfying preset operation conditions and generating a set of state variables corresponding to each of the preset operation modes; The preset fault set evaluates the transient voltage safety corresponding to each of the preset operating modes; linearly fitting the state variable sets corresponding to the multiple target operating modes to obtain the respective corresponding to each of the target operating modes Fitting weight coefficients; and, according to the fitting weight coefficients and transient voltage safety corresponding to the plurality of target operating modes, calculate the transient voltage safety index of the power system in the current operating mode. The voltage safety evaluation method and system of the above-mentioned power system can evaluate the voltage safety index of the current operation mode in real time, has good real-time performance, and has a small amount of simulation calculation, which can realize real-time online safety evaluation and save computing resources.

Description

Method and system for voltage safety assessment of power system

technical field

The invention relates to the technical field of power distribution, in particular to a voltage safety evaluation method and system for a power system.

Background technique

In recent years, with the development of industry and economy, the scale of the power system has been increasing, the structure has become more complex, and the uncertainty of its operation has also been increasing. For example, there are more types of faults in the power system, the fault process is more complex, and the impact of the fault on the safety of the power system is also greater. Security threats to ensure the safe operation of the power system.

In the prior art, there are two methods for evaluating the safety of power systems: one method is to use electromechanical transient simulation programs to analyze the transient characteristics of power systems, but electromechanical transient simulations are only applicable to devices in traditional power grids, It is impossible to accurately simulate the transient process of the AC/DC hybrid power system. Another method is to use the electromagnetic transient simulation program to analyze the transient characteristics of the power system. The electromagnetic transient simulation is suitable for the AC-DC hybrid power system, but it needs to use a cluster computer or even a distributed cloud computing technology. The shortcomings of large volume and difficulty in real-time online analysis.

Contents of the invention

Based on this, it is necessary to provide a voltage security assessment method and system for a power system to address the defect that the existing technology is difficult to accurately analyze the transient security of the power system online in real time.

The first aspect of the embodiments of the present invention provides a voltage security assessment method for a power system, which includes:

Obtaining a plurality of preset operation modes satisfying the preset operation conditions and generating a set of state variables corresponding to each of the preset operation modes;

Evaluating the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set;

performing linear fitting on the state variable sets corresponding to the plurality of target operating modes to obtain fitting weight coefficients respectively corresponding to each of the target operating modes; and

According to the fitting weight coefficients and transient voltage safety corresponding to the plurality of target operation modes, the transient voltage safety index of the power system in the current operation mode is calculated.

In one embodiment, the determining a plurality of preset operating modes satisfying preset operating conditions and generating a set of state variables corresponding to each of the preset operating modes includes:

Determining multiple initial variables for each node in the power system;

According to the Monte Carlo simulation method, generating multiple initial operation modes conforming to the preset value ranges of the multiple initial variables;

performing power flow calculations on the multiple initial operating modes to obtain multiple state variable sets corresponding to the multiple initial operating modes; and

According to the preset operating conditions, a plurality of state variable sets satisfying the preset operating conditions are screened from the plurality of state variable sets, and a corresponding preset operating mode is determined.

In one embodiment, the evaluation of the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set includes:

In each of the preset operation modes, simulating the transient voltage waveform curve of the power system when each fault in the preset fault set occurs; and

The transient voltage safety corresponding to each of the preset operation modes is evaluated according to the transient voltage waveform curve corresponding to each of the preset operation modes.

In one embodiment, the evaluation of the transient voltage safety corresponding to each of the preset operation modes according to the transient voltage waveform curve corresponding to each of the preset operation modes includes:

For each transient voltage waveform curve corresponding to the preset operation mode, judge whether the transient voltage waveform curve satisfies a preset stability condition according to the difference between the last maximum voltage value and the last minimum voltage value;

For each transient voltage waveform curve corresponding to the preset operation mode, judge whether the transient voltage waveform curve satisfies a preset drop condition according to the time interval during which the voltage is continuously lower than the preset voltage threshold; and

For any preset operation mode m _r among the plurality of preset operation modes, if the transient voltage waveform curve corresponding to the preset operation mode m _r satisfies the preset stability condition and the preset drop condition, it is safe to evaluate the safety of the transient voltage corresponding to the preset operation mode m _r , otherwise it is unsafe to evaluate the safety of the transient voltage corresponding to the preset operation mode m _r .

