ENERGY SAVER SYSTEM FOR STREET LIGHTING

FIELD OF THE INVENTION
The present invention relates to a system for saving energy in street lighting. More particularly the present invention relates to a transformer setup that can be implemented during normal and tap changing conditions to avoid transformer burnout. Advantageously the present invention brings about a design for voltage control to eliminate the failure of transformer insulation & burnout.

DESCRIPTION OF THE PRIOR ART:

Conventional set up includes a transformer that is connected in series with load. This transformer is called buck boost transformer. The primary voltage to this transformer is varied using a motorized variac that adjusts the voltage to primary of buck boost transformer depending on required output voltage. The buck boost transformer either boosts the input voltage or bucks the input voltage to maintain the required output voltage. The input voltage is sensed by the electronic control circuit known as the control module. This control module gives signal to the motorized variac to vary the output voltage. The disadvantages of the conventional system includes that in order to vary the output voltage, a motorized variac is used. This reduces the life and reliability of the system due to the limitations of mechanical moving elements of motorized variac.

Moreover, in the conventional system, the street lighting line is switched OFF due to the monetary short circuit of street lighting line for the following conditions, a tree touching street light line due to wind that results in tripping of MCB in the energy saver. Hence the street lights goes off resulting in unsafe condition for the traffic.

The purpose is achieved, in accordance with the invention and it has been proposed heretofore to provide an energy saver in a transformer..

OBJECTS OF THE INVENTION

One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.

The primary object of the present invention is directed to a system for saving energy in street lighting.

It is another object of the present invention to provide a bypass setup for the system.
It is another object of the present invention wherein the bypass setup avoids transformer bum out during normal and tap changing condition.

It is another object of the present invention wherein the system provides single toroidal transformer design for voltage control to eliminate failure of transformer insulation.
It is another object of the present invention wherein the system provides automatic bypass feature during monetary short-circuit.

It is another object of the present invention wherein the buck boost transformer is replaced with a transformer with multiple tappings in primary winding to adjust the output voltage.

It is another object of the present invention wherein, by selecting different tappings in primary winding, the required output voltage is obtained.

It is another object of the present invention wherein to eliminate the induction of high voltage, the primary winding is divided into four individual windings as illustrated in the drawings.

It is another object of the present invention wherein the system provides R1, R2, R3, R4 that are used to energise the particular primary winding.

It is another object of the present invention whereby in case of any short circuit, the electronic control circuit waits for 30 seconds to ensure that it is a monetary short circuit and automatically energizes the bypass contactor.

It is another object of the present invention wherein the system enables the street lights to be re-energized and the automatic bypass feature is achieved.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention there is provided an energy saver system for street lighting -comprising:

a transformer with one or more tappings in primary winding;

a control module;

a bypass contactor;

an energy meter; and

a remote control unit,

wherein said transformer is adapted to be a buck boost transformer to reduce and regulate output voltage,

wherein said control module senses the input voltage and gives the signal to the corresponding relays,

wherein said bypass contactor is connected across secondary winding of said transformer.

wherein contactor poles of said bypass contactor are connected in parallel with said transformer,

wherein said system avoids core saturation and transformer burnout by energizing said bypass contractor to short circuit said secondary winding of transformer during tap changing condition, wherein said secondary winding would no longer acts as inductor,

wherein in order to eliminate the induction of high voltage, the primary winding of said transformer is divided into four individual windings, and

wherein said system is provided for automatic bypass during momentary short circuit.
In accordance with another aspect of the present invention there is provided an energy
saver system for street lighting , wherein said control module has inbuilt memory.

