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LOAD SHEDDER THROUGH PC
Posted Date:
Total Responses: 0
Posted By: Hardik Panchal Member Level: Silver Points/Cash: 10
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Introduction
Today the world in which we live is the world of Digital Electronics.
The technological advancement has taken to stage where we can do nothing without the help of sophisticated instruments like computers, mobiles phones, etc.
India is a developing country. There is an acute power shortage every corner of India, it becomes unavoidable, to cut down the load from one section, & supply to other section, which can be done locally or through PC remotely.
So, it is necessary that we save power for our future. So, our project deals with power saving. Load shedder is one of the finest solutions to save power.
This Project is a very good example of embedded system as all its operations are controlled by intelligent software inside the microcontroller.
The theme of our project is to control the power grid or for the purpose of load shedding from the IBM PC keyboard.
The project “Load Shedder” is based on world’s most powerful Intel MCS-51 family of Microcontroller Atmel of 89C2051.
In this project, we are using AT89C2051 Microcontroller, since this controller has two ports which are more than enough for our project.
Technology Used
As microcontrollers are the core of the todays digital circuit design in industry, this system uses it for the centralized operation and digital processing.
The technology used here is embedded technology which is the future of today’s modern electronics.
Here we have used a very high speed Microcontroller i.e. 89C2051.
The Atmel AT89C2051 is a powerful microcontroller which provides a highly-flexible and cost effective solution to many embedded control applications.
The complete development of this system can be divided into the following stages
? Problem definition stage
? Designing block diagram
? Implementing circuits and components
? Developing flowchart for software
? Writing actual code for Microcontroller
? Compiling the code
? Burning the hex file into microcontroller with programmer
? Testing
? Running
Problem definition stage
This is the very first stage to develop any project. It actually defines the aim and the concept of the project. The aim of “Load Shedder Through PC” is to control the power grid or for the purpose of Load shedding from the IBM PC keyboard.
Designing block diagram
At this stage we have categorized the whole system into different individual modules. These modules (block diagrams) will be helpful in understanding the concept and working of the integrated system.
Implementing circuits and components
This is the actual implementation of circuit of each block. At this stage we have actually designed each block separately and finally integrated them into the complete working system.
Developing Flowchart for software
To get the logical flow of the software, the development of flowchart is having a prominent role. So that we have analyzed the complete system and organized the flowchart in such a manner that one can understand the complete working of the software.
Writing actual code for Microcontroller
After the development of the algorithm and flowchart we have actually translated them in C language for AT 89C2051 Microcontroller so that it can understand the instructions and run as per our requirement. The instructions are in ANSII C Language.
Compiling the code
The hand written code on paper was then transferred into computer. For that we have used Keil pre-install on PC. The Keil is a Computer Aided Program to simulate the working of Microcontroller in real time without burning the software into actual IC. We simulated and compiled our program for error checking. After removing several compiling errors the program was converted into machine language i.e. Intel hex format.
Burning the hex file into microcontroller with Programmer
In this stage the compiled hex format file was downloaded or burned into AT 89C2051 Microcontroller. This was done by using the Atmel in-system programming software provided by the manufacturer itself.
Testing
This time we tested our project for actual working, after loading the software into the microcontroller. Any errors found were removed successfully.
Running
This is the last and final stage of development of our project. In this stage a user flowchart or steps was made so that any one can use this system without any difficulty.
BLOCK DIAGRAM
a) On PC normally two ports are available com1 & com2. This can be connected to any available com port, through a serial cable one normally used with modem.
b) IC MAX 232 is a level converter IC. It converts the TTL level data to +12V & -12V level. In short, it is used to boost the data to send to PC. The output of MAX 232 ICE is also given to microcontroller which needs +5V level.
c) 89C2051 is a microcontroller IC. Microcontroller IC 89c2051 has inbuilt Universal Synchronous Asynchronous Receiver Transmitter (USART).
d) It is also called as Embedded Controller. An embedded controller is a chip which has a computer processor with all its support functions, memory, I/O built into the device.
e) The output of microcontroller IC 89C2051 is given to relay driver. The relay driver consists of transistors which are npn.
f) According to the load the controller will select the particular transistor & turn it ON. Thus, we can control the load as per our requirement.
