KR20140042290A - Method and apparatus for assessing voltage sag considering wind power generation - Google Patents

Abstract

The present invention relates to a method and an apparatus for assessing a voltage sag to which an intermittent characteristic of power supply of wind power generation, which exists in a power system, is reflected. The apparatus for assessing a voltage sag according to the present invention comprises: a collecting unit for collecting at least one output characteristic data of wind power generation and wind speed information, which exist in a power system; a modeling executing unit for executing a modeling for distinguishing at least one operating state of the wind power generation, based on the output characteristic data and the wind speed data; a weight value calculating unit for calculating a weight value of a combination with respect to the at least one operating state of the wind power generation, based on the modeling result of the modeling executing unit; a first evaluation value calculating unit for calculating a first evaluation value for a voltage sag of the combination with respect to the at least one operating state of the wind power generation; and a second evaluation value calculating unit for calculating a second evaluation value considering at least one intermittent output characteristic of the wind power generation, based on the first evaluation value and the weight value. [Reference numerals] (10) Power system; (110) Receiving unit; (120) Modeling unit; (130) Weight value calculating unit; (140) First evaluation value calculating unit; (150) Second evaluation value calculating unit

Description

METHOD AND APPARATUS FOR ASSESSING VOLTAGE SAG CONSIDERING WIND POWER GENERATION}

The present invention relates to a method and apparatus for evaluating instantaneous voltage drop considering wind power generation, and more particularly, to a method and apparatus for evaluating instantaneous voltage drop reflecting intermittent characteristics of power supply of wind power generation existing in a power system. .

There are multiple load buses in the power system. The technique of evaluating the instantaneous voltage drop that may occur in such a power system is as follows. Here, the instantaneous voltage drop evaluation is a technique of estimating the number of occurrences of the annual instantaneous voltage drop at a specific point in the system, which is a field of long-term system characteristic analysis.

The instantaneous voltage drop evaluation method is known using the critical distance method, fault location method, and accurate weak area calculation. The critical distance method is a method of performing instantaneous voltage drop evaluation based on the voltage distribution model, and the fault location method is a method of performing instantaneous voltage drop evaluation by determining a number of accident locations in a power system and performing a fault calculation at each location. This is the most commonly used method. The evaluation method using the vulnerable area calculation is an evaluation method that calculates the exact vulnerable area and uses the accident rate of the system by using the quadratic interpolation and the dividing method.

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 wind power generation is intermittent, accurate analysis is not easy by the conventional method described above.

In this regard, the title of the invention is "a medium on which the system, method and method for executing the method for evaluating the weak point voltage drop are recorded." The Korean Patent Laid-Open Publication No. 30 January 2009. No. 2009-0010536 exists.

An object of the present invention is to provide a method and apparatus for evaluating instantaneous voltage drop in consideration of characteristics of wind power generation.

Device for evaluating the instantaneous voltage drop of the present invention for solving the above problems is a collector for collecting output characteristics data and wind speed data of at least one wind power generation present in the power system; A modeling performer configured to perform modeling to classify operating states of at least one wind power generator based on the output characteristic data and the wind speed data; A weight calculator configured to calculate a weight of a combination of operation states of at least one wind power generator based on the modeling result in the modeling performer; A first evaluation value calculator configured to calculate a first evaluation value of an instantaneous voltage drop of a combination of operating states of at least one wind power generation; And a second evaluation value calculator configured to calculate 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.

The weight calculator may further include: a state checking unit for arranging and confirming operating states of at least one wind power generator based on the modeling result based on the same criteria; A combination for each state deriving unit for deriving a combination for each operation state of at least one wind power generation unit; And a weight determination unit for determining a weight by deriving a system connection ratio for each combination of operation states of at least one wind power generation.

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

In addition, the modeling performing unit may distinguish the at least one wind power generation when the wind speed data is higher than the starting wind speed and lower than the end wind speed when distinguishing the operating state of the at least one wind power generation.

In addition, the output characteristic data is characterized in that it includes a starting wind speed indicating the lowest wind speed that can be supplied power from the wind power generation, and a terminal wind speed indicating the highest wind speed that can be supplied power from the wind power generation.

The instantaneous voltage drop evaluation method of the present invention for solving the above problems comprises the steps of collecting the output characteristic data and wind speed data of at least one wind power generation in the power system; Modeling for distinguishing an operating state of at least one wind power generation based on the output characteristic data and the wind speed data; Calculating weights of combinations of operating conditions of at least one wind power generation based on the modeling result in the modeling performing step; Calculating a first evaluation value for the instantaneous voltage drop of the combination for each operating state 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 generation based on the first evaluation value and the weight.

In addition, the weight calculation step, the step of aligning and confirming the operating state of the at least one wind power generation on the basis of the modeling result; Deriving a combination of operating states of at least one wind power generation; And determining a weight by deriving a system connection ratio for each combination of operation states of at least one wind power generation.

According to the instantaneous voltage drop evaluation method and apparatus of the present invention, in consideration of the intermittent power supply characteristics of wind power generation, there is an effect that can evaluate the instantaneous voltage drop in the power system.

1 is a block diagram illustrating an instantaneous voltage drop evaluation apparatus according to an exemplary embodiment of the present invention.
2 is a view showing the amount of power supplied according to the wind speed according to an embodiment of the present invention.
3 is a view showing the wind speed by date of the location where the first wind power is located in accordance with an embodiment of the present invention.
4 is a view showing the wind speed by date of the location where the second wind power is located in accordance with an embodiment of the present invention.
FIG. 5 is a diagram illustrating the connection state of the power system to the second wind power generation in the embodiment shown in FIG. 4.
6 is a diagram illustrating an operating state of the first wind power generation and the second wind power generation, according to an embodiment of the present invention.
FIG. 7 is a block diagram illustrating in more detail a calculation unit of a weight included in an apparatus for evaluating an instantaneous voltage drop according to an embodiment of the present invention.
8 is a flowchart illustrating a method for evaluating an instantaneous voltage drop according to an embodiment of the present invention.
9 is a flowchart illustrating a step of calculating weight in more detail in the instantaneous voltage drop evaluation method according to an embodiment of the present invention.

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 apparatus considering wind power generation according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7.

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

First, the receiver 110 receives information data of at least one wind generator existing and operated in the power system 10 from the power system 10. This information data includes the output characteristic data of each wind generator and the wind speed data of the place where this wind generator is installed. Here, the output characteristic data of the wind power generator includes data of a preset starting wind speed (V _ci ), rated wind speed (V _R ) and end wind speed (V _co ). This is shown well in Figure 2, which shows the amount of power supplied according to the wind speed. Referring to FIG. 2, it can be seen that the power supply amount increases as the wind speed increases from the starting wind speed V _ci , and the power supply amount is 0 even if the wind speed becomes higher starting from the end wind speed V _co . In addition, it can be seen that the amount of power supplied before the preset start wind speed is zero. And, even if the wind speed increases from the rated wind speed (V _R ) it can be seen that the amount of power output is constant. That is, the start wind speed (V _ci ) is the wind speed indicating the lowest wind speed that can be supplied power from the wind power generation, the end wind speed (V _co ) is the wind speed indicating the highest wind speed that can be supplied power from the wind power generation. Therefore, it can be seen that the wind power can be supplied in a section where the wind speed is greater than the start wind speed (V _ci ) and lower than the end wind speed (V _co ), and other sections cannot supply power.

Throughout the specification, it is assumed that wind power generation is installed in two of the load busbars of the power system. This is for ease of description, and the number of such wind power generation is not limited thereto. As mentioned earlier, suppose there are two wind power generations in the power system: first wind power and second wind power. The wind speed by date of the place where the first wind power is installed is shown in Figure 3, the wind speed by date of the place where the second wind generator is installed is shown in FIG. 3 and 4 show wind speed data of one year measured at a location where each power generation is installed. Referring to the drawings, it can be seen that the wind speeds where the first wind power generation and the second wind power generation are located are variable due to the characteristics of the wind, and the wind speeds where the respective wind power generations are located are different from each other.

1, the modeling unit 120 of the instantaneous voltage drop evaluation apparatus 100 is described. The modeling unit 120 performs modeling for distinguishing at least one operation state of the wind power generation based on the information data received by the receiver 110 described above. That is, this modeling can analyze whether the wind power generation in the grid is connected to the grid. An example of this is shown in FIG. 5. This figure of FIG. 5 shows the disconnection and connection section of the grid for the second wind power generation, based on the figure of FIG. 4. Referring to FIG. 5, the wind speed data according to the date where the second wind power generation is located and the connection and disconnection parts of the grid 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 terminal wind speed V _co is set to 10 m / s. Referring to the drawings, only the wind power generated in the section between the start wind speed (V _ci ) and the end wind speed (V _co ) is used in the power system. Therefore, it should be recognized that wind power is connected to the power grid only in this section, and disconnected without being connected to the grid in other sections.

1, the weight calculator 130 of the instantaneous voltage drop evaluation apparatus 100 will be described. The weight calculator 130 calculates a weight of the combination for each operation state of the wind power generator based on the modeling result of the modeling performer 120 described above. The weight calculator 130 will be described in more detail with reference to FIGS. 6 and 7.

FIG. 6 illustrates, by date, a combination of operating states of the first wind power generator and the second wind power generator 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, it is assumed that the start wind speed V _ci of the first wind power generation is 3 m / s, and the end wind speed V _co is 8.5 m / s. In this example, it is assumed that the start wind speed V _ci of the second wind power generation is 5.5 m / s, and the end wind speed V _co is 18 m / s.

As mentioned above, the power supply characteristics of wind power generation are intermittent, such that only the first wind power is operated, only the second wind power is operated, both the first wind power and the second wind power are operated, and Four cases in which neither the first wind turbine nor the second wind turbine can operate can be derived. 6 shows the cases of these operating states separately. Here, C _A in the drawing only when the first wind power is operated, C _B in the drawing when only the second wind power is operated, C in the drawing when both the first wind power and the second wind power is operated in the drawing _AB . In the case where neither the first wind turbine nor the second wind turbine is in operation, it is indicated by C ₀ in the drawing. In this example, there are four cases above because the number of wind power generations was two, and if the number of wind power generations existing in the power system is three, eight cases can be derived.

Referring now to FIG. 7, the configuration of the weight calculator 130 is further described. The weight calculator 130 includes a state checker 131, a state-specific combination derivator 132, and a weight determiner 133. Here, after confirming the operating state of each wind power in the state check unit 131, the combination for each operating state of the wind power generation unit in the combination derivation unit 132 for each state is derived. Since this corresponds to a portion described above with reference to FIG. 6, a more detailed description thereof will be omitted. Thereafter, control is transferred to the weight determining unit 133. The weight determination unit 133 analyzes the ratio of C _A , C _B , C _AB, and C ₀ during the entire period in the example of the combination of the operation state of each of the wind power plants derived above, that is, referring to FIG. 6. Thus, the weight for each case is derived.

That is, the weight may be regarded as the ratio of the combination of the operation state of the wind power generation 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 calculator 140 of the instantaneous voltage drop evaluation apparatus 100 is described. The first evaluation value calculator 140 calculates the first evaluation value for the instantaneous voltage drop in the combination for each operation state of the wind power generation. Here, when calculating the first evaluation value, at least one of the aforementioned weak area calculation method, critical distance method, and fault location method, that is, a known instantaneous voltage drop evaluation method is used. In addition, 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 operation state of each wind power generation 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 calculation unit 150 of the instantaneous voltage drop evaluation apparatus 100 is described.

The second evaluation value calculator 150 calculates a second evaluation value based on the first evaluation value and the weight described above. Since the first evaluation value does not consider the characteristics of the wind power generation, it is necessary to calculate a value in consideration of the characteristics of the wind power generation. The equation used for this calculation is as follows.

Below, the calculation of the second evaluation value when the magnitude of the voltage drop is 0.9 [pu] and 0.6 [pu] or less, respectively. The calculation process of applying Equation 1 to the first evaluation value of the instantaneous voltage drop magnitudes 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 Multiply by and sum them.

Voltage dip evaluation for 0.9 [p.u.] = 20.986 × 0.1067 + 20.395 × 0.0356 + 20.013 × 0.2134 + 19.619 × 0.6443 = 19.8764

Evaluate transient voltage drop for 0.6 [pu] = 8.031 × 0.1067 + 7.915 × 0.0356 + 7.545 × 0.2134 + 7.427 × 0.6443 = 7.5339

The second evaluation value calculated for each of the remaining magnitudes of voltage drop through the above process is shown in Table 3 below.

Voltage drop magnitude
[pu] 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, an embodiment of the present invention has been described as having two wind turbines present in a power system for better understanding of the present invention. However, it should be appreciated that the present invention can be applied regardless of the number of wind power generations. In addition, although one embodiment of the present invention is described as modeling and ratio determination by comparing the wind speed corresponding to the date between wind power generation, where the date is the same criterion, that is, another criterion indicating the same time point or set by the user It should be recognized that it can be replaced by a standard.

Hereinafter, an instantaneous voltage drop evaluation apparatus considering wind power generation according to an embodiment of the present invention will be described with reference to FIGS. 8 and 9. For simplicity of the specification, descriptions of portions overlapping with the foregoing description are omitted in the following description.

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

First, a step (S110) of collecting output characteristic data and wind speed data of wind power generation existing in a power system is performed. As mentioned earlier, the output characteristic data includes a start wind speed that indicates the lowest wind speed that can be powered from wind power, and a longitudinal wind speed that indicates the highest wind speed that can be powered from wind power. That is, the wind power is generated only when the wind speed is higher than the start wind speed, and lower than the terminal wind speed, and the wind power is not generated elsewhere.

Thereafter, based on the collected output characteristic data and wind speed data, a step S120 of performing modeling is performed. Here, modeling is performed to analyze whether the wind power generation existing in the grid is connected to the grid, that is, whether the wind power generation takes place.

