GB2606737A

GB2606737A - A wireless energy diverter

Info

Publication number: GB2606737A
Application number: GB2107120.4A
Authority: GB
Inventors: Robin Bolwell Michael
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2022-11-23
Also published as: GB202107120D0

Abstract

A wireless energy diverter system comprising an energy sensing and load command transmitter 21 and at least one load control receiver 31-34. Preferably, the invention provides a range of load control receivers that are suited to a wider range of appliances beyond resistive tank immersion heaters, including but not limited to; washing or drying appliances, dehumidifiers, heat pumps & coolers, battery and electric vehicle chargers, kettles, hot tubs, air compressors and space heaters. The transmitter senses the export of electrical power to a grid and calls for electrical load via the transmitted signal, such that the export of power is reduced or eliminated, where each transmitted load channel signifies a load priority relative to the other load channels

Description

A Wireless Energy Diverter

FIELD OF THE INVENTION

The present invention relates to energy diverters. These are devices used within premises to prevent the export of locally generated electricity to the grid by delivering an amount power equal to the generated surplus to a load within the premises, typically a resistive tank heating element.

BACKGROUND OF THE INVENTION

Solar photovoltaic (PV) panels are commonly installed on roof tops as an environmentally friendly way of reducing the grid electricity consumption and energy costs of a building.

Unfortunately, without expensive battery systems, much of the potential benefit is lost when surplus solar PV generation is exported to the grid. Solar diverters can utilise this surplus by sensing energy export at the grid connection and seeking zero energy flow by controlling a power electronic component to deliver and regulate power to a resistive water tank heater, thus matching heater power use to surplus power generation. The financial benefit is limited as the value of the heat produced is far lower than the value of the electrical input energy. Indeed, in situations where surplus PV generation can be sold for a similar unit value to heat from fuel combustion, there is no financial benefit. A greater benefit is realised by ensuring appliances that would otherwise use grid electrical power are powered by surplus solar PV generation.

There are a variety of large and time flexible loads in a typical home or business premises that could use surplus PV power, besides resistive water heaters. For example, washing or drying appliances, dehumidifiers, heat pumps & coolers, battery and electric vehicle chargers, kettles, hot tubs, air compressors and space heaters. Solar diverter units of the art have the drawback that the power electronic component and the energy sense and control section that drives it are not separable. This makes controlling multiple loads in different rooms difficult, even where the diverter is capable of controlling multiple loads. The diverter unit is also physically too large to take the form of an inline power plug to socket device and is typically hardwired to the tank heater circuit, close to the utility electric meter. Wireless solar diverter models of the art use a radio link between the current transformer monitoring the grid energy flow and the sense and command electronics that drive the power electronic section, allowing the unit to be located adjacent and hardwired to the hot water tank. This is not a significant advance as this form of wireless link can degrade the energy sensing accuracy, due to latency in the wireless signal or inaccurate voltage measurement. It also does not facilitate plug and play user convenience, mixed multiple load types or multiple loads in different rooms.

SUMMARY OF THE INVENTION

Accordingly, in a preferred form of the invention disclosed herein, there is provided an electrical energy balancing system comprising a transmitter unit and at least one receiver unit, wherein the transmitter unit senses the export of electrical power to an electricity grid and calls for electrical load via a transmitted signal containing at least two data or pulse width modulation (PWM) load channels and wherein the receiver unit is configured to respond to a designated load channel and operate an electrical load, device or appliance, such that the export of power is reduced or eliminated; further wherein each transmitted load channel signifies a load priority relative to the other load channel or channels.

Further wherein the transmitted signal also contains data representing exported grid energy, imported grid energy, grid power and a signal or data input to the transmitter unit from at least one of; a battery state of charge input, an electrical energy unit price input, a temperature sender input and a user defined input.

Further wherein the receiver unit is controlled by a signal transmitted either electromagnetically or electrically through the infrastructure mains wiring by the transmitter unit.

Further wherein the receiver unit controls the power to the load by means of a mains power switching relay or controls the operation of the load by means of a signal switching relay.

Further wherein the receiver unit controls the power to the load by means of a semiconductor power switching component, such as a triac.

Further wherein the receiver unit modulates the power consumed by the load by means of a control signal output and wherein the control signal may be either an industry standard analogue output or may be an output tailored to a communication and control interface used by the load, such as an infra red remote receiver or serial data line or a short range radio signal such as WiFi or Bluetooth.

