JP7730116B2 - Reactive Power Demand Response System - Google Patents

Description

The present invention relates to a reactive power demand response system capable of controlling reactive power in a power system (power distribution system).

Japanese Patent No. 6572113 (Patent Document 1) discloses a power consumption control device, and states in paragraph [0019], "Furthermore, the power consumption may be active power only, reactive power only, or apparent power (the sum of active power and reactive power). Here, we will explain the case where the power consumption is apparent power (VA). Note that reactive power is not consumed, but here, the reactive power used by electrical equipment is included in the term power consumption."
In this embodiment of the power consumption control device, control of reactive power alone is not disclosed at all.

Patent No. 6572113

One of the main objectives of the present invention is to provide a reactive power demand response system capable of controlling system voltage in a power distribution system.

In order to achieve the above object, the invention described in claim 1 comprises a computer that controls each of a plurality of building multi-air conditioners so that reactive power is supplied to a power distribution system by the building multi-air conditioners, and the computer allocates the reactive power to each of the building multi-air conditioners based on a mathematical programming method related to room temperature deviation, and allocates target reactive power for each of the building multi-air conditioners .
The invention described in claim 2 is characterized in that, in the above invention, the mathematical programming is a least squares method that determines an apportionment proportional coefficient for each building multi-air conditioner for the reactive power so that the sum of the squares of each room temperature deviation is minimized, or determines an apportioned reactive power for each building multi-air conditioner that corresponds to the value obtained by multiplying the reactive power by the apportionment proportional coefficient.
The invention described in claim 3 is characterized in that, in the above invention, the building multi-air conditioner has a compressor motor, an inverter connected to the compressor motor, and an active converter that adjusts the power to the inverter.
The invention described in claim 4 is characterized in that, in the above invention, the active converter generates reactive power related to the target reactive power allocated to the building multi-air conditioner by controlling the active power for air conditioning of the building multi-air conditioner to which it belongs.

One of the main advantages of the present invention is that it provides a reactive power demand response system capable of controlling system voltage in a power distribution system.

FIG. 1 is a block diagram of a reactive power demand response system of the present invention. FIG. 2 is a block diagram of an outdoor unit in the building multi-air conditioning system of FIG. 1. 2 is a flowchart illustrating an example of the operation of the reactive power demand response system of FIG. 1 . 3 is a graph showing the principle of reactive power control by the active converter of FIG. 2 . 1B is a graph showing changes over time in active power P ^b _AC , reactive power Q ^b _AC , and room temperature deviation T ^b _SA in the reactive power demand response system of FIG. 1 ; FIG.

Embodiments and modifications of the present invention will be described below with reference to the accompanying drawings. The present invention is not limited to the following embodiments and modifications.

[Local voltage fluctuations in the power distribution system ES, etc.]
FIG. 1 is a block diagram of a reactive power demand response system 1 installed in a power distribution system ES.
First, local voltage fluctuations in the power distribution system ES, which are relevant to the reactive power demand response system 1, will be described.

Recently, DERs (Distributed Energy Resources) that can serve as both loads and power sources, such as photovoltaic power generation systems D1, battery storage systems D2, and rapid chargers D3 for electric vehicles (EVs), are being connected to the power distribution system ES, and in the near future, a large number of DERs will be connected within a relatively small area AR, typically within a radius of several kilometers.
That is, there are a plurality of businesses in the power distribution system ES that have any number of photovoltaic power generation systems D1 (one or more). Also, there are a plurality of businesses in the power distribution system ES that have any number of storage battery systems D2 (one or more). The storage battery systems D2 are BESSs (Battery Energy Storage Systems). Furthermore, there are a plurality of businesses in the power distribution system ES that have any number of quick chargers D3 (one or more). Note that the DER is not limited to the photovoltaic power generation system D1, the storage battery systems D2, and the quick chargers D3.
In this case, localized voltage fluctuations are likely to occur in the power distribution system ES. For example, fluctuations in solar radiation change the amount of power generated by the solar power generation system D1, causing voltage fluctuations in the solar power generation system D1, switching of the storage battery system D2 between a charging (load) state and a discharging (power supply) state causes voltage fluctuations in the storage battery system D2, and further voltage fluctuations occur when the quick charger D3 is charged, causing a large load for about 30 minutes per EV.
Furthermore, reverse power flows in the power distribution system ES also occur frequently and in a complex manner.

Such voltage fluctuations occur locally from moment to moment in the power distribution system ES.
Furthermore, the smoothing effect of the DER group belonging to a wide range cannot be expected to be very effective against such voltage fluctuations.
Furthermore, the sending voltage control of the distribution substation TS and the voltage adjustment equipment at fixed points have difficulty in responding to such voltage fluctuations because the locations where voltage fluctuations occur change constantly.
On the other hand, it is conceivable to deal with such voltage fluctuations by installing new dedicated voltage adjusting devices at many points throughout the power distribution system ES and keeping them on standby, but this would entail enormous costs, including the costs of manufacturing, installing, and maintaining each voltage adjusting device.

In contrast to these viewpoints, the reactive power demand response system 1 uses a group of load equipment of consumers that is already widely distributed in the distribution system ES within the area AR and has a scale equal to or greater than a predetermined level, and by controlling the reactive power locally in a relatively short period of time for one or more load equipment belonging to the load equipment group, it becomes possible to respond to such voltage fluctuations at low cost.
In the reactive power demand response system 1, DER is controlled (managed) to suppress voltage fluctuations by controlling reactive power. Therefore, the reactive power demand response system 1 is a type of DER Management System (DERMS) related to smart grid technology. Furthermore, since the reactive power demand response system 1 increases or decreases (responses) reactive power (unit: var) depending on the situation (Demand), it is appropriately referred to as VarDR in this application.
Such load equipment is widespread and therefore normally performs its intended function, and also has the ability to temporarily prioritize power source power factor control and control reactive power in order to contribute to the stability of the power distribution system ES. In other words, the load equipment can control reactive power without excessively impairing the intended function that led to its widespread use, and is capable of both the intended function and reactive power control.
An example of such load equipment is a building air conditioning system. The building air conditioning system is generally called a building multi-air conditioner (BA) and is an integrated facility of multiple indoor units (AN). Currently, building multi-air conditioners (BA) are used in many small and medium-sized commercial buildings such as office buildings in urban areas. In a power distribution system (ES), there are multiple consumers that have any number of building multi-air conditioners (BA) greater than or equal to one.

