modified single phase energy meter for rural domestic energy management supplied from solar panel...

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Electrical and Electronics Engineering: An International Journal (ELELIJ) Volume 2, No 1, February 2013

55

Modified single phase energy meter for ruraldomestic energy management supplied from

solar panel based small grid system

1Piyali Das,

2Mousam Ghosh and

3Dr. Saswati Mazumdar

1Assistant Professor, Dibrugarh University, Assam, India

[email protected] Officer, West Bengal Financial Corporation, West Bengal, India

[email protected]

3Professor, Jadavpur University, Kolkata, India

[email protected]

Abstract

In this paper the energy limiting is explored by the use of modified single phase energy meter using

PIC16F877A [1]. This paper contains the method which is used to control a predefined domestic load and

through out the day the total consumption. It also contains the advantage of using this energy saving

energy meter and the method of using this energy meter in domestic use.

Key words

Energy meter, load control, multistage load control

I. IntroductionThe main principle of this single phase energy meter is to control the wastage. For example aconventional non electrified small rural locality if electrified by solar panel based small grid

system then the locality will face a problem which can be minimized by this proposed modified

energy meter. Since those houses in this locality are electrified by solar panel and the power isstored in battery, so through out the day they can use limited amount of energy. If some of the

houses consumed maximum amount of energy in a certain time through out the day then otherhouses get hampered. So a device is required which can limit the consumption through out the

day.

Also if some of the houses consume the total energy within their specified limit but at a certaintime they may exceed the maximum power limit which is specified for them. This will again

hamper the grid voltage and due to that, the other houses get hampered.

So to get better reliability and to minimize these two unwanted situations this modified energymeter has been proposed.


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Fig.-1: Solar Panel based Rural Electrification with small grid system

II. Model Description

Fig 2: Block diagram of Modified Energy Meter with the help of Controller.


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The main principle of this single phase energy meter is to control the wastage of domestic load.

Fig.-2 shows the block diagram of modified energy meter with the help of a micro controller. A

new modified single phase energy meter system is being implemented with the help of a

controller PIC16F877A.

To develop this modified energy meter a 3200 pulse per kW-hr electronic energy meter was

selected i.e. if a one kW load is connected for a period of one hour then the energy meter gives

3200 nos. of pulses. To modify this energy meter, this pulse signal is manipulated by the

microcontroller.

Depending upon the following two principles this modified energy meter is

developed.[2][3][4][5]

i. Firstly, to limit the energy consumption in a day, the microcontroller counts the pulsethroughout the day. If for a rural house the limit of energy consumption to 1kW-hr perday is set, that microcontroller counts the pulse throughout the day. If the limit is crossed

i.e. 3200 is counted, the microcontroller trips the power for the house for that day. In thenext day it will be reset by the controller and power will be delivered to the house and

like this the process will go on.

ii. Secondly stop high power demand beyond the specified limit given to each house, themicrocontroller checks the time span between two consecutive positive edges of the pulse

signal. If any house powered on higher load than specified, this modified energy meter

trips the circuit for that instance and there is a provision for user to reset after

disconnection of the extra load. For example if it is required to limit a load of 500W for a

rural house then a time of 2.25 sec is to be set to microcontroller. In any time during the

day the load increases beyond 500W, the time span between two consecutive pulses will

be reduced below that 2.25 sec and controller trips the power for that instance.

III. Features:

Trips the power if energy consumption is more than the specified limit through out a day.There are provisions to set different settings (1/2/3 kW-hr per day) at the time of installation

by changing corresponding jumpers.

At 80% of specified energy consumption limit through out a day, this modified energy metershows a warning signal by a LED. There are further provisions for buzzer also.

In any day if one of the house in that rural locality exceeds their energy consumption limitthen they are not able to power on their lights for that day. But in the next day they will getpower automatically.


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Trips power for an instant if any house switches to more load at a time which crosses theirspecified power limit. But user can reset by pressing reset switch after disconnection of some

of the loads.

Fig 3: A prototype of the Modified energy meter circuit

IVIVIVIV. I. I. I. Instrument Details

Here in this project Anchor Electricals (P) Ltd. made energy meter is used, which is of 240V &50 Hz rating. It gives 3200 pulse/kW-hr.

Fig4: Circuit diagram of Energy meter controller by using Microcontroller


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Fig 4 shows the microcontroller based Energy Meter. In first step the single phase energy meter issupplying pulse to the Controller through an isolation circuit, which is made of R1 and opto-

coupler Opt.

By the rising edge of the pulse, the Controller is interrupted by the capture pin 17 which is

selecting the positive edge of the pulse and feeding this to the Controller input pin, this is the

second step.

In third step three output pins of Controller are operating from which one is connected with a

relay for tripping at overload condition, and two another output pins are operated to indicate atoverload condition and 80% consumption of set point condition respectively. LED1 is the

indicator of 80% consumption and LED2 is the indicator of overload condition.