Further wherein at least two receiver units are used and where each receiver unit can be assigned a priority in its use of exportable electrical power, relative to the other receiver unit or units.

Preferably, the invention provides a range of load control receiver units that can control a wider range of loads, devices and appliances other than but including resistive tank immersion heaters. The ideal loads are large loads that are time flexible and do not have a combustion alternative available. These include but are not limited to; washing or drying appliances, dehumidifiers, heat pumps & coolers, battery and electric vehicle chargers, kettles, hot tubs, air compressors and space heaters.

By moving the wireless link from between the current transformer and load calling electronics in wireless solar diverters of the art, to between the load calling electronics and the load control receiver, multiple load control devices may be located in different rooms.

Further, the load control function can be implemented uniquely by each receiver, in ways that are better suited to the load being controlled. For example, a low cost relay could be used in place of a triac in loads that need to be switched on and left on until a cycle of operation is completed. Some loads do not self start on the application of mains power and instead require a switched signal input, for example infra red, wifi, Bluetooth or a contact closure. Other loads such as heat pumps are not capable of being modulated through control of the mains input but could be modulated for accurate energy balancing by means of an analogue signal input.

Further, any load control receiver could include a timer scheduler or temperature regulation function, allowing the receiver to utilise the thermal mass within a building as part of a heating cost reduction strategy. A range of load control receiver types would allow more loads to be better matched to low cost electrical energy. The load control receivers could be made available in modular form so they may be retrofitted within an appliance by a technician, for appliances that do not respond well to control of their mains input.

BRIEF DESCRIPTION OF THE DRAWINGS

Practicable embodiments of the invention will now be described in further detail, with reference to the accompanying drawings, of which: Figure 1 shows an overview of the wireless solar diverter system Figure 2 shows a sense and command transmitter unit Figure 3 shows four examples of a load control receiver unit

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 shows an overview of the wireless solar diverter system comprising a load calling transmitter unit 21 and four controlled electrical loads 1 to 4 with load control receivers 31 to 34. There is a renewable electricity source 41 such as a solar PV array, coupled to a grid tied inverter 42. The inverter 42 is connected to the grid 10 through the premises mains cables 12, mains distribution unit 13 and the electric utility meter 11.

The loads 1, 2 and 3 are examples of loads that are not easily controlled by solar diverters of the art. This description is by no means an exhaustive illustration of examples.

Load 1 is a washing appliance that does not self start on the application of mains and therefore has a load control receiver 31 retrofitted within the appliance 1 to initiate the wash cycle and control the power to the water heating element of the appliance. The receiver 31 can provide a contact closure and vary the power used by the heating element of the appliance in line with surplus PV generation by a Pulse Width Modulation (PWM) method. The wash cycle of the appliance will naturally allow more time for the programme temperature set point to be reached but is otherwise unaffected.

Load 1 could equally be an electric vehicle home charging point. In this case, the output of the module 31 is an industry standard PWM signal that sets the maximum charging current that can be drawn by the charger of an electric vehicle. In both cases, the module would be retro-fitted within the appliance or charging point by a qualified technician.

Load 2 is an inverter heat pump. Its thermal output can be modulated by an industry standard analogue control input, such as a 0 to 10v or 4 to 20mA DC signal. This is supplied by the receiver 32 via a wired signal input 56. In the case of a split unit heat pump, the receiver 32 may be inserted into the wired communication link between the internal and external units of the heat pump 2, allowing it to intercept and modify the serial data channel controlling the operating speed of the heat pump's compressor. In this way, the power used by the heat pump 2 is matched to surplus PV generation.

Load 3 is an alternative example of a heat pump. The load control method in this case is via the infra red sensor of the appliance. By transmitting the power or temperature control codes 30 normally sent by the unit's hand held remote control, the receiver 33 can achieve indirect control of the power consumption of the appliance 3. This load control method is suitable for any type of appliance capable of being remotely controlled as the receiver 33 can either learn or be programmed to send a correctly coded signal 30.

Load 4 is the immersion heater of a hot water cylinder. The receiver 34 switches power to the heater once a renewable generation energy or power threshold has been passed. The power regulation may alternatively be achieved through PWM control, typical of solar diverter units in the art if receiver type 31 is used as a discrete, in-line unit.

Any of the load control receivers 31 to 34 may be a discrete unit, such as a one piece, mains plug to socket. Equally, any of the load control receivers 31 to 34 could be a module, intended for inclusion within a larger unit, such as the controlled appliance.