[Building multi-air conditioner BA, etc.]
The primary function of the building multi-air conditioner BA is room temperature control. The building multi-air conditioner BA has an outdoor unit OU and a plurality of indoor units AN connected thereto.
Recently, as a countermeasure against harmonics in the power distribution system ES, it has become common to initially install an active converter AC in the outdoor unit OU of a building multi-air conditioner BA, or to retrofit an active converter AC as an accessory. Active converter AC is also called an active filter or PMW converter.

FIG. 2 is a block diagram of the outdoor unit OU including the active converter AC.
The active converter AC is connected to a 200V (volt) power distribution system ES for power generation.
The active converter AC is disposed between an outdoor unit built-in inverter IN, which serves as an inverter connected to a compressor motor CM of the outdoor unit OU of the building multi-air conditioner BA, and the power distribution system ES. The compressor motor CM, the outdoor unit built-in inverter IN, and the active converter AC are installed for each consumer, the number of which corresponds to the size of the building multi-air conditioner BA.
Each active converter AC has a reactor RA, a bridge-type switching element BS, a diode DI, a resistor RS, a smoothing capacitor SC, a power supply voltage phase detection circuit PP, and a converter control circuit CC.

The reactor RA is arranged between the power distribution system ES and the bridge-type switching element BS.
The bridge-type switching element BS corresponds to a three-phase power supply and has six pairs of diodes and transistors. The bridge-type switching element BS is connected to the outdoor unit built-in inverter IN by two wires.
The diode DI is inserted in series with one line between the bridge-type switching element BS and the outdoor unit built-in inverter IN.
The resistor RS is connected in parallel with the diode DI.
The smoothing capacitor SC is inserted in parallel with the two lines between the bridge-type switching element BS and the outdoor unit built-in inverter IN.

The power supply voltage phase detection circuit PP is a circuit that detects the voltage and phase of the power supply. More specifically, the power supply voltage phase detection circuit PP detects the voltage and phase between the reactor RE and the power distribution system ES.
The converter control circuit CC is connected to the power supply voltage phase detection circuit PP. The converter control circuit CC controls the bridge-type switching element BS. More specifically, the converter control circuit CC controls the switching timing of each diode of the bridge-type switching element BS to convert at least one of the magnitude and phase of the voltage applied to the outdoor unit's built-in inverter IN into a desired one from at least one of the magnitude and phase of the power supply voltage. The minimum switching time is, for example, 50 μs (microseconds), and the converter control circuit CC can switch the current every minimum switching time.
The converter control circuit CC performs three-phase full-wave rectification using PWM control, which is becoming increasingly popular as a countermeasure against harmonics, i.e., to prevent harmonics from being applied to the outdoor unit's built-in inverter IN and disrupting its operation.
On the other hand, as described above, the converter control circuit CC can convert at least one of the magnitude and phase of the power supply voltage to a desired one, and by rewriting (including adding) the software (program) of the converter control circuit CC, it becomes possible to perform three-phase full-wave rectification while contributing to the control of reactive power in the distribution system ES.
Three-phase full-wave rectification contributes to stable operation of the compressor motor CM via the outdoor unit's built-in inverter IN, and contributes to stable operation of the building multi-air conditioner BA and contributes to room temperature control.Therefore, the converter control circuit CC, whose software has been modified, performs coordinated control of room temperature control to perform its original function and reactive power control to suppress local voltage fluctuations in the distribution system ES.
Each active converter AC regulates the power to the outdoor unit's built-in inverter IN.

In order to control reactive power, it is conceivable that the power factor of the AC input can be freely and precisely controlled in the power supply section of the building multi-air conditioner BA in order to inject and extract not only active power from the power distribution system ES but also reactive power.
If a problematic location occurs in the power distribution system ES where voltage fluctuates locally for a short period of time, the reactive power demand response system 1 flexibly selects one or more building multi-air conditioners BA of a consumer receiving power from the adjacent area, thereby controlling the local distribution voltage problematic location that moves from moment to moment in the power distribution system ES so that the problem is suppressed.

[Configuration of reactive power demand response system 1]
The reactive power demand response system 1 includes a DERMS server DS, a solar power generation intermediation server PM, a battery system intermediation server BM, a rapid charger intermediation server EM, a VarDR server VS, a first ERC1E attached to the solar power generation D1, a second ERC2E attached to the battery system D2, a third ERC3E attached to the rapid charger D3, and a fourth ERC4E attached to the building multi-air conditioner BA.
Various "servers" are server computers, each equipped with a control unit (e.g., a CPU), a storage unit (e.g., a memory), an input unit (e.g., a keyboard), an output unit (e.g., a monitor), and a communication unit (e.g., an interface).
At least one of the first ERC 1E to the third ERC 3E does not have to be included in the components of the reactive power demand response system 1.

The DERMS server DS is installed in the management area (for example, a power distribution system control center) of the power transmission organization PS.
The DERMS server DS is connected to the photovoltaic power generation intermediation server PM, the battery system intermediation server BM, and the quick charger intermediation server EM via the Internet NE so as to be able to communicate control parameters CP, etc. The DERMS server DS is also connected to the VarDR server VS so as to be able to communicate Var control parameters VP, etc.
The DERMS server DS may be connected to at least one of the photovoltaic power generation intermediation server PM, the battery system intermediation server BM, the quick charger intermediation server EM, and the VarDR server VS via a VPN (Virtual Private Network) or a dedicated network, etc. Furthermore, communication may be by at least one of wired and wireless means, and the same applies to the other communications described below.

