WO2010089607A1

WO2010089607A1 - Power management system

Info

Publication number: WO2010089607A1
Application number: PCT/GB2010/050187
Authority: WO
Inventors: Iain Bowes; David Falberg
Original assignee: Eco Designs Labs Limited
Priority date: 2009-02-05
Filing date: 2010-02-05
Publication date: 2010-08-12
Also published as: GB0901844D0

Abstract

A power management system for controlling the supply of energy to a load (L), the system comprising: a rechargeable energy store (2) having an energy level indicator; and a power controller (1) arranged to receive a main power supply (MAIN) and arranged to selectively distribute the main power supply (MAIN) to either or both of the load (L) and the rechargeable energy store (2) and further arranged to selectively connect the rechargeable energy store (2) to the load (L).

Description

POWER MANAGEMENT SYSTEM

Both domestic and commercial energy consumers are increasingly aware of the desirability to minimise their energy consumption the motivation to do so arises both from the increasing cost of energy and the general acknowledgement that a reduction in our energy consumption would be beneficial to global climatic conditions. With regards to electricity consumption, whilst commercial and domestic consumers can take various steps to minimise their individual electricity consumption, by utilising energy efficient appliances and equipment where possible, they have no direct control over the amount of electricity provided to them by the electricity generators and distributors. Consequently, it is quite common for there to be an excess of electrical energy available to domestic and commercial consumers. Some prior art systems, such as uninterruptible power supplies (UPS), provide an energy reserve that is available in the event that mains power is lost to a device or devices, the energy reserve being replenished by the mains power when the mains power is restored. However, such UPS systems do not operate when mains power is present (other than to recharge the energy reserve) and so do not ordinarily make any use of the stored energy in such a way as to reduce the consumers energy consumption overall. Typically such systems are used for single appliances, such as laptop computers where a battery is used to supply energy when the mains supply ceases or is disconnected. Such systems are well known for single appliances or devices, for example computers or networks of computers. However, such systems are generally not scalable to supply energy to domestic or commercial premises.

It known that the energy consumption across an entire network (e.g. a city) will vary with time. Some appliances such as storage heaters will preferentially use and store energy at times of low demand, such as between midnight and 6am where energy providers often offer cheaper rates to encourage use at these times. Savings can be made by a user operating electric devices at times where the energy is charged at a lower tariff. However, it is often impractical to use the appliances at this time.

It is also known that during the year there are surges in demand for electricity and the infrastructure providing the power is unable to meet the increased demand. Such disruptions may result in reduction or even loss of power to a premises. It is also known to use off-grid renewable energy sources to locally power domestic and commercial properties. Typically such sources may be used to power a single task e.g. provide energy to heat water. A problem with such sources is that they generally provide a variable energy output which may not be sufficient at all times and may not be suitable as the power source for an entire commercial or domestic property.

In order to mitigate at least some of the above problems there is provided a power management system for controlling the supply of energy to a load, the system comprising: a rechargeable energy store having an energy level indicator; and a power controller arranged to receive a main power supply and arranged to selectively distribute the main power supply to either or both of the load and the rechargeable energy store and further arranged to selectively connect the rechargeable energy store to the load.

Additionally, the power controller may be arranged to receive the indication of the energy level stored in the rechargeable energy store and in the event of the energy level being greater than an activation threshold being arranged to disconnect the main power supply from the load and connect an output of the rechargeable energy store to the load.

Additionally, if the energy store level subsequently reduces to less than a recharge threshold the power controller may be arranged to disconnect the energy store from the load and reconnect the main power supply and distribute the main power supply to both the load and the rechargeable energy store to recharge the energy store.

Additionally or alternatively, if the energy store level is less than the activation threshold the power controller is arranged to distribute the received main power supply to both the load and the rechargeable energy store to recharge the store.

In the event of a failure of the main power supply the power controller is preferably arranged to connect an output of the rechargeable energy store to the load. The connection may only occur provided the indicated stored energy level is greater than an emergency activation threshold. Additionally or alternatively, in the event of the load being greater than a predetermined load threshold the power controller may be arranged to connect an output of the rechargeable energy store to the load in addition to distributing the main power supply to the load.

