Method and system for controlling a lighting network

Abstract

A controlling of a lighting network based on traffic monitoring comprises steps of determining plurality of coverage areas of set of luminaires, where each luminaire comprises at least one light source. Information related to a presence of users in said coverage areas is received. This may relate both outdoor or indoor areas and activity. A status of at least certain luminaire is then changed to a reserve status, when a last detected user exits the coverage area. Each coverage area or luminaire is providing with an expected value for the time of when the next user is expected to arrive in the coverage area of said luminaire, A set of luminaires [R] of said luminaires with the reserve status to be controlled, such as dimmed, is then defined and information related to demand response requests [D.sub.1, . . . , D.sub.n] of an electric power grid is received. In addition controlling, such as dimming, at least one of said defined set of luminaires in said reserve is performed in order to fulfil said demand response requests at least partially.

Claims

1. A method for controlling a lighting network based on traffic monitoring, wherein the lighting network comprises set of luminaires, and each luminaire comprising at least one light source, wherein the method comprises steps of: determining plurality of coverage areas of the set of luminaires, receiving information related to a presence of users in said coverage areas, wherein the method further comprises steps of changing a status of at least certain luminaire to a reserve status, when a last detected user exits the coverage area of said luminaire, providing for each coverage area of luminaire an expected value for the time of when a next user is expected to arrive in the coverage area of said luminaire, defining a set of at least one luminaire [R] of said at least one luminaire with the reserve status based on said provided expected value, receiving information related to demand response request [D.sub.1, . . . , D.sub.n] of an electric power grid, and controlling the controlling comprises at least dimming, at least one of said defined set of at least one luminaire in said reserve in order to fulfil said demand response request at least partially, when the reserve has capacity over a predetermined level.

2. A method of claim 1, wherein the set of luminaires comprises at least one light source suitable to be controlled frequently and rapidly.

3. A method of claim 1, wherein a maximum level for dimming or the size of the coverage area of said defined set of luminaires in said reserve is determined beforehand.

4. A method of claim 3, wherein said maximum dimming level or the size of the coverage area depends on the time of day, week or year; or location of said coverage areas of the set of luminaires in reserve.

5. A method of claim 1, wherein said set of the luminaires in the reserve [R] is a subset of set of luminaires [L=(l.sub.1, . . . l.sub.n)] in an entire system, whereupon a function Select(R) is defined for providing the element of R with the highest expected value of user arrival time, as well as removing this element from R.

6. A method of claim 5, wherein the function Select(R) is parameterized so that a luminaire can only be selected after a certain delay has expired since the luminaire was last dimmed.

7. A method of claim 1, wherein the method comprises defining a function Accept(R, Di) for determining whether the reserve has capacity over a predetermined level and thereby able to accept the demand response request, and where the controlling is performed when the reserve has capacity over said predetermined level.

8. A method of claim 1, wherein the method comprises brightening luminaires selected in the demand response request Di when the presence of users is detected in the coverage areas of said luminaires; said set of luminaires is brightened at least partly, while other luminaire from the reserve are dimmed at least partly simultaneously to maintain a load shedding required by the demand response action and to avoid creating short term spikes to the electric power grid.

9. A method of claim 1, wherein information of a presence of users in coverage areas indoor or outdoor comprises information of a type of said user, whereupon the maximum diming level or the size of the coverage area is determined based on said type of the user.

10. A method of claim 1, wherein information of a presence of users in said coverage areas comprises: information from detecting sensors of traffic monitoring systems, information of position signals from vehicles or information of position signals from smart phone applications.

11. A method of claim 1, wherein providing said expected value for each luminaire comprises: obtaining it from historical statistical data for that time of day, week and/or year at that location, obtaining it by prediction algorithms using real-time measurements from traffic monitoring systems or obtaining it based on knowledge of the users planned route, such as from navigators in vehicles.