In accordance with another aspect of the present invention there is provided an energy saver system for street lighting, wherein said energy meter continuously monitors the electrical parameters providing for data acquisition of the said parameters.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting, wherein said energy meter is connected and communicates to the control module through MODBUS protocol.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein the data is polled by the said control module for a period of time which is pre defined or user configurable.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting, wherein said relay contacts are connected in series with the
tapping(s) in said primary winding.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting, wherein said system includes mechanical interlock that prevents switching on of said bypass contactor when one or more of said relays are energised.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein said control module performs the following functions:
(a) data acquisition from energy meter;
(b) control of said system through switching elements; and
(c) interaction with the remote control unit.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein said interaction with the remote control unit is by wire or wireless means such as GSM, SMS etc.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein said control module operates in one or more modes that includes:
programmed mode/ save mode; control mode; and calibration mode.
wherein switching to said modes is performed through user commands from said remote unit,
wherein said save mode is a pre-programmed mode with time slot settings for tap changing,
wherein said control mode is an user controllable mode and the full control of said system is done by the user from the remote control unit through commands via GSM, and
wherein said calibration mode has no tap changing or reduction of voltage and is similar to said save mode.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein said control module stores alert configuration in said memory whereby said alerts are available for save and calibration mode.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein in case of high current in save mode, said control module sends alerts to remote control unit and bypasses said system thereby keeping the load undisturbed.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein said commands includes one or more status commands that can be issued from the remote control unit to said control module.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein said commands includes:
(a) Slot timing configuration for ON-OFF - tap changing;
(b) Date and time configuration for the energy saver control module;
(c) List of alerts that are required and the threshold values for the alerts (low and currents, low and voltages, low and power factors); and
(d) Mode.
In accordance with another aspect of the present invention there is provided an energy saver system for street lighting , wherein configuration commands are independent of the mode.
The details of the invention, its objects and advantages are explained hereunder in greater detail in relation to non-limiting exemplary illustrations as per the following accompanying figures:
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Reference will now be made to the several drawings for a more particularized description of the invention. It is to be understood that these drawings must be considered as largely diagrammatic in nature. They are presented here however, for illustrative purposes only and intended to express the operative features of the invention.
Figure 1: is the schematic illustration of the existing system wherein the circuit diagram illustrates a transformer that is varied using motorized variac.
Figure 2: is the illustration of the transformer with multiple tappings in primary winding of the present invention.
Figure 3: is the illustration of the contractor poles that are connected in parallel with transformer secondary of the present invention.
Figure 4: is the illustration that illustrates the division of primary winding into four individual windings of the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES
As already described, the invention relates to a system that saves energy. More particularly the present invention relates to a transformer bypass setup during normal and tap changing conditions to avoid transformer burnout. Advantageously the present invention proposes a design for voltage control to eliminate the failure of transformer insulation.
Attention is now invited to accompanying Figure 1, which illustrates an existing system wherein a transformer is connected in series with load. The transformer is called Buck-Boost transformer whose primary voltage is varied using a motorized variac. The motorized variac adjust the voltage to primary of buck-boost transformer depending on the required output voltage. The Buck-Boost transformer either boosts the input voltage or bucks the input voltage to maintain the required output voltage. The input voltage is sensed by the electronic control circuit known as control module. This control module gives signal to the motorised variac to vary the output voltage. But in the system of Figure 1, in order to vary the output voltage, a motorised variac is used which reduces the life and reliability of the system due to the limitations of mechanical moving elements.