The power controller is preferably arranged to additionally receive at least one auxiliary power supply. If the indicated stored energy level is below the activation threshold then the power controller may be arranged to distribute the received auxiliary power to the rechargeable energy store to recharge the energy store whilst distributing the received main power to the load.

Additionally or alternatively, if the indicated stored energy level is above the activation threshold then the power controller may be arranged to disconnect the main power supply and distribute power to the load from both the received auxiliary power supply and an output of the rechargeable energy store.

Additionally or alternatively, the power controller may include a power aggregator unit, a power flow control unit and a data processor arranged to control the operation of said units.

The rechargeable energy store preferably includes at least one battery, a switchable battery charger and a switchable inverter.

Additionally or alternatively, the power management system may further comprise a timer with the power controller preferably being arranged to inhibit one or more functions of the power management system within one or more time periods specified by the timer.

Other aims and aspects of the invention will become apparent from the appended claim set.

Embodiments of the present invention are described below, by way of illustrative example only, with reference to the accompanying figures, of which:

Figure 1 schematically illustrates a power management system according to an embodiment of the present invention; Figure 2 schematically illustrates an arrangement of the rechargeable energy store of the power management system according to an embodiment of the present invention;

Figure 3 schematically illustrates an arrangement of the power aggregator shown in Figure 1;

Figure 4 schematically illustrates an arrangement of the flow controller shown in Figure 1 ; and

Figure 5 is a flow chart of an example of the logic used to determine how to power a load.

A schematic illustration of a power management system according to an embodiment of the present invention is illustrated in Figure 1. The power management system is designed to provide and regulate the power supplied to an entire property (or a number of properties). Such properties may be commercial or domestic. The term property may therefore refer to a house, block of flats, a single flat or office etc. Therefore, the system may be considered to regulate the power supplied on a macro scale, in that it ensures the supply of the load within a property.

The power management system includes a power controller 1 and a rechargeable energy store 2. The power controller receives as an input an electricity supply from at least a first, main, power supply. Ordinarily the main power supply would be the electricity supplied from the national grid system, but could be any other designated main power supply, such as an industrial diesel generator unit or the power supply from a local, independent, electricity generation plant. In preferred embodiments the power controller 1 is also arranged to receive one or more auxiliary (AUX) electricity supplies. The auxiliary supplies may, for example, comprise alternative renewable electricity sources such as solar panels or wind turbines. The power controller 1 has an output 5 arranged to provide a supply of electricity to a load. Typically the load will be the overall electricity requirement for a domestic or commercial user and may therefore vary in magnitude.

The power controller 1 is connected to the rechargeable energy store 2 such that electrical energy can be both provided to the rechargeable energy store from the power controller and electrical energy can be drawn from the rechargeable energy store and supplied to the load via the power controller.

The auxiliary supply (AUX) can act as the main energy supply to the load (i.e. power the premises) and it can also be used to recharge the rechargeable energy store.

In a preferred embodiment, the power controller 1 further comprises a power conditioner (not shown) to act on the output 5. Power conditions are commercially available products which are designed to ensure that the electricity delivered from a power source remains approximately stable. AC mains voltage fluctuations, common mode noise, and high energy transients can cause equipment to behave erratically and malfunction. Some equipment will even breakdown because of these problems. Failure to keep voltage stable can result in costly repairs. The power conditioner ensures that the output voltage remains stable in the event that the incoming mains voltage (from, for example, the grid) drift high or low.

The power conditioner therefore helps ensure the power supplied from the power controller 1 is supplied at a stable voltage resulting in energy efficiencies and savings to the user.

Figure 2 schematically illustrates in more detail an arrangement of the rechargeable energy store 2 according to a preferred embodiment of the present invention. The rechargeable energy store includes a battery 6, which may comprise one or more battery cells, that is arranged to receive a charging current from a charger 7. The charger receives a power input from the power controller 1. The power supplied from the charger 7 to the rechargeable energy store 2 may originate from the mains supply, the AUX supply or a combination of both sources. The selection of the power source to charge the rechargeable energy store 2 is discussed in further detail with reference to Figure 2.