In one embodiment, before performing linear fitting on the state variable sets corresponding to the plurality of target operating modes to obtain the fitting weight coefficients corresponding to each of the target operating modes, the voltage security of the power system Assessment methods also include:

Obtaining a set of state variables corresponding to the current operating mode of the power system;

Calculating the distance between each state variable set satisfying the preset operating condition and the state variable set corresponding to the current operating mode; and

It is determined that the preset operating modes corresponding to the preset number of state variable sets satisfying the preset operating conditions with the smallest distance are the multiple target operating modes.

The second aspect of the embodiment of the present invention provides a voltage safety assessment system for a power system, which includes:

A generating module, configured to acquire a plurality of preset operating modes satisfying preset operating conditions and generate a set of state variables corresponding to each of the preset operating modes;

An evaluation module, configured to evaluate the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set;

A fitting module, configured to linearly fit the state variable sets corresponding to the plurality of target operating modes to obtain fitting weight coefficients corresponding to each of the target operating modes; and

The first calculation module is used to calculate the transient voltage safety index of the power system in the current operation mode according to the fitting weight coefficients and transient voltage safety corresponding to the plurality of target operation modes.

In one embodiment, the generating module includes:

a first determining unit, configured to determine a plurality of initial variables of each node in the power system;

A generation unit, configured to generate a plurality of initial operation modes conforming to the preset value ranges of the plurality of initial variables according to the Monte Carlo simulation method;

a power flow calculation unit, configured to perform power flow calculation on the multiple initial operation modes, and obtain multiple state variable sets corresponding to the multiple initial operation modes; and

The filtering unit is configured to filter a plurality of state variable sets satisfying the preset operating conditions from the plurality of state variable sets according to the preset operating conditions, and to display the corresponding preset operating modes.

In one embodiment, the evaluation module includes:

A simulation unit, configured to simulate the transient voltage waveform curve of the power system when each fault in the preset fault set occurs in each of the preset operation modes; and

The evaluation unit is configured to evaluate the safety of the transient voltage corresponding to each of the preset operation modes according to the transient voltage waveform curve corresponding to each of the preset operation modes.

In one embodiment, the evaluation unit includes:

The first judging subunit is used for judging the transient voltage waveform curve according to the difference between the last maximum voltage value and the last minimum voltage value for each transient voltage waveform curve corresponding to the preset operation mode Whether the preset stability conditions are met;

The second judging subunit is used for judging whether the transient voltage waveform curve satisfies the preset according to the time interval during which the voltage is continuously lower than the preset voltage threshold for each transient voltage waveform curve corresponding to the preset operation mode drop conditions; and

The evaluation subunit is configured to, for any preset operation mode m _r among the plurality of preset operation modes, if the transient voltage waveform curve corresponding to the preset operation mode m _r simultaneously satisfies the preset stability condition and the preset drop condition, it is safe to evaluate the safety of the transient voltage corresponding to the preset operation mode _mr , otherwise it is unsafe to evaluate the safety of the transient voltage corresponding to the preset operation mode _mr .

In one embodiment, the voltage safety assessment system of the power system further includes:

An acquisition module, configured to acquire a state variable set corresponding to the current operation mode of the power system;

The second calculation module is used to separately calculate the distance between each state variable set satisfying the preset operation condition and the state variable set corresponding to the current operation mode; and

The determining module is configured to determine that the preset operating mode corresponding to the preset number of state variable sets with the smallest distance satisfying the preset operating condition is the plurality of target operating modes.

The voltage safety evaluation method and system of the above-mentioned electric power system, by pre-evaluating the voltage safety of multiple preset operation modes, can fit and evaluate the current The voltage safety index of the operation mode has good real-time performance and a small amount of simulation calculation, which can realize real-time online safety evaluation and save computing resources.

Description of drawings

FIG. 1 is a schematic flow chart of a voltage safety assessment method for a power system according to an embodiment of the present invention;

FIG. 2 is a schematic flowchart of a voltage safety assessment method for a power system according to another embodiment of the present invention;

FIG. 3 is a schematic flowchart of a voltage safety assessment method for a power system according to another embodiment of the present invention;

FIG. 4 is a schematic flowchart of a voltage safety assessment method for a power system according to another embodiment of the present invention;

5 is a schematic diagram of a module structure of a voltage safety assessment system for a power system according to an embodiment of the present invention;

6 is a schematic diagram of a module structure of a generation module according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a module structure of an evaluation module according to an embodiment of the present invention; and

FIG. 8 is a schematic diagram of a module structure of a voltage safety assessment system for a power system according to another embodiment of the present invention.

detailed description

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without departing from the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "first" and "second" are used for description purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

Please refer to FIG. 1 . FIG. 1 is a schematic flowchart of a method for voltage safety assessment of a power system according to an embodiment of the present invention. For example, the power system is an AC-DC hybrid power system; as another example, the voltage security assessment method is a real-time online AC-DC hybrid power system voltage security assessment method; as shown in Figure 1, the voltage security of the power system Assessment methods may include:

Step 110, determining a plurality of preset operating modes satisfying the preset operating conditions and generating a set of state variables corresponding to each of the preset operating modes.

