JP7403425B2 - load control device - Google Patents

Description

The present application relates to a load control device.

Various types of equipment are connected to the distribution lines of the power system as consumer equipment. Consumer equipment includes distributed power supply equipment such as solar power generation and storage batteries, power load equipment such as electric vehicles and electric water heaters, and power control equipment such as capacitors and reactors. As distributed power supply equipment and power load equipment become more widespread, the passing current of power distribution lines increases, and overloads that exceed the installed capacity of power systems may occur.

As a measure to avoid overloading the power system, there is a method called connect and manage. Connect & Manage means, for example, in the case of solar power generation, when applying for connection, even if there is a possibility of overload, connection is permitted with connection conditions, and the solar power generation is fully generated and the power grid is overloaded. This method suppresses the output of solar power generation based on connection conditions when a load is likely to occur. However, Connect & Manage has a problem in that it cannot effectively utilize the electricity obtained from full solar power generation.

Another measure to avoid overloading the power system is to use storage batteries. For example, a method for controlling the increase/decrease in active power and reactive power of a storage battery connected to a power transmission line has been disclosed as a means for reducing passing current in a power distribution line of a power system. In this control method, the problem is which of active power and reactive power should be controlled preferentially. In conventional control methods, power that has a greater reduction effect on the current passing through the distribution line is controlled preferentially (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2008-48500

When performing the above-described control, cost is also important because the storage battery connected to the power transmission line is equipment of the consumer. In conventional control methods, the power that has a greater reduction effect on the current passing through the distribution line is preferentially controlled between active power and reactive power, and cost is not taken into consideration. Further, although there are other equipment other than storage batteries in the customer equipment, there is a problem in that conventional control methods do not utilize the active power and reactive power of these equipment.

The present application was made in order to solve the above-mentioned problems, and an object of the present application is to provide a load control device that can utilize the power of various types of equipment of consumers and control the load of an electric power system at a low cost. With the goal.

The load control device of the present application is a load control device for controlling the load of an electric power system connected to a distribution line, and is a load control device for controlling the load of an electric power system connected to a distribution line. A command value transmitter that sends control amounts of active power and reactive power to multiple connected devices as command values, and respective controllable amounts and controls for active power and reactive power that are set in advance for each facility. and a command value determination unit that determines, as a command value, the control amount that minimizes the sum of control costs obtained by multiplying the control amount for each facility by the control unit price, based on the unit price table.

The load control device of the present application calculates the control cost obtained by multiplying the control amount for each equipment by the control unit price, based on a table of controllable amounts and control unit costs for active power and reactive power that are set in advance for each equipment. Equipped with a command value determination unit that determines the control amount that minimizes the total sum as the command value, so it is possible to control the load on the power system while making use of the power from various types of customer equipment and reducing costs. .

1 is a block diagram showing the configuration of a power distribution system according to Embodiment 1. FIG. FIG. 2 is a characteristic diagram showing the relationship between active power and reactive power in the power distribution system according to the first embodiment. 1 is a configuration diagram of a load control device according to Embodiment 1. FIG. FIG. 3 is a diagram showing a table of controllable amounts and control unit prices of a plurality of facilities of a consumer according to Embodiment 1; 1 is a schematic diagram showing an example of hardware of a load control device according to embodiments 1 to 5. FIG.

Hereinafter, a load control device according to an embodiment for carrying out the present application will be described in detail with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1.
FIG. 1 is a block diagram showing the configuration of a power distribution system to which a load control device according to Embodiment 1 is applied. As shown in FIG. 1, a power system 1 supplies high voltage AC power of, for example, 6.6 kV to a power distribution line 2. A sensor 3 is connected to the power distribution line 2 to obtain a current waveform flowing through the power distribution line 2 and a voltage waveform of the power distribution line 2 . In addition, the distribution line 2 is equipped with various types of consumer equipment, such as a storage battery-A41, a storage battery-B42, electric vehicles EV-A43 and EV-B44, a water heater-A45, a capacitor-A46, and solar power. A power generator such as PV-A47 is connected. Furthermore, a load control device 5 is provided that sends command values to a plurality of consumer facilities. The current waveform and voltage waveform of the power distribution line 2 acquired by the sensor 3 are input to the load control device 5 . In order to avoid overloading the power system 1, the load control device 5 controls the amount of control of active power and reactive power for a plurality of consumer facilities based on the current waveform and voltage waveform input from the sensor 3. Send as command value.
In the power distribution system shown in FIG. 1, the direction in which current flows from the power system 1 toward the power distribution line 2 is referred to as forward flow, and the opposite direction is referred to as reverse power flow.