12. A method of claim 1, wherein the method further comprises: defining a sequence of D=(D.sub.1, . . . , D.sub.i) as the sequence of demand response request from the electric power grid, defining a function Power(D.sub.i) for providing a load shedding requirement in [W] for said demand response request Di, defining a sequence of L=(l.sub.1, . . . l.sub.n) as the set of luminaires that is controlled, where each li in L comprises a single luminaire or a group of luminaires that are to be dimmed simultaneously, and defining a function Saving(li) for providing the load shedding in [W] when the luminaire l.sub.i is dimmed.

13. A method of claim 1, wherein the demand response request comprises an economic demand response aiming at energy efficiency goals or emergency demand response aiming rapid load shedding.

14. A method of claim 13, wherein for said emergency demand response at least portion or all luminaires are dimmed to at least predefined minimum level regardless of the traffic situation or beyond the maximum dimming that is permitted in the economic demand response.

15. A method of claim 13, wherein the emergency demand response is continuously calculated based on a total power reduction of the economic demand response request that are currently active and dimming status of all luminaires is considered in real time.

16. A system for controlling a lighting network based on traffic monitoring, wherein the lighting network comprises set of luminaires, and each luminaire comprising at least one light source, wherein the system comprises: a device for determining plurality of coverage areas of the set of luminaires, a device for receiving information related to a presence of users in said coverage areas, wherein the system further comprises a device for changing a status of at least certain luminaire to a reserve status, when a last detected user exits the coverage area of said luminaire, a device for providing for each coverage area or luminaire an expected value for the time of when a next user is expected to arrive in the coverage area of said luminaire, a device for defining a set of luminaires [R] of said luminaires with the reserve status based on said provided expected value, a device for receiving information related to demand response request [D.sub.1, . . . , D.sub.n] of an electric power grid for indicating load shedding requirement, and a controller device for controlling, such as dimming, at least one of said defined set of luminaires in said reserve in order to fulfil said demand response request at least partially, when the reserve has capacity over a predetermined level.

17. A system of claim 16, wherein the set of luminaires comprises at least one light source suitable to be controlled, frequently and rapidly.

18. A system of claim 16, wherein said set of the luminaires in the reserve [R] is a subset of set of luminaires [L=(l.sub.1, . . . l.sub.n)] in an entire system, whereupon a function Select(R) is defined for providing the element of R with the highest expected value of user arrival time, as well as removing this element from R.

19. A system of claim 18, wherein the system is configured to parameterize the function Select(R) so that luminaire can only be selected after a certain delay has expired since the luminaire was last dimmed.

20. A system of claim 16, wherein the system is configured to define a function Accept(R, Di) for determining whether the reserve has capacity over a predetermined level and thereby able to accept the demand response request, and where the controlling is performed when the reserve has capacity over said predetermined level.

21. A system of claim 16, wherein the system comprises a device for brightening luminaires selected in the demand response request Di when the presence of users is detected in the coverage areas of said luminaires indoor or outdoor; said set of luminaires is brightened at least partly, while other luminaire(s) from the reserve are dimmed at least partly simultaneously to maintain a load shedding required by the demand response action and to avoid creating short term spikes to the electric power grid.

22. A system of claim 16, wherein the system is further configured to: define a sequence of D=(D.sub.1, . . . , D.sub.i) as the sequence of demand response request from the electric power grid, define a function Power(D.sub.i) for providing a load shedding requirement in [W] for said demand response request D.sub.i, define a sequence of L=(l.sub.1, . . . l.sub.n) as the set of luminaires that may be controlled, where each l.sub.i in L comprises a single luminaire or a group of luminaires that are to be dimmed simultaneously, and define a function Saving(li) for providing the load shedding in [W] when the luminaire l.sub.i is dimmed.

23. (canceled)

24. A method of claim 2, wherein the light source comprises a LED luminaire suitable to be controlled, comprising dimming.