Attention is now invited to Figure 2, which is the illustration of the buck-boost transformer herein referred as transformer with multiple tappings in primary winding of the present invention. The motorised variac is eliminated and the buck -boost transformer is replaced with a transformer with multiple tappings in primary winding to adjust the output voltage. By selecting different tappings in primary winding, the required output voltage is obtained. The voltage obtained by different tappings is shown in the above diagram. The control module senses the input voltage and gives the signal to the corresponding relays Rl, R2, R3, and R4.
These relay contacts are connected in series with the tappings in primary winding. The control module switches these relays and sets the required output voltage as follows,
RELAY OUTPUT VOLTAGE
R\ 215V I
R2 200V
R3 TSSV
R4 170V
The system of Figure 2 has two drawbacks:
(a) Burning of transformer due to core saturation; and
(b) Transformer insulation failure due to high voltage induction.
According to Figure 1, when the unit is connected the secondary of the Buck-Boost transformer acts as an indicator and reduces the output voltage to 150-180 volts. The remaining voltage is dropped in the secondary of transformer which in turn induces very high voltage in the primary of transformer depending on turns ratio. This high voltage saturates the transformer resulting in permanent damage of the transformer causing the following effects,
(i) Due to high primary voltage, the transformer core saturates and draws heavy current leading to the burning of transformer.
(ii) The induced high voltage will damage the control module electronics.
The same problem occurs in the intermediate time taken to switch OFF one relay and switch ON another relay. The solution is implemented in Figure 3.Reference is now invited to Figure 3, wherein a bypass contactor BC is connected across the secondary of the transformer. This contactor poles are connected in parallel with 'buck-boost transformer' herein referred as 'transformer' secondary. During normal operating condition i.e when no tap changing relay is selected the bypass contactor is energized to short circuit the secondary winding of transformer. Hence the problem of core saturation and transformer burning is avoided.
The bypass contactor is energized to short circuit the secondary winding of transformer during tap changing also; hence the secondary winding will no longer acts as inductor. Thus the problem of core saturation and transformer burning is avoided. |
Along with bypass facility, a mechanical interlock feature is incorporated. This interlock prevents the switching ON of bypass contactor when any of the relay R1, R2, R3, R4 is energized. When bypass contactor is energized with any relay in ON condition, a short circuit will be created in the secondary winding of transformer resulting in permanent damage of transformer. The interlock is provided to avoid this problem.
When the unit is connected as per Figure 3, and relay R4 is energized, a high voltage will be induced in the tap 1. The magnitude of this voltage will be around l000v. This high voltage eventually damages the insulation of the transformer which will be rated for 300volts.
The solution is implemented in Figure 4 wherein to eliminate the induction of high voltage, the primary winding is divided into four individual windings. Reference is now invited to Figure 4, wherein the relays Rl, R2, R3 & R4 are used to energize the particular primary winding. All other windings remain isolated from the supply voltage hence the high voltage induction problem is avoided. The combination of relays which are energized to obtain a particular output voltage is tabulated below.
RELAYS OUTPUT
ENERGISED VOLTAGE
R1,R5,R6,R7 2T5V
R2, R6, R7 200V
R3,R7 185V
R4 TTOV
The street lighting line is switched OFF due to the momentary short circuit of street lighting line for the following conditions,
(a) A tree touching street line due to wind.
This results in tripping of MCB in the energy saver. Hence the street lights connected to the energy saver goes off resulting in unsafe condition for the traffic.
Thus in the present system, in case of any short circuit the electronic control circuit waits for 30seconds to ensure that it is a momentary short circuit and automatically energises the bypass contactor. Thus the street lights will be re-energised and Automatic bypass feature is achieved.
The control module in the system of the present invention is the brain of the energy saver. It performs the following major functions:
• Data acquisition from energy meter through MODBUS
• Control of the energy saver through switching elements
• Interaction with the remote control unit via GSM
The data acquisition system is an energy meter which is continuously monitoring the electrical parameters of the energy saver system. The energy meter is connected and communicating to the control module through MODBUS protocol. The data is polled by the control module every 15 seconds.
The control of the present invention relates to a mode machine wherein the system has three modes of operation. The system has three modes of operation as follows,
(a) Programmed Mode/Save Mode
(b) Control Mode
(c) Calibration Mode
Switching to different operating modes is only via user command from the remote control unit.
The save mode /programmed mode is the pre-programmed mode with the time slot settings for tap changing. The system keeps track of the time and as per the programmed schedule switches on the energy saver.
Boot delay/Start-up delay is the time period until which the tap changing or voltage reduction is not allowed by the system after the energy saver is switched ON. This is to ensure that the lighting load gets warmed up and reaches its maximum illumination and the load current settles down.