The photovoltaic power generation intermediation server PM is connected to the first ERC 1E via the commercial closed communication network CN so as to be able to communicate control parameters CP, system voltage periodic reports VR, and the like.
The photovoltaic power generation intermediation server PM is installed within the management area of the photovoltaic power generation resource aggregator.
The photovoltaic power generation intermediation server PM may be connected to the first ERC1E via the Internet NE, etc. The photovoltaic power generation intermediation server PM may also be installed within the management area of the power transmission organization PS, etc. Furthermore, the photovoltaic power generation intermediation server PM may be omitted, and the DERMS server DS may communicate the control parameters CP and the system voltage periodic report VR directly with the first ERC1E.

The battery system intermediation server BM is connected to the second ERC 2E via a commercial closed communication network CN so as to be able to communicate control parameters CP, system voltage periodic reports VR, and the like.
The battery system intermediation server BM is installed within the management area of the battery system resource aggregator.
The battery system intermediation server BM may be connected to the second ERC 2E via the Internet NE, etc. The battery system intermediation server BM may also be installed within the management area of the power transmission organization PS, etc. Furthermore, the battery system intermediation server BM may be omitted, and the DERMS server DS may communicate the control parameters CP and the system voltage periodic report VR directly with the second ERC 2E.

The quick charger intermediation server EM is connected to the third ERC 3E via the commercial closed communication network CN so as to be able to communicate control parameters CP, system voltage periodic reports VR, and the like.
The quick charger intermediation server EM is installed within the management area of the quick charger resource aggregator.
The rapid charger intermediation server EM may be connected to the third ERC 3E via the Internet NE, etc. The rapid charger intermediation server EM may also be installed within the management area of the power transmission organization PS, etc. Furthermore, the rapid charger intermediation server EM may be omitted, and the DERMS server DS may communicate the control parameters CP and the system voltage periodic report VR directly with the third ERC 3E.

The VarDR server VS is connected to the fourth ERC 4E via a commercial closed communication network CN so as to be able to communicate Var control parameters VP, system voltage periodic reports VR, and the like.
The VarDR server VS is located within the management domain of the VarDR resource aggregator.
The VarDR server VS may be connected to the fourth ERC 4E via the Internet NE or the like. The VarDR server VS may also be installed within the management area of the power transmission organization PS or the like. Furthermore, the VarDR server VS may be omitted, and the DERMS server DS may communicate the Var control parameters VP and the system voltage periodic report VR directly with the fourth ERC 4E. At least two of the various resource aggregators may be the same organization.

The first ERC1E controls the reactive power (unit: var) of the photovoltaic power generation system D1 based on the received control parameters CP, etc., as is done in conventional DERMSs. The first ERC1E can also control the active power (unit: W (watts)) as is done in conventional DERMSs. The ERC is an Energy Resource Controller, a control device that controls one or more DER devices belonging to a specified area (such as a consumer area). The first ERC1E has a DERMS communication function that communicates with the outside world via one or more DER devices (photovoltaic power generation system D1), as well as an aggregation function that aggregates the voltage, active power, and reactive power of each DER device for that consumer facility. However, the photovoltaic power generation system D1 is unevenly distributed in the power distribution system ES. Furthermore, the first ERC1E cannot appropriately control the reactive power depending on the power generation state of the photovoltaic power generation system D1.
The three photovoltaic power generation systems D1 are respectively connected to interconnection points GP1 to GP3 (voltages _V1 to _V3 ) of the power distribution system ES. Reactive power control in the three photovoltaic power generation systems D1 is performed by applying a reactive power control amount (reactive power amount) ΔVar (kvar) to the voltages _V1 to _V3 of the corresponding interconnection points GP1 to GP3. Active power control in the three photovoltaic power generation systems D1 is performed by applying an active power control amount ΔW (kW (kilowatts)) to the voltages _V1 to _V3 of the corresponding interconnection points GP1 to GP3. The photovoltaic power generation systems D1 have a scale of, for example, several hundred kW.
Some or all of the photovoltaic power generation units D1 may belong to different businesses or may belong to the same business.
The number of photovoltaic power generation units D1 and at least one of the interconnection points GP1 to GP3 to which they are connected are not limited to those described above. Also, the control of the active power of the photovoltaic power generation unit D1 may be omitted or may be performed by a different system.

The second ERC2E controls the reactive power in the battery system D2 based on the received control parameters CP, etc., as is done in conventional DERMSs. The second ERC2E can also control active power as is done in conventional DERMSs. The second ERC1E has a DERMS communication function that allows one or more DER devices (battery system D2) to communicate with the outside, and an aggregation function that aggregates the voltage, active power, and reactive power of each DER device for the corresponding consumer equipment. However, the battery system D2 is unevenly distributed in the power distribution system ES. Furthermore, the second ERC2E cannot appropriately control reactive power depending on the state of the battery system D2, such as when the amount of stored energy in the battery system D2 falls below a predetermined level.
The three storage battery systems D2 are respectively connected to interconnection points GP2, GP3, and GP20 (voltages _V2 , _V3 , and _V20 ) of the power distribution system ES. Reactive power control in the three storage battery systems D2 is performed by applying a reactive power control amount ΔVar to the voltages _V2 , _V3 , and _V20 of the corresponding interconnection points GP2, GP3, and GP20. Active power control in the three storage battery systems D2 is performed by applying an active power control amount ΔW to the voltages _V2 , _V3 , and _V20 of the corresponding interconnection points GP2, GP3, and GP20. The storage battery systems D2 are, for example, on the scale of several tens of kW and are used as emergency power sources for the building.
Some or all of the storage battery systems D2 may belong to different businesses or to the same business.
The number of storage battery systems D2 and at least one of interconnection points GP2, GP3, and GP20 to which they are connected are not limited to those described above. In addition, the control of the active power of storage battery system D2 may be omitted or may be performed by another system.

