While power electronics equipment can enhance efficiency and control, they can also cause distortions in the power system, leading to power quality issues. Harmonics, which distort the standard sinusoidal waveform of power, can result in various problems such as equipment overheating, malfunctions, and inefficiencies. Solid-state power meters are often considered a reliable method for power measurement, including harmonic power monitoring. But is this presumption accurate? These devices are expected to deliver precise and instant data, thereby also improving power quality management.
Traditional billing methods may not accurately represent actual power consumption in these situations. Hence, the idea of balanced billing is to be introduced. Balanced billing strives for fair and precise billing by considering the complexities of unbalanced and non-sinusoidal voltage supply.
In a previous blog post, I showed how consumers could face significant financial impacts on their electricity bills due to imbalanced network situations. On the other hand, electricity producers, regardless of whether they use coal-fired power plants, nuclear energy, or renewable sources, might remain unaffected. This indifference stems from the potential profit increase they could gain from the inefficiencies caused by these imbalanced network conditions.
Electronic meters improve the accuracy of active power measurements by including harmonics filtering. As domestic electrical appliances become more sophisticated, they produce higher harmonic levels that need to be considered in the active power measurement. While electromechanical methods can measure harmonic power up to the 5th harmonic, electronic methods can accurately estimate up to and beyond the 63rd harmonic.
Including harmonics in active energy calculations improves the accuracy of billing and grid management, especially as the occurrence of non-linear loads in domestic appliances increases. Without a standardized method for measuring harmonic power, a qualitative evaluation of electronic energy meters can help determine if a solution is capable of such measurement. Recent advancements in integrated circuit technology, as indicated by Analog Devices’ ADE product line, now allow energy meter designers to provide low-cost harmonic energy measurements, meeting the changing needs of energy providers.
Utility companies often levy additional charges on medium and large customers with low power factors. However, these charges can be unfair in situations where the installations are subject to voltage imbalance and harmonic distortion. It is crucial to establish the fairest definitions of Power Factor (PF) and their corresponding measurement methods when powering a constant impedance load or an induction motor with unbalanced and non-sinusoidal voltages.
Fairness is defined by the expectation that a meter, built based on a specific definition and measurement method, should produce values under non-ideal supply conditions that are very close to those it would yield under an ideal balanced sinusoidal supply.
To achieve this, both meter manufacturers and power distribution companies need to include a variety of computational simulation methods in their design and production processes. These methods should simulate different scenarios where a balanced customer, represented as a constant impedance load or an induction motor, incurs costs due to a voltage supply that is no longer balanced and sinusoidal. The same methodology should be applied to an induction motor under a wide range of unbalanced, non-sinusoidal supply situations.
It is crucial for utilities to have the confidence to install any meter in any electrical environment (sinusoidal or non-sinusoidal) knowing that they will all produce identical readings for the same load. Anything less is unacceptable.
My personal question is: is this being implemented? Prepaid meters were introduced many years ago when the phenomenon of harmonics, or the distortion of the normal sinusoidal waveform of power, was perhaps completely unknown. However, those prepaid meters have not been replaced, and I question whether the “new smart meters” are constructed based on the principles discussed in this paper.