The load control device 5 calculates the effective value from the current waveform and voltage waveform input from the sensor 3, and calculates the passing current value, power factor value, and voltage value of the distribution line 2, and the effective power calculated from these values. and calculate reactive power.

FIG. 2 is a characteristic diagram showing the relationship between active power and reactive power in the power distribution system of this embodiment. The active power in the distribution line 2 can be divided into a forward flow direction and a reverse power flow direction. Further, the reactive power in the power distribution line 2 can be divided into a reactor component (L component) direction and a capacitor component (C component) direction of the power distribution system. In FIG. 2, the horizontal axis is active power, and the vertical axis is reactive power. Further, the right side of the horizontal axis is the forward flow direction, and the left side is the reverse flow direction. Furthermore, the upper side of the vertical axis is the reactor component, and the lower side is the capacitor component. In FIG. 2, a circle 10 indicated by a broken line is the apparent power obtained by multiplying the maximum allowable current value, which is the installed capacity of the power system 1, by the voltage value calculated by the load control device 5. If the plot points of the calculated active power and reactive power are outside the circle 10, it means that an overload has occurred. Conversely, if it is inside this circle 10, overload of the power system 1 can be avoided. In FIG. 2, a point 11 is a position indicating the active power and reactive power calculated by the load control device 5. In this case, since the point 11 is located outside the circle 10, an overcurrent is flowing through the power distribution line 2. The load control device 5 of this embodiment controls the point 11 indicated by this passing current value to move so that it is inside the circle 10. For example, if only reactive power is controlled, point 11 moves downward as shown by arrow 12. If only active power is controlled, point 11 moves to the right as indicated by arrow 13. If both active power and reactive power are controlled, point 11 moves diagonally downward to the right as shown by arrow 14.
As shown in FIG. 2, the load control device 5 of the present embodiment is configured to control multiple customers so as to eliminate the overload when an overcurrent is flowing in the distribution line 2, that is, when the power system 1 is overloaded. The control amounts of active power and reactive power are determined for the equipment, and at this time, the control amounts are determined so that the control cost is minimized. The procedure will be explained below.

FIG. 3 is a configuration diagram of the load control device 5 according to this embodiment. The load control device 5 of the present embodiment includes a command value transmitting unit 51 that sends control amounts of active power and reactive power to a plurality of equipment connected to the distribution line 2 as command values to those equipment, and Based on the table of controllable amounts and control unit costs for the set active power and reactive power, the control amount that minimizes the total control cost obtained by multiplying the control amount for each equipment by the control unit price is set as the command value. and a command value determination unit 52 for determining the command value. A table of controllable amounts and control unit prices for active power and reactive power that are preset for each facility is stored in the storage unit 53. The current waveform and voltage waveform of the power distribution line 2 acquired by the sensor 3 are input to the command value determination unit 52.

FIG. 4 is a diagram showing a table of controllable amounts and control unit prices of various types of equipment to be controlled by consumers, which are stored in the storage unit 53. The table shown in FIG. 4 shows the controllable amount and control unit price for each of the plurality of control target facilities. The controllable amount and control unit price are individually set for active power and reactive power, respectively. Furthermore, the active power is set separately for forward power flow and reverse power flow. Regarding reactive power, it is set separately for the reactor component (L component) and the capacitor component (C component). Note that the unit of active power is kW, and the unit of reactive power is kvar. Further, the control unit price of active power is a price for a unit of active power, and its unit is yen/kW. The control unit price of reactive power is a price for a unit of reactive power, and its unit is yen/kvar. Note that the controllable amount is a range that can be increased or decreased in view of the power before control in each facility.

The command value determination unit 52 of the load control device 5 of this embodiment uses the table shown in FIG. has been decided. As a method for this, for example, the control amount can be determined by performing an optimization calculation that minimizes the control cost F using the objective function shown in equation (1) below.

Here, i is a number that identifies the equipment, and n is the total number of multiple equipment of the consumer connected to the distribution line 2. In the equipment specified by i, P _Ni is the controlled amount of active power of forward flow, P _Ri is the controlled amount of active power of reverse power flow, Q _Li is the controlled amount of L component of reactive power, and Q _Ci is the controlled amount of active power of reactive power. This is the control amount of the C component. In addition, C _PNi is the control unit price of active power for forward flow, C _PRi is the control unit price of active power for reverse flow, C _QLi is the control unit cost of L component of reactive power, and C _QCi is the control unit price of C component of reactive power. be.

