FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A system for efficient load management of a VSIG system with a ' compromised battery supply
APPLICANTS (S)
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S)
Wachasundar Shripad, Hassan Hafiz Imtiaz and Saha Raja; all of Crompton Greaves Limited, Electronics Design Centre, CG Global R&D Centre, Kanjur Marg (East), Mumbai 400042, Maharashtra, India ; all Indian Nationals.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to the field of electrical and electronics engineering.
Particularly, this invention relates to a system for efficient load management of a VSIG system with a compromised battery supply.
BACKGROUND OF THE INVENTION
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge (usually carried by electrons) to flow through an external electrical circuit. The use of generators in various applications is common. Most of these generators operate at fixed frequency and are directly connected to a load.
Generators are used to supply electrical power in places where utility (central station) power is not available, or where power is needed only temporarily. Currently, generators typically include engines connected directly to generators to produce electricity. In some cases the generators are permanently installed and kept ready to supply power to critical loads during temporary interruptions of the utility power supply.
However, loads may be varying loads. Hence, variable-speed-integrated-generators (VSIG) came into picture. Typically, a VSIG system consists of a diesel engine, a permanent magnet generator and a power converter. A control mechanism attempts to determine the load and vary the drive frequency of the VSIG system to that effect to cater to the load. Accurate mapping of load and VSIG system is

incumbent in order to achieve a good working system. Moreover, variable speed operation is preferred in order to facilitate optimum characteristics over a wide range of operation.
A VSIG may be used to improve the efficiency of the system. Other advantages of VSIGs are reduced fuel consumption, reduced noise, prolonged engine life, and reduced emissions. Ideally, in VSIG (Variable Speed Integrated Generator) system, increment of load is catered by a battery for a momentary period, until generator speed is not increased to a particular limit where the generator can deliver the required power to load. But it may happen in field that the battery is disconnected (for maintenance) or battery is in full discharged condition. Transferring the load to battery will not be fruitful at this time. The amount of load increment also cannot be found out correctly where there is no battery as the generator cannot cater the required amount of power instantly due to high inertia. Hence, load variations are not reflected with change in drive frequency of a VSIG system.
The obvious case or methodology of the VSIG system, in such cases of battery failure and load change, is to set the generator speed at maximum and then to calculate the amount of power required for setting the desired speed. But this is not an optimized technique as the generator would be running at relatively higher speed (maximum speed, hence consumption of high amount of fuel) than the required speed for a certain duration (before coming down to desired speed), which completely destroys the utility of the VSIG system.
Hence, there is a need for a system which obviates the limitations of the prior art.

OBJECTS OF THE INVENTION
An object of the invention is to provide a system for variable speed integrated generators (VSIG) to achieve efficient load management characteristics without battery in VSIG.
Another object of the invention is to provide a system which caters to changes in load by achieving changes in drive of VSIG in a relatively lesser time.
Yet another object of the invention is to provide a system which caters to changes in load, in the absence of battery, by achieving changes in drive of VSIG in a relatively lesser time.
Still another object of the invention is to provide a system which improves transient response time in drive of VSIG in a relatively lesser time.
An additional object of the invention is to provide a system, in the absence of battery, which improves transient response time in drive of VSIG in a relatively lesser time.
Yet an additional object of the invention is to provide a VSIG system, in the absence of battery, which handles load increment when no battery is connected or battery is in unhealthy condition.
Still an additional object of the invention is to provide a VSIG system with low fuel consumption.

Another additional object of the invention is to provide a VSIG system which preserves efficiency.
SUMMARY OF THE INVENTION
According to this invention, there is provided a system for efficient load management of a VSIG system with a compromised battery supply, said system comprises:
a control module adapted to sense change in load and further adapted to provide control signals to control drive of a generator of said VSIG system in accordance with change in load, said control module being adapted to provide control signals based on determination and calculation of Total Harmonic Distortion parameter values,
Typically, said control module comprises an input means adapted to allow input of reference / threshold Total Harmonic Distortion (THD) parameter value(s).
Typically, said control module comprises an input means adapted to allow input of reference / threshold Total Harmonic Distortion (THD) parameter value(s), said reference or threshold THD values being determined at maximum load and / or at maximum speed.
Typically, said control module comprises a load determination means adapted to determine change in load.
Typically, said control module comprises a load determination means adapted to determine change in load, said change in load being reflected as a trigger to said control module in order to achieve change in drive or speed of said generator.