Explanation
The circuit diagram is as shown above. We have divided the circuit diagram into different units. So that it can be easily understand.
A. Power Supply Unit
This power supply circuit is divided into the following different parts.
1. The Transformer.
2. The Rectifier.
3. The Filter.
4. The Regulator.
1. The Transformer: - The Transformer used is step down transformer which transform 230V AC to 9V AC. The current rating of the transformer is 1A. This is more than enough to supply the current to the relay unit & to all the circuits.
2. The Rectifier: - Here, the ac signal coming from transformer is rectified & converted into pulsating dc. The rectifier used here is bridge rectifier. This is more efficient than the center tap. D1, D2, D3, D4 are power rectifier diodes which forms bridge circuit.
3. The Filter: - This unit is capacitor of high value which can charge & supply its change to the circuitry in the falling edge of the input signal. This way it continuously maintains the direct cycle voltage across the circuit. The capacitor is a filter capacitor which converts pulsating dc into pure dc. The value of the capacitor C1 used is 1000µF.
4. The Regulator: - The regulator is used to give constant output whatever is its input voltage. The input to this unit is 12V D.C. & its output voltage is constant to 5V, since we are using 7805 regulator.
B. MAX Unit
Almost all digital devices which we use require either TTL or CMOS logic levels. Therefore the first step to connecting a device to the RS-232 port is to transform the RS-232 levels back into 0 and 5 Volts. This is done by RS-232 Level Converters. Here IC MAX 232 is used.
IBM PC com port is designed for telephone network which works on 12V dc whereas our controller logic is at 5V. We need to convert this data to +12V & -12V logic before it is sent to PC.
This IC has Transreceiver Level Converter. Transmitter part converts the TTL logic to com port logic & receiver part converts the signals coming from PC to TTL level before it is given to the microcontroller.
The large value of capacitors are not only bulky, but also expensive. Therefore other devices are available which use smaller capacitors and even some with inbuilt capacitors. However the MAX-232 is the most common, and thus we will use this RS-232 Level Converter.
Dual Charge-Pump Voltage Converter
The first converter uses capacitor C1 to double the +5V input to +10V on C3 at the V+ output. The second converter uses capacitor C2 to invert +10V to -10V on C4 at the V- output.
C. Relay Unit
? All relays are operated by 12V dc. IC2 is Atmel AT 89C2051 microcontroller. It has two ports, port 1 & port 3.
? This controller has inbuilt Universal Synchronous Asynchronous Receiver Transmitter (USART). Pin no. 2 is RX pin used to receive data serially & Pin no. 3 is TX pin used to transmit data serially. Through these two pins microcontroller is able to communicate with IBM PC com port. Communication baud rate is 9600 bits/sec.
? Port 1 controls all our relays. Output of this port is pulled high through pull up resistor R28 SIL (Serial In Line resistor) arrays hence the output of pin 12 to 19 are by default high at 5V. All relays stays off on power up.
? The crystal 11.0592 MHz is the standard serial communication. The external circuit connected to the reset pin of microcontroller is the RC network. This is used to auto-reset the controller whenever the power is switched on.
? Transistors Q1-Q16 is all NPN general purpose transistors. NPN transistor will becomes on when base is high.
D. Relay Circuit
1. The base of Q1 is driven by R4 connected to pin no. 12 which is at logic high, Q1 is on (conducting) & hence its collector is low. Here, transistor acts as a switch, due to which the transistor Q2 remains off.
2. To switch on Q2, we have to switch off Q1. To switch off Q1, the program inside the microcontroller must bring low logic at pin no.12. When Q1 will become off, Q2 base will get high through R12 & will become ON.
3. As Q2 turns on, relay coil RL1 will get energized & the current will pass through coil, collector of Q2, emitter to ground.
4. As relay will get energized the normally open contact will close the connection & the load will be connected to the output of contacts on con1.
