JP2018182982A - Tidal flow calculation device, tidal flow calculation method, and tidal flow calculation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the calculation accuracy of the state quantity with respect to a power system model including a voltage adjusting device that adjusts an output voltage with respect to an input voltage by a discrete adjustment operation.SOLUTION: A voltage adjustment device included in a power system model constitutes a tidal flow calculation device 1 that includes an adjustment operation control unit 121 that stops a discrete adjustment operation of the voltage adjustment device that adjusts an output voltage with respect to an input voltage by the discrete adjustment operation and a tidal flow calculation unit 122 that calculates the state quantity of each node in a state in which the discrete adjustment operation has been stopped by using a convergence calculation method including a forward calculation that sequentially calculates the state quantity of a node of a power system model from a top node on the upstream side and a backward calculation that modifies a state variable of the top node on the basis of an error of the state quantity of a bottom node on the downstream side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tidal current calculation device, a tidal current calculation method, and a tidal current calculation program.

  In the power system, for example, power flow calculation can be performed using a model of the power system in order to monitor the voltage during operation or to determine the load accommodation in the event of an accident. In the power flow calculation, unknown state quantities are calculated based on known state quantities of the power system. State quantities include the magnitude of voltage at any point (node) or connection line (branch) between nodes, phase angle of voltage, active power, reactive power, and constants of power system impedance information, etc. Can be composed of For example, as a calculation method for a radial power system such as a distribution system, there is a BFS (Backward Forward Sweep) method. In the BFS method, the state quantity is calculated by executing loop processing until the convergence condition is satisfied.

In addition, the technique of patent document 1 and 2 is known as a related technique.
The distribution system model described in Patent Document 1 is an induction machine type distributed power supply model which is used for power flow calculation of a power system in which a distributed power supply is connected and in which an induction generator is connected to the system as a distributed power supply. In this induction machine type distributed power supply model, when constant power control is performed with the active power P which is the output constant, the product of the coefficient a2 and the square term of the voltage V of the interconnection node, and the coefficient a1 and the first power of the voltage V The reactive power Q is approximated by the sum of the product of the terms and the product of the coefficient a 0 and the zero power term of the voltage V. The coefficient a2 is expressed using the effective power P, the primary leakage reactance x1 of the induction generator, the secondary leakage reactance x2, and the excitation susceptance b0. Further, the coefficients a1 and a0 are expressed using the effective power P, the primary leakage reactance x1 of the induction generator, and the secondary leakage reactance x2.

  The power system power flow calculation device described in Patent Document 2 includes an output restriction determination unit, a convergence calculation unit, a convergence determination unit, and an output unit. The output limit determination means determines whether or not the i-th approximate solution of the convergence calculation of the tidal current equation depends on the output limit of the facility capacity. The convergence calculation means stores in advance a flow equation not considering the output limit value of the installation capacity. When the i-th approximate solution depends on the output limitation of the installation capacity, the convergence calculation means changes the power flow equation of the characteristic fixed to the output limit value of the installation capacity to obtain the i + 1-th approximate solution. Further, the convergence calculation means obtains the (i + 1) -th approximate solution by the flow equation stored in advance when the i-th approximate solution does not depend on the output limitation of the facility capacity. The convergence determination means determines whether or not the convergence calculation has converged when the convergence calculation means has performed a predetermined number of convergence calculations. The output means outputs the approximate solution at that time as a tidal flow solution when the convergence judgment means judges that the convergence calculation has converged, and outputs no tidal flow solution when it is judged that the convergence calculation does not converge.

JP 2001-78358 A JP 2012-80709 A

  However, in the BFS method, there may be a large difference between the state quantity calculated in the process of loop processing before the convergence condition is satisfied and the state quantity finally obtained by satisfying the convergence condition. Therefore, when power flow calculation is performed using the BFS method for a power system model including a voltage regulator that discretely adjusts the output voltage with respect to the input voltage by tap switching or the like, the tap switching is erroneously performed in the calculation process. Etc. may occur. If tap switching or the like is performed erroneously in the calculation process, the calculation accuracy of the state quantity deteriorates.

  An object according to one aspect of the present invention is to improve the calculation accuracy of a state quantity for a power system model including a voltage regulator that regulates an output voltage with respect to an input voltage by discrete regulation operation.

  A tidal current calculation device according to one embodiment comprises an adjustment operation control unit and a tidal current calculation unit. The adjustment operation control unit is a voltage adjustment device included in the power system model, and stops the discrete adjustment operation of the voltage adjustment device which adjusts the output voltage with respect to the input voltage by the discrete adjustment operation. The power flow calculation unit uses the convergence calculation method to calculate the state quantities of the respective nodes in a state in which the discrete adjustment operation is stopped. In the convergence calculation method, the state variable of the head node is corrected based on the forward calculation which sequentially calculates the state amount of each node of the power system model from the head node on the upstream side and the error of the state amount of the downstream end node. It includes backward calculation.

  According to the power flow calculation device according to one embodiment, it is possible to improve the calculation accuracy of the state quantity for the power system model including the voltage adjustment device that adjusts the output voltage with respect to the input voltage by the discrete adjustment operation.

It is a figure showing an example of composition of a tidal current calculation device according to an embodiment. It is a figure which shows an example of the processing flow of the tidal current calculation method according to embodiment. It is a figure which shows an example of the processing flow according to the BFS method. It is a figure which shows the 1st structural example of the electric power system model which is the object of tidal current calculation. Diagram showing a data configuration example for a first configuration example of a power system model It is a figure explaining the characteristic of the transformer contained in the 1st structural example of a power system model. It is a figure explaining the tap operation of the transformer contained in the 1st example of composition of a power system model. It is a figure explaining the tidal current calculation result when tap switching of a transformer operate | moves. It is a figure explaining the tidal current calculation result when tap switching of a transformer stops. It is a figure which shows the 2nd structural example of the electric power system model which is the object of tidal current calculation. It is a figure which shows the data structural example with respect to the 2nd structural example of a power system model. It is a figure which shows the 1st structural example of the phase-matching installation contained in the 2nd structural example of an electric power grid | system model. It is a figure explaining discrete adjustment operation of a phase-matching installation included in the 2nd example of composition of a power system model. It is a figure explaining the power flow calculation result at the time of discrete adjustment operation | movement of a phase-matching installation working. It is a figure explaining the power flow calculation result when the discrete adjustment operation | movement of a phase-matching installation stops. It is a figure which shows the 2nd structural example of the phase-matching installation contained in the 2nd structural example of an electric power grid | system model. It is a figure showing an example of composition of a computer which runs a tidal current calculation program according to an embodiment.

