JP2016116290A - Load allowance calculation device, load allowance calculation method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load allowance calculation device, a load allowance calculation method, and a program that provide suitable information associated with voltage stability for an operator of an electric power system including a dispersed power source.SOLUTION: There is provided a load allowance calculation device 1 for calculating an allowance amount of a load from a predicted operation point up to a voltage stability limit of an electric power system including a dispersed electric power source. The load allowance calculation device comprises: a load-flow calculation part 12 which performs load-flow calculation based upon first information representing a predicted value of electric power to be consumed by a load and second information associated with a plurality of predicted values of the power generation amount of the dispersed electric power source so as to find a plurality of predicted operation points of an electric power system; a scenario calculation part 13 which calculates a plurality of vector amounts indicative of increments of the load when the operation point of the electric power system reaches closest voltage stability limit points from the plurality of predicted operation points based upon calculation results of the load-flow calculation part 12; and a comparison part 14 which compares the plurality of calculated vector amounts.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a load margin calculation device, a load margin calculation method, and a program.

  The voltage of the power system fluctuates when some failure occurs in the power system or when the power demand increases or decreases. In this case, the ability of the power system voltage to settle to a new equilibrium point or a property related thereto is referred to as voltage stability of the power system.

  In general, the voltage stability of a power system can be analyzed by examining the active power-voltage characteristics (hereinafter referred to as PV characteristics) of the power system. The PV characteristic is a characteristic showing the relationship between the active power P of the load in the electric power system and the bus (node) voltage V of a typical electric power station. For example, as shown in FIG. It is expressed by a PV curve formed by the locus of a plurality of points plotted on a two-dimensional coordinate plane in which P is associated and the vertical axis is associated with the bus voltage V.

  By creating the PV curve, it is possible to obtain a voltage (stable limit voltage) at which the voltage of the power system becomes unstable when the power demand increases to the upper limit value (stable limit power). It is possible to evaluate the voltage margin that is the difference between the voltage at the current operating point and the stability limit voltage, and evaluate the load margin that is the difference between the demand power at the current operating point and the stability limit power. It becomes possible. Therefore, it is possible to take measures against overload operation that occurs when an accident occurs in the power system.

  Thus, when evaluating the above-mentioned voltage margin and load margin by a PV curve, a method of changing the load in an expected demand increase direction (hereinafter referred to as a load increase scenario) is known (for example, Patent Document 1, Patent Document 2).

JP-A-3-215125 JP-A-8-130828

  When the load margin or the like is evaluated using the above-described method, the size of the load margin changes according to the selected load increase scenario. Therefore, there may be a load increase scenario in which the load margin is smaller than the selected load increase scenario. Since a load increase scenario with a smaller load margin increases the risk of voltage collapse, the load increase scenario with the smallest load margin should be most vigilant from the viewpoint of stable operation of the power system.

  Here, the operating point of the power system changes from moment to moment according to the power demand and the amount of power generation, and the load increase scenario in which the load margin is minimized also changes with the change in the operating point. In recent years, as the introduction of distributed power sources such as solar power generation devices, wind power generators, and fuel cells has progressed, it is known that the output of such distributed power sources is unstable. Therefore, it is difficult to accurately predict the operating point of the power system including the distributed power source. Since the above-mentioned patent documents do not consider such matters, it is not possible to provide appropriate information regarding voltage stability to the operator of the power system.

  One of the means for solving the above problem is a load margin calculation device for calculating the load margin from the predicted operating point of the power system to the voltage stability limit in the power system including the distributed power source. In order to obtain a plurality of predicted operating points of the power system, first information indicating a predicted value of power consumed by the load, and a plurality of predicted values regarding a plurality of predicted values of the power generation amount of the distributed power source. A first calculation unit that executes a tidal current calculation based on the two information, and an operation point of the power system is closest to each of the predicted operation points based on a calculation result of the first calculation unit A second calculation unit that calculates a plurality of vector amounts indicating an increase amount of the load when reaching the voltage stability limit point, and a comparison unit that compares the calculated vector amounts.

  In addition, the problems disclosed by the present application and the solutions thereof will be clarified by the description in the column of the embodiment for carrying out the invention and the description of the drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the appropriate information regarding voltage stability can be provided with respect to the operator of the electric power grid | system including a distributed power supply.