25. A system of claim 16, wherein the light source comprises a LED luminaire suitable to be controlled, comprising dimming.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Next the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which:

[0035] FIGS. 1-2 illustrate a principle of an exemplary method for controlling a lighting network based on traffic monitoring according to an advantageous embodiment of the invention, and

[0036] FIG. 3 illustrates an exemplary system for controlling a lighting network based on traffic monitoring according to an advantageous embodiment of the invention.

DETAILED DESCRIPTION

[0037] FIGS. 1-2 illustrate a principle of an exemplary method 100, 200 for controlling a lighting network based on traffic monitoring according to an advantageous embodiment of the invention, where in FIG. 1 a main routine 100 and in FIG. 2 manage demand response request routine are described in more details.

[0038] The method exploits the capability of individual LED luminaires to be adjusted frequently and rapidly without adverse impacts on the lifetime of the luminaire. In the method the presence of road users is detected and much more significant dimming is performed when there are no road users in the coverage range of the luminaire. There are several possibilities for performing the detection, including but not limited to: (1) traffic monitoring systems using sensors to detect road users, (2) position signals from vehicles or (3) smart phone applications. When the last road user exits the coverage range of the luminaire, no dimming action is necessarily performed, but the streetlight automation system moves that luminaire into a reserve (which may be maintained in a memory of the system exemplarily described in FIG. 3).

[0039] For each luminaire in the reserve, there is determined an expected value for the time of when the next road user will arrive in its coverage range. This expected value may be obtained in several ways, including but not limited to: (1) from historical statistical data for that time of day, week and year at that location, (2) by sophisticated prediction algorithms using real-time measurements from traffic monitoring systems or (3) based on knowledge of the road users planned route e.g. from navigators in vehicles.

[0040] The sequence D=(D.sub.1, . . . , D.sub.i) is defined as the sequence of demand response requests from the smart power grid. The function Power(D.sub.i) returns the load shedding requirement in [W] for the demand response request D.sub.i. L=(l.sub.1, . . . l.sub.n) is defined as the set of luminaires that may be controlled. Each l.sub.i in L may either be a single luminaire or a group of luminaires that should be dimmed simultaneously; henceforth, the term “luminaire” is used instead of “luminaire or a group of luminaires”. L.sub.i=(l.sub.1, . . . , l.sub.n) is a set of luminaires to be dimmed in to achieve the load shedding request D.sub.i; L.sub.i is a subset of L. The function Saving(l.sub.i) returns the load shedding in [W] when the luminaire l.sub.i is dimmed in a situation when there are no road users in its coverage range. Saving(L.sub.i) returns the load shedding of all luminaires in L.sub.i; |L.sub.i| is used to denote the number of elements in L.sub.i.

[00001]$\mathrm{Saving}.Math..Math.\left(L_i\right)=\underset{i=1}{\overset{.Math.L_i.Math.}{.Math.}}.Math..Math.\mathrm{Saving}.Math..Math.\left(l_i\right)$

[0041] The level of dimming depends on public acceptance, but according to researches, Saving(l.sub.i) could be 60% of the normal operating power of l.sub.i in urban environments; in less densely populated environments a higher percentage of 70-85% is considered acceptable. R is the set of luminaires in the reserve; R is a subset of L. The function Select(R) returns the element of R with the highest expected value of road user arrival time; the function also removes this element from R; the function may be parameterized so that luminaires can only be selected after a delay has expired since it was last dimmed. Finally, a function Accept(R, D.sub.i) determines whether the reserve has sufficient capacity to be able to accept the demand response request; the function can be configured based on historical data. The reason for not depleting the reserve below a certain threshold is to be able to handle situations in which a road user enters the coverage range of a luminaire in L.sub.i. The main routine 100 is shown in FIG. 1.