Also connected to the battery 6 is an inverter 8 that is arranged to provide an AC power supply to the power controller as required. A battery monitor 9 is preferably included to allow the energy storage status of the battery 6 to be reported to the power controller. It will however be appreciated that alternative arrangements of energy storage units may be provided that have the same functionality as the arrangement of combined charger, battery and inverter illustrated in Figure 2. For example, a flywheel energy storage system having an integrated motor/generator unit, may alternatively be used.

Referring back to Figure 1 , in preferred embodiments of the present invention the power controller includes a power aggregator (PAU) that is arranged to receive the main and auxiliary power supplies 3, 4 and to further distribute the incoming power as required. The PAU has a first power output arranged to be connected to the rechargeable energy store 2 and a second power output arranged to be connected to a power flow controller (FCU). An implementation of the PAU is described in more detail below with reference to Figure 3. The FCU 11 has a second input arranged to also be connected to the rechargeable energy store 2. The output from the FCU is arranged to be connected to the load. An implementation of the FCU is described in more detail below with reference to Figure 4. The operation of the power aggregator 10 and power flow controller 11 are controlled by a data processing unit 12, which is arranged to receive data from one or more power monitors 13-17 and also preferably from the energy store status monitor 9. The power controller 1 may additionally either include, or be arranged to connect it to, a clock/timer unit, a visual display unit and an input/output interface as required to achieve further functionality.

An implementation of the power aggregator unit (PAU) 10 that may be used in embodiments of the present invention is schematically illustrated in Figure 3. In the particular arrangement illustrated three input units 20 are provided, the main power input 3 and two auxiliary power inputs, Aux 1 and Aux 2. Each input unit 20 is arranged to provide either an AC or DC component, depending on the nature of the input supply, with each of the respective AC and DC inputs being connected together and provided separately to a power management module 22. The combined DC inputs are provided directly to the first power output arranged to be connected to the rechargeable energy store. The combined AC inputs may be selectively connected to only the second output of the PAU, arranged to be connected to the FCU, or connected to both the first and second outputs by means of a switch 24, such as a FET or suitable power switching device (the rechargeable energy store being preferably arranged to receive either AC or DC inputs). Operation of the switch 24 is controlled by control signals received at a further input 26 from the data processor 12. Figure 4 schematically illustrates an implementation of the flow controller 11 (FCU) according to an embodiment of the present invention. The FCU includes a power regulator 28 arranged to receive AC inputs from the PAU and the rechargeable energy store and to provide a proportion (0-100%) of that received power to an output arranged to be coupled to the load L as determined by the data processor 12 and as explained in more detail below. In the preferred embodiment illustrated a power monitor 17 arranged to monitor the power demand generated by the load L is included within the FCU and provides further control information to the power regulator 28 via control line 30.

The power management system of embodiments of the present invention is arranged to operate as follows. In the event of only the single main power input 3 being available and connected to the power controller, the power aggregator 10 and flow control unit 11 are controlled by the data processor 12 in combination to provide the load with power either solely from the main power input 3, solely from the rechargeable energy store 2, or a combination of both. The distribution of the incoming main power supply 3 by the power aggregator unit 10 will depend upon, amongst other factors, the state of the rechargeable energy store 2 as noted by the power monitor 9 associated with the energy store. If the energy level held within the energy store 2 is initially less than an activation threshold level (TA), or if the energy level in the energy store falls below a minimum operational threshold level, or recharge threshold TC, the power controller is arranged such that the incoming main power supply is primarily fed to the connected load but any excess power available is also provided to the rechargeable energy store to allow the energy store to be recharged. In the preferred embodiments this is accomplished by the power aggregator unit 10 distributing the main power supply to both the flow control unit and the charger 7 connected to the battery of the rechargeable energy store, whilst the inverter 8 is either deactivated or disconnected from the battery such that no power is provided from the energy store via the inverter to the flow control unit. The actual power distribution to the load is determined using the data provided by the power monitors 13, 15 and 17 that monitor the main power input level and the power level required by the load. If the energy level held within the rechargeable energy store 2 is above the initial activation threshold TA then the data processor controls the power aggregator unit to disconnect the main power input supply 3 from the power controller and causes power to be drawn from the rechargeable energy store and input to the flow control unit 11 and from there to the load, in preferred embodiments by activating the inverter 8 connected to the battery 6 of the rechargeable energy store. In this configuration no mains power is drawn by the consumer load. When the energy level stored within the energy store 2 falls to below the recharged threshold TC the main power supply is reconnected by the power controller and used to simultaneously feed the load and recharge the rechargeable energy store, with no further energy being drawn from the energy store by the load.