In this embodiment, the preset operation mode is an operation mode that satisfies a preset operation condition and is selected from various operation modes of the power system. For example, the preset operating conditions include voltage safety conditions; for example, the preset operating conditions include voltage stability conditions; for example, the preset operating conditions include voltage safety conditions and voltage stability conditions; specific voltage safety conditions and/or voltage stability conditions can be According to the existing regulations or actual experience of the power system, it is omitted here. For another example, before step 110, a step is further included: setting the preset operating condition.

Among them, the various operation modes of the power system are represented by the corresponding state variable set. The state variable set is the set of state variables of each node in the power system. Each element in the state variable set includes the state variable of a node, where each node A state variable consists of one or more variables. For example, the state variables of each node include node voltage amplitude, node voltage phase angle, node net active load, node reactive load, and so on. Specifically, the state variables can be obtained by performing power flow calculations on the initial variables of the nodes.

Step 130, evaluating the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set.

In this embodiment, the preset fault set is a set of multiple important faults of the power system. For example, important faults include faults that cause serious consequences; for example, important faults include faults that cause large voltage fluctuations; for example, important faults include faults with high risk factors; for example, important faults include faults with high historical frequency of occurrence. Among them, the preset fault set can be organized and provided by the grid company according to historical fault records.

In the specific implementation, in each preset operation mode, the operation characteristics of each node when various faults in the preset fault set occur in the power system are simulated, and the transient state of each node in each preset operation mode is analyzed according to the simulation results Voltage safety is assessed. Wherein, the transient voltage safety of each node includes safe or unsafe. As an implementation manner, 0 and 1 are used to represent safe and unsafe respectively.

Step 150, performing linear fitting on the state variable sets corresponding to the plurality of target operating modes to obtain fitting weight coefficients corresponding to each of the target operating modes.

In this embodiment, the multiple target operating modes are operating modes that are closer to the current operating mode of the power system among the above-mentioned multiple preset operating modes. Wherein, according to the distance between the state variable set of the target operating mode and the state variable set of the current operating mode, it can be judged whether the target operating mode is close to the current operating mode.

In one embodiment, before step 150, the voltage safety assessment method for the power system further includes: selecting a plurality of target operating modes from the plurality of preset operating modes. For example, according to the distance between the state variable set of each target operating mode and the state variable set of the current operating mode, select a preset number of preset operating modes with the smallest distance as the target operating mode; The preset operation mode within the distance threshold is set as the target operation mode.

In a specific implementation, after the multiple target operating modes are determined, linear fitting is performed on the multiple state variable sets corresponding to the multiple target operating modes to obtain a fitting weight coefficient corresponding to each target operating mode. For example, linear fitting based on the principle of minimum error; for example, linear fitting using the method of least squares.

Step 170, according to the fitting weight coefficients and transient voltage safety corresponding to the plurality of target operation modes, calculate the transient voltage safety index of the power system in the current operation mode.

Specifically, read the transient voltage security corresponding to each target operating mode, including the transient voltage security of each node when various faults in the preset fault set occur in each target operating mode; according to each target operating mode, the corresponding The fitting weight coefficient of , and calculate the transient voltage safety index of each node when each fault in the preset fault set occurs under the current operation mode. The transient voltage safety index of the power system includes the transient voltage safety index of all nodes in the power system.

For example, if the fitting weight coefficients corresponding to the above-mentioned multiple target operation modes are ω ₁ , ω ₂ , ..., ω _a , under the current operation mode m, when a fault k in the preset fault set occurs, any one of the power system The transient voltage safety index of node i is in Respectively represent the transient voltage safety of node i when the fault k in the preset fault set occurs in the first, second...a-th target operating mode, and a is the number of the above-mentioned multiple target operating modes.

