Does Canada Have a Power Line Network Harmonics Problem?
It would seem so, based on efforts by the Canadian Electrical Association to have the Canadian Standards Association to adopt International Electrical Commission harmonics limit standards 61000-3-2 (0-16A) and 61000-3-12 (16A-75A). The rationale given for limits on such currents is to prevent degrading the quality of the power available to where the products might no longer function correctly, or where (in rare cases) one of the system wires may overheat (covered by NEC articles 310.15 (4)(c), 368.258, 400.5 (B), Table 520.44 Note, and FPN's in 210.4, 220.61(C), 310.4(A) Exception No. 2, 310.10). The harmonic currents are generated by certain types of products which use electronics to adjust the building supply voltage to a generally lower level for other operational electronics, or, increasingly, to operate equipment in a much more efficient manner in response to energy and environmental concerns. Electronic lamp ballasts, computers, most consumer electronic equipment, some home appliances, electric vehicle battery charging systems, and adjustable speed motor drives are typical of products using such power electronics. Even new environmentally desirable products such as PV arrays and wind turbines must use electronic power converters that can generate harmonic currents.
At first glance, adopting such standards seems to be a reasonable approach for protecting other sensitive equipment and building and system wiring, especially since such standards are already mandatory in Europe. So where's the rub?
The problem is that the most cost effective means of controlling harmonic currents is at a system level rather than at the product equipment level. And numerous studies have shown that the current and predicted levels of harmonic current in buildings today is significantly less than the level that could cause damage or operational difficulties for equipment, and does not even exceed target planning levels. In contradiction, some utility interests imply that the increasing density of such loads could potentially result in future issues if the overall load profile changes.
The effort to have CSA adopt the IEC standards, which were originally developed based on European power line network characteristics, could force product manufacturers to add additional harmonic control circuitry to products marketed in Canada. This has continued for years in spite of information pointing out the shortcomings of the adoption effort and continued opposition by many industries. There is also the issue of potential trade distortion within North America if the US, Canada, and Mexico have disparate requirements. Further, since the network is in need of a major upgrade to serve future needs, the right answer is to make the entire grid more robust so that it would not be susceptible to such a new load profile. