IES20060867A2 - Remote street light energy - Google Patents

Abstract

This invention relates to a street lamp monitoring and control unit (MCU) comprising a central processing unit (CPU), a light detection device, a power supply arranged to deliver power to a lamp, a switch operable by the CPU to control the delivery of power to the lamp and means to communicate with a remote control centre. The MCU further comprises a power meter having means to monitor the power consumption of the lamp. The actual power consumption of a lamp may be accurately monitored and useful information concerning the network may be ascertained which will assist in the management of the lighting network. This invention further relates to a method of monitoring the energy consumption in a lighting network having a plurality of lamps. Energy of one or more lamps may be measured and used as representative samples for the energy consumption of groups of lamps in the lighting network. <Figure 1>

Description

This invention relates to a method and apparatus for monitoring energy consumption in street lamps.

Nowadays, local authorities are becoming much more involved in monitoring their energy usage and in particular with monitoring their energy usage in their lighting network. The lighting network, which essentially comprises the street lights and other public lighting in an area, is probably the single largest consumer of energy in a locality and takes up a substantial part of the local authorities annual budget. Therefore, local authorities are continuously looking for ways of improving their management and control of their lighting networks in order to reduce costs.

In order to manage their expenditure on the lighting network, it is vitally important for the local authority to be able to determine accurately the energy consumption of their lighting network. Not only that, but it is becoming essential for the local authorities to have the ability to segment their lighting network into smaller more manageable components and to determine those areas of their lighting network that are consuming the most energy and those areas where power consumption is relatively low. In this way, the local authority would be able to ascertain those areas of the lighting network where energy consumption is too high and thus allow them to determine the cause of the higher power consumption. In certain circumstances, this information would allow the local authority to determine, for example, that there may be a number of faulty light sensors in a particular area resulting in the street lights remaining on for too long a period and thereby increasing the amount of energy consumed, indicating perhaps that the street lights in a particular area are in need of a service. Similarly, the analysis could show that the energy consumption in one area is relatively low compared to other areas, and perhaps all the light sensors in that particular area need to be adjusted to cause the street lights to fire up at a different ambient light level closer to the remaining street lights in the lighting network. With this information, it would be possible for the local authority to gain greater control over the lighting network while at the same time they may formulate a IE 060 867 -2coherent energy consumption policy for their lighting network and develop a strategy to help them minimise their energy consumption overheads.

Ideally, it would be beneficial to monitor multiple portions of the street lighting network to determine the power consumption characteristics of those individual portions. However, this is not possible with the majority of the known lighting networks. Typically, the only data given to the local authority in relation to their lighting network from the Electricity Supplier is the total energy consumption of the entire lighting network. There is no way for the local authority to determine from that data, the energy consumption of individual parts of the lighting network and therefore the information provided is of little benefit to them if they wish to analyse the lighting network and provide a management strategy for the lighting network.

It is an object of the present invention to provide a method and apparatus for monitoring energy consumption in street lamps that overcomes at least some of these difficulties and that is both relatively simple and cost effective to implement.

Statements of Invention According to the invention there is provided a street lamp monitoring and control unit (MCU) comprising a central processing unit (CPU), a light detection device, a power supply arranged to deliver power to a lamp, a switch operable by the CPU to control the delivery of power from the power supply to the lamp and means to communicate with a remote control centre, characterised in that the MCU further comprises a power meter having means to monitor the power consumption of the lamp.

By having such a street lamp monitoring and control unit, it is possible to monitor the energy consumption of the individual street lamp itself. This was previously not possible. By having a street lamp according to the invention, it is possible to measure the energy consumption of the single lamp and this information may be extrapolated out for all the lamps in the surrounding environment to allow the local authorities determine the approximate energy consumption of a chosen street light or group of street lights. Furthermore, by having such a monitoring and control unit, the local authority is able to retrospectively fit the monitoring and control unit onto an existing lamp post and will not IE 060867 -3have to redesign the entire electricity network in order to carry out meaningful analysis on the network. Preferably, the monitoring and control unit will be able to be fitted retrospectively to one or more of an existing tube ballast, an electronic ballast, a photocell mounted on top of the lantern, an advertising street pole sign and a WIFI, radio or mobile phone transceiver.

In one embodiment of the invention there is provided a street lamp monitoring and control unit in which the means to monitor the power consumption of the lamp further comprises a current sensing device and a voltage sensing device.

In another embodiment of the invention there is provided a street lamp monitoring and control unit in which the current sensing device is one of a current transformer, a Hall Effect sensor and a shunt resistor. These are seen as particularly simple devices to use that are robust and cost efficient to implement.

