KR101932286B1 - Method and apparatus for assessing voltage sag considering wind power generation - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instantaneous voltage drop evaluation method and apparatus that reflects intermittent characteristics of the power supply of a wind power generator existing in a power system.
An instantaneous voltage drop evaluation apparatus of the present invention includes: a collector for collecting output characteristic data and wind speed data of at least one wind power generator existing in a power system; A modeling execution unit for performing modeling for distinguishing operating states of at least one wind power generator based on output characteristic data and wind speed data; A weight calculation unit for calculating a weight of a combination of at least one wind power generation operation state on the basis of the modeling result in the modeling execution unit; A first evaluation value calculation unit for calculating a first evaluation value for an instantaneous voltage drop of a combination of at least one wind power generation operation state; And a second evaluation value calculation unit for calculating a second evaluation value in consideration of the intermittent output characteristics of at least one wind power generation based on the first evaluation value and the weight value.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and an apparatus for evaluating instantaneous voltage drop in consideration of wind power generation,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instantaneous voltage drop evaluation method and apparatus considering wind power generation, and more particularly, to a method and apparatus for instantaneous voltage drop estimation that reflects intermittent characteristics of power supply of a wind power generation system .

There are a plurality of load buses in the power system. The techniques for evaluating the instantaneous voltage drop that can occur in such a power system are as follows. Here, the instantaneous voltage drop evaluation is a technique for estimating the number of occurrences of the instantaneous voltage drop at a specific point in the system, and is a field of long-term analysis of system characteristics.

The instantaneous voltage drop evaluation method is known such as the critical distance method, the failure location method, and the method using accurate weak area calculation. The critical distance method is a method of performing the instantaneous voltage drop evaluation based on the voltage distribution model and the failure location method is a method of performing instantaneous voltage drop evaluation by determining a number of accident locations in the power system, Is the most commonly used method. The evaluation method using the vulnerable area calculation is an evaluation method that calculates the accurate vulnerable area using the second interpolation method and the second method and uses the accident rate of the system.

However, consider the case where wind power is installed in some of the load buses in the power system. Here, since the amount of power supplied from the wind power generator is intermittent, it is not easy to accurately analyze the conventional method described above.

In this regard, the title of the invention is "a system for determining a vulnerable area for instantaneous voltage drop evaluation, a method and a medium on which a computer readable program for executing the method is recorded ", Korean Patent Laid- There is a 2009-0010536 issue.

It is an object of the present invention to provide an instantaneous voltage drop evaluation method and apparatus considering the characteristics of wind power generation.

According to an aspect of the present invention, there is provided an apparatus for evaluating an instantaneous voltage drop, comprising: a collector for collecting output characteristic data and wind speed data of at least one wind power generator existing in a power system; A modeling unit for modeling the operation state of the at least one wind power generator based on the output characteristic data and the wind speed data; A weight calculation unit for calculating a weight of a combination of the at least one wind turbine according to operation states based on modeling results of the modeling unit; A first evaluation value calculation unit for calculating a first evaluation value for an instantaneous voltage drop of a combination of the at least one wind turbine according to operating conditions; And a second evaluation value calculation unit for calculating a second evaluation value in consideration of the intermittent output characteristics of the at least one wind power generator based on the first evaluation value and the weight value, And multiplying the first evaluation value and the weighted value by the combination of the operating states of the power generation and adding them.

The weight calculation unit may include a state checking unit for sorting and confirming the operation states of at least one wind power generator on the basis of the modeling result, A state derivation unit for deriving a combination of at least one wind power generation operation state; And a weight determining unit for determining a weight by deriving a grid connection ratio for each combination of at least one operation state of the wind power generator.

The first evaluation value calculation unit may use at least one of the weak area calculation method, the critical distance method, and the failure location method when calculating the first evaluation value.

The modeling unit is characterized in that, when the operation state of at least one wind power generator is classified, at least one wind power generator operates when the wind speed data is higher than the starting wind speed and lower than the terminal wind speed.

The output characteristic data includes a starting wind speed indicating a minimum wind speed at which power can be supplied from the wind power generator and a terminal wind speed indicating a maximum wind speed at which power can be supplied from the wind power generator.