[0042] In the method 100 the demand response request D.sub.i is waited in step 101, and in step 102 it is determined whether the demand response request can be accepted in view of the function Accept(R, D.sub.i). If the demand response request can't be accepted, the routine moves back to the waiting step 101. Otherwise the demand response request is accepted in step 103 and an empty set L.sub.i is created and Select(R) is added to the L.sub.i in step 104. The Saving(L.sub.i) is compared to Power(D.sub.i) in step 105 to find out whether the load shedding of the luminaires [Saving(L.sub.i)] is greater than or equal to load shedding requirement [Power(D.sub.i)] If this is the case, the routine continues to step 106 to manage demand response requests with parameters D.sub.i and L.sub.i as well as back to the step 101 for waiting demand response requests until the method is ended at step 107, 108. Otherwise [if Saving(L.sub.i)<Power(D.sub.i)] the routine continues the previous steps.

[0043] The main routine 100 forks a thread into the routine 200 “Manage demand response request” described in FIG. 2, where the routine waits events in step 201. This thread will continue until the demand response request is terminated (202, 203, 204) from the grid. If the routine is terminated, all luminaires in L.sub.i are returned to R in step 203 the routine is ended in step 204. Otherwise the function Enter(Li) returns L.sub.j, which is the set of luminaires in L.sub.i with a road user in coverage range in step 205; L.sub.j is a subset of L.sub.i (207) The function Enter(Li) returns null in steps 206 if no road user has entered the coverage range of any luminaire, and the routine continues to step 201 for waiting events. In step 207, the luminaires in L.sub.j are removed from L.sub.i (the set of luminaires participating in the demand response action), so a sufficient number of additional luminaires need to be selected from the reserve R to compensate for the loss. This is accomplished in step 208: Select(R) is added to the L.sub.i. The Saving(L.sub.i) is compared to Power(D.sub.i) in step 209 to find out whether the load shedding of the luminaires [Saving(L.sub.i)] is greater than or equal to load shedding requirement [Power(D.sub.i)]. If this is the case, the routine continues to step 210. Otherwise [if Saving(L.sub.i)<Power(D.sub.i)] the routine continues the previous steps. In step 210 the following actions may be performed: ramping to nominal power of all luminaires in L.sub.j and dimming ramps of all luminaires added to L.sub.i.

[0044] The purpose of the routine is to handle the problem of a road user entering into the coverage range of a luminaire in L.sub.i, in which case that luminaire needs to be ramped to full power, while other luminaire(s) from the reserve need to be dimmed to maintain the load shedding required by the demand response action. The ramping to full power and the dimming ramp(s) are activated advantageously simultaneously to avoid creating short term spikes to the grid.

[0045] FIG. 3 illustrates an exemplary system 300 for controlling a lighting network based on traffic monitoring according to an advantageous embodiment of the invention.

[0046] The components that are installed on each street are explicitly illustrated for street light 301: the brightness of a luminaire 301c is adjusted by a control signal from a microcontroller 301b, which receives information and commands advantageously over the Internet by a wireless transducer 301a, which is used to communicate with a gateway 110a. The gateway has advantageously an Internet connection, and is able to address other systems via the cloud 360. Several street lights in the vicinity of a gateway may use the gateway for Internet access; for example, street lights 301, 302, 303 and 304 use gateway 110a and street lights 311, 312, and 313 use gateway 110b. Only a few gateways and streetlights are illustrated.

[0047] One of the reasons for using gateways instead of having an internet connection on each street light is to limit costs of electronics with internet connectivity and to limit the number of devices connected to the cloud and thus the costs charged by the cloud operator. However, an alternative solution would be to have an Internet connection on each street light. The street light automation server 330 receives traffic sensing information from a traffic monitoring system 350 and demand response requests from the smart electric grid 340 via the cloud 360. The street light automation server 330 runs the algorithms, which are specified in terms of luminaires. Each luminaire l.sub.i in the automation software has a mapping to one or more street light in the system architecture, henceforth referred to as street light i. This mapping includes the IP address of the relevant gateway as well as the address used by the gateway to communicate with the wireless transducer of street light i. The nature of this address depends on the protocol used; a possible and one example protocol is 6lowpan, in which case an IPv6 address is assigned to each street light, and its wireless transducer is an IPv6 device.