The power controller 1 of embodiments of the present invention is preferably arranged, as noted above, so as to allow power to be supplied to a load simultaneously from the main power supply 3 and by the rechargeable energy store 2. This can be accomplished by the data processor controlling the power aggregator unit to distribute all the incoming main power to the flow control unit, whilst simultaneously activating the inverter 8 of the rechargeable energy store so as to also provide power from the energy store to the flow control unit, the flow control unit thus providing both power sources to the load. This arrangement can be used, for example, when a surge in demand from the load is detected by the power monitor 17 connected on the output of the flow control unit, thus either allowing the temporary use of a load that would otherwise exceed the capability of the main power supply or to remove the surges in the load from the main supply side. This mode of operation can also be used to set a limit on the level of main power supply drawn by the consumer load, if so required.

Conversely, the power management system of embodiments of the present invention can also function as an uninterruptible power supply UPS in the event of a mains power supply failure by providing power to the load from the rechargeable energy store (from the inverter) via the flow control unit. The failure of the main power supply would be detected by the power monitor 13 monitoring the available power to the power control unit from the mains supply input.

In the event of there being an additional, renewable power source, or a plurality thereof, available to the auxiliary input 14 of the power controller then the power management system of embodiments of the present invention is arranged to utilise this auxiliary power supply in preference to the main power supply where possible. In the event of the rechargeable energy store 2 not being fully charged then the power controller is arranged to direct the auxiliary power input to the rechargeable energy store to recharge it, whilst directing power from the main power supply 3 to the connected load. When the rechargeable energy store 2 is fully charged then the entirety of the auxiliary power input can be directed to the load, either in addition to power from the main power supply, thereby reducing the power drawn from the main power supplier, or alternatively replacing the main power supply as the power source for the load if the auxiliary power supply is sufficient to meet the load demand. If the energy level in the rechargeable energy store 2 is above the activation threshold TA then the power controller can disconnect the main power supply 3 and provide power to the load from both the auxiliary power supplies 4 and the rechargeable energy store. When the energy level in the rechargeable energy store falls below the recharged threshold TC then power will no longer be drawn from the energy store and the main power supply reconnected to allow the rechargeable energy store to be recharged, either using the power from the auxiliary power input or some of the power available from the main power supply.

Figure 5 shows a flow chart of the logic used by the system, controlled by the data processing unit 12 to minimise monetary costs and provide energy savings to a premises with load L.

The power management system through the data processing unit 12 which controls the PAU 10 and FCU 11 therefore provides the logic controls which determine the source(s) used to supply the load L (and therefore power the premises). The data processing unit 12 is designed to minimise the monetary cost to the user as well as reduce the power drawn from the main power 3 supply. In embodiments which have a renewable source as the auxiliary (AUX) power source this also results in energy savings. In a preferred embodiment the auxiliary power 4 comprises a renewable source such as solar panels, wind turbines etc.

At step S 102 the data processing unit 12 determines if the PAU 10 is receiving energy from the renewable source via the auxiliary power supply 4. If the renewable source is generating power the process goes to step S 104 if the renewable source is not generating power the process goes to step S 108. At step S 104 the renewable source is generating power and the data processing unit 12 checks the status of the rechargeable energy store 2 via the battery monitor 9.

If at step S 104 the battery monitor 9 determines the rechargeable energy store 2 is not fully charged the data processing unit 12 preferentially uses the auxiliary power 4 (i.e. renewable energy) to charge rechargeable energy store 2 at step S 106. As the rechargeable energy store 2 is used to replace, or supplement, the mains supply for the load L the use of the renewable source to recharge the rechargeable energy store 2 may result in mains energy, and therefore monetary, savings for the user.

If at step S 104 the battery monitor 9 determines the rechargeable energy store 2 to be fully charged, the process goes to step Sl 12 discussed below.

