JP6311577B2 - PV curve generating apparatus, PV curve generating method and program - Google Patents

Description

  The present invention relates to a PV curve generation device, a PV curve generation method, and a program.

  The voltage of the power system fluctuates when there is some disturbance in the power system. 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.

  The voltage stability of the power system can be analyzed by examining the PV characteristics of the power system. The PV characteristic is a characteristic indicating the relationship between the active power P of the load in the power system and the bus voltage V of a typical electric station. The horizontal axis represents the active power P and the vertical axis represents the bus voltage V. It is expressed by a so-called PV curve or PV curve constituted by trajectories of a plurality of points plotted on the two-dimensional coordinate plane.

  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 (stable limit power). It is also possible to monitor the difference between the voltage at the current operating point and the stability limit voltage. It is also possible to take measures against overload operation that occurs when an accident occurs in the power system.

  Various methods for creating a PV curve are known, and one of them is a method called a Continuation method (continuous method).

  There are various types of Continuation methods, and one of them uses a prediction point calculation formula using tangent information of the PV curve represented by Formula (1) as shown in FIG. 10, for example. Then, a PV curve is created while repeatedly obtaining a predictor and a corrector.

Continuation法を用いてＰＶカーブを作成する場合には、ＰＶカーブ上の点と予測点を結ぶベクトルの長さであるステップ幅を適切に定めることが重要である。

When creating a PV curve using the Continuation method, it is important to appropriately determine a step width that is the length of a vector connecting a point on the PV curve and a predicted point.

  For example, when the step width is smaller than an appropriate value, the time required to create the PV curve increases, and when the step width is larger than an appropriate value, the accuracy of the PV curve decreases, In some cases, a PV curve cannot be created.

  Therefore, various techniques for appropriately determining the step width when using the Continuation method have been developed (see, for example, Patent Document 1 and Patent Document 2).

JP 2005-12930 A JP-A-8-147267

  However, the size and shape of the created PV curve vary depending on the target power system.

  Therefore, for example, even if the step width is determined using the technique described in Patent Document 1 or Patent Document 2 described above, the number of steps necessary to create the PV curve varies depending on the power system, Since the necessary calculation time is difficult to predict, the step width may not be appropriate.

  The present invention has been made in view of such a problem, and a PV curve generation device, PV capable of appropriately determining the step width when generating a PV curve according to the shape and size of the PV curve, PV One object is to provide a curve generation method and program.

  One of means for solving the above-described problem is a PV curve generating device that generates a PV curve representing a relationship between a voltage and a power demand in the power system, and is a first value that is a value of the power demand in the power system. The power flow is calculated a predetermined number of times while changing the power demand value from a predetermined initial value for each first predetermined amount, and the voltage value in each case where the first power demand value changes for each first predetermined amount. An approximate curve generation unit that calculates a first voltage value and generates an approximate curve of the PV curve using the first power demand value and the first voltage value; and an electric power demand indicated by the approximate curve By dividing the difference between the upper limit value and the initial value by a predetermined number of divisions, an increment calculation unit that calculates a second predetermined amount, and a second power demand value that is a value of power demand in the power system From the initial value to the second A tidal current calculation is performed while changing every fixed amount, a second voltage value which is a voltage value in each case where the second power demand value changes for each second predetermined amount is calculated, and the second power demand value is calculated. And a PV curve generation unit that generates the PV curve using the second voltage value.

  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.

  According to the present invention, the step width for generating a PV curve can be appropriately determined according to the shape and size of the PV curve.

It is a figure which shows the function structure of a PV curve production | generation apparatus. It is a figure which shows the hardware constitutions of PV curve production | generation apparatus. It is a figure which shows the memory | storage device of PV curve production | generation apparatus. It is a figure which shows an electric power grid | system. It is a flowchart which shows the flow of a process of the PV curve generation method. It is a figure which shows the tidal current calculation result for calculating | requiring the approximate curve of PV curve. It is a figure which shows the approximated curve of PV curve. It is a figure which shows a PV curve. It is a figure which shows a PV curve. It is a figure for demonstrating one method of calculating | requiring a PV curve by the Continuation method.