[0048] Based on this mapping, whenever the algorithm being run on server 330 issues a command to adjust the brightness of luminaire l.sub.i, this command is transmitted via the relevant gateway to the microcontroller of street light i, which then adjusts the control signal for the luminaire. The algorithms specify commands for starting ramps to adjust the brightness of a luminaire. In one embodiment of the invention, the command to initiate the ramp for luminaire l.sub.i as well as the parameters of the ramp are transmitted from the street light automation server 330 to the microcontroller of street light l, which is then responsible for generating the control signal to the luminaire according to the ramp parameters.

[0049] Another exemplary embodiment of the invention uses the DALI (Digital Addressable Lighting Interface) standard for communications between the gateway and street lights. In this case, the wireless transducer 301a is replaced by a wired connection to the gateway, which acts as a DALI controller.

[0050] The potential of the invention is highest if the size of the reserve is low relative to the total number of luminaires in the system. This can be achieved if the traffic level in the area is stable. Thus the invention has the highest potential when applied to a broad area, preferable to the entire area covered by the distribution grid, which often is an entire city. The minimum size of the reserve can be estimated from statistical data for the area and for the time of day, week and year. Demand response requests from the grid will only be accepted if the minimum reserve can be maintained.

[0051] The main routine 100 above describes the behavior under economic demand response. In the case of emergency demand response, the following additional features apply or may apply (not shown in the Figures). By default the system is in economic demand response mode. If an emergency demand response request is received, the system goes into emergency demand response mode, in which it does not react to economic demand response request, nor does it brighten any luminaires participating in economic demand response requests if such requests are terminated. Rather, the termination events are stored and they are processed only when the system goes back into economic demand response mode, which will happen when no emergency demand response request is active.

[0052] In is to be noted that it is advantageously expected that in most embodiments, only one emergency demand response request may be active at a time. When the emergency demand response mode is entered, for each active economic demand response request Di, all luminaires Li participating in that request are dimmed further in order to shed load. This dimming is done to a predefined level that is considered to meet minimum requirements for traffic safety during grid emergencies. In case the traffic monitoring system is able to distinguish between user types, so that the economic demand response dimming levels are different for each type of user, the said predefined dimming levels for emergency demand response may also be different for different user types. For example, one possible implementation is that for pedestrians the light could be shut down completely, while for vehicles the dimming level is determined in such a way that the change is not so abrupt as to cause danger.

[0053] In the main routine 100, the Accept( ), Select( ), Power( ) and Saving( ) functions have advantageously different parameters in economic and emergency modes, to reflect a greater tolerance for dimming and frequent changes of lighting levels in emergency mode. In the routine 200 “Manage demand response request”, the function Enter( ) may be parameterized differently in the emergency mode. The coverage areas may be smaller and certain user types such as pedestrians or bicycles may be ignored, in case the traffic monitoring system is able to distinguish between user types.

[0054] The invention has been explained above with reference to the aforementioned embodiments, and several advantages of the invention have been demonstrated. Especially it is to be noted that the invention can be applied both with outdoor and indoor solutions, such as for controlling street light systems on the outdoor roads, but also for controlling indoor lighting systems as well for example in offices, shopping centres, exhibition centres or the like.

[0055] It should be noted that the “demand response” refers to and comprises in this document both terms of “economic demand response” as well as “emergency demand response”, if specifically not otherwise stated in the connection with a certain embodiment.

[0056] In addition it should be noted that some embodiments of the invention relate for controlling an outdoor lighting network with the capability to receive information about road users, such as vehicles, bicyclists and pedestrians, in the coverage areas of the luminaires, whereas some embodiments relate for controlling an indoor lighting network with the capability to receive information about users from an occupancy detection system. As a conclusion the method and system and computer program product according to the embodiments described in this document and covered by the scope of the claims can be used for controlling both the outdoor and outdoor lighting networks, correspondingly.