I believe it is a well established fact many modern smart meters measure highly distorted waveforms inaccurately. For those unaware I'll mention results of one study found errors ranging from +500% to - 40% with a waveform produced by a string of 30 household lights on dimmers (half led, half cfl).
There was also a study done more recently that concluded the above results are "questionable", but they arrived at that conclusion by using waveforms "that meet maximum allowable THD"(according to local gov standard) . Of course if they used a lot less distorted waveforms they got a lot less error (up to 5% if I remember correctly). And they also added that "classic" resistive loads on the same AC line further improve on the measurement error and no one uses just non linear loads in their house right? (this was written in 2018 or so).
Now in 2022 in my house I pretty much only have non linear loads including 75 led lights, induction hob, all appliances with electric motors use inverters etc. I haven't checked current waveforms I have (I'm waiting for CTs to arrive from China), but I'm pretty sure I'm being overcharged by around 10%~15%. (I did all the usual checks in the past)
I imagine the error in smart meters measurements is due to not high enough sampling frequency plus the averaging method used. In my country (as well as in rest of EU I think) if you complain to the power company they will "recertify" your meter with pure sinusoidal waveform drawn by a resistive load.
So I became interested in various filtering technologies. I'm not talking about those "save thousands on electricity" scam boxes that contain a tiny capacitor, but real series and parallel filters.
Unfortunately based on what I read one needs both types of filters to cover two kinds of distortion. Voltage (distortion) sources (all devices that contain diode rectifiers and filtering capacitors) and current sources (all devices that switch on a very low impedance load for a very brief period of time such as many dimmers, led lights etc).
Techniques for design of those filters are known. Also one would probably need some sort of overcurrent bypass of series filters in case one has a high power resistive load (electric flow water heater) that is used rarely.
However, I'm starting this thread to ask if anyone already has designed and is using any filters like those I mentioned. Perhaps existing filters built to improve AC power supply quality could be used in some configuration.
Or perhaps there are some creative low(er) cost solutions to improve individual electrical loads. For example led lights or central heating water pumps (tiny inverter driven). Those electric pumps are running 24/7 in winter. They are supposed to draw 20W~50W on their setting, but it is measured more like 200W (with two of them). Perhaps sticking an isolation transformer between them and AC line would help? I don't know. So what do you think?