Field of the invention
The present invention relates to a street lighting module allowing monitoring of a proper functioning of a street lighting unit. More specifically, the present invention relates to a street lighting module for a street lighting unit (such as a street light pole) having a connection box in a base part of the street lighting unit, the connection box providing access to a power supply cable connected to a light fixture in an illumination part of the street lighting unit.
In a further aspect, the present invention relates to a method for monitoring a plurality of street lighting units, comprising a street lighting module according to any one of the present invention embodiments. In an even further aspect, the present invention relates to a system for monitoring a plurality of street lighting units, comprising a plurality of street lighting modules according to any one of the present invention embodiments, and a server arranged to communicate with the plurality of street lighting modules, and to execute the present invention method embodiments.
Background art
Presently, the proper functioning of most street lighting poles is monitored by surveying activities by government officials, or by receiving malfunction reports from local citizens. This requires a lot of effort in time, and is not very reliable as all street lighting poles under control of a specific government body can never be inspected in a short period of time.
Furthermore, smart street lighting is developed, where the illumination provided by (groups of) street lighting poles can be controlled and monitored in a dynamic manner. This, however, usually requires replacement of an entire street lighting fixture or the major components in the fixture, which is a costly and time consuming activity that also disrupts traffic.
Summary of the invention
The present invention seeks to provide a reliable, functional and compact device for monitoring the proper functioning of any street light point regardless of its light source and power supply equipment.
According to the present invention, a street lighting module as defined above is provided, wherein the street lighting module comprises a processing unit, sensing circuitry connected to the processing unit and communication circuitry connected to the processing unit. The sensing circuitry is arranged to measure a current supplied to the light fixture via the power supply cable, and the processing unit is arranged to transmit a health status message associated with the street lighting unit by means of the communication circuitry. Measuring and relaying the current use of an individual street lighting unit to a remote centralized monitoring place using the present invention street lighting module, allows to implement a cost-effective, reliable and low threshold alternative to a live monitoring implementation.
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In a further aspect of the present invention, a method of the type as defined above is provided, the method comprising determining a power consumption value of a specific one of the plurality of street lighting units from the data in the health status message, and generating a warning message if the power consumption deviates from a set value (e.g. 5W) by more than a predetermined threshold value. Alternatively or additionally, a warning message may be generated only after multiple threshold crossings. This method allows to provide a cost-effective, reliable and very efficient (remote) monitoring of street lighting units, wherein only limited investment is needed for manufacturing and installation of the associated street lighting modules.
Short description of drawings
The present invention will be discussed in more detail below, with reference to the attached drawings, in which
Fig. 1 shows a schematic view of a street lighting unit in which the present invention embodiments can be applied;
Fig. 2 shows a schematic diagram of a street lighting module according to an embodiment of the present invention; and
Fig. 3 shows a schematic system view of an embodiment of the present invention.
Description of embodiments
The present invention embodiments relate to a street lighting module which can be advantageously applied for monitoring a large number of street lighting units, e.g. street lighting poles and otherwise mounted light fixtures which are positioned at or near the side of a roadway for illuminating the roadway. The present invention embodiments can be applied for monitoring all noncontrolled street lighting units, and also for street lighting units that are possibly equipped with local dimmers.
A schematic view of such a street lighting unit 1 is shown in a schematic view of Fig. 1. The street lighting unit 1 is embodied as a lamppost with a vertically positioned pole 2, and a lighting fixture 3 at the top end of the pole 2. A connection box 8 is provided in a base part of the pole 2 of the street lighting unit 1, which connection box 8 is providing access to a primary power supply cable 7 connected to a buried cable 9 of the utility services. Normally, the cable 9 of the utility service provides a 230 Vac power supply capability. In the connection box 8, the primary power supply cable 7 is connected to a fixture cable 6, e.g. via a fuse or simple connection components. The light fixture 3 in the illumination part of the street lighting unit 1 comprises the actual light source 5, e.g. a LED, incandescent or discharge lamp, which is connected to the light fixture cable 6 (possibly via a ballast 4 or other light source power conditioning unit 4). It is noted that street lighting units 1 can have many further shapes and structural embodiments besides the pole implementation as shown in Fig. 1, but normally there will be a type of connection box 8 for a street lighting unit 1 or a number of street lighting units 1, which connection box 8 is easily accessible for inspection or maintenance personnel from the street. The present invention embodiments as discussed below
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2016.09.27 can be cost-effectively employed and used in any of such street lighting unit 1 implementation with an accessible connection box 8.
