Bizarre Frequency calculated when VT is unplugged

mycnam · November 26, 2020, 1:32am

This happens when I unplugged the VT. I believe the same will happen when the power is out and I run IoTaWatt through a UPS.

Can we skip the frequency calculation and zero out the frequency when the voltage is under a certain threshold?

github.com

boblemaire/IoTaWatt/blob/37170c9de599b6adb82ace26a9cf5fc0d1e0c0e2/Firmware/IotaWatt/samplePower.cpp#L402


      
            return 1;
          }
          if(abs(samples - (midCrossSamples * 2)) > 10){
            // DateTime now = DateTime(localTime());
            // Serial.printf_P(PSTR("%d/%02d/%02d %02d:%02d:%02d sample imbalance: %d - %d = %d, vchan %d, ichan %d\r\n"), now.month(), now.day(), now.year()%100,
            // now.hour(), now.minute(), now.second(), midCrossSamples, samples-midCrossSamples, abs(samples - (midCrossSamples * 2)), Vchan, Ichan);
            return 1;
          }
                    // Update damped frequency.
          
          
float Hz = 1000000.0  / float((uint32_t)(lastCrossUs - firstCrossUs));
          Vchannel->setHz(Hz);
          frequency = (0.9 * frequency) + (0.1 * Hz);
          
          
        // Note the sample rate.
                  // This is just a snapshot from single cycle sampling.
                  // It can be a little off per cycle, but by damping the 
                  // saved value we can get a pretty accurate average.
          
          
samplesPerCycle = samplesPerCycle * .9 + (samples / cycles) * .1;
          cycleSamples++;

overeasy · November 26, 2020, 2:47am

The problem is that sample power, and the whole way everything is scheduled, is based on the line frequency. Sure we could hack it to try to sense when there is no voltage, but it’s a power monitor. It’s whole reason for being is to measure power. So I recommend not using a UPS, just let it shut down. It boots back up in seconds

Giraffe · November 29, 2020, 9:24am

Also frequency is not a very useful measure (unless you are in the control room managing the whole grid).

mycnam · November 30, 2020, 3:21am

Would like to monitor the frequency of the backup generator, but it may not be useful since it’s an inverter generator.

When no voltage is detected the frequency seems to be random. I would think some value as undefined or invalid or zero is better than random.

Giraffe · November 30, 2020, 10:08am

In that situation I guess you are managing the whole grid (just on a smaller scale).