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

  The PV curve generation device 100 according to the present embodiment is an information processing device that generates a PV curve representing the relationship between power demand and voltage in a power system 1000 as shown in FIG. 4, for example.

  The power system 1000 shown in FIG. 4 has a power transmission end voltage of Vs, a power reception end voltage of Vr, a reactance of a line connecting the power transmission end and the power reception end is X, and active power (power) supplied to the load. Demand) is λ, the reactive power is Q, and the admittance of the phase adjusting equipment is Y.

  At this time, assuming that the phase angle between the power transmission end and the power reception end is θ, the active power λ and the reactive power Q of the load are expressed by equations (2) and (3).

そして式（２）及び式（３）をVrについて整理することにより、式（４）が得られる。

Then, formula (4) is obtained by rearranging formula (2) and formula (3) with respect to Vr.

式（４）を満たす解の集合を、横軸に有効電力λを対応させ、縦軸に受電電圧Ｖrを対応させた２次元座標平面上に描いたものがＰＶカーブになる。

A PV curve is obtained by drawing a set of solutions satisfying Expression (4) on a two-dimensional coordinate plane in which the horizontal axis corresponds to the active power λ and the vertical axis corresponds to the received voltage Vr.

  On the other hand, when such a PV curve is created using the Continuation method, the value of the load power demand λ is set to a predetermined initial value with respect to the power flow equation shown in the equation (5) established at the operating point of the power system 1000. Then, the voltage v is sequentially obtained while changing (increasing or decreasing) every predetermined step width, and a locus of points on the two-dimensional coordinate plane determined by the power demand λ and the voltage v is drawn.

f (v, λ) = 0 (v is voltage, λ is power demand) (5)
The PV curve generation device 100 according to the present embodiment can appropriately set the step width when generating such a PV curve using the Continuation method according to the shape and size of the PV curve. .

  The structure of the PV curve generation apparatus 100 which concerns on this embodiment is shown in FIGS. FIG. 1 is a diagram for explaining a functional configuration of the PV curve generation device 100, and FIG. 2 is a diagram for explaining a hardware configuration of the PV curve generation device 100. FIG. 3 is a diagram illustrating a state in which the control program 600, the system information 700, and the control data 710 are stored in the storage device 140 included in the PV curve generation device 100.

  As illustrated in FIG. 1, the PV curve generation device 100 includes an approximate curve generation unit 101, an increment calculation unit 102, and a PV curve generation unit 103.

  The approximate curve generation unit 101 uses the first step width (first predetermined amount), the number of calculations (predetermined number of times), and the system information 700, which will be described later, and the value (first value) of the power demand λ in the power system 1000. While increasing the power demand value) from the predetermined initial value for each first step width, the power flow calculation shown in Equation (5) is performed a predetermined number of times, and the value of the power demand λ (first power demand value) in the power system 1000 is The voltage value (first voltage value) in each case increased for each first step width is calculated.

  Here, the grid information 700 is the electrical characteristics of each component of the power grid 1000 (power generation equipment, transmission lines, transformers, phase adjusting equipment, load equipment, etc.), the connection relation of each component, and operating point information (currently Data representing the configuration and state of the power system 1000 including the power demand λ and the voltage v at the operating point.

  The first step width is an increment when the value of the power demand λ is increased when the approximate curve generation unit 101 performs the power flow calculation. The first step width can be set to an optimum value based on past experience and results. For example, the first step width can be determined based on the system capacity of the power system 1000. By determining in this way, the value of the first step width can be easily determined, and the working efficiency can be improved. At this time, for example, if the first step width is set to about 1/100 of the reference power (system capacity of the power system), the step width is sufficiently larger than the size of the PV curve assumed in the general power system 1000. Therefore, when the approximate curve generation unit 101 increases the power demand λ by the first step width and performs the power flow calculation, the power flow calculation exceeds the tip of the PV curve (stable limit power). It becomes possible to prevent.

  In addition, the initial value when performing the tidal current calculation can be determined based on past experience and results. For example, the initial value may be determined based on the value of the power demand λ at the operating point of the power system 1000. At this time, for example, the current power demand λ at the operating point may be used as the initial value as it is, or the average value of the power demand λ at the same time in the past predetermined period may be set as the initial value. Alternatively, when a PV curve at a certain future time is predicted, a predicted value of the power demand λ at the predicted time may be used as an initial value. This initial value may be included in the system information 700, may be input from the input device 150 of the PV curve generation device 100 described later, or similarly, via the communication device 130 described later. You may make it acquire from another computer (not shown).