  Hereinafter, embodiments will be described in detail based on the drawings.

<Configuration of tidal current calculation device>
FIG. 1 is a diagram showing a configuration example of a tidal current calculation device according to the embodiment. In the configuration example shown in FIG. 1, the power flow calculation device 1 includes an input unit 11, a calculation unit 12, a storage unit 13, an output unit 14, and a communication unit 15.

  The input unit 11 is, for example, a keyboard, a mouse, and / or a touch panel. The communication unit 15 is, for example, a wired or wireless transceiver for communicating with another information processing apparatus (not shown). System data of a power system model used for power flow calculation is input to the input unit 11 or the communication unit 15.

  The system data to be input includes, for example, data on a system configuration, equipment constants, and operating conditions. The system configuration data is, for example, the connection state of a generator, a transformer, a phase adjusting facility, and a distribution line. The equipment constant data is, for example, impedance and admittance of each equipment and equipment, and tap information of a transformer. The operating condition data is, for example, the amount of power generation and the amount of load at each node. The input system data is stored in the storage unit 13. The storage unit 13 is, for example, a random access memory (RAM) or a read only memory (ROM).

  The calculation unit 12 is a central processing unit (CPU), a multi-core CPU, or a programmable device (such as a field programmable gate array (FPGA) or a programmable logic device (PLD)). The calculation unit 12 includes an adjustment operation control unit 121 and a tidal current calculation unit 122.

  The adjustment operation control unit 121 stops the discrete adjustment operation of the voltage adjustment device included in the power system model which is the target of the power flow calculation. In addition, when the difference voltage between the output voltage of the voltage regulator calculated by the power flow calculator 122 and the target voltage of the voltage regulator is larger than the voltage dead zone width set for the discrete adjustment operation, The adjustment operation control unit 121 operates the discrete adjustment operation.

  The voltage regulator included in the power system model is a device that regulates the output voltage with respect to the input voltage by discrete regulation operation. The input voltage is a system voltage detected by the voltage regulator at a connection point of the voltage regulator. The voltage regulator performs discrete adjustment operation so that the output voltage approaches the target voltage. The voltage regulator may be, for example, a transformer connected in series to a distribution line of the power system model and discretely adjust the output voltage with respect to the input voltage by tap switching, and includes an SVR (step Voltage Regulator) or the like. Also, the voltage regulator may be, for example, a phase-adjusting facility with an automatic voltage control function that is connected in parallel to the distribution line of the power system model and discretely adjusts the reactive power input amount to the input voltage.

  The tidal current calculation unit 122 performs tidal current calculation using the system data stored in the storage unit 13. Specifically, the power flow calculation unit 122 calculates the amount of state of each node included in the power system model in a state where the discrete adjustment operation is stopped or operated. The state quantities obtained by the power flow calculation can include the voltage and phase difference of each node, and the transmission active power and transmission reactive power of the branch. The result of the tidal current calculation is stored in the storage unit 13.

  In the power flow calculation performed by the power flow calculation unit 122, the head node is calculated based on the forward calculation that sequentially calculates the state quantity of each node of the power system model from the head node on the upstream side and the error of the state quantity of the terminal node on the downstream side. A convergence calculation method is used which includes backward calculation to correct the state variables of. An example of such a convergence calculation method is the BFS method.

  The output unit 14 is, for example, a liquid crystal display or a CRT (Cathode Ray Tube) display. The output unit 14 outputs the result of the tidal current calculation. The result of the tidal current calculation may be output from the communication unit 15 to another information processing apparatus.

<Process flow of tidal current calculation method>
The tidal current calculation device 1 performs tidal current calculation, for example, according to the processing flow as shown in FIG. 2 and FIG. FIG. 2 is a diagram showing an example of a processing flow of the tidal current calculation method according to the embodiment. FIG. 3 is a diagram showing an example of a processing flow according to the BFS method.

  In step S101, system data of a power system model to be subjected to power flow calculation is input to the power flow calculation apparatus 1 via the input unit 11 or the communication unit 15, and the storage unit 13 stores the system data. In step S102, the adjustment operation control unit 121 reads out the system data from the storage unit 13, and determines based on the system data whether or not the voltage adjustment device including the discrete adjustment operation is included in the power system model.

  If it is determined that the voltage regulator including the discrete adjustment operation is not included in the power system ("NO" in step S102), the series of processes proceeds to step S108. If it is determined that the voltage adjustment device including the discrete adjustment operation is included in the power system ("YES" in step S102), the series of processes proceeds to step S103.

  In step S103, the adjustment operation control unit 121 stops the discrete adjustment operation of the voltage adjustment device. For example, when the voltage regulator is a transformer as described above, the adjustment operation control unit 121 maintains the tap of the voltage regulator at the tap initially set in the system data. In step S104, the tidal current calculation unit 122 performs tidal current calculation using a convergence calculation method as shown in FIG. That is, the tidal current calculation unit 122 calculates the state quantities of each node in a state in which the discrete adjustment operation is stopped.

  In step S201, the power flow calculation unit 122 sets the load amount and the power generation amount of the power system by initial value calculation. In step S202, the power flow calculation unit 122 sequentially calculates the power equation from the leading node on the upstream side of the power system model toward the end on the downstream side, and determines each state quantity of the power system model (forward calculation). In step S203, the power flow calculation unit 122 determines whether a predetermined convergence condition is satisfied. The convergence condition is, for example, whether the state quantity at the terminal node is smaller than the judgment reference value, ie, whether the tidal current calculation has converged or not, or the number of calculations in step S202 is a predetermined number of calculations or calculation time. It is a condition such as whether it has reached or not.