As can be seen from equation (1), the control cost for each facility is the active power control cost calculated by multiplying the controlled amount of active power by the unit price for the unit of active power, and the controlled amount of reactive power multiplied by the unit price for the unit of reactive power. It is the sum of the reactive power control cost multiplied by the unit price. The active power control cost is calculated by multiplying the active power control amount P _Ni for forward power flow by the unit price C _PNi for forward flow, and multiplying the active power control amount P _Ri for reverse power flow by the unit price C _PRi for reverse power flow. It is the sum of things. In addition, the reactive power control cost is calculated by multiplying the reactive power control amount _QLi for the reactor component by the unit price _CQLi for the reactor component, and multiplying the reactive power control amount _QCi for the capacitor component by the unit price _CQCi for the capacitor component. It is the sum of things.

At this time, if the threshold value of the passing current value flowing through the distribution line 2 determined by the installed capacity of the power system 1 is I _limit , the passing current value needs to be below I _limit as a constraint condition. In other words, it is necessary to satisfy the following equation (2) as a constraint.

Here, P is the active power of the distribution line 2 before control, Q is the reactive power of the distribution line 2 before control, and V is the voltage of the distribution line.
Furthermore, since the control amounts of active power and reactive power must not exceed the controllable amounts listed in the table shown in FIG. 4, they must satisfy all of the equations (3) below.

The command value determination unit 52 of the load control device 5 of the present embodiment satisfies the constraint conditions shown in equations (2) and (3), and also sets the demand so that the control cost F shown in equation (1) is minimized. Determine the control amount of active power and reactive power for multiple equipment in the house. Then, the command value transmitting unit 51 of the load control device 5 sends the control amount determined in this manner as a command value to a plurality of facilities of the customer. The active power and reactive power of the plurality of facilities are controlled based on command values sent from the load control device 5. As a result, overload on the power system 1 is eliminated.

The load control device 5 configured in this manner can utilize the power of various types of equipment of consumers and control the load on the power system while reducing costs.

Note that in the load control device of this embodiment, the table shown in FIG. 4 is stored in advance in a storage section inside the load control device, but it may not be stored in an external storage device provided outside the load control device. may have been done. Alternatively, the load control device may obtain the table shown in FIG. 4 from an external server, cloud, or the like. However, since the controllable amount is within a range that can be adjusted to increase or decrease in light of the power before control, it is preferable that the load control device communicates with a plurality of consumer facilities and obtains it from each facility.
Furthermore, the objective function used in the optimization calculation performed by the command value determining section is not limited to the function shown in equation (1), but may be another function.

Embodiment 2.
In general, since active power is used to input and output energy in multiple facilities of a consumer, the unit cost for controlling active power becomes high. On the other hand, since reactive power does not take in or out energy, the control unit cost of reactive power is lower than the control unit cost of active power. In the load control device of the first embodiment, the command value determination unit performs optimization calculation using an objective function in order to minimize control costs. In the load control device of Embodiment 2, the command value determination unit minimizes the control cost by determining the control amount in order from the equipment corresponding to the item with the lowest control unit cost instead of the optimization calculation.

From the table shown in FIG. 4 of the first embodiment, it can be seen that the control unit price of reactive power is lower than the control unit price of active power. The command value determination unit of the load control device of this embodiment sets the control amount by selecting equipment in order from the item corresponding to the lowest control unit cost, and sets the control amount that minimizes the total control cost as the command value. decide. The procedure will be explained below. In the following description, it is assumed that the control unit price of reactive power is lower than the control unit price of active power.

Assume that an overcurrent is currently flowing through the power distribution lines, that is, the power system is overloaded. The load control device calculates the effective value from the current waveform and voltage waveform input from the sensor, and calculates the passing current value, power factor value, voltage value of the distribution line, and the active power and reactive power calculated from these values. Calculate. When the calculated reactive power is a capacitor component, the command value determining unit selects the equipment to be controlled in order of the equipment with the lowest control unit cost of the reactor component. On the other hand, when the calculated reactive power is a reactor component, the command value determination unit selects the equipment to be controlled in order of the equipment with the lowest control unit cost of the capacitor component. Next, the command value determination unit determines a command value by setting the control amount of reactive power of the equipment selected as the control target to be equal to or less than the corresponding controllable amount of reactive power in the table shown in FIG. Next, the command value transmitter sends the command value determined by the command value determiner to the selected equipment.

