An Electronic Apparatus for the Optimised Control of the Electrical Power of a Public Lighting System and Operating Method thereof

Technical Field

The present invention relates to an electronic apparatus for controlling the electrical power in a public lighting system, and to the operating method thereof.

Background Art

As is well known, currently existing public lighting systems comprise a plurality of lamps, typically high intensity discharge lamps, which are appropriately distributed over a public area to be lighted, and a main power supply line able to supply the lamps with the electrical power necessary for their operation.

It is also well known that the operation of the public lighting systems described above is based essentially on two types of control: a first control entails regulating the times of supply/interruption of electrical power on the main power supply line in order to vary the time interval in which the lamps are lighted and not lighted according to the season, whereas the second control entails reducing by a predetermined value the electrical power supplied to the lamps starting from a reduction-start instant, which is delayed by a fixed time interval from the instant when the lamp where lighted, i.e. from the instant in which the supply of electrical power on the power supply line starts.

The systems described above have the great drawback that the second control is extremely limited and poorly efficient from the viewpoint of the optimisation of energy saving, in that it carries out a power reduction according to a single reduction profile and by a reduction time interval with a fixed duration, which starts with the same delay from the instant power is initially supplied, regardless of the current season. At each season, the first control changes the time interval of lighting in such a

way as to meet seasonal luminosity requirements, and this variation causes a corresponding translation of the power reduction time interval, which being configurable only for one season is not completely adequate to meet the power and luminosity reduction requirements of the remaining three seasons of the year.

Disclosure of Invention

An object of the present invention therefore is to provide an electronic apparatus that is simple and economical and that allows to regulate in optimal, automatic fashion the electrical power supplied to the lamps of a public lighting system according to the current season.

According to the present invention, an electronic apparatus is obtained as indicated in claim 1 and, preferably, in any one of the subsequent claims, depending directly or indirectly on claim 1.

According to the present invention, a lighting system as indicated in claim 5 and 6 is obtained.

According to the present invention, an operating method of a lighting system is provided as claimed in claim 7 and, preferably, in any one of the subsequent claims, depending directly or indirectly on claim 7.

Brief Description of the Drawings

The present invention shall now be described with reference to the accompanying drawings, which illustrate a non limiting embodiment thereof, in which:

- Figure 1 schematically shows a lighting system obtained according to the teachings of the present invention;

- Figure 2 shows a block diagram of the electronic apparatus included in the lighting system shown in Figure 1 ;

- Figure 3 schematically shows a time interval and a time window associated to the power control implemented by the electronic apparatus shown in Figure 2;

- Figures 4 and 5 show respective power modulation functions in two different seasons of the year.

Description of the Illustrative Embodiment

With reference to Figure 1 , the number 1 globally designates a lighting system, which is able to light a public area, such as a square, a road, or any other type of area of public utility and, unlike known lighting systems, it is capable of modulating the electrical power used for lighting according to each season of the year. hi other words, the present invention is essentially based on the idea of modulating the power supply of the lighting system 1 according to a series of pre-set modulation functions, which are associated to the respective four seasons of the year and whereof each is defined by a determined power variation law.

The lighting system 1 essentially comprises a plurality of lamps 2, e.g. high pressure sodium lamps or any other type of similar high intensity discharge lamp, and a main power supply line 3, which is able to supply the lamps 2 with a predetermined electrical power during a time interval AT ₁ of lighting/shutting down of the lamps 2 (shown in Figures 3, 4 and 5), which is varied by a power supply device 3a connected upstream of the line 3, according to the seasons of the year.

The lighting system 1 further comprises a series of electronic apparatuses 4, each of which is able to determine the current season, as a function of the time interval AT ₁ , to modulate, instant by instant, the electrical power supplied to a corresponding lamp 2 as a function of the current season thus determined.