According to an aspect of the present invention, there is provided an instantaneous voltage drop evaluation method comprising the steps of: collecting output characteristic data and wind speed data of at least one wind power generator existing in a power system; Performing modeling to distinguish the operating state of the at least one wind power generator based on the output characteristic data and the wind speed data; Calculating a weight of a combination of the at least one wind turbine according to operation states based on modeling results in the modeling step; Calculating a first estimate of the instantaneous voltage drop of the combination of operating states of the at least one wind turbine; And calculating a second evaluation value in consideration of the intermittent output characteristic of the at least one wind power generator based on the first evaluation value and the weight value, wherein the second evaluation value includes an operation state of each wind power generator The first evaluation value is multiplied by a weight, and these values are summed up.

The weight calculation step may include: sorting and confirming the operation states of at least one wind power generator on the basis of the same reference based on the modeling result; Deriving a combination of at least one wind power generation operation state; And determining a weight by deriving a grid connection ratio for each combination of at least one operation state of the wind power generator.

According to the instantaneous voltage drop evaluation method and apparatus of the present invention, the instantaneous voltage drop in the power system can be evaluated in consideration of the intermittent power supply characteristic of the wind power generation system.

1 is a block diagram illustrating an instantaneous voltage drop evaluation apparatus according to an embodiment of the present invention.
FIG. 2 is a graph showing a supply amount of electric power according to a wind speed according to an embodiment of the present invention.
FIG. 3 is a graph showing wind speeds by date of a first wind power generator according to an embodiment of the present invention.
FIG. 4 is a graph showing wind velocities by date at a location where a second wind power generator is located according to an embodiment of the present invention.
FIG. 5 is a diagram showing a connection state of a power system in a second wind power generation in the embodiment shown in FIG. 4;
FIG. 6 is a diagram showing the operation states of the first wind power generator and the second wind power generator according to an embodiment of the present invention.
FIG. 7 is a block diagram showing more specifically a weight calculation unit included in the instantaneous voltage drop evaluation apparatus according to an embodiment of the present invention.
8 is a flowchart illustrating an instantaneous voltage drop evaluation method according to an embodiment of the present invention.
FIG. 9 is a flowchart illustrating a step of calculating a weight in an instantaneous voltage drop evaluation method according to an embodiment of the present invention in more detail.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Hereinafter, an instantaneous voltage drop evaluation device considering wind power generation according to an embodiment of the present invention will be described with reference to FIG. 1 to FIG.

1 is a block diagram illustrating an instantaneous voltage drop evaluation apparatus according to an embodiment of the present invention.

First, the receiving unit 110 receives information data of at least one wind turbine generator that is present and operated in the power system 10 from the power system 10. This information data includes output characteristic data of each wind turbine generator and wind speed data of the place where the wind turbine generator is installed. Here, the output characteristic data of the wind power generator includes data of a predetermined starting wind speed (V _ci ), a rated wind speed (V _R ) and a termination wind speed (V _co ). This is shown in FIG. 2, which shows the supply amount of electric power according to the wind speed. Referring to FIG. 2, it can be seen that the supply amount of electric power increases with the increase of the wind speed from the starting wind speed V _ci , and the supply amount of electric power is 0 even when the wind speed becomes higher from the longitudinal wind speed V _co . It can be seen that the supply amount of electric power before the predetermined starting wind speed is zero. It can be seen that the amount of output power is constant even if the wind speed increases with the rated wind speed V _R as a starting point. That is, the starting wind speed (V _ci ) is the wind speed representing the minimum wind speed at which power can be supplied from the wind power generation, and the terminal wind speed (V _co ) is the wind speed representing the maximum wind speed at which power can be supplied from the wind power generation. Therefore, it can be seen that the power can be supplied in a section where the wind speed is higher than the startup wind speed (V _ci ) and lower than the terminal wind speed (V _co ), and the other sections can not supply power.

Throughout the specification, it is assumed that wind power is installed in two of the load buses of the power system. This is for ease of explanation, and the number of such wind power generation is not limited thereto. As mentioned above, let's assume that there are two wind power generators in the power system: the first wind power generator and the second wind power generator. FIG. 3 shows the wind speed of the place where the first wind power generator is installed, and FIG. 4 shows the wind speed by the date of the place where the second wind power generator is installed. FIGS. 3 and 4 show the wind speed data for one year measured at the places where the respective power plants are installed. Referring to the drawings, it can be seen that the wind speed at the locations where the first wind power generator and the second wind power generator are located is variable depending on the characteristics of the wind, and the wind speeds at the places where the wind power generators are located are different from each other.

