Mitigating Industrial Power Consumption Through Automatic Power Factor Correction Using PIC Microcontroller

There are very large/high electronics components, but most of the industrials and commercial zones are using inductive components and that causes the power factor reducing. Electricity board cannot allow it. So we have to control and minimize it by Automatic Power Factor Correction APFC panel using PIC microcontroller. In it we connect PIC microcontroller improve it. It’s the reason for producing losses in distribution PIC microcontroller and maximum number capacitors bank will help us.There are very large/high electronics components, but most of the industrials and commercial zones are using inductive components and that causes the power factor reducing. Electricity board cannot allow it. So we have to control and minimize it by Automatic Power Factor Correction APFC panel using PIC microcontroller. In it we connect PIC microcontroller improve it. It’s the reason for producing losses in distribution PIC microcontroller and maximum number capacitors bank will help us. The problem of power factor is occurring to all the industrial inductive components. The Automatic Power Factor Correction APFC is very helpful at this situation. We are using PIC Microcontroller for this purpose as well as show the load power factor. APFC also helps to connect the power factor. In industries majority loads are inductive in nature. Due to highly induction it causes power factor poor. When APFC connect to the inductive loads so it can improves the power factor.

1) To improves the power factor of industrial loads.

2) To minimizing penalty in industrial power consumptions, due to low power factor.

3) To Maintains power factor in the range i.e, 0.8-0.9.

Comparator Section

The 220 V, 50 Hz is step downed using voltage transformer and current transformer is used to extract the waveforms of current. The output of the voltage transformer is proportional to the voltage across the load and output of current transformer is proportional to the current through the load. These waveforms are fed to Voltage Comparators constructed using LM358 op-amp. Since it is a zero crossing detector, its output changes during zero crossing of the current and voltage waveforms. These outputs are fed to the PIC which does the further power factor calculations.

 

Microcontroller Section

PIC 16F877A microcontroller is the heart of this Automatic Power Factor Controller, it find, displays and controls the Power Factor.. To correct power factor, first we need to find the current power factor. It can be find by taking tangent of ratio of time between zero crossing of current and voltage waveforms and two successive zero crossing of voltage waveform. Then it displays the calculated power factor in the 16×2 LCD Display and switches ON the capacitors if required.

 

Correction Section

When load is connected the power factor is calculated by the PIC microcontroller. If the calculated power factor is less than 0.9 then the relay switches on the capacitor. The relays are switched using ULN2003which is basically a driver IC. ULN2003 consists of seven DARLINGTON PAIRS.

The current lead in capacitor compensates the corresponding current lag which is usually present in loads. Hence the phase difference between the current and voltage will be reduced.

Power Factor Correcting capacitor connected parallel to load through relay, if the relay is energized by microcontroller it will connect  the capacitor parallel with load, if relay deenergized it will remove the capacitor from the load. When the resistive load is on the power factor will be near to unity so the microcontroller doesn’t energize the relay coil. When the inductive load is on the power factor decrease now the microcontroller energize the relay coil in order to compensate the excessive reactive power. Hence according to the load the power factor is corrected.

1) Reduces System Losses in Electrical Systems

Although the financial return from conductor loss reductionalone is sufficient to justify the installation of capacitors, it issometimes an attractive additional benefit; especially in older plants with long feeders or in field pumping operations. Systemconductor losses are proportional to the power losses and, since thecurrent is reduced in direct proportion to the power factorimprovement, the losses are inversely proportional to the squareof the power factor.

2) Reduced Electricity Bills

Poor Power factor is caused due to inductive loads whichrequire reactive power. This increase in reactive power causesincrease in required total power which is supplied by the utility.If the power factor is low, the percentage of the measured KVAwill be significantly greater than the KW demand. Improvingthe power factor through power factor correction will thereforelower the use of reactive power and hence lower the demandcharge, helping to reduce your electricity bill.

3) Increase Load Carrying Capabilities of System

Loads drawing reactive power also demand reactive current.Installing power factor correction capacitors at the end ofexisting circuits near the inductive loads reduces the currentcarried by each circuit. The reduction in current flow resultingfrom improved power factor may allow the circuit to carry newloads, saving the cost of upgrading the distribution networkwhen extra capacity is required for additional machinery orequipment, saving your company thousands of dollars inunnecessary upgrade costs. In addition, the reduced currentflow reduces resistive losses in the circuit.

4) Eliminate Power Factor Penalty

Consumers are charged additional fee when Powerfactor is less. Thus, this can be avoided by implementing powerfactor correction. Even when the Power Factor of the system ismaintained above 0.8, some supply companies provideincentives to the Consumers.

Main equipment used in APFC design are 220V single-phase 50Hz Power Supply, Potential Transformer, Current transformer, Zero-crossing detector, PIC16F877A Microcontroller, LCD Display, Relay driver, Relays, Switching Capacitors.

Microcontrollers cannot operate onthe voltages which are greater than 5 volts. If microcontroller is made to be operated upon the voltage greater than 5 volts, it will burn out and damage. For microcontroller to be operated uponthe circuits of high voltages we have to make use of potential transformers which step down the value steeply around 5V Current Transformer.

The Op-Amp requires the current lesser than the 50mA, so the current transformers are used to lower the value of current from the single phase current toaround 50mA.

 Zero-crossing detector-The Op-Amp LM358 is used as zero-crossing detector which will convert the sine wave inputsignal to the square wave output. It has two inputs viz. invertingand non-inverting. Inverting end is grounded and non-invertingend is given a high signal from CT or PT. The zero crossing is detected and an output signal is generated which is sent to the microcontroller.

Microcontroller-PIC16F877A is used. The use of the microcontroller is to perform various calculations and to take decisions and give relative output. The current and voltage received from zero crossing detectors are compared in microcontroller to calculate phase difference between two signals and ultimately the Power Factor.These values of Power factor, Current and voltage will be sent to LCD display and on the basis of present value of Power factor, the decision will be taken by microcontroller to switch in the capacitors.