The load calling transmitter unit 21 senses energy export from the premises to the grid 10 by means of the current transformer 22 and signal wire 52. The output from the transmitter unit 21 is a transmitted wireless signal 20 that contains at least two data or pulse width modulation (PWM) load channels, alongside data representing measured power and energy flow to the grid 10. Each load channel signifies a load priority relative to the other load channels in the use of surplus power generation. When energy export is first detected, the highest priority channel will transmit a PWM signal to which receiver 31 is assigned, while setting all other channels to be OFF. As the wireless signal 20 is within the negative feedback loop of the transmitter unit 21 and receiver 31, balancing of the load 1 against surplus generation is achieved through PWM. When the surplus generation exceeds the maximum consumption of load 1 or load 1 is not present, the highest priority signal is set to ON and PWM control is passed to the second priority channel to which load control receiver 32 is assigned. This process repeats with the remaining signal channels as solar generation increases, each higher priority channel being set to ON and passing PWM control to the next lower priority channel, until either all surplus generation is used or all load channels are set to ON. In the absence of energy export, all load channels are set to OFF.

The transmitted signal 20 may also carry at least one auxiliary data channel from at least one signal input. The signal inputs can represent the current price of utility power, the state of charge of a battery, the outdoor temperature or any other parameter that can influence the determination of cost effective energy use within the premises. As an example, there is shown an optional solar battery unit 101 and an energy cost monitor 102. The state of charge of the battery unit 101 and the unit cost of electricity data 102 are passed to the transmitter unit 21 via auxiliary data inputs 54 and 53. These inputs are then incorporated within the transmitted signal 20 and relayed to the load control receivers. The receivers 31, 32, 33 and 34 can respond to low rate grid power, a fully charged battery or a very low temperature by enabling the loads 1, 2,3 and 4. The parameters of the receiver response for each auxiliary transmitter input 53, 54 and 55 can be user defined on each receiver.

There is sufficient information within the transmitted signal 20 to allow a wireless energy display unit 35 to be used. This may show the transmitted channel states, grid power and energy imported, exported or diverted as well as the state of the auxiliary inputs 53, 54 and 55 to the transmitter unit 21. The wireless display 35 could also serve as a signal repeater to extend the range of the transmitter 21.

This signalling approach allows programmable flexibility within each of the load control receivers 31 to 34 as to how each of the transmitted load switching channels is implemented. This may be as the received PWM signal or as a latched switch at a preset surplus energy or power threshold or as an analogue output, depending on the receiver type. In addition, the thresholds for each load can be varied or overridden, dependent on how the load control receivers are set to respond to the auxiliary data. Any of the load control receivers 31 to 34 may also include a scheduling programmer or a temperature sensor.

Figure 2 shows the load calling transmitter unit 21 with a mains input 51 and current transformer signal input 52. There are three auxiliary data inputs, 53, 54 and 55. Within the transmitter unit 21 there is an energy meter 23 for tracking the magnitude and direction of both power and energy at the grid connection 10. These values are calculated from the grid current transformer input 52 and the grid voltage input 51. The grid voltage input 51 also provides operating power to the unit 21. The meter 23 provides data to the load caller 24, whose output is at least two load calling channels with a channel priority signified. The three auxiliary data inputs 53,54 and 55 allow user inputs that may be used to determine cost effective energy use within the premises to be forwarded to the load controllers (figure 1, 31 to 34). This user data input could be a grid energy cost input 53, a battery state of charge input 54 or any other user defined input 55. The data generated by the meter 23, load caller 24 and the auxiliary inputs 53, 54 and 55 is packaged into the transmitted signal 20 by the transmitter 25.

Figure 3 shows four examples of the wireless load control receivers, 31, 32, 33 and 34.

Receiver 31 has a solid state triac switched output 61, with load control in the form of a pulse width modulated (PWM) mains output. This is normally implemented as phase angle control or burst fire control of the AC waveform. An alternative form of load control suitable for an electric vehicle charging point could be a pulse with a 1kHz PWM signal output. A signalling relay 62 is also shown and could be connected in parallel with a start button of the appliance.