  When the current power demand λ at the operating point is used as it is as the initial value, the power flow calculation using the initial value can be omitted. As a result, the number of tidal current calculations can be reduced by one and the calculation time can be shortened.

  The number of calculations (predetermined number) is the number of times that the approximate curve generation unit 101 performs the tidal current calculation. FIG. 6 shows three points determined by the set of power demand λ and voltage v obtained by the approximate curve generation unit 101 according to the present embodiment performing the tidal current calculation a predetermined number of times (two or three times). . In the present embodiment, the value of the power demand λ is increased by a predetermined step width, that is, treated as a parameter, and the load parameter on the horizontal axis in FIGS. 6 to 9 indicates the power demand λ.

  Subsequently, the approximate curve generation unit 101 generates an approximate curve of the PV curve using the power demand value λ (first power demand value) and the voltage value v (first voltage value). The approximate curve generation unit 101 according to the present embodiment employs a quadratic curve as an approximate curve of the PV curve.

The quadratic curve is expressed in the form of λ (v) = a + bv + cv ² , and the coefficients a, b, and c can be easily calculated from the calculation results of the three points shown in FIG. An example of the approximate curve created by the approximate curve generation unit 101 in this way is shown in FIG.

  By adopting a quadratic curve as the approximate curve, the approximate curve generation unit 101 can easily calculate an approximate curve in which the deviation from the actual PV curve does not become so large.

  In addition, since only three sets of the power demand value λ and the voltage value v are required to determine the shape of the quadratic curve that is an approximate curve of the PV curve, the approximate curve can be obtained in a short time. it can.

  Of course, it is possible to obtain an approximate curve that can be expected to be closer to the actual PV curve by obtaining a quadratic curve by performing four or more values of power demand λ and voltage v. In this case, The coefficients a, b, and c of the quadratic curve are determined using a method such as a least square method.

  Alternatively, a higher order curve such as a cubic curve or a quartic curve can be adopted as an approximate curve, or various nonlinear functions such as exponential functions, elliptic functions, trigonometric functions, or combinations thereof can be adopted. It is. In this case, the number of values of the power demand λ and the voltage v necessary to determine the approximate curve is determined according to the type of the approximate curve.

  Note that the system information 700, the first step width, and the number of calculations used in the above calculation are stored in the storage device 140 shown in FIG. 3 (the first step width and the number of calculations are included in the control data 710). )

  Returning to FIG. 1, the increment calculation unit 102 calculates the difference between the upper limit value of the power demand λ indicated by the approximate curve of the PV curve generated by the approximate curve generation unit 101 and the initial value by a predetermined number of divisions. By dividing, the second step width (second predetermined amount) is calculated.

A quadratic curve shown in FIG. 7, for example, the voltage at the nose tip of the approximate curve (power demand lambda voltage v ₁ when the upper limit lambda ₁₎ is v ₁ = -b / (2c), and the time the The power demand λ ₁ is calculated as λ ₁ = λ (v ₁ ) = a + bv ₁ + cv ₁ ² . If the initial value of power demand is λ ₀ , the distance from the initial value λ ₀ to the tip of the nose is λ ₁ -λ ₀ . Therefore, when the set number of divisions is 10, the value of the second step width is (λ ₁ −λ ₀ ) / 10.

  In this case, if the power flow calculation shown in Formula (5) is performed while increasing the value of the power demand λ in the power system 1000 for each second step width from the initial value, the initial value is obtained regardless of the shape and size of the PV curve. If the tidal current calculation using values is omitted, the power demand λ in the tenth tidal current calculation is the power demand λ at or near the nose tip of the PV curve.

  For this reason, compared with the case where the tidal flow calculation is repeated with a small step width from the beginning, the number of tidal current calculations required to obtain the PV curve can be greatly reduced, and the overall calculation time can be greatly reduced. Is possible.