Next, when the calculated active power is a forward power flow, the command value determination unit selects the equipment to be controlled in order from the lowest control unit cost of the active power of the reverse power flow. On the other hand, when the calculated active power is for reverse power flow, the command value determination unit selects the equipment to be controlled in order of the lowest control unit cost of active power for forward flow. Next, the command value determination unit determines a command value by setting the control amount of active power of the equipment selected as the control target to be equal to or less than the corresponding controllable amount of active power in the table shown in FIG. Next, the command value transmitter sends the command value determined by the command value determiner to the selected equipment. Even if the command value is determined using such a procedure, the total control cost obtained by multiplying the control amount for each facility by the control unit cost will be close to the minimum value.

The load control device configured in this manner can utilize the power of various types of equipment of consumers and control the load of the power system while reducing costs.

Embodiment 3.
In the power distribution system of the first embodiment, as shown in FIG. 1, one sensor 3 is connected to the power distribution line 2 of the power distribution system to obtain the current waveform and voltage waveform flowing through the power distribution line 2. In the power distribution system of Embodiment 3, a plurality of sensors are provided at a plurality of points on the power distribution line. Current waveforms and voltage waveforms respectively acquired by a plurality of sensors are input to the load control device of this embodiment. This load control device controls the load of the power system when at least one of the passing current values calculated from the current waveform and voltage waveform respectively input from the plurality of sensors exceeds a threshold value. The control performed by the load control device of this embodiment is the same as the control described in the first and second embodiments.

The load control device configured in this manner can utilize the power of various types of equipment of consumers and control the load of the power system while reducing costs. Furthermore, since the sensors are provided at multiple points on the power distribution line, the reliability of the power distribution system is improved.

Embodiment 4.
The load control devices of the first to third embodiments control the load of the power system immediately when the passing current value of the distribution line exceeds a predetermined threshold value. However, the amount of power generated by solar power generation varies greatly, and the time when the passing current of the distribution line exceeds the threshold value may range from several seconds to several minutes. Immediately controlling the load on the power system when the passing current of the power distribution line exceeds the threshold value for several seconds to several minutes would actually make the power distribution system unstable.

The load control device of Embodiment 4 controls the load of the power system only when the passing current value of the distribution line exceeds a threshold value continuously for a preset elapsed time or more. Note that the command value determined by the command value determination unit of the load control device of this embodiment is the same as any of the command values described in Embodiments 1 to 3. When calculating a passing current value from a measured value input from a sensor, the load control device of this embodiment determines whether the calculated passing current value exceeds a threshold value continuously for a preset elapsed time or more. to judge. The preset elapsed time is determined by the types of a plurality of equipment of consumers connected to the distribution line. To give one example, when solar power generation is connected as a consumer's equipment, the preset elapsed time is about 5 to 10 minutes. The command value transmitting section of the load control device transmits the command value determined by the command value determining section when the passing current value exceeds the threshold value continuously for a preset elapsed time or more. Conversely, if the passing current value does not exceed the threshold value continuously for a preset elapsed time or more, the command value transmitting section of the load control device does not transmit the command value determined by the command value determining section.

The load control device configured in this manner can utilize the power of various types of equipment of consumers and control the load of the power system while reducing costs. It also improves the stability of the power distribution system.

Embodiment 5.
A plurality of consumer facilities control active power and reactive power based on command values sent from a load control device, but these facilities are not necessarily controlled according to the command values. This is because when it comes to controlling the equipment of the consumer, the demands of the consumer may take priority. For example, there are cases where the customer's equipment is a storage battery, and the factory equipment is operated with the electric power from the storage battery. In such a case, even if the consumer's equipment receives a command value to reduce the active power, it may not be controlled in accordance with the command value.

The load control device of Embodiment 5 stores, as a history, information as to whether active power and reactive power are controlled according to the command value when the command value is sent to a plurality of facilities of a consumer. Based on the stored history, the load control device of this embodiment calculates the actual rate of control of active power and reactive power for each facility according to the command value. Then, in the control methods of Embodiments 1 to 4, the load control device of the present embodiment selects and controls the equipment in order of priority, starting with the equipment with the highest performance rate, until the passing current value of the distribution line becomes equal to or less than the threshold value. Determine the amount.

The load control device configured in this manner can utilize the power of various types of equipment of consumers and control the load of the power system while reducing costs. In addition, since the control amount is determined in order of preference starting from the equipment with the highest performance rate, the time required to avoid overloading the power system is shortened.

