Lighting system optimized for cost reduction
A method and corresponding system is disclosed for use in a Networked Lighting Control System whereby communication costs (e.g. costs associated with LTE technologies), variable electric rates and traffic models are analyzed to maximize cost savings. In one example, the system consists of receiving cellular usage rates, electric usage rates, and generated traffic models or statistics to manage transmission and broadcast of usage rates to lighting poles. An apparatus associated with the lighting pole can then use this information to determine frequency of sending lighting commands to nearby poles.
1. A method for use in a light-on-demand system, the system comprising a plurality of lights and utilizing one or more communication protocols, wherein each communication protocol having transmission and network traffic parameters, said method comprising:
receiving, in a server, the transmission and network traffic parameters for communication between the plurality of lights, said transmission and network traffic parameters including movement activity triggers relating to the plurality of lights, and/or communication costs for the one or more communication protocols;
receiving energy usage parameters for the plurality of lights;
deriving a probability density function associated with the movement activity triggers;
estimating an on-time parameter for a light of the plurality of lights based on the probability density function and the energy usage parameters and transmission and network traffic parameters;
determining, after a movement activity trigger in light, whether to transmit a light turn-on command to other lights of the plurality of lights based on an arrival time between the movement activity trigger in the light and a previous movement activity trigger in the light using the on-time parameter.
2. The method of claim 1 further comprising the step of
transmitting to at least one of the plurality of lights, an on-time parameter and a command to turn on.
3. The method of claim 1 wherein the probability density function is estimated based on received movement activity triggers.
4. The method of claim 1 wherein the turn-on time parameter is determined by finding an on-time time parameter that minimizes an expected value cost function (E[C]).
5. The method of claim 4 wherein the expected value cost function (E[C]) is expressed as the following function:
E
[
C
]
=
P
[
t
≥
t
ON
]
·
(
m
+
e
·
t
ON
)
+
∫
t
ON
-
t
min
t
ON
p
(
t
)
·
(
m
+
e
·
t
)
dt
where:
t is Inter-arrival time between two consecutive activity triggers
m is Cost of transmitting a message
e is Cost of energy per unit time
t min is Minimum time that light remains on after activity
t on is Turn-on time parameter
C is Cost of the light consumed per activity trigger
p(t) is Inter-arrival probability density function.
6. A light-on-demand system which utilizes one or more communication protocols for which a cost is associated with at least one protocol; the light-on-demand system comprising:
a plurality of lights; and,
a light management server configured to receive transmission and network traffic parameters for communication between the plurality of lights for communication for the one or more communication protocols, wherein each communication protocol having transmission and network traffic parameters for the one or more communication protocols, said parameters including movement activity triggers relating to the plurality of lights, and/or communication costs for the one or more communication protocols; receiving energy usage parameters for the plurality of lights; energy, derive a probability density function associated with the movement activity triggers; estimate an on-time parameter for a light of the plurality of lights based on the probability density function and the energy usage parameters and transmission and network traffic parameters; determine, after a movement activity trigger in the light in the plurality of lights, whether to transmit a light turn-on command to other lights of the plurality of lights based on an arrival time between the movement activity trigger in the light and a previous movement activity trigger in the light using the on-time parameter.
7. The light-on-demand system of claim 6 wherein the turn-on time parameter is determined by finding an on-time time parameter that minimizes an expected value cost function (E[C]).
8. The light-on-demand system of claim 7 wherein the expected value cost function (E[C]) is expressed as the following function:
E
[
C
]
=
P
[
t
≥
t
ON
]
·
(
m
+
e
·
t
ON
)
+
∫
t
ON
-
t
min
t
ON
p
(
t
)
·
(
m
+
e
·
t
)
dt
where:
t is Inter-arrival time between two consecutive activity triggers
m is Cost of transmitting a message
e is Cost of energy per unit time
t min is Minimum time that light remains on after movement activity trigger
t on is Turn-on time parameter
C is Cost of the light consumed per activity trigger
p(t) is probability density function.