The third ERC 3E controls the reactive power of the quick charger D3 based on the received control parameters CP, etc., as is done in a conventional DERMS. The third ERC 3E can also control active power, as is done in a conventional DERMS. The third ERC 3E has a DERMS communication function that allows one or more DER devices (quick charger D3) to communicate with the outside, and an aggregation function that aggregates the voltage, active power, and reactive power of each DER device for the corresponding customer facility. However, the quick chargers D3 are unevenly distributed in the power distribution system ES. Furthermore, the third ERC 3E may not be able to appropriately control reactive power depending on the state of the quick charger D3, such as during quick charging.
The three rapid chargers D3 are respectively connected to interconnection points GP3, GP20, and GP39 (voltages _V3 , _V20 , and _V39 ) of the power distribution system ES. Reactive power control in the three rapid chargers D3 is performed by applying a reactive power control amount ΔVar to the voltages _V3 , _V20 , and _V39 of the corresponding interconnection points GP3, GP20, and GP39. Active power control in the three rapid chargers D3 is performed by applying an active power control amount ΔW to the voltages _V3 , _V20 , and _V39 of the corresponding interconnection points GP3, GP20, and GP39. The rapid chargers D3 have a capacity of several hundred kW, for example, sufficient for approximately 10 EVs.
Some or all of the rapid chargers D3 may belong to different operators or may belong to the same operator.
The number of quick chargers D3 and at least one of the interconnection points GP3, GP20, and GP39 to which they are connected are not limited to those described above. Also, the control of the active power of quick charger D3 may be omitted or may be performed by a separate system.

The fourth ERC4E controls the reactive power in the building multi-air-conditioner BA based on the received Var control parameter VP, etc. The fourth ERC4E can also control active power as is done in conventional DERMS. The fourth ERC4E has a DERMS communication function that allows one or more DER devices (building multi-air-conditioners BA) to communicate with the outside, and an aggregation function that aggregates the voltage, active power, and reactive power of each DER device for the corresponding customer equipment. In addition, the fourth ERC4E has a function to allocate the reactive power control amount ΔVar allocated to the customer equipment from the DERMS reactive power (the total amount of reactive power in a specific area within the area AR) to each DER device (building multi-air-conditioner BA) as a reactive power control command (target reactive power).
A large number (e.g., 23) of building multi-air conditioners BA are connected to interconnection points GP20, GP40 (voltages _V20 , _V40 ) of the power distribution system ES. Compared to other DER devices (photovoltaic power generation D1, battery storage system D2, rapid charger D3), building multi-air conditioners BA are widespread in the power distribution system ES and are originally installed widely throughout the entire power distribution system ES. Reactive power control in each building multi-air conditioner BA is performed by applying a reactive power control amount ΔVar to the voltages _V20 , _V40 , etc. of the corresponding interconnection points GP20, GP40, etc. Active power control in each building multi-air conditioner BA is performed by applying an active power control amount ΔW to the voltages _V20 , _V40 , etc. of the corresponding interconnection points GP20, GP40, etc.
Some or all of the building multi-air conditioners BA may belong to different customers, or may belong to the same customer.
Hereinafter, the interconnection points GP1 to GP40 may be collectively referred to as the interconnection point GP. Furthermore, at least one of the interconnection points GP1 to GP40 may be referred to as the interconnection point GP.
The numbers at the interconnection points GP1 to GP40 and their positions on FIG. 1 do not indicate the distance from the distribution substation TS, and do not imply a spatial distribution of the points.
The number of building multi-air conditioners BA and at least one of the interconnection points GP20, GP40, etc. to which they are connected are not limited to those described above. Also, control of the active power of the building multi-air conditioners BA may be omitted or may be performed by a separate system.

[Example of operation of reactive power demand response system 1 (reactive power allocation method)]
The following describes an example of the operation of the reactive power demand response system 1. The example of the operation includes an example of a reactive power allocation method.

FIG. 3 is a flowchart relating to this operation example.
The DERMS server DS determines whether reactive power control is necessary to stabilize the system voltage at each predetermined point in the power distribution system ES based on various system voltage periodic reports VR (step S1), and if necessary (Yes), calculates the total amount of reactive power necessary at that point (step S2), and calculates the reactive power control amount ΔVar for each consumer facility by proportionally dividing the total amount of reactive power among the consumer facilities of adjacent building multi-air conditioners BA (step S3).The DERMS server DS then transmits a Var control parameter VP (reactive power control command) based on the calculated reactive power control amount ΔVar to the fourth ERC 4E via the VarDR server VS (step S4).
The DERMS server DS determines whether reactive power control is necessary, calculates the total amount of reactive power and each reactive power control amount ΔVar when necessary, and transmits the Var control parameter VP at predetermined timings appropriate at that time (for example, every few seconds to every few tens of minutes). Note that the timings may be different for some or all of the determination of whether reactive power control is necessary, the calculation of the total amount of reactive power and each reactive power control amount ΔVar when necessary, and the transmission of the Var control parameter VP.
The fourth ERC 4E controls the operation of each building multi-air conditioner BA based on the received Var control parameter VP. One customer facility generally includes about 10 building multi-air conditioners BA, and each building multi-air conditioner BA performs air conditioning operation independently. Therefore, the fourth ERC 4E, which manages each building multi-air conditioner BA for each customer, allocates the target reactive power based on the requested reactive power control command to each building multi-air conditioner BA belonging to one customer (step S5). Note that the VarDR server VS may perform part of the processing of the DERMS server DS or act as an intermediary in that processing. For example, the VarDR server VS may receive the total amount of reactive power in the area it is responsible for and allocate this to each of multiple consumer equipment units as a reactive power control amount ΔVar, and each fourth ERC4E of those consumer equipment units may then allocate the reactive power control amount ΔVar allocated by the VarDR server VS to each building multi-air conditioner BA.
Each Var control parameter VP is a parameter of a V-Q droop curve. The V-Q droop curve is drawn on a coordinate system where the horizontal axis represents V (connection point voltage), the positive side of the vertical axis represents the amount of reactive power injected into the interconnection point, and the negative side of the vertical axis represents the amount of reactive power injected into the interconnection point. The V-Q droop curve includes a straight line segment of a predetermined length sloping downward to the right on the coordinate system, and two horizontal line segments connecting to both the left and right sides of the straight line segment. The straight line segment intersects with the horizontal axis at a predetermined reference point (e.g., a system voltage of 6600 V). The slope of the straight line segment is determined by the amount of reactive power injected into the interconnection point GP when the voltage drops by a predetermined amount from the reference point, and the amount of reactive power drawn from the interconnection point GP when the voltage drops by a predetermined amount from the reference point. The value of the slope of the straight line segment of this V-Q droop curve is the Var control parameter VP. If reactive power is injected into the grid-connection point GP and the phase of the current at the grid-connection point GP is advanced, the voltage at the grid-connection point GP will increase. Furthermore, if reactive power is withdrawn from the grid-connection point GP and the phase of the current at the grid-connection point GP is delayed, the voltage at the grid-connection point GP will decrease. The DERMS server DS determines each V-Q droop curve (each Var control parameter VP) based on the status of the grid-connection points GP belonging to the area AR. The DERMS server DS may transmit information on the V-Q droop curve to the fourth ERC 4E instead of or together with the Var control parameter VP. Furthermore, each Var control parameter VP may be a value other than the slope of the linear portion of the V-Q droop curve.