At the end of the boot delay, the control module sends the ON-message to remote control unit. The ON message is the indication that the energy saver is switched on properly. The reason for sending this message at the end of the boot delay is that the energy saver may send the stabilized electrical parameters in this message if it is sent at the end of the boot delay. '
These parameters are used to evaluate the present number of burning lights by comparing them against the base parameters.
Tap changing is executed by programmed time. During the save mode the system keeps track of the time and if the time matches with the programmed schedule for tap changing, the control module changes to the corresponding tapping of the transformer without disconnecting the load (On-load tap changing) provided the input voltage is within the accepted limits.
Tap changing for input voltage fluctuation is explained wherein the system of the present invention maintains a constant output voltage to the lamps with a threshold of +/- 5V irrespective of the input voltage. This is done by the control module by switching the energy saver to the appropriate voltage tappings. So when the input voltage exceeds or falls below the threshold limit the control module switches to a lower tapping to increase the output voltage or to a higher tapping to decrease the output voltage correspondingly. This is an independent operation from the scheduled tapping time and is performed based on the input voltage level after the boot delay is complete.
The control mode is the user controllable mode and the full control of the system of the present invention is done by the user from the remote control unit through commands via GSM. The user has the control to perform the following apart from the normal user commands available in the save mode.
1. Switch ON
2. Change to the desired tapping/reduce voltage after the boot delay
3. Switch OFF
The normal commands that are available regardless of the mode are explained in the last section of the document.
The calibration mode is much similar to the save/programmed mode except that there will be no tap changing/reduction of voltage to achieve energy savings. This no energy saving mode is just the programmed ON-OFF mode. The tap changing is not done for input voltage fluctuations too.
There are different types of commands. In particular there are two types of status commands that can be issued from the remote control unit to the control module
1. live status
2. programmed status
These two commands are irrespective of the modes and the control module responds to these commands with the latest available status of the energy saver system.
The control module responds to this command by providing the present data from the data acquisition system (here from the energy meter) directly. The live status consists of the values electrical parameters like voltage, current, power, power factor, energy consumed, date and time of the energy saver, ON time of the energy saver on that particular day, error code in case of any prevailing errors. As soon as the control module receives the command from the remote control unit, it acquires the data from the energy meter, formats it and sends it back to the remote control unit.
The program status is the list of configuration done by the user for the functioning of the energy saver in the save/programmed mode. The program status gives the present configuration of the energy saver for the following
(a) Slot timing configuration for ON-OFF - tap changing
(b) Date and time of the energy saver control module
(c) List of alerts configured
(d) Mode
The user configuration commands are also independent of the mode. The following configurations can be done by the user from the remote control unit at any point of operation.
(a) Slot timing configuration for ON-OFF - tap changing
(b) Date and time configuration for the energy saver control module
(c) List of alerts that are required and the threshold values for the alerts (low and currents, low and voltages, low and power factors)
(d) Mode
The four configurations mentioned above are done by using four different commands form the remote control unit.
The control module stores the alert configuration in the memory and it constantly checks for the threshold limits. If the threshold value is met for the alert configured, an independent alert message is sent to the remote control unit stating the error code for the corresponding alert without the initiation/intervention of the remote control unit. The threshold alerts are available only for the save mode and the calibration mode.
An important feature of the alert system is that in case of a trip or a high current during the save mode, the control module in addition to sending the alerts to the remote control unit, bypasses the energy saver unit and the load is kept undisturbed.
Some additional alerts are available irrespective of the mode of the control module. They are
1. real time clock fail alert in case of the clock failure in the control module.
2. communication fail alert in case the control module is not able to acquire data from the control unit.
Autonomous reports for the save mode and the calibration mode corresponds such that, the control module after switching OFF the energy saver as per the programmed schedule, automatically sends a complete energy report for the run time. This report includes the energy consumption and the ON time which are very critical in estimating the energy savings.
Interaction with remote control unit between the remote control unit and the control module of the energy saver is via GSM - SMS. The commands are encoded in a fixed format as short messages that are understood both by the remote control unit and the control module of the energy saver. The control module is programmed to respond to a single remote control unit. It rejects the data from other control units or mobile numbers.