Typically, said control module comprises an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means adapted to determine instantaneous THD parameter values.
Typically, said control module comprises an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means adapted to sense instantaneous THD parameter values, said sensing done at the output of a permanent magnet generator.
Typically, said control module comprises an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means, said sensing means being a FFT based sensing means adapted to obtain FFT based Total Harmonic Distortion (THD) parameter value(s).
Typically, said control module comprises a processing means adapted to compare instantaneous THD parameter value(s) with reference or threshold THD parameter value(s) and further adapted to provide control signals for changing drive of generator in relation to compared output.
Preferably, said control module comprises a processing means adapted to compare instantaneous THD parameter value(s) with reference or threshold THD parameter value(s) within a 10% tolerance range and further adapted to provide control signals for changing drive of generator in relation to compared output.
According to this invention, there is also provided a method for efficient load management of a VSIG system with a compromised battery supply, said method comprises the steps of:

a. defining reference / threshold Total Harmonic Distortion (THD) parameter
value(s);
b. determining load change;
c. determining instantaneous reference / threshold Total Harmonic Distortion
(THD) parameter value(s);
d. determining if instantaneous reference / threshold Total Harmonic Distortion
(THD) parameter value(s) is within pre-determined conditions of reference /
threshold Total Harmonic Distortion (THD) parameter value(s); and
e. changing speed of said generator, accordingly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates a schematic of a VSIG (Variable Speed Integrated Generator) system of the prior art.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 2 illustrates a schematic of a VSIG (Variable Speed Integrated Generator) system, in accordance with this invention;
Figure 3 illustrates a flowchart of the control module of the VSIG system of Figure 2; and
Figure 4 illustrates a time response chart of the VSIG system of the prior art in comparison to the VSIG system of the current invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates a schematic of a VSIG (Variable Speed Integrated Generator) system of the prior art.
A generator (typically, a diesel generator) is represented by reference numeral DG. A permanent magnet generator (PMG), in-line, is driven by the generator (DG). Output from the permanent magnet generator (PMG) is given to a Variable Speed Integrated Generator (VSIG) before being given to a load (L). A battery (B) provides backup power supply. The Variable Speed Integrated Generator (VSIG) is adapts to the load and provides a drive output commensurate with the load. Changes in the load leads in operating the generator (DG) to a maximum speed or drive or frequency of operation, until the Variable Speed Integrated Generator (VSIG) gauges the (change in) load and varies the operating speed of the generator (DG) to that effect. This is reflected in Figure 2 by the solid line curve. Maximum speed is attained for a time period before optimum operating speed is achieved. This results in wastage of time as well as fuel. Generally, battery (B) back-up is provided in order to cater to change in load by allowing variations (rise) in speed or drive of the generator (DG). However, in battery fail or unhealthy condition, the Variable Speed Integrated Generator (VSIG) is not able to immediately cater to change in load.
According to this invention, there is provided a system for efficient load management of a VSIG system with a compromised battery supply.
Figure 2 illustrates a schematic of a VSIG (Variable Speed Integrated Generator) system, in accordance with this invention.

In accordance with an embodiment of this invention, there is provided a control module (100) adapted to sense change in load and further adapted to provide control signals to control drive of a generator in accordance with change in load in a relatively shorter span of time, and without making the generator reach maximum speed. This control module enables the Variable Speed Integrated Generator (VSIG) to operate in battery fail or in battery unhealthy condition.
In accordance with another embodiment of this invention, the control module (100) comprises an input means adapted to allow input of reference Total Harmonic Distortion (THD) parameter value(s). Typically, reference or threshold THD values are determined at maximum load and / or at maximum speed. This may be the threshold THD value(s).
In accordance with yet another embodiment of this invention, the control module (100) comprises a load determination means adapted to determine change in load. Change in load may be reflected as a trigger to the control module (100) in order to achieve change in drive or speed of the generator.
In accordance with yet another embodiment of this invention, the control module (100) comprises an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means adapted to determine instantaneous THD values. Typically, this is done at the output of the permanent magnet generator (PMG). The sensing means is a FFT bases sensing means adapted to obtain FFT based Total Harmonic Distortion (THD) parameter value(s).
In accordance with still another embodiment of this invention, the control module comprises a processing means adapted to compare instantaneous THD parameter value(s) with reference or threshold THD parameter value(s). If the compared