It is a figure which shows an example of PV curve. It is a figure which shows an example of the electric power grid | system in which load margin is calculated in this embodiment. It is a block diagram which shows the function of the load margin calculation apparatus in this embodiment. It is a flowchart which shows the flow of the load margin calculation in this embodiment. It is a graph which shows an example of the prediction of the electric power consumed by load, and the prediction of the electric power generation amount of a solar power generation device in the time slot | zone of a day. It is a graph which shows an example of the prediction of the electric power supplied to the load from the generator side in the time zone of one day. It is a graph which shows an example of the relationship between the operating point of an electric power system, and a voltage collapse curved surface. It is a figure which shows an example of the calculation result of the increase amount of load. It is the figure which displayed the result of FIG. 8 with the bar graph.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== Power system for load margin calculation ===
With reference to FIG. 2, the power system which is the object for which the load margin is calculated in the present embodiment will be described. As shown in FIG. 2, the power system 100 includes generators 111 and 112, a solar power generation device 113, first to fourth nodes 121 to 124, and lines 131 to 134 that connect these nodes to each other, Is provided.

  More specifically, the generators 111 and 112 supply power to the second and fourth nodes 122 and 124 that are load nodes via the lines 131 to 134.

  The solar power generation device 113 is an example of a distributed power source, and is connected to the second node 122 in the present embodiment. The solar power generation device 113 may represent a plurality of solar power generation facilities connected to the second node 122, and also represents a wind power generator and a fuel cell connected to the second node 122. Also good. The electric power generated in the solar power generation device 113 is supplied to a load connected to the second node 122. Of the amount of power generated by the solar power generation device 113, surplus power excluding the power supplied to the load at the second node 122 may be supplied to the load of the fourth node 124 via the line 134. Note that, as will be described later, even when the power consumed in the load of the second node 122 does not change, the generator 111, 112 side changes to the second node 122 according to the increase or decrease of the power generation amount of the solar power generation device 113. The supplied power varies (see FIG. 6).

  The first and third nodes 121 and 123 are generator nodes connected to the generators 111 and 112, and the second and fourth nodes 122 and 124 are load nodes connected to a load (not shown). . As described above, the solar power generation device 113 is connected to the second node 122. The first and second nodes 121 and 122 are connected by a line 131, the first and fourth nodes 121 and 124 are connected by a line 133, and the third and fourth nodes 123 and 124 are connected by a line 132. The second and fourth nodes 122 and 124 are connected by a line 134. However, the first node 121 and the third node, and the second node 122 and the third node 123 are not connected.

  Here, it is assumed that the first node 121 is designated as a slack node. The slack node is a node that can supply electric power sufficient to cover a transmission loss and bear an excess of demand that cannot be handled by other generators. The slack node is arbitrarily selected as long as the required power generation capacity is satisfied. In addition, the amplitude and phase angle of the voltage at the slack node are constant, and this phase angle is a reference for the voltage at the other node. The active power and reactive power in the slack node depend on the active power and reactive power in the other nodes.

  In the present embodiment, it is assumed that the load margin is calculated for the power system having two generator nodes and two load nodes in this way. But the load margin calculation apparatus and load margin calculation method in this embodiment are applicable to the electric power system which has many nodes.

  In the calculation of the load margin in the present embodiment, it is assumed that the voltage amplitude v is specified and the phase angle is 0 degree in the first node 121 that is a slack node. In addition, the active power P and the voltage amplitude v are specified in the third node 123 that is a generator node, and the active power P and the reactive power Q are specified in the second and fourth nodes 122 and 124 that are load nodes. Shall.

=== Load margin calculation device ===
With reference to FIG. 3 to FIG. 9, the load margin calculating apparatus in the present embodiment will be described. FIG. 3 is a block diagram showing the function of the load margin calculation device, FIG. 4 is a flowchart showing the flow of load margin calculation, and FIG. 5 is a prediction of the power consumed by the load in the time zone of one day, FIG. 6 is a graph showing an example of prediction of power supplied from the generator side to the load in the time zone of one day, and FIG. 7 is an operating point of the power system. FIG. 8 is a graph showing an example of the calculation result of the load increase amount, and FIG. 9 is a graph showing the result of FIG. 8 as a bar graph. In this embodiment, 100 MVA is adopted as a reference system capacity, and in FIG. 8 and FIG. 9, the active power and reactive power of the node are shown by a unit method based on 100 MVA.

<Device configuration>
The load margin calculation device 1 is a device that calculates the load margin from the operating point to the voltage stability limit in the power system 100. As shown in FIG. 3, the input margin 11 and the power flow calculation unit 12 (first 1 calculation unit), a scenario calculation unit 13 (second calculation unit), and a comparison unit 14.