The allocation of target reactive power to a plurality of building multi-air conditioners BA in customer equipment to which the reactive power control amount ΔVar is allocated by the fourth ERC4E (step S5) will be described in further detail.
The DERMS reactive power command value (total reactive power in the consumer equipment) for consumer equipment c ( _{number for each consumer equipment) is QcADR} ^, and the fourth ERC4E allocates the total reactive power ^QcADR to B building multi-air conditioners BA as _Qb ^{^} _AC (b = 1, 2, ..., b, ..., B). Here, the "^" in Qb ^{^} _AC is normally written above b, but due to expression constraints, it may be written to the right of b.
If _the total reactive power ^QcADR related to consumer equipment c is allocated evenly to B building multi-air conditioners BA, for example, if the building multi-air conditioner BA numbered b=1 has been in operation for a considerable period of time and is operating at a relatively low power consumption, while the building multi-air conditioner BA numbered b=2 has just started operation and is operating at a relatively high power consumption, the current air conditioning status of each building multi-air conditioner BA will not be taken into account, and the operation of the building multi-air conditioner BA numbered b=1, which has more surplus power, will likely be hindered, and the current air conditioning status of each building multi-air conditioner BA will not be taken into account. Furthermore, even if the allocation is proportionally distributed based on the rated power consumption ^PbR of each building multi-air conditioner _BA , the current air conditioning status of each building multi-air conditioner BA will still not be taken into account.
In _the reactive power demand response system 1 of the present invention, the allocation of target reactive power is determined by the algorithm expressed by the following equation (1): Here, [ ^k1PAC ,..., ^kbPAC ,..., _kBPAC ] is the proportional coefficient of _the active power (current value) _PbAC of each building multi-air-conditioner ^{BA, and [k1TSA} _{, ...} ^, _kbTSA ^, ..., ^kBTSA ] is the proportional coefficient ^of the room temperature deviation ^TbSA indicating the air-conditioning comfort state of each building multi-air-conditioner _BA . _The room temperature deviation ^TbSA is the average of the difference between the current room temperature and the set temperature in each indoor unit AN of the building multi-air-conditioner BA. [k1 ^* _TSA ,...,kb ^* _TSA ,...,kB ^* _TSA ] will be explained shortly. As is well known, the set temperature is obtained from the building multi-air conditioner BA (each indoor unit AN), and the current room temperature is obtained from a temperature sensor in each air-conditioning target (each indoor unit AN).

The fourth ERC 4E allocates and distributes the current power of each building multi-air conditioner BA measured by a known method as it is for the current power proportional coefficient [k ¹ _PAC , . . . , k ^b _PAC , . . . , ^{k B} _PAC ].
On the other hand, the fourth ERC4E allocates the room temperature deviation proportional coefficients [k ¹ _TSA , ..., k ^b _TSA , ..., k ^B _TSA ] indicating the indoor comfort level, taking into account the following property: A small deviation of ±1°C or less is unnoticeable or tolerated by many ordinary people, whereas a deviation exceeding ±1°C is noticeable by ordinary people and reduces the sense of comfort. The larger the deviation, the more rapidly the comfort level decreases nonlinearly. In consideration of this property, the VarDR server VS allocates and distributes [k ¹ _TSA , ..., k ^b _TSA , ..., k ^B _TSA ] using the following formula (2) to obtain the apportionment proportional coefficients [k ^{1 *} _TSA , ..., k ^{b *} _TSA , ..., k ^{B *} _TSA ]. Here, the function argmin indicates extraction of the element [k ¹ _TSA , ..., k ^b _TSA , ..., k ^B _TSA ] that minimizes the variable (the sum of the squares of each T ^b _SA ). The subscript * indicates optimal allocation.

That is, the meaning of equation (2) is to allocate and distribute the square of the room temperature deviation T ^b _SA of each building multi-air conditioner BA at that time when the DERMS control command is apportioned, by the room temperature deviation proportional coefficient [k ¹ _TSA , ..., k ^b _TSA , ..., k ^B _TSA ] so that the sum of all units is minimized (allocation using the least squares method).
In the reactive power demand response system 1, the fourth ERC4E determines the allocation of the target reactive power based on equation (2), so that the impact on the air conditioning capacity required by each building multi-air conditioner BA at that time, and ultimately the room temperature deviation indicating the comfort of each building multi-air conditioner BA, is minimized, and the fourth ERC4E can achieve the target reactive power based on the requested reactive power control command, contributing to power stability in the distribution system ES.
The fourth ERC 4E also stores the received Var control parameter VP and references (looks up) it at specific timings (for example, at intervals of several tens of seconds to several minutes) to determine the target reactive power allocation each time. When the Var control parameter VP is updated by receiving a new parameter, the fourth ERC 4E references the Var control parameter VP.
Note that instead of the least squares method, the allocated room temperature deviation proportional coefficients [k ^1* _TSA , ..., k ^b* _TSA , ..., k ^B* _TSA ] may be determined by other mathematical programming (mathematical optimization), such as an optimal search method. The mathematical programming may be linear programming or nonlinear programming. Furthermore, instead of the proportional coefficients of the room temperature deviation for apportioning the reactive power, the apportioned reactive power corresponding to the value obtained by multiplying the reactive power to be apportioned by the proportional coefficient of the room temperature deviation may be directly determined.