1, the modeling unit 120 of the instantaneous voltage drop evaluation apparatus 100 will be described. The modeling unit 120 performs modeling for distinguishing the operation state of at least one wind power generator based on the information data received by the receiving unit 110 described above. That is, this modeling can analyze whether the wind power existing in the grid is connected to the grid. An example of this is shown in Fig. The diagram of FIG. 5 shows the separation and connection section of the system for the second wind power generation, based on the diagram of FIG. Referring to FIG. 5, the date-specific wind speed data and the connection and disconnection portions of the system where the second wind power generator is located are shown. In the example of FIG. 5, it is assumed that the starting wind speed V _ci is set to 2 m / s and the termination wind speed V _co is set to 10 m / s. Referring to the drawing, only the power of wind power generated in the interval between the starting wind speed (V _ci ) and the terminal wind speed (V _co ) is used in the power system. Therefore, it should be appreciated that wind power is only connected to the power system in this section, and that the other sections are not connected to the system.

1, the weight calculation unit 130 of the instantaneous voltage drop evaluation apparatus 100 will be described. The weight calculation unit 130 calculates the weight of the combination of the wind power generation operation states on the basis of the modeling result in the modeling execution unit 120 described above. The weight calculation unit 130 will be described in more detail with reference to FIG. 6 and FIG.

FIG. 6 shows a combination of the operating states of the first wind power generator and the second wind power generator by date based on the output characteristic data and the wind speed data of the first wind power generator and the second wind power generator. Here, FIG. 6 shows only one month of data, unlike FIGS. 3 and 4, for ease of explanation. In this example, the starting wind speed (V _ci ) of the first wind power generator is assumed to be 3 m / s, and the termination wind speed (V _co ) is assumed to be 8.5 m / s. In this example, the starting wind speed (V _ci ) of the second wind power generator is assumed to be 5.5 m / s, and the terminal wind speed (V _co ) is assumed to be 18 m / s.

As described above, since the power supply characteristic of the wind power generation is intermittent, when only the first wind power generation operates, only the second wind power generation operates, both the first wind power generation and the second wind power generation operate, Four cases where both the first wind power generation and the second wind power generation do not work can be derived. Fig. 6 shows the case of these operating states separately. Here, in the case where only the first wind power generator operates, C _A in the drawing, C _B in the case where only the second wind power generator operates, and C _{B in} the case where both the first wind power generator and the second wind power generator operate, _AB . And the case where both the first wind power generation and the second wind power generation do not operate is indicated by C ₀ in the drawing. In this example, there are four cases because the number of wind power generators was two, and if there are three wind generators in the power system, eight cases can be derived.

Referring now to FIG. 7, the configuration of the weight calculation unit 130 will be further described. The weight calculation unit 130 includes a state check unit 131, a condition-based combination derivation unit 132, and a weight determination unit 133. [ Here, after confirming the operation state of each wind power generator in the state checking unit 131, the combination deriving unit 132 for each state derives a combination for each operation state of each wind power generator. Since this is a portion corresponding to the portion described with reference to FIG. 6, a more detailed description will be omitted. Thereafter, the control is transmitted to the weight determining unit 133. [ The weight determining unit 133 determines the combination of the operating states of the respective wind turbines derived above, that is, the ratio of C _A , C _B , C _AB, and C ₀ during the entire period in the example mentioned above with reference to FIG. 6 , And derives a weight for each case.

In other words, these weights can be regarded as the ratio of the wind power generation operation states generated within a specific period. The weights for each case in this example are shown in Table 1 below.

C ₀ C _A C _B C _AB weight 0.1067 0.0356 0.2134 0.6443

1, the first evaluation value calculating unit 140 of the instantaneous voltage drop evaluating apparatus 100 will be described. The first evaluation value calculation unit 140 calculates the first evaluation value for the instantaneous voltage drop in the combination of the operation states of the wind power generation. Here, when calculating the first evaluation value, at least one of the aforementioned weak region calculation method, the critical distance method, and the failure location method, that is, a known instantaneous voltage drop evaluation method, is used. Further, the first evaluation value is calculated for each magnitude of the instantaneous voltage drop. The first evaluation value of the combination of the magnitude of the instantaneous voltage drop and the operating state of each wind power generator is shown in Table 2 below.

Voltage drop size
[pu] C ₀
[sag / year] C _A
[sag / year] C _B
[sag / year] C _AB
[sag / year] ? 0.9 20.986 20.395 20.013 19.619 ≤0.8 15.436 15.341 15.197 15.074 ? 0.7 11.860 11.714 11.321 11.096 ? 0.6 8.031 7.915 7.545 7.427 0.5 5.288 5.194 4.899 4.803 ? 0.4 3.263 3.195 3.029 2.985 0.3 1.744 1.705 1.547 1.522 ≤0.2 0.834 0.815 0.724 0.710 ≤0.1 0.313 0.312 0.306 0.304

1, the second evaluation value calculating unit 150 of the instantaneous voltage drop evaluating apparatus 100 will be described.