  In addition, as described above, the second step width is determined so as to reach the vicinity of the nose tip if a predetermined number of tidal currents are calculated. For example, when the step width is too large compared to the size of the PV curve. As described above, it is possible to prevent wastefulness that the tip of the PV curve is exceeded by only a few times (for example, about a few times), and that the step width is readjusted and the power flow is recalculated. For this reason, it becomes possible to create a PV curve efficiently.

  Furthermore, by obtaining the second step width as described above, the number of tidal current calculations necessary for obtaining the PV curve can be made the same number regardless of the power system 1000. It becomes possible to obtain the PV curve with a calculation time of about.

  The number of divisions described above is 10 as an example, but other values such as 5, 20, 50 may be used as a matter of course.

  Further, as illustrated in FIG. 1, the increment calculation unit 102 may include a mode selection unit 104 and a predetermined division number setting unit 105 so that the number of divisions can be changed.

  The mode selection unit 104 receives information specifying the accuracy when generating the PV curve from the input device 150 or the communication device 130. For example, the mode selection unit 104 receives input of information for selecting either the first mode for generating the PV curve with the first accuracy or the second mode for generating the PV curve with the second accuracy.

  The predetermined division number setting unit 105 sets the predetermined division number to the first value when the first mode is selected, and sets the predetermined division number to the first value when the second mode is selected. A second value different from the value is set. For example, when the PV division is generated with the first accuracy, the predetermined division number setting unit 105 increases the division number so that the number of tidal current calculations is smaller than when the PV curve is generated with the second accuracy. Set to a small value.

  According to such an aspect, it is possible to obtain the PV curve with the appropriate number of tidal current calculations according to the accuracy required for the PV curve.

  Next, the PV curve generation unit 103 uses the above-described second step width (second predetermined amount) and the system information 700 to calculate the value of the power demand λ (second power demand value) in the power system 1000. While increasing from the predetermined initial value for each second step width, the power flow calculation shown in Expression (5) is performed, and the value of the power demand λ (second power demand value) in the power system 1000 is calculated for each second step width. The voltage value (second voltage value) in each increased case is calculated. Then, the PV curve generation unit 103 generates a PV curve using the value of the power demand λ (second power demand value) and the value of the voltage v (second voltage value).

  FIG. 8 shows the PV curve generated by the PV curve generation unit 103 when the first mode is selected. FIG. 9 shows a PV curve generated by the PV curve generation unit 103 when the second mode is selected.

  The number of tidal current calculations required to generate a PV curve when the first mode is selected is substantially the same regardless of the shape and size of the PV curve. Similarly, the number of tidal current calculations required to generate a PV curve when the second mode is selected is substantially the same regardless of the shape and size of the PV curve.

  Thus, according to the PV curve generation device 100 according to the present embodiment, it is possible to appropriately determine the step width when generating the PV curve according to the shape and size of the PV curve.

  Similarly to the approximate curve generation unit 101, the PV curve generation unit 103 can omit the power flow calculation using the initial value when the current power demand λ at the operating point is used as it is as the initial value. Thus, it is possible to reduce the number of times the tidal current calculation is performed and to reduce the calculation time.

  Next, the hardware configuration of the PV curve generating apparatus 100 according to the present embodiment is shown in FIG.

  The PV curve generation device 100 according to this embodiment includes a CPU (Central Processing Unit) 110, a memory 120, a communication device 130, a storage device 140, an input device 150, an output device 160, and a recording medium reading device 170. Computer.

  The CPU 110 is responsible for overall control of the PV curve generation device 100, and reads out and executes the control program 600 composed of codes for performing various operations according to the present embodiment stored in the storage device 140 to the memory 120. By doing so, various functions as the PV curve generating device 100 are realized.

  For example, the control program 600 is executed by the CPU 110 and cooperates with hardware devices such as the memory 120, the communication device 130, and the storage device 140, whereby the approximate curve generation unit 101, the increment calculation unit 102, the PV curve generation unit 103, A mode selection unit 104, a predetermined division number setting unit 105, and the like are realized.

  The memory 120 can be configured by a semiconductor memory device, for example.

  The communication device 130 is a network interface such as a network card. The communication device 130 receives data from another computer via a network such as the Internet or a LAN (Local Area Network), and stores the received data in the storage device 140 or the memory 120. Further, the communication device 130 transmits data stored in the storage device 140 or the memory 120 to another computer via the network.