We Claim:

1. An energy saver system for street lighting comprising: a transformer with one or more tappings in primary winding; a control module; a bypass contactor; an energy meter; and a remote control unit,
wherein said transformer is adapted to be an buck boost transformer to reduce and regulate output voltage,
wherein said control module senses the input voltage and gives the signal to the corresponding relays,
wherein said bypass contactor is connected across secondary winding of said transformer,
wherein contactor poles of said bypass contactor are connected in parallel with said transformer,
wherein said system avoids core saturation and transformer burnout by energizing said bypass contractor to short circuit said secondary winding of transformer during tap changing condition, wherein said secondary winding would no longer acts as inductor, wherein in order to eliminate the induction of high voltage, the primary winding of said transformer is divided into four individual windings, and
wherein said system is provided for automatic bypass during momentary short circuit.

2. An energy saver system for street lighting as claimed in claim 1, wherein said control module has inbuilt memory.

3. An energy saver system for street lighting as claimed in anyone of claims 1 and 2, wherein said energy meter continuously monitors the electrical parameters providing for data acquisition of the said parameters.

4. An energy saver system for street lighting as claimed in claims 1 and 3, wherein said energy meter is connected and communicates to the control module through MODBUS protocol.

5. An energy saver system for street lighting as claimed in claims 1, 3 and 4, wherein the data is polled by the said control module for a period of time which is pre defined or user configurable.

6. An energy saver system for street lighting as claimed in claim 1, wherein said relay contacts are connected in series with the tapping(s) in said primary winding.

7. An energy saver system for street lighting as claimed in anyone of claims 1 to 6, wherein said system includes mechanical interlock that prevents switching on of said bypass contactor when one or more of said relays are energised.

8. An energy saver system for street lighting as claimed in anyone of claims 1 to 7, wherein said control module performs the following functions:

(a) data acquisition from energy meter;

(b) control of said system through switching elements; and

(c) interaction with the remote control unit.

9. An energy saver system for street lighting as claimed in claim 8, wherein said interaction with the remote control unit is by wire or wireless means such as GSM, SMS etc.

10. An energy saver system for street lighting as claimed in anyone of claims 1 to 9, wherein said control module operates in one or more modes that include:
programmed mode/ save mode;
control mode; and
calibration mode,
wherein switching to said modes is performed through user commands from said remote unit,
wherein said save mode is a pre-programmed mode with time slot settings for tap changing,
wherein said control mode is an user controllable mode and the full control of said system is done by the user from the remote control unit through commands via GSM, and
wherein said calibration mode has no tap changing or reduction of voltage and is similar to said save mode.

11. An energy saver system for street lighting as claimed in anyone of claims 1 to 10, I wherein said control module stores alert configuration in said memory whereby said alerts are available for save and calibration mode.

12. An energy saver system for street lighting as claimed in anyone of claims 1 to 11, wherein in case of high current in save mode, said control module sends alerts to remote control unit and bypasses said system thereby keeping the load undisturbed.

13. An energy saver system for street lighting as claimed in anyone of claims 1 to 12, wherein said commands includes one or more status commands that can be issued from the remote control unit to said control module.

14. An energy saver system for street lighting as claimed in anyone of claims 1 to 13, wherein said commands includes:

(e) Slot timing configuration for ON-OFF - tap changing;
(f) Date and time configuration for the energy saver control module;
(g) List of alerts that are required and the threshold values for the alerts (low and currents, low and voltages, low and power factors); and
(h) Mode.

15. An energy saver system for street lighting as claimed in anyone of claims 1 to 14, wherein configuration commands are independent of the mode.