5. Diode D6 connected across relay coil is to protect the circuit from the induced emf generated by the relay coil during ON/OFF operation. Hence it acts as a freewheeling diode. All relays circuit works in the same manner.
The Software
;
org 0
;
ajmp X0100
;
org 0bh
;
ajmp X0140
;
org 100h
;
X0100: acall X010c
mov b,#55h
X0105: mov pcon,#1
mov p2,r1
sjmp X0105
;
X010c: anl tmod,#0fh
orl tmod,#21h
mov th1,#0f4h
mov scon,#50h
mov th0,#3ch
mov tl0,#0b0h
setb tr0
setb et0
setb ea
mov r1,#0ffh
ret
;
clr acc.0
mov c,int0
mov acc.0,c
mov c,int1
mov acc.1,c
mov c,t0
mov acc.2,c
mov c,t1
mov acc.3,c
mov c,rd
mov acc.4,c
anl a,#1fh
ret
;
X0140: push acc
push b
push psw
mov th0,#3ch
mov tl0,#0b0h
mov r1,#0ffh
clr p1.4
clr p1.5
clr p1.6
clr p1.7
mov a,#0ffh
mov c,p1.0
mov acc.0,c
mov c,p1.1
mov acc.1,c
mov c,p1.2
mov acc.2,c
mov c,p1.3
mov acc.3,c
cjne a,#0ffh,X016e
ljmp X0215
;
X016e: mov r2,#0
mov r3,#0
clr p1.4
setb p1.5
setb p1.6
setb p1.7
X017a: mov a,#0ffh
mov c,p1.0
mov acc.0,c
mov c,p1.1
mov acc.1,c
mov c,p1.2
mov acc.2,c
mov c,p1.3
mov acc.3,c
setb c
cjne a,#0ffh,X0192
sjmp X019b
;
X0192: rrc a
jnc X01ca
inc r3
cjne r3,#4,X0192
sjmp X0215
;
X019b: mov a,r2
add a,#4
cjne a,#10h,X01a3
sjmp X0215
;
X01a3: mov r2,a
setb c
mov a,#0ffh
mov c,p1.4
mov acc.4,c
mov c,p1.5
mov acc.5,c
mov c,p1.6
mov acc.6,c
mov c,p1.7
mov acc.7,c
rlc a
mov c,acc.4
mov p1.4,c
mov c,acc.5
mov p1.5,c
mov c,acc.6
mov p1.6,c
mov c,acc.7
mov p1.7,c
sjmp X017a
;
X01ca: mov a,r2
add a,r3
add a,#30h
mov r1,a
clr c
subb a,#3ah
jc X01d8
clr c
add a,#41h
mov r1,a
X01d8: mov a,r1
cjne a,#0ffh,X01de
sjmp X0215
;
X01de: clr t1
setb tr1
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,#7eh
acall X020d
mov a,b
acall X020d
mov a,r1
acall X020d
mov r1,#0ffh
sjmp X0215
;
X020d: mov sbuf,a
X020f: jnb ti,X020f
clr ti
ret
;
X0215: clr tr1
setb t1
pop psw
pop b
pop acc
reti
;
mov a,#0dh
lcall X020d
mov a,#0ah
lcall X020d
ret
;
mov r7,#0
inc r7
mov a,r7
cjne a,#0ffh,X0231
;
org 250h
;
anl 53h,a
anl a,#55h
anl a,@r0
anl a,@r1
anl a,r0
anl a,r1
anl a,r2
ajmp X0362
;
xrl 64h,#65h
xrl a,@r0
;
; Miscellaneous Equates
;
; These are addresses referenced in the code but
; which are in the middle of a multibyte instruction
; or are addresses outside the initialized space.