In one embodiment, multiple intervals are pre-divided, and the safety of the transient voltage of the node can be evaluated according to the interval in which the transient voltage safety index of the node is located. For example, when When , it is considered that the transient voltage of node i is safe under the current operating mode; when When , it is considered that under the current operating mode, the transient voltage security of node i is poor; when When , it is considered that the transient voltage of node i is not safe under the current operation mode.

In another example, after step 170, the step of: outputting the transient voltage safety index of the power system under the current operation mode is further executed; as another example, the step of: according to the transient voltage safety index of the power system under the current operation mode, Judging whether the power system is safe under the current operation mode, otherwise setting or adjusting the power system; for example, calculating or selecting at least one alternative operation that satisfies preset operation conditions according to the transient voltage safety index and the state variable set mode, setting or adjusting the power system according to the alternative operation mode. In another example, according to the transient voltage safety index and the state variable set, at least one alternative operation mode satisfying preset operation conditions is obtained through dynamic fitting, and the power system is set or adjusted according to the alternative operation mode.

The voltage safety assessment method of the above-mentioned power system, by pre-evaluating the voltage security of multiple preset operation modes, can fit and evaluate the current operation mode in real time according to the voltage security of multiple target operation modes in the preset operation mode The voltage safety index has better real-time performance, and the simulation calculation amount is small, which can realize real-time online safety evaluation and save computing resources.

As shown in Figure 2, in one embodiment, step 110 includes:

Step 111, determine multiple initial variables of each node in the power system.

In this embodiment, the multiple initial variables include node active output, node voltage amplitude, node voltage phase angle, node active load, node reactive load, and induction motor load ratio; wherein for any node in the power system i, the active output of the node is expressed as The node voltage amplitude is expressed as V ⁱ , the node voltage phase angle is expressed as θ ⁱ , and the node active load is expressed as Node reactive load is expressed as The induction motor load ratio is expressed as α _i ; i∈Ω _bus , and Ω _bus represents the node set of the power system.

As an implementation, multiple initial variables of node i are expressed as Among them, the power system includes three types of nodes: Vδ node, PV node, and PQ node. If node i is a Vδ node, the variables in n _i can be directly given; if node i is a PV node, then the variables in n _i θ ⁱ cannot be given, it is set to null; if node i is a PQ node, then the variable in n _i Neither V ⁱ nor θ ⁱ can be given, and both are set to null.

Step 113, according to the Monte Carlo simulation method, generate a plurality of initial operation modes conforming to the preset value ranges of the plurality of initial variables.

In the specific implementation, the value ranges of the above-mentioned multiple initial variables are set in advance for various nodes, and an operation mode conforming to the value ranges is generated according to the Monte Carlo simulation method. For example, for different nodes, the preset value ranges of the above multiple initial variables include:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; \&cup;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; Q</span>}}<span\; class="notranslate">\; ;</span>$

$\mathrm{<span\; class="notranslate">\; 0.9</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 1.1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; \&cup;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; Q</span>}}<span\; class="notranslate">\; ;</span>$

$\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; \&cup;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; Q</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; \&Omega;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ;</span>$

0≤α _i ≤1, i∈Ω _bus .

in, Represents the collection of PV nodes, represents the set of Vδ nodes, Represents a collection of PQ nodes.

Step 115, performing power flow calculation on the multiple initial operation modes to obtain multiple state variable sets corresponding to the multiple initial operation modes.

For example, the power flow calculation tool is used to calculate the power flow for the above-mentioned multiple initial operation modes, and the state variables of each node in the power system under each operation mode are obtained by solving the power flow equation built in the power flow calculation tool. In this embodiment, the state variable of node i obtained from the power flow solution in any initial operation mode m' is expressed as Then the state variable set corresponding to the initial operation mode m' is expressed as Ω _bus represents the node set of the power system.

In one embodiment, before step 115, the input variables required by the power flow calculation tool are also calculated according to the initial variables. For example, input variables required by power flow calculation tools include and V ⁱ ; V ⁱ and θ ⁱ of the Vδ node; and in

Step 117, according to the preset operating conditions, filter a plurality of state variable sets satisfying the preset operating conditions from the plurality of state variable sets, and determine the preset operation corresponding to the plurality of state variable sets satisfying the preset operating conditions Way.

In this embodiment, the preset operating condition is an operating condition that each element of the state variable set should satisfy. For example, the preset operating conditions include voltage safety conditions; for example, the preset operating conditions include voltage stability conditions; for example, the preset operating conditions include voltage safety conditions and voltage stability conditions.