The second evaluation value calculation unit 150 calculates the second evaluation value based on the first evaluation value and the weight value described above. Since the first evaluation value does not take into consideration the characteristics of the wind power generation, it is necessary to calculate a value considering the characteristics of the wind power generation. The following equation is used for this calculation.

Below is the calculation of the second evaluation value when the instantaneous voltage drop is 0.9 [pu] or less and 0.6 [pu] or less, respectively. The calculation process of applying Equation (1) to the first evaluation value having the instantaneous voltage drop sizes of 0.9 [pu] and 0.6 [pu] or less is as follows. That is, the moment, respectively, the voltage drop size 0.9 [pu] and 0.6 [pu] at less intervals, C _A, C _B, C _AB, and a ratio of C _0, that is, weight of C _A, C _B, C _AB and C ₀ And summing them.

Instantaneous voltage drop evaluation for 0.9 [pu] = 20.986 x 0.1067 + 20.395 x 0.0356 + 20.013 x 0.2134 + 19.619 x 0.6443 = 19.8764

Instantaneous voltage drop evaluation for 0.6 [pu] = 8.031 x 0.1067 + 7.915 x 0.0356 + 7.545 x 0.2134 + 7.427 x 0.6443 = 7.5339

The second evaluation value calculated according to the remaining instantaneous voltage drop size through the above process is shown in Table 3 below.

Voltage drop size
[pu] The second evaluation value
[sags / year] ? 0.9 19.8764 ≤0.8 15.1485 ? 0.7 11.2472 ? 0.6 7.5339 0.5 4.8891 ? 0.4 3.0316 0.3 1.5575 ≤0.2 0.7301 ≤0.1 0.3058

Throughout the specification, one embodiment of the present invention has been described as a case in which the number of wind turbines existing in the power system is two to help understand the present invention. However, it should be appreciated that the invention can be applied regardless of the number of wind turbines of the present invention. In addition, although an embodiment of the present invention is described as modeling and determining the ratio by comparing the wind speed corresponding to the date of wind power generation, the date may be the same as the reference, that is, It should be appreciated that the standard may be substituted.

Hereinafter, an instantaneous voltage drop evaluation device considering wind power generation according to an embodiment of the present invention will be described with reference to FIG. 8 and FIG. For the sake of brevity of description, the description of the parts overlapping with those of the preceding description in the following description is omitted.

8 is a flowchart illustrating an instantaneous voltage drop evaluation method according to an embodiment of the present invention.

First, step S110 of collecting wind speed data and output characteristic data of wind turbines existing in the power system is performed. As mentioned above, the output characteristic data includes the starting wind speed indicating the minimum wind speed at which power can be supplied from the wind power generator, and the terminal wind speed indicating the maximum wind speed at which power can be supplied from the wind power. That is, the wind power generation is performed only when the wind speed is higher than the starting wind speed and lower than the terminal wind speed, and other wind power generation is not performed.

Then, the modeling is performed (S120) based on the collected output characteristic data and the wind speed data. Here, the modeling is performed to analyze whether the wind power existing in the system is connected to the system, that is, whether the wind power is generated.

After step S120, a weighting value of the combination of the wind power generation operation states is calculated (S130) based on the modeling result. Assuming that the number of wind power generators in the power system is two, only the first wind power generator operates, only the second wind power generator operates, and the combination of the first wind power generator and the second wind power generator All four cases in which both the first wind power generation and the second wind power generation do not operate. Here, the weight is a ratio of a combination of wind power generation operation states generated within a specific time period.

Thereafter, a step S140 of calculating a first evaluation value of the instantaneous voltage drop of each combination of the operation states of the wind power generation is performed. Here, the calculation of the first evaluation value is performed using at least one of the conventional momentary voltage drop evaluation method, that is, the weak area calculation method, the critical distance method, and the failure location method. This first evaluation value calculation is calculated in consideration of the magnitude of the instantaneous voltage drop for each combination of the operating states of the respective wind turbines. However, since the intermittent characteristic of the wind power generation is not considered in the case of the first evaluation value, the control is transferred to the step S150 for the instantaneous voltage drop evaluation considering the intermittent characteristic of the wind power generation.

