Automatic Load Sharing Transformer Using Microcontroller

The transformer is the vital component within the electrical power transmission and distribution system. In this project, we show the Automatic load sharing transformer using a microcontroller, here we have three transformers connected in parallel through microcontroller and change over relay.
The microcontroller compares the load on the primary transformer with a reference value. When the load exceeds the reference value, the slave transformer will automatically be connected in parallel with the first transformer and share the additional load. Therefore, a variety of transformers work efficiently under overload conditions and therefore the damage is often prevented.
In this work, the slave transformers share a load of the master transformer in the case of an overload condition. A sensor circuit containing a microcontroller is designed to log the info from the master transformer and if it's found to be in an overload condition, immediately the slave transformer is going to be connected within the parallel to the master transformer, and therefore the load is shared. The microcontroller monitor’s the load current and temperature of the transformer and displays the values on LCD. Whenever loads are added to the secondary side of the transformer, the secondary side rises.
As the load current exceeds the rated current rating of the transformer, therefore the microcontroller will send a visit signal to the relay, thereby turning on the slave transformers. Initially when we switched ON the load that load is going to be shared by the primary transformer. Once the load has been increased on the first transformer above its rated capacity then the stand by the second transformer will share the load automatically. In this project, three modules are made to control the load current. The first module is the sensing unit, which is used to sense the current of the load; a second module is a control unit in which the relay plays the main role, and its function is to vary the position with reference to the control signal and the last module is a microcontroller.
It will read the digital signal and perform some calculations and eventually gives a control signal to the relay. For monitoring the load current continuously, the current transformer is employed, and therefore the output of the current transformer is fed to micro-controller through an A-D converter. The automatic load sharing of the transformer or overload protection of the transformer is completed by various means like by using a microprocessor, by using relays. In this work, we used a relay for automatic load sharing between three transformers.

Project Scope

It has a vast scope as it is important for every transformer's safety. The purpose of our project is to protect the transformer when the load exceeds during peak hours from overloading and overheating, there is a temperature sensor on the top of each transformer which measures their temperature continuously and gives signals to the microcontroller. Also, it has an oil level detector which detects the transformer’s oil and continuously reports to the microcontroller. There are voltage and the current sensor which sense voltages and currents.

Intended users

Automatic load sharing transformer using a microcontroller can be used widely in industrial areas, it can be used in substations, it can be used in process industrial power, and it can be used in the Distribution station. As it provides automatic load switching and sharing of the transformer so there will be no manual error. It prevents the main transformer from overloading and heating by sharing loads by slave transformers, therefore it provides uninterrupted power supply.

Working Function of  Load Sharing Control System Using Microcontroller

Automatic load sharing transformer using microcontroller, we are using the three identical 1:1 couple transformers which are connected in parallel through change over relay. Transformer-T1 may be the main transformer we called it a master transformer and transformer-T2 and T3 is an auxiliary transformer and that we called it a slave transformer. Each transformer has its own load handling capacity.
In the case of normal operation, the master transformer shares the load and the remaining 2 slave transformers will remain off but as the load is increased beyond the rated capacity of the main transformer so the slave transformer,  connected in parallel,  automatically turns on and shares the load. Now two transformers T1 and T2 are running. Now when the load is increased beyond the rated capacity or current increased beyond the reference current set by the user then the third transformer that is T3 will turn on automatically and the load is distributed and shared between all three transformers.
When a load is reduced or current is reduced then the third transformer T3 will automatically shut down and the load is shared and distributed between 2 transformers, when a further load is reduced then the second T2 transformer will also shut down, and now only the master transformer that is T1 runs alone. We have set the voltage sensor which measures the voltage across the load, we have set the current sensor which measures the current of the load as the load increased gradually current sensor detect current and send a signal to the microcontroller which then operates relays, we have set the temperature sensor on each of the transformers which detect the temperature on each transformer.
If the temperature of the transformer increased beyond the set value so then the transformer will automatically shut off and when the transformer cools down and the temperature will be reduced then the transformer will again turn on. We have set an oil sensor which measures the oil of each transformer from 0% to 50% and 50% to 100%. when the load on the master transformer is more than the rated capacity the transformer Relay has closed. T2 second transformer is automatically connected in parallel with the main transformer and if the load is increased to such an amount that can’t be handled with the two transformers then the T3 third transformer is automatically connected in parallel with T1 transformers & T2 transformers and shares the load. Due to which the  T1 transformer is not overloaded and the problem like the burning of winding of a transformer, overheating, and un-interruption of supply is gets eliminated by this arrangement. The indicator lights contain the LED’s which shows the ON/OFF status of all transformers.

Block diagram

Comprehensive schematic

COMPONENTS

1. ARDUINO UNO 1
2. ZMPT 101B VOLTAGE SENSOR 1
3. ACS712 CURRENT SENSOR 1
4. BUCK CONVERTER 1
5. 100W BULB WITH HOLDER 3
6. SWITCHBOARDS WITH SOCKETS 6
7. OIL BOTTLES 3
8. AC WIRES
9. ARDUINO WIRES
10. RELAY MODULE 3
11. TRANSFORMER 1:1  3

Advantage of Automatic load sharing transformer using microcontroller

1. The load is shared by transformers is automatic.
2. No manual errors are taking place. 
3. It prevents the most transformer from damage by problems like overload and overheats. 

Applications of Automatic load sharing transformer using microcontroller

1. This system can be used in Hostels and Hotels.
2. This system can be used in Offices
3. This technique is often utilized in industrial applications.
4. This system can be used in Electrical Substations.
5. This system can be used in power grids.
6. Un-interrupted power supply to the consumers is supplied.

Conclusion

By designing an Automatic load sharing transformer using a microcontroller we have concluded that as we all know the transformer is the most important equipment in the power system, so its safety is very important. This project is about the importance of transformer load sharing so that the power that can be transferred is uninterrupted. 

We observed that if the load on one transformer is increased then the relay will sense the change in current and the microcontroller operates and other transformers come automatically in operation to share the load and when the load decreases then again the relay will sense the change in current and the load distribute and share back to the single main transformer. While the voltage sensor, current sensor oil sensor, temperature sensor measurement will be shown on LCD on each step.