Fig. 4 is a graph showing the principle of control of reactive power Q by the active converter AC of a building multi-air conditioner BA. The horizontal axis of the graph in Fig. 4 represents the active power P component of the apparent power, and the vertical axis represents the reactive power Q component.
The reactive power Q is controlled by manipulating the active power P and power factor cos θ (θ in radians) for the outdoor unit's built-in inverter IN using the active converter AC. An increase in reactive power corresponds to a leading power factor, and a decrease in reactive power corresponds to a lagging power factor.
Furthermore, the control of reactive power Q involves limitations based on the minimum operating power factor cos θ _max of the active converter AC and the outdoor unit built-in inverter IN, and limitations based on the rated capacity S _max (unit: VA) of the active converter AC and the outdoor unit built-in inverter IN. The circle CL in the graph of Fig. 4 has its center at the origin and its radius at the rated capacity S _max , and the power of the active converter AC and the outdoor unit built-in inverter IN during operation falls within this circle CL.

When the target reactive power commanded by the DERMS server DS to the fourth ERC 4E of the building multi-air-conditioner BA based on the Var control parameter VP is Q _TGT , the fourth ERC 4E switches its operation so as to generate the target reactive power Q _TGT according to its own operation mode, thereby achieving the target reactive power Q _TGT while suppressing a decrease in the comfort of the air conditioning by the building multi-air-conditioner BA, and making it possible to supply the target reactive power Q TGT to the distribution system ES through its own interconnection point GP.
The active powers P ₀ to P ₃ located at the boundaries of each operation mode are expressed by the following equations (3) to (6).

When the fourth ERC 4E is in the first operation mode M1 in which the range of active power P is _P0 < P≦ _P1 due to operation of the building multi-air-conditioner BA, it consumes active power P proportional to reactive power Q in order to correspond to the target reactive power _QTGT while maintaining the minimum operating power factor cos θ _max . The range of reactive power Q in the first operation mode M1 is Q≦Ptan θ _max .
In a normal building multi-air conditioner BA that does not support the target reactive power Q _TGT , when the room temperature reaches near the set temperature, the operation of the outdoor unit OU is stopped and the supply of refrigerant to each indoor unit AN is stopped (so-called thermo-off), so if you try to maintain the minimum operating power factor cos θ _max , you will not be able to supply reactive power Q either.
Therefore, when the fourth ERC 4E corresponds to the target reactive power Q _TGT , it supplies reactive power Q, and consumes active power P even if the room temperature reaches near the set temperature. However, when the room temperature deviation exceeds a predetermined value (for example, ±2°C), it stops responding to the target reactive power Q _TGT (opt-out) in order to suppress the impact of a decrease in comfort. In other words, the fourth ERC 4E allows room temperature deviation within a predetermined value and consumes active power P to supply reactive power Q.

When the fourth ERC 4E is in the second operation mode M2 in which the range of the active power P is _P1 < P≦ _P2 , it can operate at the minimum operating power factor cos θ _max or more at any active power P and can supply the target reactive power Q _TGT , so it is not subject to restrictions on the active power P and can control the room temperature in the same way as under normal conditions.
The range of the reactive power Q in the second operation mode M2 is Q≦Q _TGT .

In the fourth ERC4E, when the range of the active power P is _P2 < P≦ _P3 , the supply of reactive power Q is reduced due to the limitations of the rated capacity _Smax (= _P3 ) of the active converter AC and the outdoor unit built-in inverter IN in the third operation mode M3.
Therefore, the fourth ERC 4E reduces the active power P to the active power _P2 that can supply the target reactive power _QTGT or less.
The range of the reactive power Q in the third operation mode M3 is Q≦(S _max ² −P ² ) ^1/2 .

In this way, the active converter AC controlled by the fourth ERC4E controls the active power P for air conditioning of the building multi-air conditioner BA to which it belongs, thereby generating reactive power Q related to the target reactive power _QTGT allocated to that building multi-air conditioner BA.

[Simulation example of reactive power demand response system 1]
A computer simulation was performed on the reactive power demand response system 1 and the comparative example using a model of a building multi-air conditioner BA.
The fourth ERC4E in the reactive power demand response system 1 allocates the total reactive power Q ^c _ADR to multiple building multi-air conditioners BA belonging to one consumer facility c using the above equations (1) and (2), and generates a reactive power output command Q ^{b^} _AC for the building multi-air conditioner BA numbered b.
The coefficients k ^b _PAC and k ^{b *} _TSA that allocate the total reactive power Q ^c _ADR , which corresponds to the reactive power control amount ΔVar requested for consumer equipment c, to each building multi-air-conditioner BA are given by the following equations (7) and (8): where α ₁ is the sensitivity coefficient for power consumption (set to 1.0 here), α ₂ is the sensitivity coefficient for average room temperature deviation (set to 2.0 here), P ^b is the active power (kW) consumed for air conditioning by the building multi-air-conditioner BA numbered b, P ^b _max is the rated power consumption (kW) of the building multi-air-conditioner BA numbered b, and T ^b _SA is the room temperature setting deviation (°C) weighted averaged by the capacity of multiple indoor units AN connected to the building multi-air-conditioner BA numbered b.
The information required for calculating equations (1), (2), (7), and (8) is sent to the VarDR server VS and the DERMS server DS, which store this information.
Furthermore, in the reactive power demand response system 1, the allocation of the total reactive power Q ^c _ADR is performed every five minutes, for example.