In a first embodiment, the present invention relates to a street lighting module 10 for a street lighting unit 1 having a connection box 8 in a base part of the street lighting unit 1, the connection box 8 providing access to a power supply cable 6, 7 connected to an light fixture 3 in an illumination part of the street lighting unit 1. As shown in the schematic diagram of Fig, 2, the street lighting module 10 comprises a processing unit 12, sensing circuitry 14 connected to the processing unit 12 and communication circuitry 16 connected to the processing unit 12. The sensing circuitry 14 is arranged to measure a current supplied to the light fixture 3 via the power supply cable 6, 7, and the processing unit 12 is arranged to transmit a health status message associated with the street lighting unit 1 by means of the communication circuitry 16. The health status message may include an identification of the street lighting module 10 (and thus of the specific street lighting unit 1).
The sensing circuitry 14 is e.g. arranged to clamp around one phase of the power supply cable 7, 8, i.e. it uses contactless sensing for sensing and measuring the current through the power cable 6, 7 to the light fixture 3.
The street lighting module 10 can be arranged to measure the data needed to determine the health of a particular street lighting unit 1 (and send the health status message) several times (e.g. 2-8) per night, when electrical power is available from the cable 9 from the utility provider. The moments can e.g. be limited to one at the start and one at the end of a night period. The night period can be detected using the presence or absence of power on the primary power supply cable 7. Alternatively, a separate (light) detector or a real time clock 15 may be used.
Such a street lighting module 10 can easily be installed in the connection box 8 of the street lighting unit 1, without any need to use any complex and expensive equipment to reach the light fixture 3. Advantageously, the dimensions of the street lighting module 10 are adapted to fit most of the (connection box 8 of) presently used street lighting units 1. The street lighting module 10 is e.g. embodied in a housing having dimensions of less than 30 x 40 x 75 mm.
In a further embodiment, the processing unit 12 is further arranged to include additional data in the health status message. The additional data, may include, but is not limited to, an identification code (ID), measurement and time data, calculated power consumption, etc. To that end, the processing unit 12 is e.g. connected to a memory module 13, and optionally to a clock module 15, e.g. a real time clock.
As shown in the schematic diagram of Fig. 2, the communication circuitry 16 is connected to an appropriate antenna 17, which allows the street lighting module 10 to transmit the health status message to a proper receiver which is remotely located from the street lighting unit 1. In a specific embodiment, the communication circuitry 16 comprises a low data rate communication unit, as the health status message can be of limited data size, and is not transmitted very frequently. E.g. the communication circuitry 16 is a unit operating in accordance with the LoRa standard, which is a long range, low power radio transmission standard which allows data exchange of low volumes of data with a very low power consumption. As a LoRa communication uses the 868 MHz frequency band, there will be no interference from presently often used communication standards in urban
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2016.09.27 and rural areas, such as WiFi, Bluetooth, and other IEEE 802 types of (often high data rate) communication standards. In further alternative embodiments, the communication circuitry 16 may anyway be implemented according to one of these standards, e.g. to advantageously utilize the easy and cost-effective availability of such radio modules.
The embodiment of the street lighting module 10 as shown in Fig. 2 is also provided with a local power supply unit 18, which is arranged to provide operating power to the street lighting module components (processing unit 12, sensor circuitry 14 and communication circuitry 16. The local power supply unit 18 may simply interface with the primary power supply cable 7, and adapt the provided (often 230 Vac) voltage to a voltage suitable for use in the street lighting module 10.
In a further embodiment the local powersupply unit 18 comprises an energy storing element 19, such as a battery or capacitor. This would allow the street lighting module 10 to operate also when the cable 9 of the utility provider is not energized, and the voltage on the primary power supply cable 7 is zero.
Alternatively or additionally, the local power supply unit 18 comprises an energy harvesting unit, which allows to obtain and store electrical energy from outside of the street lighting module 10. The energy harvesting unit can be one or more of: an induction based energy harvesting unit, a photovoltaic module based energy harvesting unit, a wind energy based energy harvesting unit. When using an induction based energy harvesting embodiment of the local power supply unit 18, the street lighting module 10 can be installed easily in the street lighting unit 1 by simply placing the street lighting module 10 in the vicinity of the power cable 6, 7 in the connection box 8. Once the power cable 6, 7 is energized, the local power supply unit 18 can then harvest and store electrical power.
In a further, alternative embodiment, the street lighting module 10 further comprises a primary terminal connection and a secondary terminal connection, which are connectable to the power supply cable 6, 7. E.g. the primary terminal connection can be connected to the primary power supply cable 7, and the secondary terminal connection to the light fixture cable 6. The street lighting module 10 is then connected in between the primary power cable 7 and the light fixture cable 6, similar to the sometimes present fuse.