(Input section)
Information related to the first to fourth nodes 121 to 124 and the lines 131 to 134 configuring the power system 100 is input to the input unit 11. As information regarding the first to fourth nodes 121-124, for example, there is information indicating the voltage v, active power P, and reactive power Q according to the types of nodes described above, and information regarding the lines 131-134 is included. For example, there is information indicating the line impedance Z and the line admittance Y. Such information may be input by an operator via an input device (not shown), or from a monitoring device (not shown) of the power system 100 through a communication line based on an instruction from the operator. It may be acquired automatically.

  In addition, the input unit 11 includes information (first information) indicating a predicted value of power consumed by the load in the power system 100, and information regarding a plurality of predicted values for the power generation amount of the solar power generation device 113 (second information). Information). Specifically, the predicted value of the power consumed by the load is calculated based on the actual value of the past power demand. For example, for each load node, the same past season (for example, early November), the same time zone It is given as an average value of actual values of power demand at (for example, 10:00 to 11:00). Moreover, although the predicted value of the power generation amount of the solar power generation device 113 is also calculated based on the past actual value, in the present embodiment, the power generation amount of the solar power generation device 113 varies greatly depending on weather conditions. A plurality of actual values related to the power generation amount are provided. The actual value of the power generation amount is preferably a power generation result under similar weather conditions in the same season and time zone in the past. For example, when clear weather is expected at a certain date and time, the value of the actual power generation result under clear weather conditions in the past simultaneous period may be used.

  In the present embodiment, it is assumed that the information indicating the predicted value of the above-described power demand and power generation amount is provided from an external information device (not shown) through a communication line. Such information includes, for example, predicted values for every hour from the time the information is provided to 24 hours ahead, and every 6 hours such as 0:00, 6 o'clock, 12 o'clock, and 18 o'clock. It shall be updated from time to time. Alternatively, the load margin calculation device 1 uses the analysis method such as multivariate analysis based on the weather forecast information provided by the Japan Meteorological Agency, for example, for each of the predetermined time intervals for the predicted value of power consumption and the amount of power generation. A predicted value may be calculated. Note that weather information such as weather (sunny, cloudy, rain, snow, etc.), temperature, pressure, wind speed / wind direction, and the like may be input to the input unit 11 from an external information device (not shown).

  When the input unit 11 receives the information regarding the node and the line, the information indicating the predicted value of the power consumption of the load, and the information regarding the predicted value of the power generation amount of the solar power generation device 113, the input unit 11 receives the received information. Output to the tidal current calculator 12.

(Tidal current calculator)
The power flow calculation unit 12 obtains the predicted operation points L and Lmax of the power system 100 (information indicating the predicted value of power consumed by the load (first information)) and the power generation amount of the solar power generation device 113. The tidal current calculation is executed based on the information on the predicted value (second information).

  Specifically, when receiving various information from the input unit 11, the tidal current calculation unit 12 first calculates the distribution of these predicted values based on information related to the predicted value of the power generation amount of the solar power generation device 113. As an example of such distribution, in this embodiment, an average and a standard deviation are adopted. For example, when a plurality of predicted values related to the power generation amount are given as a plurality of predicted values for each hour up to 24 hours ahead, the average and standard deviation are 24 pieces having values for each hour up to 24 hours ahead. It is calculated as a numerical value.

  And the tidal current calculation part 12 is the information which shows the average of the predicted value of the electric power generation calculated in this way, the information regarding the 1st-4th node 121-124 and the track | line 131-134, and the 2nd which is a load node. Then, the power flow calculation is executed based on the information indicating the predicted value of the power demand at the fourth nodes 122 and 124, and the voltage vector v2-v4 of the second to fourth nodes 122-124 is calculated. The voltage vector v2-v4 calculated in this way corresponds to the operating point L. Further, the tidal current calculation unit 12 performs tidal current calculation based on the standard deviation of the predicted value of the power generation amount in addition to the above various information, and calculates the voltage vector v2'-v4 'corresponding to the operating point Lmax. In this way, the power flow calculation unit 12 calculates a plurality of operating points L and Lmax. For example, when the predicted values related to the power generation amount and power demand described above are given up to 24 hours ahead every hour, the voltage vectors v2-v4, v2'-v4 'and the operating points L, Lmax are up to 24 hours ahead. 24 voltage vectors and operating points are calculated for each hour.

  Here, the operating point Lmax is predicted to be taken by the power system 100 when the photovoltaic power generation device 113 generates power by three times the standard deviation from the average of the predicted power generation amount in the corresponding time zone. Indicates the operating point. This operating point Lmax corresponds to a situation in which the photovoltaic power generation device 113 generates only the smallest amount of power generation among a plurality of predicted power generation amounts, as indicated by a broken line near the horizontal axis in FIG. . Under this situation, the generator nodes 121 and 123 need to bear a part of the power demand that was expected to be covered by the solar power generation device 113, and as shown by the upper broken line in FIG. In addition, more power must be supplied to the load nodes 122 and 124. Therefore, the operating point Lmax indicates a state closer to the voltage collapse than the operating point L, as shown in FIG.