Note that the load control device 5 according to the first to fifth embodiments includes a processor 100 and a storage device 101, as an example of hardware is shown in FIG. Although not shown, the storage device 101 includes a volatile storage device such as a random access memory and a nonvolatile auxiliary storage device such as a flash memory. Further, an auxiliary storage device such as a hard disk may be provided instead of the flash memory. Processor 100 executes a program input from storage device 101. In this case, the program is input from the auxiliary storage device to the processor 100 via the volatile storage device. Furthermore, the processor 100 may output data such as calculation results to a volatile storage device of the storage device 101, or may store data in an auxiliary storage device via the volatile storage device.

Although this application describes various exemplary embodiments, various features, aspects, and functions described in one or more embodiments may be limited to the application of particular embodiments. Rather, they are applicable to the embodiments alone or in various combinations.
Therefore, countless variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, this includes cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of other embodiments.

1 Power system, 2 Distribution line, 3 Sensor, 5 Load control device, 41 Storage battery-A, 42 Storage battery-B, 43 EV-A, 44 EV-B, 45 Water heater-A, 46 Capacitor-A, 47 PV- A, 51 command value transmitting section, 52 command value determining section, 53 storage section, 100 processor, 101 storage device.

Claims (10)

A load control device for controlling the load of an electric power system connected to a distribution line,
In order to make the passing current value of the distribution line less than or equal to a predetermined threshold value, the load control device transmits a plurality of control amounts of active power and reactive power to a plurality of facilities connected to the distribution line as command values. a command value transmitter that sends to the equipment;
A total control cost obtained by multiplying the control amount for each facility by the control unit price based on a table of controllable amounts and control unit costs for the active power and the reactive power that are set in advance for each facility. A load control device comprising: a command value determination unit that determines the control amount with a minimum value as the command value. The control unit price preset for each facility is individually set as a unit price for the active power and a unit price for the reactive power, and the control cost for each facility is The active power control cost is the sum of the active power control cost obtained by multiplying the control amount of power by the unit price of the active power per unit power, and the reactive power control cost obtained by multiplying the control amount of the reactive power by the unit price of the reactive power per unit power. The load control device according to claim 1, characterized in that: The unit price of the active power per unit power is set separately for the unit price for forward flow and the unit price for reverse power flow, and the control amount of the active power is the control amount of active power for forward flow and the active power for reverse power flow. The active power control cost is set separately for the control amount of active power for the forward flow multiplied by the unit price for the forward flow, and the control amount of active power for the reverse flow multiplied by the unit price for the forward flow. 3. The load control device according to claim 2, wherein the amount is the sum of products multiplied by a unit price for power flow. The unit price of the reactive power per unit power is set separately for the reactor component and the capacitor component, and the reactive power control amount is the reactive power control amount for the reactor component and the reactive power for the capacitor component. The reactive power control cost is determined by multiplying the reactive power control amount for the reactor component by the unit price for the reactor component, and the reactive power control cost for the capacitor component multiplied by the reactive power control amount for the capacitor component. 4. The load control device according to claim 2, wherein the amount is the sum of products multiplied by unit prices for the components. The controllable amount for the active power is set separately for the controllable amount for the forward power flow and the controllable amount for the reverse power flow, and the controllable amount for the reactive power is set by the controllable amount for the reactor component and the controllable amount for the capacitor component. 5. The load control device according to claim 4, wherein the controllable amount is individually set. The control amount that minimizes the sum of the control costs is such that the control amount of active power for the forward flow and the control amount of active power for the reverse power flow for each facility are the controllable amount for the forward flow and the reverse power flow, respectively. The active power control cost and the reactive power control cost for each of the facilities are subject to the following constraints: 6. The load control device according to claim 5, wherein the load control device is obtained by optimization calculation of an objective function defined by a summation. The command value determination unit sequentially selects the equipment corresponding to the item with the smallest control unit price, and controls the selected equipment in order until the passing current value of the distribution line becomes equal to or less than the predetermined threshold value. The load control device according to claim 1, wherein the command value is determined by setting an amount. The load control device according to any one of claims 1 to 7, wherein the passing current value of the distribution line is a passing current value at a plurality of points on the distribution line. 9. The command value transmitting unit transmits the command value to the equipment only when the passing current value exceeds the threshold value continuously for a preset elapsed time or more. The load control device according to item 1. The load control device stores, as a history, information indicating whether or not the equipment has controlled active power and reactive power in accordance with the command value when the command value is sent to the equipment, and performs control based on the history. calculates the performance rate of controlling active power and reactive power according to the command value for each of the equipment, and sends the command value to the equipment in order from the equipment with the highest performance rate. The load control device according to any one of claims 1 to 9.

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