In addition, in the comparative example, the total reactive power Q ^c _ADR required for the building multi-air conditioner BA numbered b is simply divided by the number B of building multi-air conditioners BA belonging to the customer facility c, as shown in the following equation (9), and is allocated evenly as a reactive power output command Q ^{b^} _AC to each building multi-air conditioner BA.

The model of the building multi-air-conditioner BA is mainly formed by a recursive equation linking the instantaneous power consumption of the building multi-air-conditioner BA and the building's indoor air temperature. The computer that executes the simulation performs a recursive calculation of the power recurrence equations expressed by the following equations (10) to (12) and the room temperature recurrence equations expressed by the following equations (13) to (15) every predetermined time (here, every second).
The power recursion equation is related to the DEAMS simulator (power distribution system ES).
The DEAMS simulator is implemented with a model of the control principle of reactive power Q by the active converter AC of a building multi-air conditioner BA, as shown in Figure 4 etc., and a model of the control principle of reactive power Q (equal distribution) according to a comparative example.

Table 1 below shows various execution parameters in the simulation.
Here, in both the reactive power demand response system 1 and the comparative example, it is assumed that two building multi-air conditioners BA (numbered b=1, 2) belong to a certain consumer facility c. There is the following difference in the air conditioning status of these two building multi-air conditioners BA. That is, the internal heat generation load of the building multi-air conditioner BA numbered b=2 is 1.8 times the internal heat generation load of the building multi-air conditioner BA numbered b=1. It is assumed that the internal heat generation load does not fluctuate in the simulation.
Furthermore, the DERMS server DS requests the consumer facility c via the VarDR server VS to supply a total reactive power ^QcADR of 20 (var) to the power distribution system ES from t=10 (min (minutes)) onwards, and _the reactive power demand response system 1 and the comparative example each respond to the total reactive power ^QcADR by allocating the total reactive power _QcADR to the two belonging building multi-air ^conditioners BA (fourth _ERC4E ). Such a simulation is performed up to t=30 min.

5A is a graph showing the changes over time of active power P ^b _AC , reactive power Q ^b _AC , and room temperature deviation T ^b _SA in the comparative example, and FIG. 5B is a graph showing the changes over time of active power P ^b _AC , reactive power Q ^b _AC , and room temperature deviation T ^b _SA in the reactive power demand response system 1.
Before control of reactive power Q ^b _AC begins (t<10), in both reactive power demand response system 1 and the comparative example, each building multi-air conditioner BA with numbers b=1 and 2 is in a steady state where heat balance is achieved at the set temperature between heat load and cooling capacity, and room temperature deviation T ^b _SA remains at 0° C. However, the active power at which heat balance is achieved varies depending on the heat load of the building multi-air conditioner BA, with the building multi-air conditioner BA with number b=1, which has a low heat load, consuming approximately 10 kW, while the building multi-air conditioner BA with number b=2, which has a high heat load, consuming approximately 14 kW.
After control of the reactive power Q ^b _AC starts (t≦10), in the comparative example, the total reactive power Q ^c _ADR =20 is evenly distributed, and each of the building multi-air conditioners BA with numbers b=1 and 2 supplies 10 kvar of reactive power Q ^b _AC .
Here, in the building multi-air conditioner BA with low heat load number b ⁼ 1, even if the reactive power ^Q1AC is supplied at 10 kvar while the active power _P1AC is maintained at 10 kW, the apparent power is 14.1 kVA, which does not exceed the rated capacity _Smax =15 kVA of the active converter AC and the outdoor unit built _- in inverter IN. If the active power ^P1AC is maintained _, the cooling capacity is also maintained, so _the room temperature deviation ^T1SA is kept at 0°C.
Meanwhile, in the building multi-air-conditioning unit BA ⁽ number b=2) with a high thermal load, even if reactive power ^Q2AC is supplied at 10 kvar while real power _P2AC is maintained at 14 kW, the apparent power becomes 17.2 kVA, exceeding the rated capacity _Smax = 15 kVA of the active converter AC and the outdoor unit's built _- in _inverter IN. Therefore, reactive power ^Q2AC cannot be supplied at 10 kvar. Therefore, the fourth ERC4E of the building multi-air-conditioning unit BA (number b=2) reduces real _power ^P2AC by using the third operating mode M3. This reduces the _cooling capacity of the building multi-air-conditioning unit BA (number b=2), disrupting the thermal balance with the thermal load and causing the room temperature to rise. At t=30 min, the end of the simulation, the room temperature deviation ^T1SA is 0°C, but _{the room temperature deviation T2SA} ^exceeds the target of +1°C for maintaining comfort.