  The procedure in which the power flow calculation unit 12 calculates the voltage vectors v2-v4 and v2'-v4 'will be described later. Since the voltage amplitude and phase angle at the first node 121 selected as the slack node are specified as described above, they are not calculated by the power flow calculation unit 12.

  After calculating the voltage vectors v2-v4, v2'-v4 'corresponding to the operating points L and Lmax, the power flow calculation unit 12 outputs the calculation result to the scenario calculation unit. The tidal current calculation unit 12 may calculate an operating point other than L and Lmax. For example, another operating point L ′ may be calculated using a value obtained by estimating the power generation amount of the solar power generation apparatus 113 to be smaller than the average by twice the standard deviation or the maximum value of the predicted power generation amount. By calculating the operating point using various values in this way, it is possible to provide various information to the operator, and thus it is expected that the range of measures that the operator can take will be widened. Moreover, you may use the median of a predicted value as an average of the predicted value of electric power generation amount. For example, when an extremely large or small value is included in the predicted value, an appropriate operating point can be obtained by using the median value.

(Scenario calculation department)
Based on the calculation result of the power flow calculation unit 12, the scenario calculation unit 13 performs the operation when the operation point of the power system 100 is predicted from the plurality of operation points L and Lmax to the nearest voltage stability limit points L 1 and L 2. Vector amounts p1 and p2 indicating the load increase amount are calculated. The set of vector quantities p1 is a load increase scenario in which the voltage of the power system 100 collapses with the minimum load increase from the operating point L. Similarly, the set of vector quantities p2 is the minimum load from the operating point Lmax. This is a load increase scenario in which the voltage of the power system 100 collapses with the increase amount. For example, when the predicted values of power generation and power demand are given as predicted values up to 24 hours ahead every hour, the load increase scenarios p1 and p2 are calculated 24 sets up to 24 hours ahead every hour. .

  The elements of such load increase scenarios p1 and p2 are active power P2 and P4 and reactive power Q2 and Q4 at the load node at the second and fourth nodes 122 and 124, which are load nodes, respectively. In a certain third node 123, it is the active power P3 in the generator node (see FIG. 8). However, since the active power and reactive power of the first node 121 selected as the slack node are determined according to the active power and reactive power of the second to fourth nodes, they are not calculated by the scenario calculation unit 13. A method for calculating the load increase scenarios p1 and p2 by the scenario calculation unit 13 will be described later.

  When the scenario calculation unit 13 calculates the load increase scenarios p1 and p2, the scenario calculation unit 13 outputs the calculation result to the comparison unit 14.

(Comparison part)
When the comparison unit 14 receives the calculation result from the scenario calculation unit 13, the comparison unit 14 compares the elements of the calculated vector quantities p <b> 1 and p <b> 2 and outputs them to the display device 2. For example, by obtaining the difference or ratio of the elements of the vector quantities p1 and p2 for the same time zone, the operator can determine how much each element of the vector quantity is when the operating point transitions from the point L to the point Lmax or It is possible to easily grasp how much the ratio increases (decreases). Further, for example, the same element of the same vector amount is compared for different time zones so that the Q2 element of the vector amount p2 is compared between the time zone of 10:00 to 11:00 and the time zone of 11:00 to 12:00. Thus, the operator can take appropriate measures in a timely manner while predicting a time change of the same vector amount.

  The display device 2 is, for example, a liquid crystal display device, and displays the absolute values of the elements of the vector quantities p1, p2 calculated by the scenario calculation unit 13, for example, in a table or a bar graph (see FIGS. 8 and 9). For example, when 24 sets of load increase scenarios p1 and p2 are calculated respectively corresponding to the predicted values of power generation and power demand being given as predicted values for every hour up to 24 hours ahead, the table of FIG. And the graph of FIG. 9 are 24 tables and graphs showing changes in the load increase scenario up to 24 hours ahead.

  Such a function of the load margin calculation device 1 is executed by a computer having a ROM, a RAM, and a CPU executing a program.

<Calculation of load increase scenario>
With reference to FIG. 4, steps S1-S4 in which the load margin (increase amount) from the operating points L, Lmax to the voltage stability limit are calculated will be described.

-Step 1: Enter information
In step S <b> 1, various information is input to the input unit 11. Specifically, information on the first to fourth nodes 121-124 and the lines 131-134 constituting the power system 100 is input by the worker or based on the instructions of the worker. Moreover, the information (first information) indicating the predicted value of the power consumed by the load and the information (second information) regarding a plurality of predicted values for the power generation amount of the solar power generation device 113 are set at regular time intervals. (For example, every 6 hours). As described above, such a predicted value is given as a predicted value every hour, for example, up to 24 hours ahead.