Wherein, the voltage safety condition specifies the fluctuation range of the voltage, for example, 0.9≦V ⁱ ≦1.1, for example, 0.95≦V ⁱ ≦1.05. The voltage stability condition specifies the fluctuation range of the voltage phase angle, for example in

In one embodiment, the above-mentioned multiple state variable sets are screened according to the preset operating conditions, and the filtered multiple state variable sets satisfying the preset operating conditions are stored, for example, a plurality of state variable sets satisfying the preset operating conditions are stored Sets are stored in preset database A.

In one embodiment, a number threshold is preset, and when the number of filtered state variable sets meeting the preset operating conditions reaches the number threshold, step 130 is performed; otherwise, step 110 is continued. For example, the number threshold is N, and the variable count is used to record the number of records in the database. Whenever a new record is added in database A, let count=count+1. When count<N, continue to execute step 110, and when count≥N, execute step 130. Wherein, the number threshold can be set according to the complexity of the power system, for example, N=10000, for example, N=8000.

As shown in Figure 3, in one embodiment, step 130 includes:

Step 131, in each of the preset operation modes, simulate the transient voltage waveform curve of the power system when each fault in the preset fault set occurs.

Specifically, for each preset operation mode, the transient voltage waveform curve of each node in the power grid is simulated sequentially when each fault in the preset fault set occurs by using a transient simulation tool. In a preferred embodiment, the simulation time is set to 10s, the fault time is set to 0.2s, and the fault clearing time is set to 0.3s.

Step 133 , evaluating the safety of the transient voltage corresponding to each of the preset operation modes according to the transient voltage waveform curve corresponding to each of the preset operation modes.

Specifically, step 133 includes the following steps:

a. For the transient voltage waveform curve corresponding to each preset operation mode, judge whether the transient voltage waveform curve satisfies the preset stability according to the difference between the last maximum voltage value and the last minimum voltage value condition.

In this embodiment, the preset stable condition includes voltage fluctuation within a certain range. For example, the difference between the maximum voltage value and the minimum voltage value is less than a certain threshold; for example, the difference between the average value of the maximum voltage value and the average value of the minimum voltage value is less than another threshold value; The difference between the small values is less than another threshold value; for example, the average value of the difference between each pair of adjacent voltage maximum and voltage minimum values is less than another threshold value; for example, the last voltage maximum value and the last voltage minimum value The difference is less than a further threshold; for example, the difference between the first voltage maximum value and the first voltage minimum value is less than another threshold value.

As an implementation, for the pause voltage waveform curve corresponding to each preset operation mode, identify each maximum point (t _max , V _max ) and each minimum value point (t _min , V _min ), record The set of maximum points is Ω _Vmax , and the set of minimum points is Ω _Vmin . Read the last element at the time point in Ω _Vmax and Ω _Vmin respectively, namely and calculate and judge Whether it is less than a preset fluctuation threshold, if it is judged yes, then it is determined that the pause voltage waveform curve satisfies a preset stability condition. For example, if Then it is determined that the pause voltage waveform curve satisfies the preset stability condition.

b. For the transient voltage waveform curve corresponding to each preset operation mode, judge whether the transient voltage waveform curve satisfies a preset drop condition according to the time interval during which the voltage is continuously lower than the preset voltage threshold.

In this embodiment, a preset voltage threshold V _th and a duration threshold T _th are set to identify all time intervals in which the voltage in the pause voltage waveform curve is continuously lower than the preset voltage threshold V _th . Judging whether there is a time interval whose duration is greater than or equal to the duration threshold, if it does not exist, that is, the time for the voltage to return to the preset voltage threshold V _th after each fault does not exceed the above-mentioned duration threshold T _th , determine the above-mentioned pause voltage waveform curve The preset drop condition is met, and if it exists, it is determined that the above pause voltage waveform curve does not meet the preset drop condition.

In a preferred embodiment, the preset voltage threshold is 0.75pu, and the duration threshold is 0.3s.

c. For any one of the preset operation modes m _r among the plurality of preset operation modes, if the transient voltage waveform curve corresponding to the preset operation mode m _r satisfies the preset stability conditions and the preset drop conditions, it is safe to evaluate the safety of the transient voltage corresponding to the preset operation mode m _r , otherwise it is unsafe to evaluate the safety of the transient voltage corresponding to the preset operation mode m _r .