In a further embodiment of the invention there is provided a street lamp monitoring and control unit in which the voltage sensing device further comprises an attenuator.

In one embodiment of the invention there is provided a street lamp monitoring and control unit in which the power meter further comprises a current filter and a voltage filter. By having the voltage and current filters, it will be possible to more accurately determine the true value of RMS voltage and the true value of RMS current so that the power calculations will be more accurate.

In another embodiment of the invention there is provided a street lamp monitoring and control unit in which the power meter further comprises means to calculate the true RMS values of the voltage and current signals. These will allow for an accurate calculation of the power consumption of the lamp to be obtained.

In a further embodiment of the invention there is provided a street lamp monitoring and control unit in which the power meter further comprises means to perform phase correction on the incoming voltage and current signals.

IE 060867 -4ln one embodiment of the invention there is provided a street lamp monitoring and control unit in which the power meter has means to calculate the true power consumption of the lamp.

In another embodiment of the invention there is provided a street lamp monitoring and control unit in which the power meter further comprises an amplifier.

In a further embodiment of the invention there is provided a street lamp monitoring and control unit in which the CPU has means to store power readings taken from the power meter. In this way, the CPU may store the values until a request for the power reading is received by the MCU from the control centre. Once the request is received, the CPU may then retrieve the appropriate power reading from memory and transmit the data to the control centre.

In one embodiment of the invention there is provided a street lamp monitoring and control unit in which the light detection device further comprises a photocell.

In another embodiment of the invention there is provided a street lamp monitoring and control unit in which there is provided an Analog to Digital Converter (ADC) located intermediate the photocell and the CPU.

In a further embodiment of the invention there is provided a street lamp monitoring and control unit in which the switch further comprises a relay assisted triac (RAT) switch.

In one embodiment of the invention there is provided a street lamp monitoring and control unit as in which the MCU further comprises a power supply unit (PSU) comprising one of a linear PSU having a transformer, diodes and a regulator or a switch mode circuit.

In another embodiment of the invention there is provided a street lamp monitoring and control unit as in which the means to communicate with a remote control centre further comprises a modem. By having a modem, it will be possible for the MCU to transmit the data to a control centre in a remote location and it will not be necessary for maintenance personnel to periodically manually retrieve data from the MCU.

|E 0 60 867 -5In a further embodiment of the invention there is provided a street lamp monitoring and control unit in which the modem is one of a GSM, GPRS, LONWorks, IMS, TCP/IP wireless modem. These are seen as particularly useful for the operation of a wireless modem as the device will not have to be connected to the main telephony network and will be able to have an always on GPRS connection or a one off SMS message over the GSM network if desired.

In one embodiment of the invention there is provided a street lamp monitoring and control unit in which the modem is a wired modem.

In another embodiment of the invention there is provided a street lamp monitoring and control unit in which the street lamp further comprises an infrared link.

In a further embodiment of the invention there is provided a method of monitoring energy consumption of street lamps in a lighting network, the lighting network comprising a control centre and a plurality of street lamps, each of the street lamps comprising a monitoring and control unit (MCU), at least some of the MCUs having a power meter having means to monitor the power consumption of the lamp and means to communicate with the control centre, the method comprising the steps of; dividing the lighting network into a plurality of lighting groups, each lighting group containing one or more street lamps therein and at least one of the street lamps, a reference lamp, in each lighting group having an MCU with a power meter having means to monitor the power consumption of the lamp; measuring the power consumption of the reference lamp and transmitting the power consumption data from the MCU to the control centre; determining the power consumption for the entire lighting group based on the power consumption ofthe reference lamp.

This is seen as a particularly useful method of monitoring the energy consumption of street lights in a street light network. In this way, a single MCU with a power meter is -6IE 0 6 0 661 sufficient as the information from that meter may be extrapolated out for an entire group of street lights surrounding that street light. Therefore, the size of the group may be selected by the person monitoring the group of lights.

In one embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the method comprises the initial step of the control centre sending a power consumption reading request to a reference lamp. In this way, the control centre determines when information is transferred and may obtain information if and when it is needed.

In another embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the steps of sending a power consumption reading request and transmitting the power consumption data from the MCU to the control centre are carried out using an SMS message. This is a particularly simple and cost effective mechanism for sending the information.