  If it is determined that the predetermined convergence condition is satisfied ("YES" in step S203), the tidal current calculation unit 122 ends the convergence calculation. On the other hand, when it is determined that the predetermined convergence condition is not satisfied (“NO” in step S203), the tidal current calculation unit 122 corrects the state variable of the lead node from the state quantity error of the terminal node (step S204, reverse calculation). ), Return to the process of step S202. Then, the power flow calculation unit 122 repeats the loop process of steps S202 to S204 until it is determined that the convergence condition is satisfied.

  In step S105, the adjustment operation control unit 121 calculates a difference voltage ΔE between the output voltage of the voltage regulator calculated by the power flow calculator 122 and the target voltage of the voltage regulator. Then, in step S106, the adjustment operation control unit 121 compares the absolute value of the difference voltage ΔE with the voltage dead zone width set for the discrete adjustment operation.

  If the absolute value of the difference voltage ΔE is less than or equal to the voltage dead zone width (“NO” in step S106), the series of processes proceeds to step S109. If the absolute value of the difference voltage ΔE exceeds the voltage dead zone width (“YES” in step S106), the series of processes proceeds to step S107.

  In step S107, the adjustment operation control unit 121 operates the discrete adjustment operation of the voltage adjustment device. For example, if the voltage regulator is a transformer as described above, the adjustment operation control unit 121 operates tap switching in accordance with the input voltage.

  In step S108, the tidal current calculation unit 122 performs tidal current calculation using the convergence calculation method as described above with reference to FIG. That is, when the power flow calculation of step S108 is performed after step S107, the power flow calculation unit 122 calculates the state quantity of each node in a state in which the discrete adjustment operation is in operation.

  In step S109, the power flow calculation unit 122 outputs the amount of state of each node which is the result of the power flow calculation. The output state quantity is stored in the storage unit 13. The output state quantity may be output by the output unit 14 or the communication unit 15.

  As described above, in the power flow calculation method according to the embodiment, when the voltage regulator with the discrete adjustment operation is included in the power system model, the discrete adjustment operation is stopped and the convergence calculation method such as the BFS method is performed. Tidal current calculation using is performed first. Then, only when the difference between the output voltage of the voltage regulator obtained by the power flow calculation and the target voltage of the voltage regulator exceeds the voltage dead zone width, the discrete adjustment operation is operated to use the convergence calculation method. The tidal current calculation is performed again. Therefore, according to the power flow calculation method according to the embodiment, since the erroneous discrete adjustment operation is suppressed in the process of power flow calculation, it is possible to improve the calculation accuracy of the state quantity for the power system model.

  Below, the power flow calculation method according to the embodiment will be further described by showing a specific configuration example of the power system model.

<First Configuration Example>
FIG. 4 is a diagram showing a first configuration example of a power system model which is an object of power flow calculation. FIG. 4 shows a distribution system 2 in which distribution lines called “feeders” extend radially from a substation on the power source side as a first configuration example of the power system model. In the configuration example shown in FIG. 4, the distribution system 2 includes distribution lines 21-1 to 21-22, a feeder circuit breaker (FCB (Feeder Circuit Breaker)) 22, a transformer 23, and a switch 24. Moreover, the power distribution system 2 includes utility poles 25-1 to 25-22 and customers 26-1 to 26-4. The number of distribution lines, switches, power poles, and consumers included in the distribution system 2 is not limited to the numbers shown in FIG. 4 and may be any number.

  The transformer 23 is an example of a voltage regulator connected in series to the distribution line of the power system model. The transformer 23 can be installed, for example, on a distribution line with a large voltage fluctuation. In the distribution system 2, power transmission is performed via the feeder breaker 22 and the switch 24 and the like. In the example shown in FIG. 4, the feeder breaker 22 is set to the on state, and the switch 24 is set to the off state.

<< Systematic data in the first configuration example >>
As shown in FIG. 4, in the distribution system 2, the feeder breaker 22 and the utility poles 25-1 to 25-22 are defined as nodes, and the distribution lines 21-1 to 21-22 are defined as branches. Moreover, the transformer 23 is defined as a branch, and the secondary side connection point of the transformer 23 is also defined as a node. By such definition, the distribution system 2 is digitized as numerical values shown in FIG. 5 (A) and FIG. 5 (B). FIG. 5 is a diagram showing an example of data configuration for the first configuration example of the power system model.

  For example, in the distribution system 2, the impedance of the distribution line 21-1 between the feeder breaker 22 and the first power pole 25-1 downstream from the feeder breaker 22 is line resistance R = 0.080 [Ω And the line reactance X = 0.160 [Ω]. Moreover, the load amount of the customer 26-1 connected to the telephone pole 25-1 is 16.4 [kW] and 6.8 [kVar], and the amount of power generation such as sunlight is 2.2 [kW] , 0.2 [kVar] is set.

  When feeder breaker 22 is defined as node N1 and utility pole 25-1 is defined as node N2, nodes N1 and N2 are the first and second rows of the node table shown in FIG. 5A in the setting as described above. It is digitized as As described above, in the nodes N1 to N24 included in the distribution system 2, the node name, the load amount, and the power generation amount are associated with each other and converted into data. The node table is stored in the storage unit 13 as system data.

  Further, if the distribution line 21-1 is defined as the branch B1, the branch B1 is converted into data as shown in the first row of the branch table shown in FIG. 5B in the setting as described above. As described above, the branches B1 to B23 included in the distribution system 2 are converted into data in correspondence with the branch name, the power supply side node name, the load side node name, the branch type, and the impedance, respectively. The branch table is stored in the storage unit 13 as system data.

  Next, the transformer 23 is set to the characteristics as shown in FIG. FIG. 6 is a diagram for explaining the characteristics of the transformer included in the first configuration example of the power system model. Specifically, FIG. 6 (A) shows the specification of the transformer, and FIG. 6 (B) shows the relationship between the tap of the transformer and the rated voltage. The characteristic shown in FIG. 6 is an example of the characteristic of the transformer 23, and the transformer 23 may be set to a characteristic different from the characteristic shown in FIG.