If the renewable source is not providing power (e.g. a solar panel at night time) at step S102 the process goes to step S108. At step S108 the charge level of the rechargeable energy store 2 is determined. If the charge level is below a user determined minimum charge level, such as 10%, the process goes to step SI lO and the data processing unit 12 ensures that the FCU 11 will draw the energy to supply the load L solely from the mains power 3. As described above any excess supply from the mains power 3 may be used to recharge the rechargeable energy store 2 at this time. The decision of whether to charge the rechargeable energy store 2 from the mains supply may be made against monetary considerations. For example, when the energy tariff for mains supply is at a maximum rate, it may not be desirable to charge the rechargeable energy store 2 at that time.

In a further embodiment, regardless of the tariff if the rechargeable energy store 2 drops below an absolute minimum level, for example 5%, the rechargeable energy store 2 is charged from the mains supply 2 to ensure a minimum charge in the rechargeable energy store 2 at all times.

If the charge level determined at step S 108 is above the minimum level, the process continues at step Sl 12. At step Sl 12 the data processing unit 12 uses the renewable source to provide power to the load L via the FCU 11. The level of the load L supplied by the rechargeable energy store 2 is determined by the data processing unit 12 at step Sl 12. If the rechargeable energy store 2 has sufficient charge to supply the whole load L then the load L will be supplied entirely from the rechargeable energy store 2 via the FCU 11 at step Sl 14. Therefore in step Sl 12 the data processing unit 12 selectively disconnects the main supply 3 from the load L.

If the rechargeable energy store 2 (and/or the renewable energy source) is unable to supply the entire load L then the FCU 11 supplements the load L with the mains supply 3 at step Sl 16. During steps Sl 14 and Sl 16the remaining charge in the renewable energy store 2 is monitored by the battery monitor 9. When the charge in the renewable energy store drops below a predetermined amount, typically 10%, the data processing unit 12 preferentially uses only the mains supply 3 to power the load L. Therefore in step Sl 16 the data processing unit 12 selectively reduces the main supply 3 from the load L.

The reduction in the main supply 3 to the load L can be expressed as reduction from the baseline normally provided by the main supply 3. For example, if a property has a baseline consumption of 5 KWh, the baseline may be reduced to 2 KWh if the rechargeable energy store is sufficiently charged to provide 3 KWh i.e. the main supply 3 has been reduced by 3 KWh. This further ensures that in the event of a peak or spike in load L form the property the power management system 2 is enabled to meet the load requirements.

The processes used to determine which loads are used in preference can be changed according to the requirements of the user. For example, if the user's main consideration is for monetary savings, the FCU 11 would preferentially use the rechargeable energy store 2 at times where the energy tariff is at the highest and preferentially charge rechargeable energy store 2 at times of low energy tariff and not charge the rechargeable energy store 2 when the energy tariff is at a maximum.

In further embodiments, if the renewable source is producing energy at step 102, the power controller can selectively use the renewable source to directly power the load L, instead of recharging the rechargeable energy store 2. Alternatively, if the energy produced by the renewable source is sufficient it may be selectively used to power the load L directly and any excess is used to recharge the rechargeable energy store 2. Given the variable nature of the renewable source, in the preferred embodiment a power conditioner is used to ensure a constant energy flow. In further embodiments, if the rechargeable energy store 2 is fully charged, the energy produced by the renewable source may be sold to a local energy provider in accordance to any prearranged agreements.

In embodiments of the present invention where a timer is either included within or connected to the power controller 1, the power management system may be set to defer charging of the rechargeable energy store 2 until specified times, for example only during the hours in which cheaper, off-peak, mains power supply is available. Such arrangements may result in monetary savings for the user, as they are able to store energy in the rechargeable energy store 2, which is purchased at a lower tariff, and supply the load from the rechargeable energy store 2 (in preference to, or as a supplement to, the mains supply) at periods of a higher energy tariff.

In some embodiments of the present invention an emergency by-pass may be provided to allow the mains power supply to be connected directly to the load. This operation may be controlled by the power management system, for example in the event of any detection of a fault within the power management system, or manually to allow the power management system to be disconnected by a user, for example to allow maintenance to be performed, or a combination of both.