In this embodiment, the sensing circuitry 14 may be further arranged to measure a voltage over the secondary terminal connection. This would allow more, alternative and more complex measurements by the street lighting module 10, which measurement data may then be processed by the processing unit 12 to be included in the health status message.
In a further aspect, the present invention relates to a method for monitoring a plurality of street lighting units 1 which comprise a street lighting module 10 according to any one of the present invention embodiments. The method then comprises determining a power consumption value of a specific one of the plurality of street lighting units 1 from the data in the health status message, and generating a warning message if the power consumption deviates from a set value (e.g. 5W) by more than a predetermined threshold value. The predetermined threshold value may also be selected as a signed deviation threshold, such that a warning message is created if the power consumption is below the set value. This method allows to provide a reliable and cost-effective
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2016.09.27 monitoring of a large number of street lighting units 1 in a geographical area, reducing the need of ‘live’ inspections on site, and without needing complex and costly modifications or replacement of the existing street lighting units 1. As an example, the health status message is created and sent if a current is measured which exceeds the maximum possible current for the respective light source 5 in the street lighting unit 1: a current that high would definitely indicate a malfunction such as a short or a current leakage in that specific street lighting unit 1.
The method may alternatively comprise that a warning message is only generated if more than x (consecutive) measurements are detected with such a deviation. This will reduce the number of false warning messages that are created.
In a further embodiment, determining the power consumption value is executed using a measured current value and a pre-set operating voltage associated with the respective street lighting unit. This is especially useful if an embodiment of the street lighting module 10 is used, which is only able to measure the current flowing in the power cable 6, 7 in a non-contact manner (as then no voltage can be measured). From such a measured parameter as the current flowing to an individual light fixture 3 of a street lighting unit 1, it is possible to derive relevant data for logistic purposes. E.g. it is known that for certain types of light source 5, the current consumed rises substantially (20-25%) when the light source 5 is nearing its end of operational life time, also it is possible to e.g. check whether a further component of the light fixture 3 is operating properly.
A health status is determined of cable sections 9 between the plurality of street lighting units 1 from the data in the received health messages in a further embodiment. E.g. when no power use is measured in a number of adjacent street lighting units 1 (often connected to the same phase of cable 9 of the utility provider), it can be deduced that a fault is present in the cable 9, and appropriate action can be initiated. Such an analysis may also be executed for determining whether or not an entire group of street lighting units 1 is not functioning properly, or even that one phase of a power supply of the utility provider is not providing power to the connected street lighting units 1.
In addition, or alternatively, a health status is determined of one or more components of the street lighting unit 1 using data from the received health message, i.e. of the entire light fixture 3, the ballast 4 or the light source 5. This also allows to determine which actions are appropriate, and would allow scheduling of the needed repair resources. E.g. in some types of street lighting units 1, the life time of a light source 5 is prolonged by using a duty cycle in the light source power conditioning unit 4 (e.g. 80%). If an actual current use is measured which is higher than the maximum of the light source 5 taking into account the duty cycle, it may be deduced that the light source power conditioning unit 4 is malfunctioning and needs to be replaced.
Further complex embodiments of the present invention method comprise that the data from the health status messages is stored, and executing trend analyses using the stored data. This would allow to monitor the street lighting unit 1 components consistently, and even allow to predict if and when one or more of the components might fail, and take precautionary actions to prevent actual failure. Furthermore, the historic data may also be used to analyse the quality and performance (e.g. actual life span versus offered life span) of one of the components of the street lighting units 1, or of the combination of components. By combining data concerning the current
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Fig. 3 shows a schematic view of an entire system for monitoring street lighting units. As shown, a plurality of street lighting modules 10 are present, which street lighting module 10 may be any one of the embodiments described above. Furthermore, a server 20 is present which is arranged to communicate with the plurality of street lighting modules 10, and to execute the method according to any one of the method embodiments described herein. This allows to implement a cost-efficient and reliable monitoring system for managing and controlling a large number of street lighting units, e.g. in an entire city. The monitoring system can be coupled to further systems, such as maintenance scheduling and personnel dispatching systems, to fully automate the logistic handling of a large group of street lighting units 1. This may e.g. be implemented using an Internet connection or other wide area network connection of the server 20.
In an even further embodiment (as actually shown in Fig. 3), the system further comprises one or more gateways 21, wherein each of the one or more gateways 21 is located within communication range of a subset of the plurality of street lighting modules 10, and the one or more gateways 21 are in operative communication with the server 20. This would allow to efficiently monitor a very large area with street lighting units 1, wherein the street lighting units 1 and gateways 21 are grouped for most efficient and reliable data communication (e.g. using the LoRa embodiments of the communication circuitry 16). The gateways 21 can then be arranged to efficiently and robustly communicate with the server 20, e.g. using WiFi or even wired communication connections.