Step S150 is a step of calculating a second evaluation value from the first evaluation value and the weight value. As mentioned above, the method of calculating the second evaluation value has been described above, and is omitted here. Therefore, the second evaluation value is an evaluation value considering the characteristics of the wind power generation, since the actual ratio of each combination of the wind power generation operation states is considered.

FIG. 9 is a flowchart illustrating a weight calculation step (S130) of the instantaneous voltage drop evaluation method according to an embodiment of the present invention.

Referring to FIG. 9, step S131 of checking the operating state of the wind power generator is performed. This is done to confirm the combination of the connection states of the wind power generation systems based on the same criteria, since the power supply characteristics of each wind power plant are intermittent. Here, the same criterion is a term including the same date in the above description, and can be replaced with another criterion indicating the same time point.

Thereafter, a step S132 of deriving a combination for each operating state of the wind power generation is performed.

Based on the result derived in step S132, the ratio of each combination of operation states is derived in step S133, and the ratio is used as a weight.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: Instantaneous voltage drop evaluation device
110: Receiving unit 120: Modeling unit
130: weight calculation unit 140: first evaluation value calculation unit
150: second evaluation value calculating section

Claims (10)

A collector for collecting wind speed data and output characteristic data of at least one wind power generator existing in the power system;
A modeling unit for modeling the operation state of the at least one wind power generator based on the output characteristic data and the wind speed data;
A weight calculation unit for calculating a weight of a combination of the at least one wind turbine according to operation states based on modeling results of the modeling unit;
A first evaluation value calculation unit for calculating a first evaluation value for an instantaneous voltage drop of a combination of the at least one wind turbine according to operating conditions; And
And a second evaluation value calculation unit for calculating a second evaluation value in consideration of the intermittent output characteristic of the at least one wind power generator based on the first evaluation value and the weight value,
Wherein the second evaluation value is calculated by multiplying the first evaluation value for each combination of the operating states of the wind turbines by a weight and adding them together. The method according to claim 1,
The weight calculation unit may calculate,
A state checking unit for sorting and confirming the operation states of the at least one wind power generator on the basis of the modeling result;
A state derivation unit for deriving a combination of at least one wind power generation operation state; And
And a weight determiner for deriving a grid connection ratio for each combination of the at least one wind turbine generator according to operation states to determine a weight value. The method according to claim 1,
Wherein the first evaluation value calculating section calculates,
Wherein when calculating the first evaluation value, at least one of the weak area calculation method, the critical distance method, and the failure location method is used. The method according to claim 1,
The modeling unit may include:
Wherein the at least one wind power generator operates when the wind speed data is higher than the starting wind speed and lower than the terminal wind speed when the operating state of the at least one wind power generator is classified. The method according to claim 1,
The output characteristic data includes:
A starting wind speed indicating a minimum wind speed at which power can be supplied from the wind power generator, and a terminal wind speed indicating a maximum wind speed at which power can be supplied from the wind power generator. Collecting wind speed data and output characteristic data of at least one wind power generator existing in the power system;
Performing modeling to distinguish the operating state of the at least one wind power generator based on the output characteristic data and the wind speed data;
Calculating a weight of a combination of the at least one wind turbine according to operation states based on modeling results in the modeling step;
Calculating a first estimate of the instantaneous voltage drop of the combination of operating states of the at least one wind turbine; And
And calculating a second evaluation value considering the intermittent output characteristic of the at least one wind power generator based on the first evaluation value and the weight value,
Wherein the second evaluation value is calculated by multiplying the first evaluation value for each combination of the operating states of the wind turbines by a weight and summing the first evaluation value and the second evaluation value. The method according to claim 6,
Wherein the weight calculating step includes:
Sorting and confirming the operating states of the at least one wind turbine based on the modeling result on the same basis;
Deriving a combination of operating states of the at least one wind power generator; And
And deriving a grid connection ratio for each combination of the at least one wind turbine generator according to operation states to determine a weight value. The method according to claim 6,
Wherein the first evaluation value calculating step includes:
Wherein when calculating the first evaluation value, at least one of the weak area calculation method, the critical distance method, and the failure location method is used. The method according to claim 6,
The modeling step may include:
Wherein the at least one wind turbine is operated when the wind speed data is higher than the starting wind speed and lower than the terminal wind speed when the operation state of the at least one wind power generator is classified. The method according to claim 6,
The output characteristic data includes:
A start wind speed indicating a minimum wind speed at which power can be supplied from the wind power generator, and a terminal wind speed indicating a maximum wind speed at which power can be supplied from the wind power generator.

Images