output is in breach of defined rules, then control signals for changing drive of generator is provided. Typically, the instantaneous THD parameter value should be within 10% of the defined threshold THD parameter value.
According to this invention, there is provided a method for efficient load management of a VSIG system with a compromised battery supply.
Figure 3 illustrates a flowchart of the control module of the VSIG system of Figure 2.
The steps for achieving this method are as follows:
Step 1: Define reference / threshold Total Harmonic Distortion (THD) parameter
value(s).
Step 2; Determine load change. If NO, retain state. If YES, go to next step.
Step 3: Determine instantaneous reference / threshold Total Harmonic Distortion
(THD) parameter value(s).
Step 4: Determine if instantaneous reference / threshold Total Harmonic Distortion
(THD) parameter value(s) is within reference / threshold Total Harmonic
Distortion (THD) parameter value(s). If NO, return to Step 2. If YES, go to next
step.
Step 5: Change speed of generator.
Figure 4 illustrates a time response chart of the VSIG system of the prior art in comparison to the VSIG system of the current invention.
The graphical representation shows the difference of catching the desired speed by using the system of this invention (dotted line) and by using prior art system and technique (solid line). The shaded part indicates the energy lost by prior art system and technique. Reference numeral 22 illustrates maximum speed. X-axis is for

time. Y-axis is for speed / power. Reference numeral 24 illustrates initial speed. Reference numeral 26 illustrates desired speed.
The technical advancement of this invention lies in provisioning a generator which directly goes to the desired speed instead of coming down from the maximum speed, which will preserve the efficiency of the VSIG system. This technique settles the generator at optimum speed by finding the THE) (Total Harmonic Distortion, by FFT) of generator AC voltage. This results in relatively low fuel consumption and preservation of efficiency of the system, in general.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A system for efficient load management of a VSIG system with a
compromised battery supply, said system comprising:
a control module adapted to sense change in load and further adapted to provide control signals to control drive of a generator of said VSIG system in accordance with change in load, said control module being adapted to provide control signals based on determination and calculation of Total Harmonic Distortion parameter values.
2. A system as claimed in claim 1 wherein, said control module comprising an input means adapted to allow input of reference / threshold Total Harmonic Distortion (THD) parameter value(s).
3. A system as claimed in claim 1 wherein, said control module comprising an input means adapted to allow input of reference / threshold Total Harmonic Distortion (THD) parameter value(s), said reference or threshold THD values being determined at maximum load and / or at maximum speed.
4. A system as claimed in claim 1 wherein, said control module comprising a load determination means adapted to determine change in load.
5. A system as claimed in claim 1 wherein, said control module comprising a load determination means adapted to determine change in load, said change in load being reflected as a trigger to said control module in order to achieve change in drive or speed of said generator.

6. A system as claimed in claim 1 wherein, said control module comprising an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means adapted to determine instantaneous THD parameter values.
7. A system as claimed in claim 1 wherein, said control module comprising an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means adapted to sense instantaneous THD parameter values, said sensing done at the output of a permanent magnet generator.
8. A system as claimed in claim 1 wherein, said control module comprising an instantaneous Total Harmonic Distortion (THD) parameter value(s) sensing means, said sensing means being a FFT based sensing means adapted to obtain FFT based Total Harmonic Distortion (THD) parameter value(s).
9. A system as claimed in claim 1 wherein, said control module comprising a processing means adapted to compare instantaneous THD parameter value(s) with reference or threshold THD parameter value(s) and further adapted to provide control signals for changing drive of generator in relation to compared output.
10. A system as claimed in claim 1 wherein, said control module comprising a processing means adapted to compare instantaneous THD parameter value(s) with reference or threshold THD parameter value(s) within a 10% tolerance range and further adapted to provide control signals for changing drive of generator in relation to compared output.

11. A method for efficient load management of a VSIG system with a compromised battery supply, said method comprising the steps of:
a. defining reference / threshold Total Harmonic Distortion (THD) parameter
vafue(s);
b. determining load change;
c. determining instantaneous reference / threshold Total Harmonic Distortion
(THD) parameter value(s);
d. determining if instantaneous reference / threshold Total Harmonic Distortion
(THD) parameter value(s) is within pre-determined conditions of reference /
threshold Total Harmonic Distortion (THD) parameter value(s); and
e. changing speed of said generator, accordingly.