  In an example shown in FIG. 6A, the tap control of the transformer 23 is an automatic mode in which the tap position is autonomously switched by the transformer 23, and the operation method is a LDC (Line Drop Compensation) control method. The target voltage of the transformer 23 is 6600 [V] in high voltage conversion, and the voltage dead band width set for discrete adjustment operation by tap switching, that is, the voltage set above and below the primary side rated voltage of each tap The dead zone width is 132 [V]. Further, among the nine taps included in the transformer 23, the through tap is the tap T5, and the tap position before the power flow calculation, that is, the current tap is the tap T5.

  In the example illustrated in FIG. 6B, the primary side rated voltages of the taps T1 to T9 are 7200 [V], 7050 [V], 6900 [V], 6600 [V], 6450 [V], 6300 [V], 6150 [V], and 6000 [V]. Moreover, the secondary side rated voltage of each of the tap T1 to the tap T9 is 6600 [V].

  When the transformer 23 is set to the characteristics shown in FIG. 6 (A) and FIG. 6 (B), the transformer 23 is digitized as in the voltage regulator setting table shown in FIG. 5 (C). The voltage regulator setting table shown in FIG. 5C is stored in the storage unit 13 as system data.

<< tidal current calculation in the first configuration example >>
When the transformer 23 is set to the characteristics shown in FIG. 6 (A) and FIG. 6 (B), the transformer 23 performs the tap operation as shown in FIG. FIG. 7 is a diagram for explaining the tap operation of the transformer included in the first configuration example of the power system model. As described above, the voltage dead zone width of 132 [V] is set for discrete adjustment operation by tap switching. For example, a voltage dead zone of 132 [V] exists above and below the primary side rated voltage 6600 [V] of the tap T5 which is the current tap. Therefore, when the input voltage of the transformer 23, that is, the voltage of the node N20 which is the primary side connection point of the transformer 23 is within the range of 6468 V to 6732 V, the transformer 23 switches taps. Do not do. On the other hand, as shown in FIG. 7, for example, when the input voltage of the transformer 23 exceeds 6732 [V], the transformer 23 performs a tap operation to raise the tap from the tap T5 to the tap T4 by one stage. There is a voltage dead zone of 132 [V] above and below the primary side rated voltage 6750 [V] of the tap T4. Therefore, when the input voltage of the transformer 23 is in the range of 6618 [V] to 6882 [V], the transformer 23 does not perform tap switching. On the other hand, as shown in FIG. 7, when the input voltage of the transformer 23 falls below 6618 [V], the transformer 23 performs a tap operation to lower the tap by one stage from the tap T4 to the tap T5.

  Thus, when the absolute value of the difference between the input voltage and the primary side rated voltage of the current tap exceeds the voltage dead band, the transformer 23 switches the tap. That is, the transformer 23 has nine steps in steps of 150 V rising and falling voltage widths so that the voltage of the node N21 which is the secondary side connection point of the transformer 23, that is, the output voltage becomes the target voltage 6600 [V]. Activate the tap. Therefore, temporarily, in a state where tap switching of the transformer 23 is operated, that is, when the power flow calculation of step S108 is executed without going through steps S102 to S107 shown in FIG. 2, the power flow calculation as shown in FIG. 8 Results may be derived. FIG. 8 is a diagram for explaining the result of power flow calculation when tap switching of the transformer is activated.

  FIG. 8A shows the result of the first forward calculation according to the BFS method (FIG. 3) when the tidal current calculation of step S108 is performed without going through steps S102 to S107. In the forward calculation of step S202 according to the BFS method, the power flow calculation unit 122 calculates the state quantities of each node in order from the leading node N1 on the upstream side. As shown in FIG. 8A, in the forward calculation of the first step S202, the power flow calculator 122 calculates the input voltage of the transformer 23, that is, the voltage of the node N20 at 6740 [V]. In this case, the difference between the voltage of the node N20 and the target voltage 6600 [V] exceeds the voltage dead band 132 [V]. Therefore, as shown in FIG. 5C, since the current tap before the power flow calculation is the tap T5, the power flow calculation unit 122 simulates a tap operation in which the tap of the transformer 23 is lowered by one stage to the tap T4. Then, the power flow calculation unit 122 sets the output voltage of the transformer 23, that is, the voltage of the node N21 to 6590 [V] (6740 [V]-150 [V]).

  In the forward calculation in the first step S202, an error may occur in the state quantity of the end node due to a power loss or the like on the distribution line due to the distribution line impedance such as the line resistance shown in the branch table of FIG. . Therefore, the tidal current calculation unit 122 corrects the state variable of the leading node based on the error (step S204, backward calculation), returns to step S204 until the convergence condition is satisfied (step S203), and calculates the state quantities of each node. Recalculate.

  FIG. 8B shows the result of the second forward calculation according to the BFS method when the tidal current calculation of step S108 is performed without going through steps S102 to S107. As shown in FIG. 8 (B), when the power flow calculation unit 122 calculates the voltage of the node N20 at 6680 [V] in the forward calculation of the second step S202, the voltage of the node N20 and the target voltage 6600 [V] Of the voltage dead band 132 [V]. Therefore, the tidal current calculation unit 122 simulates the tap operation of maintaining the tap of the transformer 23 at the tap T4, and sets the voltage of the node N21 to 6530 [V] (6680 [V]-150 [V]).

  FIG. 8C shows the final calculation result according to the BFS method when the flow calculation in step S108 is performed without going through steps S102 to S107. As a result of satisfying the convergence condition (“YES” in step S203), the voltage of the node N20 is finally calculated as 6700 [V], the tap of the transformer 23 is T4, and the voltage of the node N21 is 6550 [V].

  As described above, since the BFS method is a method of correcting the power loss and the like in the distribution line in the loop processing of step S202 to step S204, the error at the terminal node becomes large in the first calculation. Therefore, the voltage at each node calculated in the first process may greatly differ from the voltage finally obtained by satisfying the convergence condition.

  In the example shown in FIG. 8, even if the tap of transformer 23 is maintained at tap T5 before power flow calculation until the final calculation result is obtained, the voltage of node N20 is finally around 6700 [V] It may be calculated. If the voltage at node N20 is near 6700 [V], the tap of transformer 23 is maintained at tap T5.