In a further embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the steps of sending a power consumption reading request and transmitting the power consumption data from the MCU to the control centre are carried out using GPRS communications. This is seen as useful as the communication channel will always be “on”, thereby allowing communications at any time which is very useful if very frequent monitoring is being carried out.

In one embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the steps of sending a power consumption reading request and transmitting the power consumption data from the MCU to the control centre are carried out using a combination of IMS radio and the Public Switched Telephone Network (PSTN).

In another embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the steps of sending a power consumption reading request and transmitting the power consumption data from the MCU to the control centre are carried out using peer to peer IMS radio communications. 60 86? -7ln a further embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the steps of sending a power consumption reading request and transmitting the power consumption data from the MCU to the control centre are carried out using LONWorks networks.

In one embodiment of the invention there is provided a method of monitoring energy consumption in a lighting network in which the steps of sending a power consumption reading request and transmitting the power consumption data from the MCU to the control centre are carried out using a combination of peer to peer IMS radio communications and LONWorks networks.

Detailed Description of the Invention The invention will now be more clearly understood from the following description of some embodiments thereof, given by way of example only, in which: Figure 1 is a block diagram of a street lamp monitoring and control unit according to the invention; Figure 2 is a diagrammatic view of a monitoring system using SMS communications for command and data transfer; Figure 3 is a diagrammatic view of an alternative monitoring system using GPRS communications for command and data transfer; and Figure 4 is a is a diagrammatic view of another still alternative monitoring system using a combination of IMS radio and the PSTN telephone lines for communication of command and data transfer.

Referring to the drawings and initially to Figure 1 thereof there is shown a street lamp monitoring and control unit (MCU), indicated generally by the reference numeral 1, comprising a central processing unit (CPU) 3 and a power supply 5 arranged to deliver power to a lamp (not shown). A relay assisted triac (RAT) switch 7 is operable by the CPU 3 to control the delivery of power from the power supply 5 to the lamp and the MCU IE 0 60 86 7 -8is provided with means 9 to communicate with a remote control centre (not shown). The MCU further comprises a power meter circuit 11, a current sensing device, provided by way of transformer 13, and a voltage sensing device, provided by way of attenuator 15. In addition to these, there is provided a Power Supply Unit (PSU) 17 to provide a suitable power supply to the individual components of the MCU and a photocell 19 which feeds a signal directly proportional to the light value to the CPU via an Analog to Digital Converter (ADC) 21. The means 9 to communicate with the remote control centre further comprises a wireless modem module 23, suitable for communications using the GSM, IMS, GPRS, G3, TCP/IP or other such protocol, and a wired modem module 25, suitable for communications using the PSTN, Broadband, LONWorks and TCP/IP protocols.

The power circuit meter further comprises amplifiers (not shown) and a circuit (not shown) to allow filtering of the mains voltage and current signals, calculation of true RMS voltages and currents, phase correction and calculation of true power consumption. It is envisaged that various different circuit architectures for carrying out these tasks that are well known in the art could be used for these purposes. A digital device (not shown) is used to carry out the correction and calculation processes.

In use, the metered MCU as shown is placed into a luminaire of a lamp (not shown) in place of the existing MCU. This is a relatively simple operation that may be carried out by a technician and no further additional circuitry is required. In fact, one of the main benefits of the system is the ease with which the power meter may be incorporated into an existing lamp. The old MCU is simply replaced with a new MCU with the device already incorporated therein. The unit will preferably be a sealed unit provided by the supplier of the energy measuring apparatus so that the unit cannot be tampered with to change the energy readings, for example. Once in position, the photocell 19 operates in the known manner and monitors the ambient light around the street light. It sends this light information to the CPU via the ADC 21. When the light value falls below a predetermined minimum amount, the CPU 3 will cause the RAT switch 7 to connect the power supply 5 to the lamp (not shown). This is achieved by first of all ensuring that the triac, which is in parallel with the switch, is conducting before switching the switch. This helps to protect the switch from damage as it does not switch at high loads. Once the lamp is connected to the power supply 5 it will consume power. As the lamp consumes power, the mains voltage is measured using the attenuator 15 and the mains current is IE 0 60 867 -9measured using the transformer 13. These measured values are fed to the power meter circuit 11 which filters the signals, passes them through an amplifier if necessary and then calculates the true power consumption of the lamp. This value is passed to the CPU 3 for storage where it stays until a meter reading request is received from the control centre via one of the modems 23, 25. When a meter reading request is received, the CPU 3 sends the reading to the control centre via the modem. Instead of the power reading, other readings could be sent in its place if desired such as fault data collected by the CPU 3. The value of the power consumption of this lamp may then be used to determine the power consumption for a group of neighbouring street lamps and the power consumption characteristics of a particular area in the street lighting network may be ascertained.