Furthermore, analysing the data received (or not received) in the health status messages from the various street lighting modules 10 can also provide relevant information on how the communication interfaces (between street lighting modules 10 and gateways 21, and between gateways 21 and server 20) are functioning, and pinpoint any possible problems. For this, the processing unit 12 of the street lighting module 10 may be arranged to send e.g. at least one health status message to the server 20, even if no abnormal functioning of the associated street lighting unit 1 is detected. The at least one health status message may then be interpreted as a node status of the associated street lighting module 10, indicating proper functioning of the communication circuitry 16 of the street lighting module 10 to the server 20. Combined analysis of all related data (thus including whether a specific street lighting module 10 is on-line or off-line) in the server 20 can then provide an indication of the type of malfunction in the power supply network (cables 9 of the utility provider). If taking the geographical locations of individual street lighting units 1 (in combination with the identification of each associated street lighting module 10) into account, the combined status of neighbouring street lighting units 1 can be used to diagnose the proper functioning of the communication network (LoRa) to the gateways 21.
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The present invention embodiments may be summarized in a number of interrelated embodiment descriptions:
Embodiment 1. Street lighting module for a street lighting unit (1) having a connection box (8) in a base part of the street lighting unit (1), the connection box (8) providing access to a power supply cable (7) connected to a light fixture (3) in an illumination part of the street lighting unit (1), the street lighting module (10) comprising a processing unit (12), sensing circuitry (14) connected to the processing unit (12) and communication circuitry (16) connected to the processing unit (12), wherein the sensing circuitry (14) is arranged to measure a current supplied to the light fixture (3) via the power supply cable (7), wherein the processing unit (12) is arranged to transmit a health status message associated with the street lighting unit (1) by means of the communication circuitry (16).
Embodiment 2. Street lighting module according to embodiment 1, wherein the processing unit (12) is further arranged to include additional data in the health status message.
Embodiment 3. Street lighting module according to embodiment 1 or 2, wherein the communication circuitry (16) comprises a low data rate communication unit.
Embodiment 4. Street lighting module according to anyone of embodiments 1-3, wherein the street lighting module (10) further comprises a local power supply unit (18), arranged to provide operating power to the street lighting module components.
Embodiment 5. Street lighting module according to embodiment 4, wherein the local power supply unit (18) comprises an energy storing element (19).
Embodiment 6. Street lighting module according to embodiment 4 or 5, wherein the local power supply unit (18) comprises an energy harvesting unit, the energy harvesting unit is one or more of: an induction based energy harvesting unit, a photovoltaic module based energy harvesting unit, a wind energy based energy harvesting unit.
Embodiment 7. Street lighting module according to anyone of embodiments 1-6, wherein the street lighting module (10) further comprises a primary terminal connection and a secondary terminal connection, which are connectable to the power supply cable (7).
Embodiment 8. Street lighting module according to embodiment 7, wherein the sensing circuitry (14) is further arranged to measure a voltage over the secondary terminal connection.
Embodiment 9. Method for monitoring a plurality of street lighting units (1) comprising a street lighting module (10) according to any one of embodiments 1-8, comprising determining a power consumption value of a specific one of the plurality of street lighting units (1) from the data in the health status message, and generating a warning message if the power consumption value deviates from a set value by more than a predetermined threshold value.
Embodiment 10. Method according to embodiment 9, wherein determining the power consumption value is executed using a measured current value and a pre-set operating voltage associated with the respective street lighting unit (1).
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Embodiment 11. Method according to embodiment 9 or 10, wherein a health status is determined of cable sections between the plurality of street lighting units (1) from the data in the received health status messages.
Embodiment 12. Method according to any one of embodiments 9-11, wherein a health status is determined of one or more components of the street lighting unit using data from the received health status message.
Embodiment 13. Method according to any one of embodiments 9-12, wherein the data from the health status messages is stored, the method further comprising executing trend analyses using the stored data.
Embodiment 14. System for monitoring a plurality of street lighting units, comprising a plurality of street lighting modules (10) according to any one of embodiments 1-8, and a server (20) arranged to communicate with the plurality of street lighting modules (10), and to execute the method according to any one of embodiments 9-13.
Embodiment 15. System according to embodiment 14, further comprising one or more gateways (21), wherein each of the one or more gateways (21) is located within communication range of a subset of the plurality of street lighting modules (10), and the one or more gateways (21) are in operative communication with the server (20).
The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.
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