  As described above, the switching from tap T5 to tap T4 is only generated during the process of power flow calculation using the BFS method, and in the actual distribution system simulated by the power system model, the transformer tap is currently tap T5. It is likely to be maintained. Therefore, due to the tap malfunction in the calculation process, the state quantity obtained by the power flow calculation deviates from the actual state quantity of the distribution system, and the calculation accuracy of the power flow calculation becomes worse.

  Therefore, in the tidal current calculation method according to the embodiment, the processes of step S102 to step S107 are performed before the tidal current calculation of step S108 is performed. For example, when the transformer 23 is included in the distribution system 2 (“YES” in step S102), the adjustment operation control unit 121 stops tap switching of the transformer 23 and maintains the tap of the transformer 23 at tap T5 at present. Do. Then, the tidal current calculation unit 122 simulates the tap operation in which the tap of the transformer 23 is currently maintained at the tap T5 and executes the tidal current calculation of step S104. When the tidal current calculation of step S104 is performed, a tidal current calculation result as shown in FIG. 9 can be derived. FIG. 9 is a diagram for explaining the result of the power flow calculation when the tap switching of the transformer is stopped.

  FIG. 9A shows the result of the first forward calculation according to the BFS method when the flow calculation in step S104 is performed. As shown in FIG. 9A, when the power flow calculation unit 122 calculates the voltage of the node N20 at 6740 [V] in the forward calculation of the first step S202, the voltage of the node N20 and the target voltage 6600 [V] The voltage difference exceeds the dead band 132 [V]. However, the power flow calculation unit 122 simulates the tap operation of maintaining the tap of the transformer 23 at the current tap T5, which is a transparent tap, and sets the voltage of the node N21 to 6740 [V].

  FIG. 9B shows the result of the second forward calculation according to the BFS method when the flow calculation in step S104 is performed. As shown in FIG. 9B, the power flow calculation unit 122 calculates the voltage of the node N20 as 6680 [V] in the forward calculation of step S202 for the second time. Then, the power flow calculation unit 122 simulates the tap operation of maintaining the tap of the transformer 23 at the current tap T5, and sets the voltage of the node N21 to 6680 [V].

  FIG. 9C shows a final calculation result according to the BFS method when the flow calculation in step S104 is performed. As a result of satisfying the convergence condition (“YES” in step S203), the voltage of the node N20 is finally calculated as 6700 [V], the tap of the transformer 23 is T5, and the voltage of the node N21 is 6700 [V].

  When the voltage of the node N21 is calculated as 6700 [V] in step S104, the difference voltage ΔE between the output voltage of the transformer and the target voltage is 100 [V] (step S105). Since the absolute value of difference voltage ΔE is equal to or less than voltage dead zone width 132 [V] (“NO” in step S106), power flow calculator 122 outputs 6700 [V] as a power flow calculation result for the voltage of node N21, for example. (Step S109).

  In addition, in order to clarify description, the voltage of the node N20 which is a primary side connection point of the transformer 23 was made the same voltage in description of FIG.8 and FIG.9. However, not only the amount of state of each node downstream of transformer 23 but also the amount of state of each upstream node may differ depending on whether or not tap switching of transformer 23 is stopped.

  As described above, in the power flow calculation method according to the embodiment, when the voltage regulator with the discrete adjustment operation is included in the power system model, the discrete adjustment operation is stopped and the convergence calculation method such as the BFS method is performed. Tidal current calculation using is performed first. Therefore, according to the power flow calculation method according to the embodiment, since the erroneous discrete adjustment operation is suppressed in the process of power flow calculation, it is possible to improve the calculation accuracy of the state quantity for the power system model.

Second Configuration Example
FIG. 10 is a diagram showing a second configuration example of the power system model which is the target of the power flow calculation. In FIG. 10, a distribution system 3 called a feeder, in which distribution lines extending radially from a substation on the power supply side, is shown as a second configuration example of the power system model. In the configuration example shown in FIG. 10, the distribution system 3 includes distribution lines 31-1 to 31-23, a feeder breaker 32, a phase adjusting facility 33, and a switch 34. Moreover, the distribution system 3 includes utility poles 35-1 to 35-23 and customers 36-1 to 36-4. The number of distribution lines, switches, power poles, and consumers included in the distribution system 3 is not limited to the numbers shown in FIG. 10 and may be any number.

  The phasing facility 33 is an example of a voltage regulator connected in parallel to the distribution line of the power system model. The phase-adjusting equipment 33 may be installed, for example, on a distribution line which is heavily loaded depending on the time zone and the voltage drop is large. In the power distribution system 3, power transmission is performed via the feeder breaker 32 and the switch 34 and the like. In the example shown in FIG. 10, the feeder breaker 32 is set to the on state, and the switch 34 is set to the off state.

<< Systematic data in the second configuration example >>
As shown in FIG. 10, in the distribution system 3, the feeder breaker 32 and the utility poles 35-1 to 35-23 are defined as nodes, and the distribution lines 31-1 to 31-23 are defined as branches. By such definition, the distribution system 3 is digitized as numerical values shown in FIGS. 11 (A) and 11 (B). FIG. 11 is a diagram showing an example of data configuration for the second configuration example of the power system model.

  For example, when the feeder breaker 32 is defined as the node N1 'and the utility pole 35-1 is defined as the node N2', respectively, the nodes N1 'and N2' are similar to the node table shown in FIG. Data is converted as shown in the first and second lines of the node table shown in 2.). Further, when the distribution line 31-1 is defined as a branch B1 ', the branch B1' is converted into data as shown in the first row of the branch table shown in FIG. 11B, like the branch table shown in FIG. 5B. Be done. The node table and the branch table are stored in the storage unit 13 as system data.

  Next, for example, as in the first configuration example shown in FIG. FIG. 12 is a diagram illustrating a first configuration example of the phase matching facility included in the second configuration example of the power system model. In the configuration example shown in FIG. 12, the phase adjusting installation 33 includes three capacitors 331-1 to 331-3 connected in parallel. Capacitors 331-1 to 331-3 are connected in series with corresponding switches 332-1 to 332-3 and reactors 333-1 to 333-3. In addition, the phase adjusting equipment 33 includes a voltage detector 334 and a voltage controller 335. The voltage detector 334 detects the voltage at the connection point with the distribution line. The voltage controller 335 adjusts the reactive power input amount output to the distribution system by turning on or off the switches 332-1 to 332-3 so that the detected voltage becomes the target voltage. For example, the reactive power input amounts of the capacitors 331-1 to 331-3 are set to 100 [kVar], 200 [kVar], and 300 [kVar], respectively.