Receiver 32 outputs an industry standard wired analogue signal output 56 of a form commonly used in heating, ventilation and air conditioning systems, such as a voltage output of 0-5V or a current output of 4-20mA. The output 56 controls the compressor speed and power drawn by a heat pump 2. The signal output 56 could also be used as the control input to a variable frequency motor drive inverter. This could be used as a method for matching refrigeration loads to surplus generation. The analogue signal may be derived by averaging of the transmitted PWM channel, from the transmitted power or energy values or some combination of these.

Receiver 33 has a wireless signal output 30, such as an infra-red LED, WiFi or Bluetooth signal. The receiver 33 also includes a temperature sensor 64 and a programming or scheduling capability 63. This allows the receiver 33 to utilise thermal mass within the premises by directing surplus generation to a heat pump 3, while also performing the temperature control and scheduling function normally performed by the heating system controller. Diverting surplus generation to a heat pump yields typically a threefold gain in thermal output, compared to diversion to a resistance heater.

Receiver 34 has a relay switched output 65. The relay may be configured to latch on at one or more thresholds of low energy cost, battery charge or of exported power or energy. This threshold may be settable at the receiver and compared with the transmitted power and energy values. Similarly, the relay 65 may be configured to latch off at a preset level of battery discharge, high energy cost or imported power or energy. The receiver 34 may provide a switched mains output or a floating contact closure or both.

The energy diversion system described in this system allows for a low cost and versatile approach to renewable energy use. The transmitter 21 requires no power electronic components and this reduces the unit size and cost. It also makes the electrical installation of the unit simple enough that it may be undertaken by a layperson. There is little thermal dissipation requirement for the transmitter 21 and this also facilitates installation of the transmitter 21 in a poorly ventilated space, such as a meter cupboard.

The receiver could be equally compact and low cost if of the relay type, 34. Additional or challenging loads can readily be added to the system at any time without changing the existing installation. Similarly, new features or implementations can be introduced, such as a Time of Use utility rate transmitter 102, a solar battery 101 or a greater load switching capability to cope with an expansion of the self generation capacity 41 and 42, either wind, solar or a micro CHP unit.

By allowing the operation of appliances to be influenced the amount of renewable electricity generation, net building load or electricity unit price, the use of renewable electricity within a premises is maximised and conversely the use of utility power is minimised, particularly at times when electricity unit pricing is high.

In developing the technical features of the energy diverter device described herein, it has also become apparent that it may be possible to control the operation of various appliances such that the grid power consumed changes in response to a change in the utility grid frequency, in order that the energy diverter device may provide a dynamic frequency response service to the utility grid.

The energy diverter concept described in this patent allows for a high degree of flexibility in the method of implementation, installation, the configuration and the mode of operation of the invention. It will be appreciated by the skilled person that the present invention may take many alternative forms without deviating from the scope of this patent.

Claims

Claims 1. An electrical energy balancing system comprising a transmitter unit and at least one receiver unit, wherein the transmitter unit senses the export of electrical power to an electricity grid and calls for electrical load via the transmitted signal containing at least two data or pulse width modulation (PWM) load channels and wherein the receiver unit is configured to respond to a designated load channel and operate an electrical load, device or appliance, such that the export of power is reduced or eliminated; further wherein each transmitted load channel signifies a load priority relative to the other load channel or channels. 2. 3. 4. 5. 6. 7. 8.
A system as claimed in claim 1, wherein the transmitted signal also contains data representing exported grid energy, imported grid energy, grid power and a signal or data input to the transmitter unit from at least one of; a battery state of charge input, an electrical energy unit price input, a temperature sender input and a user defined input.
A system as claimed in claims 1 or 2, wherein the receiver unit is controlled by a signal transmitted either electromagnetically or electrically through the infrastructure mains wiring by the transmitter unit.
A device as claimed in any previous claim, wherein the receiver unit device controls the power to the load by means of a mains power switching relay or controls the operation of the load by means of a signal switching relay.
A device as claimed in any previous claim, wherein the receiver unit device controls the power to the load by means of a semiconductor power switching component, such as a triac.
A device as claimed in any previous claim, wherein the receiver unit device modulates the power consumed by the load by means of a control signal output.
The device of claim 6, wherein the control signal may be an industry standard analogue output.
The device of claim 6, wherein the control signal may be tailored to a communication and control interface used by the load, such as an infra red remote receiver or serial data line or a short range radio signal such as WiFi or Bluetooth.
9. A system as claimed in any previous claim, wherein at least two receiver units are used and where each receiver unit can be assigned a priority in its use of exportable electrical power, relative to the other receiver unit or units.