//Measuring AC mains energy use the non-invasive current transformer method
//Experimental Voltage synthesis method.
//OpenEnergyMonitor.org project licenced under GNU General Public Licence
//Author: Trystan Lea

   //For analog read
   double value;

   //Constants to convert ADC divisions into mains current values.
   double ADCvoltsperdiv = 0.0048;
   double VDoffset = 2.4476; //Initial value (corrected as program runs)
   
   //Calibration values
   //Calculated from comparison of Irms calculated here with Irms from commercial meter.
   double Ioffset = -0.08;
   //factorA = CT sens reduction factor / Rsens
   double factorA = 15.2;

   //Constants set voltage waveform amplitude.
   double SetV = 228.0;
   double peakV = SetV * sqrt(2.0);

   //Used for generating voltage waveform
   double time=0.0;
   double dtime=0.0;
   double upeak=0.0;

   //Counter
   int i=0;

   int samplenumber = 2000;
 
   //Used for calculating real, apparent power, Irms and Vrms.
   double sumI=0.0,sumV=0.0,sumP=0.0;
 
   int sum1i=0;
   double sumVadc=0.0;

   double Vadc,Vsens,Isens,Imains,Vsynth,sqI,sqV,Irms,Vrms;
   double realPower,apparentPower,powerFactor;
   
   long t,lt,dt;   
   
   //Increasing this value from 0 will decrease the power factor.
   //opossite to what i thought it did originally?
   double vstart = 0.0;
   
   //plotted against pf - if as v3 increases pf becomes more stable
   //especially good near whole numbers. 8 up is probably good
   double v3 = 8.0;
   
   //frequecy 50Hz
   double freq=5.0;
   
   //What changes power factor?
   //Powerfactor is max when freq is closest to grid freq
   //does not change with value of rsens or ctsens
   //max when v3 is larger than 3 and a whole number
   //max when vstart=0
   //but max is still lower than measured on comercial meter?
   
   
   double twopi = 2.0 * 3.1415;
   
   double Vmax=0.0,Vmin=5.0;

void setup()
{  
  Serial.begin(115200);
}

void loop()
{ 
   value = analogRead(0);
   
   //Summing counter
   i++;

   //Voltage at ADC
   Vadc = value * ADCvoltsperdiv;

   if (Vadc>Vmax) Vmax = Vadc;
   if (Vadc<Vmin) Vmin = Vadc; 

   //Remove voltage divider offset
   Vsens = Vadc-VDoffset;
                
   //Current transformer scale to find Imains
   Imains = Vsens;
                  
   //Calculates Voltage divider offset.
   sum1i++; sumVadc = sumVadc + Vadc;
   if (sum1i>=1000) {VDoffset = sumVadc/sum1i; sum1i = 0; sumVadc=0.0;}

   lt=t; t = micros();
   dt=t-lt;

   //Infer voltage waveform from current waveform
   dtime=(twopi*freq*(dt/100000.0));
   time=time+dtime;          
   if (Imains>=upeak) {upeak = Imains; time=vstart*dtime;} 
   if (time>=(v3*twopi)) {upeak=upeak/2.0; time=0.0;}
   Vsynth = peakV * cos(time);

   //Root-mean-square method current
   //1) square current values
   sqI = Imains*Imains;
   //2) sum 
   sumI=sumI+sqI;

   //Root-mean-square method voltage
   //1) square voltage values
   sqV = Vsynth*Vsynth;
   //2) sum 
   sumV=sumV+sqV;

   //Real power calculation
   //1) sum 
   sumP=sumP+(Vsynth*Imains);

   if (i>=samplenumber) 
   {  
      i=0;
      //Calculation of the root of the mean of the current squared (rms)
      Irms = factorA*sqrt(sumI/samplenumber)+Ioffset;
      //Calculation of the root of the mean of the voltage squared (rms)
      Vrms = sqrt(sumV/samplenumber); 
                     
      realPower = factorA*(sumP/samplenumber);
      apparentPower = Irms * Vrms;
      powerFactor = realPower / apparentPower;

      //Output values to serial
      Serial.print(realPower);
      Serial.print("A");
      Serial.print(apparentPower);
      Serial.print("B");      
      Serial.print(powerFactor);
      Serial.print("C");
      Serial.print(Vrms);
      Serial.print("D");
      Serial.print(Irms);
      Serial.print("E");
      //Serial.print(Vmax);
      //Serial.print(" ");
      //Serial.println(Vmin);
      
      //Serial.print(" ");
      Vmax =0.0;
      Vmin=5.0;

      //Reset values ready for next sample.
      sumI=0.0;
      sumV=0.0;
      sumP=0.0;
      
      upeak=0.0;
      time=0.0;
            
   }
}