  The input device 150 is a device such as a keyboard, a mouse, or a microphone, and functions as a user interface for accepting input of information by an operator of the PV curve generation device 100.

  The output device 160 is a device such as an LCD (Liquid Crystal Display), a printer, and a speaker, and is a device that functions as a user interface for outputting information such as the above-described PV curve and approximate curve.

  The storage device 140 can be constituted by, for example, a hard disk device or a semiconductor storage device. The storage device 140 is a device that provides a physical storage area for storing various programs, data, tables, and the like. Note that the storage device 140 may be configured to be included in another computer that is communicably connected.

  FIG. 3 shows a state where the control program 600, the system information 700, and the control data 710 are stored in the storage device 140.

  The system information 700 includes the electrical characteristics of each component of the power system 1000, the connection relationship of each component, and the operating point information (the values of power demand λ and voltage v at the current operating point). Or data representing the state.

  The control data 710 includes various setting data used when the PV curve generation device 100 performs a power flow calculation. For example, the control data 700 includes the first step width, the second step width, the number of calculations, the number of divisions, the order of the approximate curve, and the like.

  The control program 600 is read out from the recording medium (various optical disks, magnetic disks, semiconductor memories, etc.) 800 to the storage device 140 using the recording medium reader 170, and is stored in the PV curve generation device 100. It can also be stored in the PV curve generation device 100 by obtaining from another computer that is communicably connected via the communication device 130.

  Next, the process flow of the PV curve generation method according to the present embodiment will be described with reference to the flowchart shown in FIG.

  First, the PV curve generation device 100 acquires operating point information (S1000). The PV curve generation device 100 according to the present embodiment uses the power demand λ and voltage v included in the operating point information as initial values as they are, and uses the current power demand λ value included in the operating point information as it is. The tidal current calculation used is omitted.

  Therefore, the PV curve generation device 100 adds the first step width to the power demand λ (first power demand value) included in the operating point information (S1010), and then adds the power demand λ (first power). The power flow is calculated using the demand value) and the system information 700 (S1020). Then, the PV curve generation device 100 calculates a voltage v (first voltage value) in the power system 1000.

  Thereafter, the PV curve generation device 100 repeats the power flow calculation a predetermined number of times while adding the value of the power demand λ (first power demand value) by the first step width (S1010, S1020, S1030). At this time, when the approximate curve is generated using three sets of the value of the power demand λ (first power demand value) and the value of the voltage v (first voltage value), the predetermined number of times is two.

  Then, the PV curve generation device 100 generates an approximate curve of the PV curve using the value of the power demand λ (first power demand value) and the value of the voltage v (first voltage value) (S1040), A second step width (second predetermined amount) is calculated by dividing the difference between the upper limit value of power demand λ indicated by the approximate curve and the initial value by a predetermined number of divisions (S1050).

  Then, the PV curve generation device 100 adds the second step width to the power demand λ (second power demand value) included in the operating point information acquired in S1000, and adds the power demand λ (second power demand value). The power flow is calculated using the power system information 700 and the voltage v (second voltage value) in the power system 1000 is calculated (S1060).

  The PV curve generation device 100 repeatedly performs the power flow calculation while adding the value of the power demand λ (second power demand value) by the second step width, and when the predetermined end condition is satisfied (S1070), the above power demand A PV curve is generated using the set of the value of λ (second power demand value) and the value of voltage v (second voltage value) (S1080).

  The end condition is, for example, when the value of the power demand λ (second power demand value) exceeds the nose tip (stability limit power) of the PV curve and the solution of the power flow calculation cannot be obtained, When the difference between the solution and the lower solution is equal to or less than a predetermined value, it can be set using various methods as appropriate.

  As described above, the PV curve generation device 100, the PV curve generation method, and the control program 600 according to the present embodiment have been described in detail. However, according to these embodiments, the step width when generating the PV curve is set to It becomes possible to determine appropriately according to the shape and size.

  As a result, the calculation amount, the number of calculations, and the calculation time required for obtaining the PV curve can be made comparable even when obtaining the PV curve of any power system 1000.