  Also, the phase adjusting equipment 33 is set, for example, as follows. The maximum reactive power input amount is set to a phase advance of 600 [kVar], the voltage target value is set to 6600 [V] in high voltage conversion, and the reactive power change width is set to 100 [kVar]. Since the reactive power change width is set to 100 [kVar], the phase-adjusting facility 33 adjusts the voltage at the connection end with discrete values in 100 [kVar] steps. The initial reactive power input capacity is 100 [kVar], the voltage dead zone width is ± 50 [V], and the control mode is set to the automatic voltage control mode. Therefore, the phase adjusting equipment 33 is converted into data as in the voltage adjustment device setting table shown in FIG. The voltage adjustment device setting table is stored in the storage unit 13 as system data.

<< tidal current calculation in the second configuration example >>
When the phase adjusting equipment 33 is set as described above, the phase adjusting equipment 33 performs the discrete adjustment operation as shown in FIG. FIG. 13 is a diagram for explaining the discrete adjustment operation of the phase adjusting installation included in the second configuration example of the power system model.

  As described above, a voltage dead zone width of ± 50 [V] is set for discrete adjustment operation in which connection of capacitors 331-1 to 331-3 is switched by turning on or off switches 332-1 to 332-3. ing. Specifically, a voltage dead zone of ± 50 [V] is set above and below the target voltage 6600 [V]. Therefore, when the voltage at the connection end detected by the voltage detector 334, that is, the voltage at the node N21 'is in the range of 6550 [V] to 6650 [V], the phase adjusting equipment 33 performs the discrete adjustment operation. Absent. That is, the voltage control device 335 maintains the current on or off state of each of the switches 332-1 to 332-3.

  On the other hand, as shown in FIG. 13, for example, when the voltage of the node N21 'exceeds 6550 [V], the phase adjusting equipment 33 performs discrete adjustment operation. That is, the voltage control device 335 turns on or off the switches 332-1 to 332-3 to raise the reactive power input amount by the capacitors 331-1 to 331-3 from 100 [kVar] to 200 [kVar].

  Furthermore, after the reactive power input amount is increased to 200 [kVar], if the voltage at the node N21 'exceeds 6650 [V], the phase adjusting equipment 33 performs discrete adjustment operation as shown in FIG. That is, the voltage control device 335 turns on or off the switches 332-1 to 332-3 to reduce the reactive power input amount by the capacitors 331-1 to 331-3 from 200 [kVar] to 100 [kVar].

  As described above, when the absolute value of the difference between the input voltage of the phase adjusting installation 33 and the target voltage exceeds the voltage dead band, the phase adjusting installation 33 performs the discrete adjustment operation. That is, the phase-adjusting facility 33 performs discrete adjustment operation in increments of 100 [kVar] of reactive power so that the voltage of the node N21 ′, which is a connection point of the phase-matching facility 33, becomes the target voltage 6600 [V]. . Therefore, assuming that the discrete adjustment operation of the phasing facility 33 is operated, that is, if the power flow calculation in step S108 is performed without going through steps S102 to S107 shown in FIG. 2, as shown in FIG. Different tidal current calculation results may be derived. FIG. 14 is a diagram for explaining the result of the tidal current calculation when the discrete adjustment operation of the phasing facility is operated.

  In the forward calculation of step S202 according to the BFS method, the power flow calculation unit 122 calculates the state quantities of each node in order from the leading node N1 'on the upstream side. At that time, when the forward calculation in step S202 reaches the node N21 ′ to which the phase adjusting equipment 33 is connected, the power flow calculation unit 122 sets the reactive power of the phase advance so that the voltage of the node N21 ′ becomes the target voltage. Put in discretely and calculate. For example, as shown in FIG. 14, in the forward calculation of the first step S202, the power flow calculation unit 122 calculates the input voltage of the phasing facility 33, that is, the voltage of the node N21 ′ as 6540 [V]. In this case, the difference between the voltage of the node N21 'and the target voltage 6600 [V] is 60 [V], which exceeds the voltage dead zone width 50 [V]. Therefore, the tidal current calculation unit 122 simulates a discrete adjustment operation in which the reactive power input amount of the phasing equipment 33 is increased by one stage from 100 [kVar] to 200 [kVar]. As a result, the voltage of the node N21 'rises, and the power flow calculation unit 122 calculates the voltage of the node N21' as 6610 [V].

  In the forward calculation of the first step S202, an error may occur in the state quantity of the end node due to a power loss on the distribution line due to the distribution line impedance such as the line resistance shown in the branch table of FIG. . Therefore, the tidal current calculation unit 122 corrects the state variable of the leading node based on the error (step S204, backward calculation), returns to step S204 until the convergence condition is satisfied (step S203), and calculates the state quantities of each node. Recalculate.

  As shown in FIG. 14, when the power flow calculation unit 122 calculates the voltage of the node N21 'at 6612 [V] in the forward calculation in the second step S202, the voltage of the node N21' and the target voltage 6600 [V] The difference is 12 [V] and within the voltage dead zone width 50 [V]. Therefore, the tidal current calculation unit 122 simulates the discrete adjustment operation of maintaining the current on or off state of the switches 332-1 to 332-3 of the phasing facility 33. Then, as a result of the loop processing of step S202 to step S204, for example, as shown in FIG. 14, the voltage of the node N21 'is 6620 [V], and the reactive power input amount of the phase adjusting facility 33 is 200 [kVar]. Converge on

  As described above, since the BFS method is a method of correcting the power loss and the like in the distribution line in the loop processing of step S202 to step S204, the error in the terminal node becomes large in the first forward calculation. Therefore, the voltage at each node calculated in the first process may greatly differ from the voltage finally obtained by satisfying the convergence condition.