As an implementation, to Indicates the transient voltage safety of node i when fault k occurs under the default operation mode m _r . For example, Indicates the transient voltage safety of node i, Indicates that the transient voltage of node i is not safe.

In one embodiment, after the transient voltage safety of each node is evaluated, the evaluation result is stored in the database. For example, the evaluation result is stored in the same database as the selected state variable sets satisfying the preset operating conditions; for example, the evaluation result is stored in another database B.

As an implementation, the evaluation results are presented as format to store. in, Indicates the evaluation result corresponding to the preset operation mode m _r ; Indicates the set of state variables corresponding to the preset operation mode m _r , that is, the set of state variables of all nodes in the power system under the default operation mode m _r ; Indicates the set of transient voltage safety of each node in the power system when a fault k occurs under the operating mode m _r , namely

As shown in Figure 4, in one embodiment, selecting multiple target operating modes from the plurality of preset operating modes includes:

Step 141, acquiring a set of state variables corresponding to the current operating mode of the power system.

In this embodiment, the current operation mode of the power system is denoted as m, then the state variable set corresponding to the current operation mode is

Step 143, respectively calculating the distance between each state variable set satisfying the preset operating conditions and the state variable set corresponding to the current operating mode.

In this embodiment, the state variable x _m corresponding to the current operating mode m and the state variable corresponding to any preset operating mode m _r The distance between in,

For each preset operation mode, the distance between its state variable set and the state variable set of the current operation mode is calculated respectively to obtain multiple distances, wherein each distance corresponds to a preset operation mode.

Step 145 , determining the preset operating modes corresponding to the preset number of state variable sets with the smallest distances satisfying the preset operating conditions as the plurality of target operating modes.

In this embodiment, the target operating mode is a preset operating mode that is closer to the current operating mode. Specifically, a preset number of minimum distances is selected from the plurality of distances obtained in step 143, and a preset number of preset operation modes corresponding to the preset number of minimum distances are determined as target operation modes. For example, 10-50 minimum distances are selected, and the corresponding 10-50 preset operation modes are target operation modes. For example, 15-40 minimum distances are selected, and the corresponding 15-40 preset operation modes are target operation modes. For example, 20 minimum distances are selected, and the corresponding 20 preset operation modes are target operation modes.

The voltage safety assessment method of the above-mentioned power system, by pre-evaluating the voltage security of multiple preset operation modes, can fit and evaluate the current operation mode in real time according to the voltage security of multiple target operation modes in the preset operation mode The voltage safety index has better real-time performance, and the simulation calculation amount is small, which can realize real-time online safety evaluation and save computing resources.

FIG. 5 is a schematic diagram of a module structure of a voltage safety assessment system for a power system according to an embodiment of the present invention. For example, the voltage safety assessment system of the power system is realized by using the voltage safety assessment method described in any of the above-mentioned embodiments; as another example, the voltage safety assessment system of the power system includes the steps of the voltage safety assessment method described in any of the above-mentioned embodiments The corresponding functional modules are capable of implementing the corresponding steps of the voltage safety assessment method.

For example, as shown in Figure 5, the voltage safety assessment system of the power system includes:

A generating module 510, configured to acquire a plurality of preset operating modes satisfying preset operating conditions and generate a set of state variables corresponding to each of the preset operating modes;

An evaluation module 530, configured to evaluate the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set;

A fitting module 550, configured to perform linear fitting on the state variable sets corresponding to the plurality of target operating modes to obtain fitting weight coefficients corresponding to each of the target operating modes; and

The first calculation module 570 is configured to calculate the transient voltage safety index of the power system in the current operation mode according to the fitting weight coefficients and transient voltage safety corresponding to the plurality of target operation modes.

As shown in Figure 6, in one embodiment, the generation module 501 includes:

The first determination unit 511 is configured to determine a plurality of initial variables of each node in the power system;

A generation unit 513, configured to generate a plurality of initial operation modes conforming to the preset value ranges of the plurality of initial variables according to the Monte Carlo simulation method;

A power flow calculation unit 515, configured to perform power flow calculation on the multiple initial operation modes to obtain multiple state variable sets corresponding to the multiple initial operation modes; and

The screening unit 517 is configured to screen a plurality of state variable sets satisfying preset operating conditions from the plurality of state variable sets according to preset operating conditions, and determine a corresponding preset operating mode.