In contrast, in the reactive power demand response system 1, after the control of the reactive power Q ^b _AC starts (t≦10), the total reactive power Q ^c _ADR is re-allocated every five minutes.
In the first allocation at t=10 min, the room temperature deviation T ^b _SA of each of the building multi-air conditioners BA numbered b=1 and 2 is both 0°C, with no difference, but the building multi-air conditioner BA numbered b=2 consumes more active power P ^b _AC than the building multi-air conditioner BA numbered b=1, so the reactive power is allocated so that Q ¹ _AC > Q ² _AC . In the building multi-air conditioner BA numbered b=2, active power P ² _AC is reduced to supply reactive power Q ² _AC , so the room temperature deviation T ² _SA rises.
In the second allocation at t=15 min, for the building multi-air conditioner BA with number b=2, the room temperature deviation T ² _SA has increased compared to the first allocation, and the active power P ² _AC has also decreased, so the total value of k ^b _PAC + k ^{b *} _TSA remains almost unchanged, and as a result, there is no change in the distribution of the allocated reactive power Q ^b _AC .
In the third allocation at t=20 min, the room temperature deviation ^T2SA of the building multi-air conditioner BA numbered b= ₂ rises further to 0.5°C, while the room temperature deviation ^T1SA of the building multi-air conditioner _BA numbered b=1 remains around 0°C and there is a margin for indoor comfort, so the reactive power ^Q1AC of the building multi-air conditioner BA numbered b=1 increases, while the reactive power _Q2AC of the building multi-air conditioner BA numbered b= ² decreases.Here, the building multi-air conditioner BA numbered b=1 also reduces _{its active} power ^P1AC to save on the capacity of the outdoor unit's built-in inverter IN, so the thermal balance between cooling capacity and heat load is disrupted and _the room temperature deviation ^T1SA begins to rise. In addition, in the building multi-air conditioner BA with number b=2, the decrease in reactive power Q ² _AC allows the active power to increase, and the cooling capacity to increase, so the rise in room temperature deviation T ¹ _SA becomes gradual.
The fourth allocation at t=25 min shows the same tendency as the third allocation at t=20 min.
In this way, the reactive power demand response system 1 allocates the total reactive power ^QcADR to each _reactive power ^QbAC according to the room temperature comfort margin of each building multi-air conditioner BA. Therefore, the reactive power demand response system 1 contributes to the stabilization of the power distribution system ES in accordance with the total reactive power ^QcADR , while preventing the room temperature deviation _TbSA at t = 30 min _, the end of the simulation ^, from exceeding +1° _C for any of the building multi-air conditioners BA, thereby suppressing a decrease in the comfort of the air conditioning provided by each building multi-air conditioner BA.

[Effects of the invention for transformer overload protection in substations]
The reactive power demand response system 1 described above has a computer (fourth ERC4E ₎ that controls each building multi-air conditioner BA so that the total reactive power ^QcADR (reactive power) requested for the consumer equipment is supplied to the power distribution system ES by the multiple building multi-air conditioners BA.
Therefore, a reactive power demand response system 1 is provided that can control the voltage of the interconnection point GP by controlling the input/output and amount of reactive power Q to/from the interconnection point GP associated with multiple building multi-air conditioners BA in the distribution system ES. Because building multi-air conditioners BA are originally widely present in the distribution system ES, the reactive power demand response system 1 can accommodate multiple building multi-air conditioners BA adjacent to points in the distribution system ES that require voltage control. Furthermore, compared to other DER devices (photovoltaic power generation system D1, storage battery system D2, rapid charger D3), building multi-air conditioners BA can provide reactive power Q for a longer period of time without significantly impairing their original functions, and the reactive power demand response system 1 controls the voltage of the interconnection point GP at a more appropriate timing (to be able to respond more quickly to voltage fluctuations in the distribution system ES).

Furthermore, the fourth ERC 4E _allocates the total reactive power ^QcADR to each building multi-air conditioner BA based on mathematical programming related to _the room temperature deviation ^TbSA , and allocates the target reactive power _QTGT to each building multi-air conditioner BA. Thus, the reactive power demand response system 1 can supply reactive power Q to the power distribution system ES while taking into consideration the comfort of the air conditioning in each building multi-air conditioner BA.
Furthermore, the mathematical programming is a least squares method that determines the apportionment proportional coefficients [k 1* TSA , ..., k ^{b *} _TSA , ..., k ^{B *} _TSA ] for each building multi-air conditioner BA for the total reactive power Q ^c _ADR requested from the consumer equipment _so that the sum of the squares _of each room temperature deviation T b SA is minimized. Therefore, the reactive power demand response system 1 can supply reactive power Q to the distribution system ES while more easily considering the air conditioning comfort of each building multi-air conditioner BA.

In addition, each building multi-air conditioner BA has a compressor motor CM, an outdoor unit built-in inverter IN connected to the compressor motor CM, and an active converter AC that adjusts the power to the outdoor unit built-in inverter IN. Therefore, in the reactive power demand response system 1, reactive power Q is supplied to the power distribution system ES more efficiently in each building multi-air conditioner BA.
Furthermore, each active converter AC controls the active power P for air conditioning of the building multi-air conditioner BA to which it belongs, thereby generating reactive power Q related to the target reactive power _QTGT allocated to that building multi-air conditioner BA. Therefore, in the reactive power demand response system 1, reactive power Q is supplied to the power distribution system ES more efficiently in each building multi-air conditioner BA.

[Examples of changes]
At least one of the embodiments and simulations of the present invention is not limited to the above-described embodiments and modifications, and may include further modifications as follows.
At least one of the number of various computers and their arrangement on the network, the configuration of the power system, various formulas, and circuits and commands related to control may be changed to other logically equivalent ones.

1: Reactive power demand response system, 4E: 4th ERC (computer), AC: Active converter, BA: Building multi-air conditioner, CM: Compressor motor, DS: DERMS server, ES: Power distribution system, IN: Inverter built into outdoor unit (inverter), P: Active power, Q: Reactive power, ^Qc _ADR : Total reactive power, _QTGT : Target reactive power, ^Tb _SA : Room temperature deviation, VS: VarDR server.

Claims (4)

a computer that controls each of the plurality of building multi-air-conditioners so that reactive power is supplied to the power distribution system by the building multi-air-conditioners ;
The computer allocates the reactive power to each of the building multi-air conditioners based on a mathematical programming method related to room temperature deviation, and allocates target reactive power to each of the building multi-air conditioners.
A reactive power demand response system comprising: The reactive power demand response system described in claim 1, characterized in that the mathematical programming method determines an apportionment proportional coefficient for each building multi-air conditioner for the reactive power so that the sum of the squares of each room temperature deviation is minimized, or is a least squares method that determines an apportioned reactive power for each building multi-air conditioner equivalent to the value obtained by multiplying the reactive power by the apportionment proportional coefficient. The reactive power demand response system of claim 1 or 2, characterized in that the building multi-air conditioner has a compressor motor, an inverter connected to the compressor motor, and an active converter that adjusts the power to the inverter. The reactive power demand response system described in claim 3, characterized in that the active converter generates reactive power related to the target reactive power allocated to the building multi-air conditioner by controlling the active power for air conditioning of the building multi-air conditioner to which it belongs.