  In the example shown in FIG. 14, even if the reactive power input of the phase-adjusting facility 33 is maintained at the initial reactive power input until the final calculation result is obtained, the voltage of the node N21 'is 6600 [V] It may be finally calculated in the vicinity. If the voltage of the node N21 'is around 6600 [V], the reactive power input of the phase-adjusting facility 33 is maintained at the initial reactive power input of 100 [kVar].

  As described above, the change in reactive power input due to discrete adjustment operation occurs only in the process of power flow calculation using the BFS method, and in the actual distribution system simulated by the power system model, reactive power input is It is likely to be maintained at the initial value. Therefore, due to the erroneous discrete adjustment operation in the calculation process, the state quantity obtained by the power flow calculation is different from the actual state quantity of the distribution system, and the calculation accuracy of the power flow calculation becomes worse.

  Therefore, in the tidal current calculation method according to the embodiment, the processes of step S102 to step S107 are performed before the tidal current calculation of step S108 is performed. For example, when the phase-matching facility 33 is included in the distribution system 3 (“YES” in step S102), the adjustment operation control unit 121 stops the discrete adjustment operation of the phase-matching facility 33 and sets the reactive power input to the initial state. Maintain reactive power input. Then, the power flow calculation unit 122 simulates the discrete adjustment operation for maintaining the current on or off state of the switches 332-1 to 332-3 and executes the power flow calculation of step S104. When the tidal current calculation of step S104 is performed, a tidal current calculation result as shown in FIG. 15 can be derived. FIG. 15 is a diagram for explaining the result of the tidal current calculation when the discrete adjustment operation of the phasing facility is stopped.

  As shown in FIG. 15, when the power flow calculation unit 122 calculates the voltage of the node N21 'at 6540 [V] in the forward calculation of the first step S202, the voltage of the node N21' and the target voltage 6600 [V] The difference exceeds the voltage dead band 50 [V]. However, the power flow calculation unit 122 simulates the discrete adjustment operation for maintaining the current on or off state of the switches 332-1 to 332-3, and sets the voltage of the node N21 'to 6540 [V].

  The power flow calculation unit 122, for example, calculates the voltage of the node N20 as 6552 [V] in the forward calculation of the second step S202. The power flow calculation unit 122 simulates the discrete adjustment operation for maintaining the current on or off state of the switches 332-1 to 332-3, and sets the voltage of the node N21 'to 6552 [V]. Then, as a result of repeating the loop processing of step S202 to step S204, the voltage of the node N21 'is finally calculated as 6560 [V], and the reactive power input amount of the phase adjusting equipment 33 is 100 [kVar].

  When the voltage of the node N21 'is calculated to be 6560 [V] in step S104, the difference voltage ΔE between the voltage of the node N21' and the target voltage is 40 [V] (step S105). Since the absolute value of the difference voltage ΔE is equal to or less than the voltage dead zone width 50 [V] (“NO” in step S106), for example, the power flow calculator 122 calculates 6560 [V] as a power flow calculation result for the voltage of the node N21 ′. It outputs (step S109).

  As described above, in the power flow calculation method according to the embodiment, when the voltage regulator with the discrete adjustment operation is included in the power system model, the discrete adjustment operation is stopped and the convergence calculation method such as the BFS method is performed. Tidal current calculation using is performed first. Therefore, according to the power flow calculation method according to the embodiment, since the incorrect discrete adjustment operation in the process of power flow calculation is suppressed, it is possible to improve the calculation accuracy of the state quantity for the power system model.

  In addition, you may comprise the phase adjusting installation 33 by a shunt reactor like the 2nd structural example shown in FIG. FIG. 16 is a diagram showing a second configuration example of the phase matching facility included in the second configuration example of the power system model. In the configuration example shown in FIG. 16, the phase adjusting installation 33 includes three reactors 331′-1 to 331′-3 connected in parallel. The reactors 331′-1 to 331′-3 are connected in series to the corresponding switches 332′-1 to 332′-3. Further, the phase adjusting equipment 33 'includes a voltage detector 333' and a voltage controller 334 '. The voltage detector 333 'detects the voltage at the connection point with the distribution line. The voltage control device 334 'adjusts the reactive power input amount output to the distribution system by turning on or off the switches 332'-1 to 332'-3 so that the detected voltage becomes the target voltage. . For example, the reactive power input amounts of the reactors 331′-1 to 331′-3 may be set to 100 [kVar], 200 [kVar], and 300 [kVar], respectively.

  When the phase-matching facility 33 is configured as in the second configuration example, the tidal current calculation method according to the embodiment is the same as that described above for the case where the phase-matching facility 33 is configured as the first configuration example It can be explained similarly.

<Other configuration example>
The present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the scope of the present invention.

  For example, a plurality of voltage regulators (for example, a plurality of transformers, a plurality of phase-matching facilities, or a combination of a transformer and a phase-matching facility) are included in a power system model which is a calculation target of the power flow calculation method according to the embodiment. It may be included.

  When a plurality of voltage regulators are included in the power system model, for example, the process of the power flow calculation method illustrated in FIG. 2 may be modified as follows. That is, when it is determined that the power system model includes a plurality of voltage adjusting devices ("YES" in step S202), the adjusting operation control unit 121 stops the discrete adjusting operations of all the voltage adjusting devices (step S203). ). As a result of the power flow calculation in step S204, when there is a voltage adjustment device in which the differential voltage ΔE exceeds the voltage dead zone width (“YES” in step S206), the processing of the power flow calculation method shown in FIG. It is corrected. That is, the adjustment operation control unit 121 sequentially operates the discrete adjustment operation from the upstream voltage adjustment device among the voltage adjustment devices in which the differential voltage ΔE exceeds the voltage dead zone width, and the power flow calculation unit 122 calculates the power flow in step S208. Do one by one.

  Even when the power system model includes a plurality of voltage regulators, according to the power flow calculation method according to the embodiment, it is possible to improve the calculation accuracy of the state quantity for the power system model.

  Next, the tidal current calculation method according to the embodiment as described above can also be implemented by a computer that executes a tidal current calculation program that regulates the procedure of the tidal current calculation process according to the embodiment. FIG. 17 is a diagram illustrating a configuration example of a computer that executes a tidal current calculation program according to the embodiment.