  Further, according to the PV curve generation device 100, the PV curve generation method, and the control program 600 according to the present embodiment, when determining the step width, the accuracy required for the PV curve is taken into account, and an appropriate value according to the required accuracy is obtained. The PV curve can be obtained by the number of tidal current calculations.

  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.

100 PV curve generating device 101 Approximate curve generating unit 102 Increment calculating unit 103 PV curve generating unit 104 Mode selecting unit 105 Predetermined division number setting unit 110 CPU
120 Memory 130 Communication Device 140 Storage Device 150 Input Device 160 Output Device 170 Recording Medium Reading Device 600 Control Program 700 System Information 710 Control Data 800 Recording Medium 1000 Power System

Claims (6)

A PV curve generation device that generates a PV curve representing a relationship between voltage and power demand in a power system,
Power flow calculation is performed a predetermined number of times while changing a first power demand value, which is a value of power demand in the power system, from a predetermined initial value for each first predetermined amount, and the first power demand value is the first predetermined amount. Approximate curve generation that calculates a first voltage value that is a voltage value in each case that changes every time and generates an approximate curve of the PV curve using the first power demand value and the first voltage value And
An incremental calculation unit that calculates a second predetermined amount by dividing the difference between the upper limit value of the power demand indicated by the approximate curve and the initial value by a predetermined number of divisions;
A power flow calculation is performed while changing a second power demand value, which is a value of power demand in the power system, from the initial value for each second predetermined amount, and the second power demand value is calculated for each second predetermined amount. Calculating a second voltage value that is a voltage value in each case that changes, and using the second power demand value and the second voltage value, a PV curve generating unit that generates the PV curve;
A PV curve generating device comprising: The PV curve generating device according to claim 1,
A mode selection unit that receives input of information for selecting either the first mode for generating the PV curve with a first accuracy or the second mode for generating the PV curve with a second accuracy;
When the first mode is selected, the predetermined division number is set to a first value, and when the second mode is selected, the predetermined division number is different from the first value. A predetermined division number setting unit to be set to the second value;
The PV curve generating device further comprising: The PV curve generating device according to claim 1 or 2,
The PV curve generation device according to claim 1, wherein the first predetermined amount is a value determined based on a system capacity of the power system. The PV curve generating device according to any one of claims 1 to 3,
The initial value is a value determined based on a value of power demand at an operating point. A PV curve generation method for generating a PV curve representing a relationship between voltage and power demand in a power system,
Power flow calculation is performed a predetermined number of times while changing a first power demand value, which is a value of power demand in the power system, from a predetermined initial value for each first predetermined amount, and the first power demand value is the first predetermined amount. A procedure for calculating a first voltage value, which is a voltage value in each case that changes every time,
Using the first power demand value and the first voltage value to generate an approximate curve of the PV curve;
A procedure for calculating the second predetermined amount by dividing the difference between the upper limit value of the power demand indicated by the approximate curve and the initial value by a predetermined number of divisions;
A power flow calculation is performed while changing a second power demand value, which is a value of power demand in the power system, from the initial value for each second predetermined amount, and the second power demand value is calculated for each second predetermined amount. A procedure for calculating a second voltage value, which is a voltage value in each case of changing,
Using the second power demand value and the second voltage value to generate the PV curve;
A PV curve generation method characterized by comprising: In a PV curve generating device that generates a PV curve representing the relationship between voltage and power demand in a power system,
Power flow calculation is performed a predetermined number of times while changing a first power demand value, which is a value of power demand in the power system, from a predetermined initial value for each first predetermined amount, and the first power demand value is the first predetermined amount. A procedure for calculating a first voltage value, which is a voltage value in each case that changes every time,
Using the first power demand value and the first voltage value to generate an approximate curve of the PV curve;
A procedure for calculating the second predetermined amount by dividing the difference between the upper limit value of the power demand indicated by the approximate curve and the initial value by a predetermined number of divisions;
A power flow calculation is performed while changing a second power demand value, which is a value of power demand in the power system, from the initial value for each second predetermined amount, and the second power demand value is calculated for each second predetermined amount. A procedure for calculating a second voltage value, which is a voltage value in each case of changing,
Using the second power demand value and the second voltage value to generate the PV curve;
A program for running

Images