It is found that the use of the renewable and rechargeable sources to supplement the mains supply can lead to monetary savings as the energy is stored at cheaper tariffs for use during peak tariffs. Additionally, the use of renewable sources leads to energy savings. Furthermore, the use of an energy cleanser on the power management system 1 may be supplemented by commercially available voltage reduction systems resulting in further efficiencies as many appliances are designed to function at lower voltages.

Other advantages of the power management system 1 occur when the mains supply 3 fails. The data processing unit 12 would ensure that the load L is supplied from the rechargeable energy store 2 and any auxiliary source 4. Also in times of energy surges, the mains supply 3 may not be able to supply the entire load L, data processing unit 12 supplements the mains supply 3 with the rechargeable energy store 2 ensuring the demand is met. A power management system according to embodiments of the present invention allows a more efficient use of the available mains power supply to be made by a consumer, thus providing the consumer with an overall energy and cost savings. The power management system has the further advantages of providing an emergency power supply and the ability to connect one or more auxiliary, renewable, energy sources in an easy and integrated manner.

Claims

1. A power management system for controlling the supply of energy to a load for a property, the system comprising: a rechargeable energy store having an energy level indicator; and a power controller arranged to receive a main power supply and arranged to selectively distribute the main power supply to either or both of the load and the rechargeable energy store, including to selectively disconnect, or reduce the main power supply from the load and is further arranged to selectively connect the rechargeable energy store to the load including when the mains power supply has been selected to be disconnected or reduced.

2. A power management system according to claim 1, wherein the system further comprises a renewable energy source, and the power controller is enable to selectively connect the renewable energy source directly to the load and/or the rechargeable energy store.

3. A power management system according to claims 1 or 2, wherein the reduction of the main power supply is a reduction from a baseline level.

4. A power management system according to any preceding claim, wherein the power controller is arranged to receive the indication of the energy level stored in the rechargeable energy store and in the event of the energy level being greater than an activation threshold being arranged to disconnect the main power supply from the load and connect an output of the rechargeable energy store to the load.

5. A power management system according to claim 4, wherein if the energy store level subsequently reduces to less than a recharge threshold the power controller is arranged to disconnect the energy store from the load and reconnect the main power supply and distribute the main power supply to both the load and the rechargeable energy store to recharge the energy store.

6. A power management system according to any preceding claim, wherein if the energy store level is less than the activation threshold the power controller is arranged to distribute the received main power supply to both the load and the rechargeable energy store to recharge the store.

7. A power management system according to any preceding claim, wherein the event of a failure of the main power supply the power controller is arranged to connect an output of the rechargeable energy store to the load.

8. A power management system according to claim 7, where said connection only occurs provided the indicated stored energy level is greater than an emergency activation threshold.

9. A power management system according to any preceding claim, wherein in the event of the load being greater than a predetermined load threshold the power controller is arranged to connect an output of the rechargeable energy store to the load in addition to distributing the main power supply to the load.

10. A power management system according to any preceding claim, wherein the power controller is arranged to additionally receive at least one auxiliary power supply.

11. A power management system according to claim 10, wherein if the indicated stored energy level is below the activation threshold then the power controller is arranged to distribute the received auxiliary power to the rechargeable energy store to recharge the energy store whilst distributing the received main power to the load.

12. A power management system according to claim 10 or 11, wherein if the indicated stored energy level is above the activation threshold then the power controller is arranged to disconnect the main power supply and distribute power to the load from both the received auxiliary power supply and an output of the rechargeable energy store.

13. A power management system according to any preceding claim, wherein the power controller includes a power aggregator unit, a power flow control unit and a data processor arranged to control the operation of said units.

14. A power management system according to any preceding claim, wherein the rechargeable energy store includes at least one battery, a switchable battery charger and a switchable inverter.

15. A power management system according to any preceding claim, further comprising a timer and the power controller being arranged to inhibit one or more functions of the power management system within one or more time periods specified by the timer.

16. A power management system according to any preceding claim, further comprising a power conditioner and/or a voltage reduction system.

17. A power management system according to any preceding claim, wherein the main power supply has a variable tariff and the rechargeable energy store, and optionally the renewable energy source if dependent on claim 2, are selectively connected to the load when the main power supply is at a higher tariff.