Now in fourth step Phout is going to one of the relay pins and Nout is going to neutral of the loadrespectively (as load needs phase and neutral to operate). Load phase is being fed from another

relay pin. This relay will operate when the initially set pulse in the Controller exceeds and willdisconnect the load from the supply. Controller gets supply from a 5V supply and the relay gets

supply from a 12V supply. The relay can be replaced by 240V contactor.

Table:1 List of Circuit Components

SL.

NO.LEGENT NAME VALUE

1 U1Micro-

ControllerPIC 16F877A

2 S1 Switch Push on switch

3 R1 Resistor 1K /0.25W

4 R2 Resistor 5.6K /0.25W

5 R3 Resistor 560 /0.25W

6 C1, C2, C5 C Capacitor 1F/63V

7 R4,R8 Resistor 5.6K/0.25W

8 R5,R7 Resistor 330/0.25W

9 C3, C4 Capacitor 15PF/25V

10 XT1 Crystal 4 MHz

11 R6 Resistor 2.2K/0.25W

12 Rel1 Relay 12V 1CO, 10Amp,


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V. Flow Chart for self explanation

START

Initialize all the Variables.

Configure the Capture Pin as Interrupt Capture

at Every Rising Edge of Input Pulse.

Configure Parallel IN/OUT Ports

SET all Variables to default

SET all the O/P Port to ZERO

Counting Sec, Min, Hr with 4MHz crystal

as reference

Is Pulse Rising

Edge Interrupt

Occur ?

Increment the Pulse Counting,

Reset theTimer_ConsecutivePulse

Is Pulse counting = Set

Point (for a KWh) ?

Y

Power OFF

SET that bit 0

Y

1

2

N

NIs Pulse counting =

80% of Set Point (for a

KWh) ?

2

Warning

SET that bit 1

Y

N


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Is 24 Hours

Completed ?

2

Pulse Counting Reset to Zero

Power ON

SET that bit 1 and

Reset Warning Bit

Y

N

Is

Timer_ConsecutivePulse

> Ref time for given

Power OFF

SET that bit 0

and OL O/P bit1

SET a Flag Power_OFF_OL= 1

Y

N

Check INPUT of

Over Load Reset

Pin

Is User Reset The

OVER LOAD

Condition?

Is Flag

Power_OFF_OL

Y

Power ON

SET that bit 1

RESET a Flag Power_OFF_OL= 0

1


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VI. Conclusion:

In many rural place conventional electricity is yet not supplied and with a solar panel based small

grid system is installed to serve the people. In those places the main object is to enlighten them at

night. For these places, low wattage CFL or LED based lighting systems are more suitable. These

lamps are fed by the stored energy in battery through solar panel (or any other non-conventionalsource). The stored energy is limited so if one or some of the houses in that locality connected

with that grid consumes maximum amount of energy then other houses connected with that grid

get hampered. Also if they consume within the limit but at a certain interval draw a high load

current, it also hampers the grid voltage as well as other circuits of the arrangement and system

stability will be reduced. These reduce the system reliability also. So to overcome these situationsfor small grid system this modified energy meter, which is basically a small modification of

existing electronic energy meter with the use of a microcontroller, will be of great use.

References

[1] Application Note ofPIC 16F877A from www.alldatasheet.com.[2] A single phase microcontroller based energy meter, Loss, P.A.V., Lamego, M.M., Sousa, G.C.D.,Vieira, J.L.F., Instrumentation and Measurement Technology Conference, 1998. IMTC/98. ConferenceProceedings. IEEE, Date of Conference: 18-21 May 1998, Volume: 2, Page(s): 797 - 800 vol.2, Product

Type: Conference Publications

[3] United States Patent- Programmable Electrical Energy meter using Multiplexed Analog-to-DigitalConverter, Inventor- Rodney C. Hamminger, Mark L. Munday, Assignee- ABB Power T & D Company

Inc., Raleigh, N. C. , Patent number: 5544089, Filing date: 7 Jun 1995, Issue date: 6 Aug 1996.

[4] Programmable electrical energy meter and methods therefore, Inventor- Mark L. MundayRodney, C. Hamminger, Assignee- ABB Power T & D Company Inc., Raleigh, N. C. , Patent number:

5631843, Filing date: 6 Jun 1996, Issue date: 20 May 1997.

[5] Power Energy Meter in a Low Cost Hardware/Software, Libano, F., Dept. of Electr. Eng., PUC-RS, Paranhos, I. ; Melchiors, J. ; Mano, O. ; Fehlberg, R. ; Braga, R. ; Muller, S.; Volume: 3,Page(s):1712 1715; Industrial Electronics, 2006 IEEE International Symposium on 9-13 July 2006

modified single phase energy meter for rural domestic energy management supplied from solar panel...

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