  The input unit 11 outputs this information to the power flow calculation unit 12 together with information about the node and the line every time information about the predicted value of power consumption and power generation amount is input.

-Step 2: Power flow calculation
When the tidal current calculation unit 12 receives the above-described information from the input unit 11, tidal current calculation is performed in step S2 to obtain the operating points L and Lmax. The tidal current calculation is executed by the tidal current calculation unit 12.

  Prior to the tidal current calculation, the tidal current calculation unit 12 calculates the average and standard deviation of these predicted values based on information related to the predicted power generation amount of the photovoltaic power generation apparatus 113. For example, the average and standard deviation of the predicted values of the power generation amount are calculated as 24 values each hour up to 24 hours ahead as described above. Further, the power flow calculation unit 12 generates an admittance matrix [Y] based on the information on the line impedance Z or the line admittance Y.

  Then, for example, the power flow calculation unit 12 solves the node equation represented by the following Equation 1 under the specified node condition, and the voltage vectors v2-v4, v2′− at the second to fourth nodes 122-124 are obtained. v4 ′ is obtained. The voltage vectors v2-v4, v2'-v4 'are calculated as values for every hour up to 24 hours ahead as described above, for example.

本実施形態では、電圧ベクトルｖ２−ｖ４の算出の際、太陽光発電装置１１３の平均的な発電量を想定して、第２ノード１１２について指定された有効電力Ｐの値から、太陽光発電装置１１３の予測される発電量の平均を減算した値を、第２ノード１１２の有効電力Ｐ’とする。また、電圧ベクトルｖ２’−ｖ４’の算出の際には、太陽光発電装置１１３が予想の最低水準で発電する場合を想定して、ノード１１２について指定された有効電力Ｐの値から、太陽光発電装置１１３の予測される発電量の平均を減算し、太陽光発電装置の予測される発電量の標準偏差の３倍を加算した値を、第２ノード１１２の有効電力Ｐ’’とする（図５，図６参照）。つまり、
電圧ベクトルｖ２−ｖ４の算出に用いられる第２ノードの有効電力Ｐ’
＝ 指定された有効電力Ｐ − 太陽光発電装置の発電量の期待値
電圧ベクトルｖ２’−ｖ４’の算出に用いられる第２ノードの有効電力Ｐ’’
＝ 指定された有効電力Ｐ
−（太陽光発電装置の発電量の期待値−太陽光発電装置の発電量の標準偏差の３倍）
として、２種類の運転点Ｌ、Ｌｍａｘに対応する電圧ベクトルを算出する。

In the present embodiment, when calculating the voltage vector v2-v4, assuming the average power generation amount of the solar power generation device 113, the solar power generation device is calculated from the value of the active power P specified for the second node 112. A value obtained by subtracting the average of the predicted power generation amount 113 is set as the active power P ′ of the second node 112. Further, when calculating the voltage vector v2′−v4 ′, it is assumed that the solar power generation device 113 generates power at the expected minimum level, and the solar power is calculated from the value of the active power P specified for the node 112. A value obtained by subtracting the average of the predicted power generation amount of the power generation device 113 and adding three times the standard deviation of the predicted power generation amount of the solar power generation device is set as the active power P ″ of the second node 112 ( (See FIGS. 5 and 6). That means
Active power P ′ of the second node used for calculation of the voltage vector v2-v4
= Specified active power P-Expected value of the amount of power generated by the photovoltaic power generation system
Second node active power P ″ used to calculate voltage vector v2′−v4 ′
= Specified active power P
-(Expected value of power generation amount of solar power generation device-3 times standard deviation of power generation amount of solar power generation device)
As a result, voltage vectors corresponding to the two types of operating points L and Lmax are calculated.

  The node equation may be expressed by using the voltage amplitude v, the phase angle θ, the active power P, the reactive power Q, and the Jacobian matrix [J] at each node, but in this case as well, the voltage vector v2-v4, v2'-v4 'is obtained.

  Based on the voltage vectors v2-v4, v2′−v4 ′ thus obtained, the voltage vector v1 (= v1 ′) of the designated slack node, and the admittance matrix [Y], the following formula 2 Is used to calculate the active power P and reactive power Q of each node corresponding to the operating points L and Lmax, respectively. In addition, the active power P and the reactive power Q of each node corresponding to the operating points L and Lmax are given as, for example, values every hour up to 24 hours ahead.