As shown in Figure 7, in one embodiment, the evaluation module 530 includes:

The simulation unit 531 is configured to simulate the transient voltage waveform curve of the power system when each fault in the preset fault set occurs in each of the preset operation modes; and

The evaluation unit 533 is configured to evaluate the safety of the transient voltage corresponding to each of the preset operation modes according to the transient voltage waveform curve corresponding to each of the preset operation modes.

In one embodiment, the evaluation unit 533 includes:

The first judging subunit is used for judging the transient voltage waveform curve according to the difference between the last maximum voltage value and the last minimum voltage value for each transient voltage waveform curve corresponding to the preset operation mode Whether the preset stability conditions are met;

The second judging subunit is used for judging whether the transient voltage waveform curve satisfies the preset according to the time interval during which the voltage is continuously lower than the preset voltage threshold for each transient voltage waveform curve corresponding to the preset operation mode drop conditions; and

The evaluation subunit is configured to, for any preset operation mode m _r among the plurality of preset operation modes, if the transient voltage waveform curve corresponding to the preset operation mode m _r simultaneously satisfies the preset stability condition and the preset drop condition, it is safe to evaluate the safety of the transient voltage corresponding to the preset operation mode _mr , otherwise it is unsafe to evaluate the safety of the transient voltage corresponding to the preset operation mode _mr .

As shown in Figure 8, in one embodiment, in addition to the generation module 510, the evaluation module 530, the fitting module 550 and the first calculation module 570, the voltage safety evaluation system of the power system also includes:

An acquisition module 541, configured to acquire a set of state variables corresponding to the current operating mode of the power system;

The second calculation module 543 is used to separately calculate the distance between each state variable set satisfying the preset operation condition and the state variable set corresponding to the current operation mode; and

The determining module 545 is configured to determine that the preset operating mode corresponding to the preset number of state variable sets with the smallest distance satisfying the preset operating condition is the plurality of target operating modes.

The above-mentioned voltage safety evaluation system of the power system, by pre-evaluating the voltage safety of multiple preset operation modes, can fit and evaluate the current operation mode in real time according to the voltage security of multiple target operation modes in the preset operation modes The voltage safety index has better real-time performance, and the simulation calculation amount is small, which can realize real-time online safety evaluation and save computing resources.

It should be noted that, in the above-mentioned system embodiment, each module included is only divided according to the functional logic, but is not limited to the above-mentioned division, as long as the corresponding function can be realized; in addition, the specific name of each functional module It is only for the convenience of distinguishing each other, and is not used to limit the protection scope of the present invention.