With reference to Figure 2, each electronic apparatus 4 essentially comprises a PFC (acronym of Power Factor Corrector) module, a power module 6, a detection module 7, a command module 8, and preferably a filtering module 9. hi particular, the PFC module 5 is connected to the power supply line 3 to receive as an input the electrical power supply, and its function is appropriately to regulate the power factor in such a way as to maintain it above a pre-set minimum value, whilst the power module 6 can be constituted by an inverter connected

downstream of the PFC module 5 to receive the electrical power, and it is provided with a series of internal switching circuits (not shown), which are able to modulate the electrical power supplied to a related lamp 2, according to a command signal

ScOM-

With regard to the filtering module 9, it can be preferably defined by a low-pass filter, which is interposed between the power module 6 and the lamp 2 to filter out high frequencies, and eliminate the direct components of the current, potentially harmful to the lamp 2; whilst the detection module 7 can be defined by an electrical measuring circuit, which is connected at the input to the power supply line 3 to output a signal S _RΓV indicating the presence/absence of electrical power (voltage or current) on the power supply line 3.

With reference to Figure 2, the command module 8 receives at its input the signal S _R1V3 and processes it to output the command signal S _COM through which it drives the power module 6 in such a way as to vary the electrical power to be supplied to the lamps 2.

In particular, in the example illustrated in Figure 2, the command module 8 comprises a memory 10 able to store a first table containing a plurality of numeric values defining a first function F _T (AT ₁ ) which enables to determine, for each time interval AT ₁ of lighting/shutting down, a corresponding season of the year; and a processing device 11 , which serves the purpose of determining the time interval AT ₁ as a function of the signal S _RJV , and which is able to implement the first function F _T (AT ₁ ) to determine, on the basis of the calculated time interval AT ₁ , the current season, i.e. the season present at the time of lighting.

The memory 10 further comprises a series of modulation functions Fi(ΔT _l5 t), each of which is associated to a determined season of the year and indicates for each instant t the value of the power to be supplied to the lamps 2. The processing device 11 co-operates with the memory 10 to identify, on the basis of the determined current season, the respective modulation function Fj(ΔT _l3 t) and implements the latter in such a way as to generate the command signal S _CO M which regulates, through the power

module 6, the power supplied to the lamps 2.

Each modulation function Fj(AT ₁ ,t) can provide a power regulation according to a linear or non-linear continuous profile, or according to a non-continuous profile within one or more time windows ATd;, each of which can be placed in any position within the lighting/shutting down time interval AT ₁ .

In particular with reference to Figure 3, the processing device 11 implementing a modulation function Fj(AT ₁ , t) can be able to vary the duration and/or the position of the each time window ΔTd; within the time interval AT ₁ according to the current season. In the specific case, the time window ATd; lies between an initial instant Ti and a final instant Tp and the processing device 11 is able to vary the initial instant T ₁ of the time window ATd; relative to an initial instant T _K of lighting of the lamp 2, according to the determined current season.

Figures 4 and 5 show by way of example to modulation function stored in the memory 10. The first modulation function F ₁ (AT ₁₅ Q shown in Figure 4 is associated to the summer season and it entails, starting from the instant Ti, progressively reducing power to a first predetermined value (e.g., 60% of the nominal value) in a first time window ATd ₁ , maintaining power to the first predetermined reduced value in a second time window ATd ₂ , and progressively increasing power to the nominal value in a third time interval ATd ₃ until the final instant T _F -

In use, the command module 8 receives as an input the signal S _RΓV output by the detection module 7 and processes it to determine the time interval ATj. It should be specified that the command module 8 can be able to calculate and store in the memory 10 the time interval AT ₁ every day, in order to be able to identify, through the first table, during a subsequent lighting the current season according to the time interval AT ₁ calculated and stored the previous day.

At this point the processing device 11 identifies, through the memory 10, the modulation function according to the current season, and proceeds to implement it in order to command instant by instant through the command signal

Sco _M the power module 6, thus varying power according to the implemented modulation function.

The electronic apparatus 4 described above, in addition to being extremely simple to construct and hence economical to manufacture, has the great advantage of being able automatically to regulate electrical power specifically for each season of the year, thereby allowing to configure a suitable luminosity profile for each season, whilst reducing energy consumption with respect to the consumption values measured in the lighting systems that use a same power reduction profile for all seasons.

Lastly, it is clear that the electronic apparatus 4 described herein can be subject to modifications and variants without thereby departing from the scope of the present invention, defined by the accompanying claims.