運転点Ｌは、例えば図７に示されるように、第２−第４ノード１２２−１２４における有効電力Ｐ２（Ｌ）−Ｐ４（Ｌ）及び無効電力Ｑ２（Ｌ）−Ｑ４（Ｌ）で与えられる。同様に、運転点Ｌｍａｘは、有効電力Ｐ２（Ｌｍａｘ）−Ｐ４（Ｌｍａｘ）及び無効電力Ｑ２（Ｌｍａｘ）−Ｑ４（Ｌｍａｘ）で与えられる。なお、例えばＰ２（Ｌ）は、運転点Ｌにおける第２ノード１２２の有効電力Ｐを意味する。

The operating point L is given by active power P2 (L) -P4 (L) and reactive power Q2 (L) -Q4 (L) in the second-fourth nodes 122-124, for example, as shown in FIG. . Similarly, the operating point Lmax is given by active power P2 (Lmax) -P4 (Lmax) and reactive power Q2 (Lmax) -Q4 (Lmax). For example, P2 (L) means the active power P of the second node 122 at the operating point L.

-Step 3: Calculate the load increase scenario
When the operating points L and Lmax are calculated by the power flow calculation, a load increase scenario is calculated in step S3. The calculation of the load increase scenario is executed by the scenario calculation unit 13. In the present embodiment, load increase scenarios p1 and p2 are calculated such that the amount of increase in load from each of the operating points L and Lmax to the voltage collapse curved surface Σ is minimized. As described above, the load increase scenarios p1 and p2 are calculated as values every hour up to 24 hours ahead, for example.

  Here, the voltage collapse curved surface Σ is a curved surface indicating the voltage stability limit of the power system, and when the operating point of the power system reaches the voltage collapse curved surface Σ, the voltage of the power system collapses. It is known that the voltage collapse curved surface Σ is determined to be substantially constant regardless of power demand and voltage increase / decrease when devices (including loads, lines, and phase adjusting equipment) constituting the power system are designated. There are innumerable combinations of load increases (load increase scenarios) in which the operating point of the power system extends from a specific operating point to the voltage collapse curved surface Σ, but what is calculated in this embodiment is the increase in load This is a combination of the load increase amounts of the individual nodes such that the amount is minimized for the entire system.

  An example of a load increase scenario will be described with reference to FIG. In FIG. 7, the voltage collapse curved surface Σ of the power system 100 in the present embodiment is shown on a coordinate plane with the effective power P2 of the second node 122 and the effective power P4 of the fourth node 124 as axes. However, the voltage collapse curved surface Σ can also be shown on a coordinate plane having other elements such as reactive power Q2 of the second node 122 and active power P3 of the third node 123 as axes. FIG. 7 also shows operating points L and Lmax and coordinates (p2 (L), p4 (L)) and (p2 (Lmax), p4 (Lmax)) corresponding to these operating points.

  In FIG. 7, when the power demands P2 and P4 at the second and fourth nodes 122 and 124 increase or decrease, the operating point moves. For example, the operating point may reach from the point L to the voltage collapse point L1 (p2 (L1), p4 (L1)) or to another voltage collapse point L2 (p2 (L2), p4 (L2)). Sometimes. In either case, the voltage of the power system 100 collapses. However, since the line segment L-L1 is orthogonal to the voltage collapse curved surface Σ, the load increase scenario reaching the point L1 has the smallest load margin among all the load increase scenarios in relation to the operating point L. . Therefore, from the viewpoint of stable operation of the electric power system 100, for the operating point L, it is appropriate to obtain the load increase scenario L-L1. Similarly, for the operating point Lmax, it is appropriate to obtain a load increase scenario Lmax-L2 that minimizes the distance to the voltage collapse curved surface Σ.

  Therefore, the scenario calculation unit 13 solves the following equations 3 and 4 for each of the operating points L and Lmax, and calculates a voltage collapse point at which the distance from the operating point to the voltage collapse curved surface Σ is minimized. The straight lines L-L1 and Lmax-L2 connecting the voltage collapse point calculated in this way and the operating point are the worst load increase scenarios for the operating points L and Lmax.

ただし、ｘ０は運転点Ｌ，Ｌｍａｘに対応する電圧ベクトル、ｘは電圧安定限界点における電圧ベクトル、ｐは負荷増加シナリオ、Ｆ（ｘ，ｘ０，ｐ）は負荷余裕、ｆ（ｘ）は潮流方程式、Ｊ（ｘ）はｆ（ｘ）のヤコビアン行列、ｗはヤコビアン行列の左固有ベクトルである。

Where x0 is a voltage vector corresponding to the operating points L and Lmax, x is a voltage vector at the voltage stability limit point, p is a load increase scenario, F (x, x0, p) is a load margin, and f (x) is a power flow equation. , J (x) is the Jacobian matrix of f (x), and w is the left eigenvector of the Jacobian matrix.