In addition, those skilled in the art can understand that all or part of the steps in the methods of the above embodiments can be implemented by instructing related hardware through programs, and the corresponding programs can be stored in a readable storage medium.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A voltage safety assessment method of a power system, characterized in that, comprising: Obtaining a plurality of preset operation modes satisfying the preset operation conditions and generating a set of state variables corresponding to each of the preset operation modes; Evaluating the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set; performing linear fitting on the state variable sets corresponding to the plurality of target operating modes to obtain fitting weight coefficients respectively corresponding to each of the target operating modes; and Calculate the transient voltage safety index of the power system in the current operation mode according to the fitting weight coefficients and the transient voltage security respectively corresponding to the multiple target operation modes. 2. The voltage safety assessment method of a power system according to claim 1, characterized in that, determining a plurality of preset operation modes satisfying preset operation conditions and generating state variables corresponding to each of the preset operation modes set, including: Determining multiple initial variables for each node in the power system; According to the Monte Carlo simulation method, generating multiple initial operation modes conforming to the preset value ranges of the multiple initial variables; performing power flow calculations on the multiple initial operating modes to obtain multiple state variable sets corresponding to the multiple initial operating modes; and According to the preset operating conditions, a plurality of state variable sets satisfying the preset operating conditions are screened from the plurality of state variable sets, and a corresponding preset operating mode is determined. 3. The voltage safety evaluation method of a power system according to claim 1, wherein the evaluation of the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set includes: In each of the preset operation modes, simulating the transient voltage waveform curve of the power system when each fault in the preset fault set occurs; and The transient voltage safety corresponding to each of the preset operation modes is evaluated according to the transient voltage waveform curve corresponding to each of the preset operation modes. 4. The voltage safety assessment method of a power system according to claim 3, characterized in that, according to the transient voltage waveform curve corresponding to each of the preset operation modes, the transient voltage corresponding to each of the preset operation modes is evaluated. Transient voltage safety, including: For each transient voltage waveform curve corresponding to the preset operation mode, judge whether the transient voltage waveform curve satisfies a preset stability condition according to the difference between the last maximum voltage value and the last minimum voltage value; For each transient voltage waveform curve corresponding to the preset operation mode, judge whether the transient voltage waveform curve satisfies a preset drop condition according to the time interval during which the voltage is continuously lower than the preset voltage threshold; and For any preset operation mode m _r among the plurality of preset operation modes, if the transient voltage waveform curve corresponding to the preset operation mode m _r satisfies the preset stability condition and the preset drop condition, it is safe to evaluate the safety of the transient voltage corresponding to the preset operation mode m _r , otherwise it is unsafe to evaluate the safety of the transient voltage corresponding to the preset operation mode m _r . 5. The voltage safety assessment method of an electric power system according to claim 1, wherein the state variable sets corresponding to the plurality of target operating modes are linearly fitted to obtain each of the target operating modes respectively Before the corresponding fitting weight coefficient, the voltage safety assessment method of the power system also includes: Obtaining a set of state variables corresponding to the current operating mode of the power system; Calculating the distance between each state variable set satisfying the preset operating condition and the state variable set corresponding to the current operating mode; and It is determined that the preset operating modes corresponding to the preset number of state variable sets satisfying the preset operating conditions with the smallest distance are the multiple target operating modes. 6. A voltage safety assessment system for a power system, comprising: A generating module, configured to acquire a plurality of preset operating modes satisfying preset operating conditions and generate a set of state variables corresponding to each of the preset operating modes; An evaluation module, configured to evaluate the transient voltage safety corresponding to each of the preset operation modes according to the preset fault set; A fitting module, configured to linearly fit the state variable sets corresponding to the plurality of target operating modes to obtain fitting weight coefficients corresponding to each of the target operating modes; and The first calculation module is used to calculate the transient voltage safety index of the power system in the current operation mode according to the fitting weight coefficients and transient voltage safety corresponding to the plurality of target operation modes. 7. The voltage safety assessment system of an electric power system according to claim 6, wherein the generating module includes: a first determining unit, configured to determine a plurality of initial variables of each node in the power system; A generation unit, configured to generate a plurality of initial operation modes conforming to the preset value ranges of the plurality of initial variables according to the Monte Carlo simulation method; a power flow calculation unit, configured to perform power flow calculation on the multiple initial operation modes, and obtain multiple state variable sets corresponding to the multiple initial operation modes; and The filtering unit is configured to filter a plurality of state variable sets satisfying preset operating conditions from the plurality of state variable sets according to preset operating conditions, and determine a corresponding preset operating mode. 8. The voltage safety evaluation system of a power system according to claim 6, wherein the evaluation module includes: A simulation unit, configured to simulate the transient voltage waveform curve of the power system when each fault in the preset fault set occurs in each of the preset operation modes; and The evaluation unit is configured to evaluate the safety of the transient voltage corresponding to each of the preset operation modes according to the transient voltage waveform curve corresponding to each of the preset operation modes. 9. The voltage safety evaluation system of a power system according to claim 8, wherein the evaluation unit includes: The first judging subunit is used for judging the transient voltage waveform curve according to the difference between the last maximum voltage value and the last minimum voltage value for each transient voltage waveform curve corresponding to the preset operation mode Whether the preset stability conditions are met; The second judging subunit is used for judging whether the transient voltage waveform curve satisfies the preset according to the time interval during which the voltage is continuously lower than the preset voltage threshold for each transient voltage waveform curve corresponding to the preset operation mode drop conditions; and The evaluation subunit is configured to, for any preset operation mode m _r among the plurality of preset operation modes, if the transient voltage waveform curve corresponding to the preset operation mode m _r simultaneously satisfies the preset stability condition and the preset drop condition, it is safe to evaluate the safety of the transient voltage corresponding to the preset operation mode _mr , otherwise it is unsafe to evaluate the safety of the transient voltage corresponding to the preset operation mode _mr . 10. The voltage safety assessment system of the power system according to claim 6, wherein the voltage safety assessment system of the power system further comprises: An acquisition module, configured to acquire a state variable set corresponding to the current operation mode of the power system; The second calculation module is used to separately calculate the distance between each state variable set satisfying the preset operation condition and the state variable set corresponding to the current operation mode; and The determining module is configured to determine that the preset operating mode corresponding to the preset number of state variable sets with the smallest distance satisfying the preset operating condition is the plurality of target operating modes.