After the step S120, a step (S130) of calculating the weight of the combination for each operating state of the wind power generation is made based on the modeling result. Here, the combination for each operation state, assuming that the number of wind power generation in the power system is two, when only the first wind power is operated, when only the second wind power is operated, the first wind power and the second wind power It means four cases in which both are operating and in which neither the first wind turbine nor the second wind turbine is in operation. Here, the weight is the ratio of the combination of the wind power generation by the operating state generated within a certain period.

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

In step S150, the second evaluation value is calculated based on the first evaluation value and the weight. As mentioned above, the method for calculating the second evaluation value is omitted here because it has been described above. Therefore, since this second evaluation value is a value in which an actual ratio for each combination of operation states of wind power generation is considered, this value is an evaluation value in consideration of the characteristics of wind power generation.

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

Referring to FIG. 9, first, a step (S131) of checking an operating state of wind power generation is performed. Since the power supply characteristics of each wind power generation are intermittent, this is done to check the combination of the connection status of the wind power grids based on the same criteria. Here, the same criterion is a term including the same date in the above description, and may be replaced with another criterion indicating the same time point.

Thereafter, a step (S132) of deriving a combination for each operation state of wind power generation is performed.

Based on the result derived in this step S132, a ratio for each case of the combination for each operation state is derived in step S133, which is also used as a weight.

As described above, the best embodiment has been disclosed in the drawings and the 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: receiver 120: modeling unit
130: weight calculation unit 140: first evaluation value calculation unit
150: second evaluation value calculation unit

Claims (10)

A collection unit for collecting output characteristic data and wind speed data of at least one wind power generation existing in the power system;
A modeling performer configured to perform modeling for classifying an operating state of the at least one wind power generation based on the output characteristic data and the wind speed data;
A weight calculator configured to calculate a weight of a combination of operation states of the at least one wind power generator based on the modeling result of the modeling performer;
A first evaluation value calculator configured to calculate a first evaluation value for an instantaneous voltage drop of each of the combinations of the at least one wind power generation by the operating states; And
And a second evaluation value calculator configured to calculate 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. The method of claim 1,
The weight calculation unit may calculate,
A state checking unit for aligning and confirming operating states of the at least one wind power generation on the basis of the modeling result;
A state-specific combination derivation unit for deriving a combination for each operation state of the at least one wind turbine; And
And a weight determination unit configured to determine a weight by deriving a grid connection ratio for each combination of operating states of the at least one wind power generation. The method of claim 1,
The first evaluation value calculation unit,
When calculating the first evaluation value, at least one of weak area calculation method, critical distance method and fault location method, characterized in that the instantaneous voltage drop evaluation apparatus. The method of claim 1,
The modeling execution unit,
When distinguishing the operating state of the at least one wind power generation, when the wind speed data is higher than the starting wind speed and lower than the end wind speed, characterized in that the at least one wind power generation, characterized in that the voltage drop evaluation device. The method of claim 1,
The output characteristic data,
An apparatus for evaluating instantaneous voltage drop, characterized in that it comprises a starting wind speed indicating the lowest wind speed capable of supplying power from the wind power generation, and a terminal wind speed indicating the highest wind speed capable of supplying power from the wind power generation. Collecting output characteristic data and wind speed data of at least one wind power generation existing in the power system;
Modeling for distinguishing an operating state of the at least one wind power generation based on the output characteristic data and the wind speed data;
Calculating weights of combinations for each operation state of the at least one wind power generation based on the modeling result in the modeling step;
Calculating a first evaluation value for an instantaneous voltage drop of each of the combinations of the at least one wind power generation by an operating state; And
And calculating a second evaluation value in consideration of the intermittent output characteristic of the at least one wind power generation, based on the first evaluation value and the weight value. The method according to claim 6,
The weight calculation step,
Arranging and confirming operating states of the at least one wind turbine on the same basis based on the modeling result;
Deriving a combination for each operation state of the at least one wind turbine; And
And determining a weight by deriving a grid connection ratio for each combination of operation states of the at least one wind power generation. The method according to claim 6,
The first evaluation value calculating step,
When calculating the first evaluation value, characterized in that at least one of the weak area calculation method, the critical distance method and the fault location method, characterized in that the instantaneous voltage drop evaluation method. The method according to claim 6,
The modeling performing step,
And when the wind speed data is higher than a starting wind speed and lower than a terminal wind speed when distinguishing the operating state of the at least one wind power generation, distinguishing that the at least one wind power generation is operated. The method according to claim 6,
The output characteristic data,
And a starting wind speed indicating a lowest wind speed capable of supplying electric power from the wind power generation, and a terminal wind speed indicating the highest wind speed capable of supplying electric power from the wind power generation.

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