  That is, the scenario calculation unit 13 minimizes F (x, x0, p) in Equation 3 under the voltage collapse constraint condition shown in Equation 4 for each of the operating points L and Lmax. Calculate the margin. Then, p1 and p2 when F (x, x0, p) is minimized are calculated as the worst load increase scenarios for the operating points L and Lmax.

Such load increase scenarios p1 and p2 are indicated as follows for a specific time, for example.
Scenario p1:
(P2, Q2, P3, P4, Q4) = (0.1507, 0.3457, 0.3672, 0.1608, 0.1308)
Scenario p2:
(P2, Q2, P3, P4, Q4) = (0.2503, 0.3657, 0.2972, 0.1802, 0.1101)
Here, P2, Q2, P3, P4, and Q4 are node labels, and the first characters P and Q in the node label represent active power and reactive power, respectively, and the subsequent numbers are the second to fourth nodes 122- A node number corresponding to 124 is shown. Further, each element of the scenarios p1 and p2, that is, the load margin, is displayed by a unit method based on 100 MVA. In the present embodiment, the amount of increase in reactive power in the third node 123 that is a generator node is not calculated.

  For example, as shown in FIG. 8, the calculation results as described above are compared as a table including node labels, node numbers, node elements, and load margins as elements for each of the operating points L and Lmax. Is output to the unit 14. The node element indicates whether the corresponding node is a load node or a generator node.

-Step 4: Comparison
When the load increase scenarios p1 and p2 are output from the scenario calculation unit 13, these scenarios are compared and output to the display device 2 in step S4. The operation in step S4 is executed by the comparison unit 14.

  For example, the same elements of the operating points L and Lmax in the same time zone as shown in FIG. 8 are compared based on the difference and ratio. Moreover, the same element of the same driving | running point in a different time slot | zone may be compared. Then, the result of such comparison may be added to the table of FIG. 8 or the graph of FIG. Or it can be said that it is also a kind of comparison that the same elements of the operating points L and Lmax in the same time zone are displayed next to each other as in the graph of FIG. Note that when the load increase scenario is calculated up to 24 hours ahead every hour, 24 graphs in FIG. 9 are created. Or the calculated value for every hour may be displayed for every element of a scenario so that the change of each element of a scenario can be grasped | ascertained easily.

  The display device 2 displays the table or graph output from the comparison unit 14 on the screen. As a result, the operator has the greatest influence on the voltage collapse in both cases where the photovoltaic power generation device 113 generates power as expected and when the power generation amount of the solar power generation device 113 is at the lowest expected level. It is possible to easily grasp the factors and the degree of giving. Therefore, for example, even when the power generation amount of the solar power generation device 113 is drastically reduced from the average value to the lowest level, the operator has the most influence on the voltage collapse based on the table of FIG. 8 and the graph of FIG. The effective power P or reactive power of the exerting node (reactive power Q of the second node 122 in FIGS. 8 and 9) can be grasped. Therefore, in the example of FIGS. 8 and 9, the operator can quickly take appropriate measures such as operating the phase adjusting equipment in order to suppress the increase in the reactive power Q in the second node 122.

  Then, after a predetermined time interval (for example, 6 hours), a table or a graph indicating a new load increase scenario is generated and displayed on the display device 2. In this regard, it is known that the predicted value of the power generation amount and the power demand has a higher reliability as it is closer to the point in time when the prediction is made, and shows a tendency to vary greatly as the previous time is reached. Therefore, the reliability of the load increase scenario is improved by updating the predicted value at a predetermined time interval (for example, 6 hours).

  As described above, the load margin calculation device 1 is an example of the first information indicating the predicted value of the power consumed by the load and the distributed power source in order to obtain a plurality of predicted operating points L and Lmax of the power system 100. As a power system 100 based on the calculation result of the tidal current calculation unit 12 and the tidal current calculation unit 12 that executes the tidal current calculation based on the second information regarding the plurality of predicted values for the power generation amount of the photovoltaic power generation device 113 as A scenario calculation unit 13 that calculates vector amounts p1 and p2 indicating the amount of increase in load when the operating point is reached to the closest voltage stability limit point L1 or L2 from each of the plurality of operating points L and Lmax predicted; And a comparison unit 14 for comparing the calculated vector quantities p1 and p2. According to such an embodiment, by comparing a plurality of vector amounts (load increase scenario) corresponding to a plurality of operating points, scenario elements affected by fluctuations in the output of the solar power generation device 113 and the degree of the influence Therefore, appropriate information regarding voltage stability can be provided to the operator of the power system 100 including the distributed power source.