Referring to Figure 2 of the drawings there is shown a system in which the method according to the invention operates. The lighting network, indicated generally by the reference numeral 40, comprises a plurality of street lamps 41 separated into individual groups of street lamps 43, 45, 47 and a control centre, shown here as a mobile telephone 49. At least one of the street lamps in each group of street lamps 43, 45, 47 is a reference street light and this street light has an MCU with an energy meter for calculation of energy in that street lamp. That information is transmitted to the control centre, the mobile telephone 49 by SMS message. Therefore, the system shown is a GSM system and typically the information is sent in response to a request for information from the Control Centre 49, which is also transmitted to the reference street light by way of an SMS message. Of course it will be understood that the invention is not limited to 2 or 3 lights per metered street light and dozens of lights could fall within a particular group monitored using a single metered street light. Furthermore, instead of a mobile phone, the control centre could in fact be a PC with a GSM modem attached but for reasons of simplicity only a mobile phone is shown for this embodiment. It is envisaged that the meter could be provided in an existing tube ballast (not shown) in the lamp column and may include both WIFI and a mobile phone transmitter. Alternatively, the meter could be provided in an advertising sign mounted on the lamp column or formed integrally with the lamp column.

Referring to Figure 3, where like parts have been given the same reference numeral as before, the system in this instance communicates between the control centre and the IE 060 86Ζ - 10reference street lights (those street lights with energy meters) using a GPRS communications channel. Therefore, there is essentially an “always on” channel between the control centre and the reference street light thereby allowing very frequent monitoring to take place. Instead of a mobile phone, the control centre is provided by a PC 51 with a GPRS modem 53. This method is advantageous as it allows for continuous gathering of data and fault reporting to be carried out.

Referring to Figure 4, where like parts have been given the same reference numeral as before, the system in this instance communicates between the control centre and the reference street lights in each group using a combination of IMS radio and the Public Switched Telephone Network communications channel. The control centre comprises a PC 51 and a modem 55. Each of the metered photocells in the reference street lights of the groups 43, 45, 47 further comprises an IMS radio module (not shown) and this module communicates with a counterpart transceiver 57 located a short distance away. The counterpart transceiver 57 is equipped with a PSTN modem allowing data and command transfer over the phone lines 59.

It will be understood that in the embodiments of MCU shown, a transformer is used to calculate the current but it will be understood that as an alternative a shunt resistor could be used instead of the transformer or alternatively a Hall Effect sensor could be used. As an alternative to having the power meter incorporated into the MCU per se, it would also be possible to have the power meter mounted hardwired into the lamp and in communication with the control centre either through independent means or alternatively through the communication means of the MCU.

In this specification the terms “comprise, comprised, comprises and comprising and the terms “include, included, includes and including” are all deemed totally interchangeable and should be afforded the widest possible interpretation.

The invention is in no way limited to the embodiments hereinbefore described but may be varied in both construction and detail within the scope of the claims.

IE 0 60 867

Claims (4)

Claims:

1) A street lamp monitoring and control unit (MCU) comprising a central processing unit (CPU), a light detection device, a power supply arranged to deliver power to 5 a lamp, a switch operable by the CPU to control the delivery of power from the power supply to the lamp and means to communicate with a remote control centre, characterised in that the MCU further comprises a power meter having means to monitor the power consumption of the lamp. 10

2. ) A street lamp monitoring and control unit as claimed in claim 1 in which the means to monitor the power consumption of the lamp further comprises a current sensing device and a voltage sensing device.

3. ) A method of monitoring energy consumption in a lighting network, the lighting 15 network comprising a control centre and a plurality of street lamps, each of the street lamps comprising a monitoring and control unit (MCU), at least some of the MCUs having a power meter having means to monitor the power consumption of the lamp and means to communicate with the control centre, the method comprising the steps of: dividing the lighting network into a plurality of lighting groups, each lighting group containing one or more street lamps therein and at least one of the street lamps, a reference lamp, in each lighting group having an MCU with a power meter having means to monitor the power consumption of the lamp; measuring the power consumption of the reference lamp and transmitting the power consumption data from the MCU to the control centre; determining the power consumption for the entire lighting group based on the 30 power consumption of the reference lamp.

4. ) A street lamp monitoring and control unit (MCU) substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings. IE 0 60 867 - 12A method of monitoring energy consumption in a lighting network substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.