  In the configuration example shown in FIG. 17, the computer 4 includes a CPU 41 which is an example of a processor, a memory 42 such as a RAM, an input device 43 such as a keyboard and a mouse, and an output device 44 such as a liquid crystal display or a CRT display. . The computer 4 further includes a storage device 45 such as a hard disk drive. The computer 4 further includes a storage medium driving device 46 that writes data to the portable storage medium and reads data from the portable storage medium, and a network connection device 47 that connects to a communication network such as the Internet. These components 41 to 47 included in the computer 4 are connected to one another via a bus 48.

  The power flow calculation program according to the embodiment may be stored in a portable storage medium such as a magnetic disk, an optical disk, a magneto-optical disk, or a flash memory. The power flow calculation program stored in the portable storage medium is read via the storage medium drive 46 and installed in the storage 45. In addition, the flow calculation program according to the embodiment is installed in the storage device 45 by the computer 4 acquiring the flow calculation program stored in another computer device (not shown) through the network connection device 47. May be The CPU 41 executes the tidal current calculation program according to the embodiment by reading the tidal current calculation program from the storage device 45 to the memory 42 and executing the tidal current calculation program.

  By causing a computer to execute the tidal current calculation program according to the embodiment, the above-described effects obtained from the tidal current calculation method according to the embodiment can be obtained.

Reference Signs List 1 power flow calculation device 2, 3 distribution system 4 computer 11 input unit 12 calculation unit 13 storage unit 14 output unit 15 communication unit 21-1 to 21-22 distribution line 22 feeder breaker 23 transformer 24 switch 25-1 to 25 -22 Power pole 26-1 to 26-4 Customer 31-1 to 31-23 Distribution line 32 Feeder breaker 33 Phase adjustment equipment 34 Switch 35-1 to 35-23 Power pole 36-1 to 36-4 Customer 41 CPU
42 Memory 43 Input Device 44 Output Device 45 Storage Device 46 Storage Medium Drive Device 47 Network Connection Device 48 Bus 121 Adjustment Operation Control Unit 122 Power Flow Calculation Unit 331-1 to 331-3 Capacitor 332-1 to 332-3 Switch 333-1 333-3 reactor 334 voltage detector 335 voltage controller 331'-1 to 331'-3 reactor 332'-1 to 332'-3 switch 333 'voltage detector 334' voltage controller N1 to N24, N1 'to N24 'nodes B1 to B23, B1' to B23 'branches

In the example illustrated in FIG. 6B, the primary side rated voltages of the taps T1 to T9 are 7200 [V], 7050 [V], 6900 [V], 6750 [V], 6600 [V], 6450 [V], 6300 [V], 6150 [V], and 6000 [V]. Moreover, the secondary side rated voltage of each of the tap T1 to the tap T9 is 6600 [V].

On the other hand, as shown in FIG. 13, for example, when the voltage of the node N21 ' falls below 6550 [V], the phase adjusting equipment 33 performs discrete adjustment operation. That is, the voltage control device 335 turns on or off the switches 332-1 to 332-3 to raise the reactive power input amount by the capacitors 331-1 to 331-3 from 100 [kVar] to 200 [kVar].

When a plurality of voltage regulators are included in the power system model, for example, the process of the power flow calculation method illustrated in FIG. 2 may be modified as follows. That is, when it is determined that the power system model includes a plurality of voltage adjusting devices ("YES" in step S102 ), the adjusting operation control unit 121 stops the discrete adjusting operations of all the voltage adjusting devices (step S102 ). S 103 ). Power flow calculation result in step S 104, when the difference voltage ΔE is present a voltage regulator which exceeds the voltage dead zone width ( "YES" in step S 106), processing of flow calculation method shown in FIG. 2, for example, the following As corrected. That is, the adjustment operation control unit 121 sequentially operates the discrete adjustment operation from the upstream voltage adjustment device among the voltage adjustment devices in which the difference voltage ΔE exceeds the voltage dead zone width, and the power flow calculation unit 122 performs the power flow in step S108. Perform calculations sequentially.

Claims (6)

An adjusting operation control unit configured to stop the discrete adjusting operation of the voltage adjusting device, which is a voltage adjusting device included in a power system model, which adjusts an output voltage to an input voltage by the discrete adjusting operation;
Forward calculation which sequentially calculates the state quantity of each node of the power system model from the head node on the upstream side, and backward calculation which corrects the state variable of the head node based on the error of the state quantity of the downstream end node And a tidal current calculation unit for calculating the state quantities of the respective nodes in a state in which the discrete adjustment operation is stopped by using a convergence calculation method including: The adjustment operation control unit is configured to set the differential voltage between the output voltage calculated by the power flow calculation unit and the target voltage of the voltage adjustment device to a value larger than the voltage dead zone width set for the discrete adjustment operation. Activating the discrete adjustment operation,
The tidal current calculation device according to claim 1, wherein the tidal current calculation unit calculates the state quantities of the respective nodes in a state in which the discrete adjustment operation is operated, using the convergence calculation method. The power flow calculation device according to claim 1, wherein the voltage regulator is connected in series to a distribution line of the power system model. The power flow calculation device according to claim 1, wherein the voltage regulator is connected in parallel to a distribution line of the power system model. A voltage adjusting device included in a power system model, which stops the discrete adjusting operation of the voltage adjusting device adjusting the output voltage according to the input voltage by the discrete adjusting operation;
Forward calculation which sequentially calculates the state quantity of each node of the power system model from the head node on the upstream side, and backward calculation which corrects the state variable of the head node based on the error of the state quantity of the downstream end node A power flow calculation method in which a computer executes processing including calculation of the state quantities of the respective nodes in a state in which the discrete adjustment operation is stopped using a convergence calculation method including: A voltage adjusting device included in a power system model, which stops the discrete adjusting operation of the voltage adjusting device adjusting the output voltage according to the input voltage by the discrete adjusting operation;
Forward calculation which sequentially calculates the state quantity of each node of the power system model from the head node on the upstream side, and backward calculation which corrects the state variable of the head node based on the error of the state quantity of the downstream end node A power flow calculation program that causes a computer to execute processing including calculating the state quantities of the respective nodes while the discrete adjustment operation is stopped using a convergence calculation method including:

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