;
X0231: equ 231h
X0362: equ 362h
;
end
;
HEX CODE
:10000000210000000000000000000021400000006E
:10010000310C75F05575870189A080F953890F432B
:100110008921758DF4759850758C3C758AB0D28C98
:10012000D2A9D2AF79FF22C2E0A2B292E0A2B392EA
:10013000E1A2B492E2A2B592E3A2B792E4541F22E4
:10014000C0E0C0F0C0D0758C3C758AB079FFC29415
:10015000C295C296C29774FFA29092E0A29192E1DA
:10016000A29292E2A29392E3B4FF030202157A00F4
:100170007B00C294D295D296D29774FFA29092E05F
:10018000A29192E1A29292E2A29392E3D3B4FF02EF
:1001900080091350350BBB04F9807AEA2404B410AB
:1001A000028072FAD374FFA29492E4A29592E5A21F
:1001B0009692E6A29792E733A2E49294A2E59295F2
:1001C000A2E69296A2E7929780B0EA2B2430F9C378
:1001D000943A4004C32441F9E9B4FF028037C2B520
:1001E000D28E747E510D747E510D747E510D747ECD
:1001F000510D747E510D747E510D747E510D747EBF
:10020000510DE5F0510DE9510D79FF8008F5993058
:1002100099FDC29922C28ED2B5D0D0D0F0D0E032B2
:10022000740D12020D740A12020D227F000FEFB43A
:1002500052535455565758595A6162636465660043
:00000001FF
END
STEP 1:
START?PROGRAMS?ACCESSORIES? COMMUNICTION?HYPERTERMINAL?HYPERTERMINAL.EXE?
ENTER?
New connection window will open enter the name as load shedder and press ok.
STEP 2:
Connect to window will open. Choose connect using direct to com1 or com2 whatever port is available in your computer and then click ok.
STEP 3:
com1 property window will open .Select bits per second as 9600 and flow control to none.
click ok.
STEP 4:
Switch on the power to the circuit board and you will receive the massage as shown.
STEP 5:
Follow the menu press key 1 to 8 from you pc keyboard will receive the messages as follows
applications
Our project can be used for various applications wherever you require control using PC.
? Street Light Management.
? Home Automation.
? High Voltage Grid Control.
? Electro, Hydraulic & Pneumatic Valve Control
? Robotic Control.
? Hotel Power Management.
? Load Shedding.
? Industrial Automation.
* Hotel Power Management:-
Normally customers come to hotel & while going out from there they often leave the lights & fan ON. Normally customers surrender the key to the reception counter while leaving. If the reception staff could switch off, the power to the unoccupied rooms through there computer keyboard immediately, they can save lot of power, time and energy. Similarly, while handling over the keys to the customer they can again switch on the power to the power to the rented room. So, our project “Load Shedder” plays an important role in hotel power management.
*Load Shedding:-
Load shedding is a procedure in which parts of an electric power system are disconnected in an attempt to prevent failure of the entire system due to overlapping.
Load shedding is normally used in industrial, large commercial & utility operation is monitoring electric usage continuously & shutting down certain pre-arranged electric loads or devices if a certain upper threshold of electric usage is approached.
Example:
If a factory has a 500A backup generator but draws 800A when all its equipment is in use, a safety contractor or load shedder may be used to automatically turn off non-essential equipment keeping demand, in the event of power failure, below 500A. When the normal supply is restored the safety contractor may be operated to bring non-essential equipment back on line.
• Industrial Automation:
In industries, mostly induction loads are used. If we switched on all the loads at a time it will lead to heavy overloads & breaker Tripp. It will also load to interruption of power supply & breaker down. Such loads should be switched on sequentially to avoid cover loading & tripping. So, by using Load Shedder it is capable of controlling eight such loads sequentially after a pre-programmable time delay. In industries, sometimes only one or two loads are required out of eight loads. So, it is not necessary to keep the other loads on. For this, Load Shedder is the fine solution to such requirements.
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Project Feedbacks
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| Author: unaza | Member Level: Bronze | Revenue Score:  | You've written that we'll write the code in ANSII C, but you've given it in assembly, why? And what is ANSII C?
| | Author: rakesh | Member Level: Gold | Revenue Score: | The block diagrams are not displayed in the report. Can you please mail the report to rakesh.guggilam@gmail.com
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