  Moreover, the 2nd information regarding the predicted value of the electric power generation amount of the solar power generation device 113 shows an average and a standard deviation as an example of the distribution of a plurality of predicted values. A load increase scenario p1 based on the amount and a load increase scenario p2 in the case where the power generation amount of the solar power generation device 113 increases or decreases from the expected value are obtained. Therefore, a statistically reliable load increase scenario can be provided.

  Further, the tidal current calculation unit 12 should obtain an operating point corresponding to the average of a plurality of predicted values related to the power generation amount and an operating point corresponding to a value obtained by subtracting three times the standard deviation from the average of the plurality of predicted values. By executing the power flow calculation, the operator can take a countermeasure in advance assuming a severe situation in which the power generation amount of the solar power generation device 113 is drastically reduced from an average value to a minimum level.

  Further, the tidal current calculation unit 12 repeatedly executes tidal current calculation based on the updated first and second information at predetermined time intervals, and the tidal current calculation unit 12 executes tidal current calculation in the scenario calculation unit 13. The vector quantities p1 and p2 are calculated every time, and the comparison unit 14 preferably compares the calculated vector quantities p1 and p2 each time the scenario calculation unit 13 calculates the vector quantities p1 and p2. Since the vector amount (load increase scenario) is regularly updated, a highly reliable load increase scenario based on the latest information can be obtained.

  The embodiments described above are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and equivalents thereof are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Load margin calculation apparatus 11 Input part 12 Power flow calculation part 13 Scenario calculation part 14 Comparison part 2 Display apparatus 100 Electric power system 111,112 Generator 113 Solar power generation apparatus 121-124 1st-4th node 131-134 Line

Claims (8)

A load margin calculation device for calculating a load margin from a predicted operating point of the power system to a voltage stability limit in a power system including a distributed power source,
In order to obtain a plurality of predicted operating points of the power system, first information indicating a predicted value of power consumed by the load, and second information regarding a plurality of predicted values of the power generation amount of the distributed power source, A first calculation unit for executing a tidal current calculation based on
Based on the calculation result of the first calculation unit, a plurality of vector quantities indicating an increase amount of the load when the operating point of the power system reaches the nearest voltage stability limit point from each of the predicted operating points A second calculation unit for calculating
A comparison unit for comparing the calculated vector quantities;
A load margin calculation apparatus comprising: The load margin calculation apparatus according to claim 1, wherein the second information indicates a distribution of the plurality of predicted values. The load margin calculation apparatus according to claim 2, wherein the second information indicates an average and a standard deviation of the plurality of predicted values. The first calculation unit obtains an operating point corresponding to the average of the plurality of predicted values and an operating point corresponding to a value obtained by subtracting a predetermined multiple of the standard deviation from the average of the plurality of predicted values. The load margin calculation device according to claim 3, wherein tidal current calculation is executed as much as possible. The first calculation unit repeatedly executes a power flow calculation based on the updated first and second information at predetermined time intervals,
The second calculation unit calculates the vector quantities each time the first calculation unit executes a tidal current calculation,
The load according to any one of claims 1 to 4, wherein the comparison unit compares the plurality of calculated vector amounts each time the second calculation unit calculates the plurality of vector amounts. Margin calculation device. The load distribution calculating device according to claim 1, wherein the distributed power source is a solar power generation device. A load margin calculation method for calculating a load margin from a predicted operating point of the power system to a voltage stability limit in a power system including a distributed power source,
In order to obtain a plurality of predicted operating points of the power system, first information indicating a predicted value of power consumed by the load, and second information regarding a plurality of predicted values of the power generation amount of the distributed power source, , Perform tidal calculations based on
Based on the result of the power flow calculation, calculate a plurality of vector quantities indicating an increase in load when the operating point of the power system reaches the closest voltage stability limit point from each of the predicted operating points. ,
A load margin calculation method comprising comparing the calculated vector quantities. In order to calculate the amount of load margin from the predicted operating point of the power system to the voltage stability limit in the power system including the distributed power source,
In order to obtain a plurality of predicted operating points of the power system, first information indicating a predicted value of power consumed by the load, and second information regarding a plurality of predicted values of the power generation amount of the distributed power source, A first function for performing a tidal current calculation based on
Based on the calculation result of the first function, a plurality of vector quantities indicating an increase in load when the operating point of the power system reaches the closest voltage stability limit point from each of the predicted operating points. A second function to calculate,
A third function for comparing the calculated vector quantities;
A program that executes

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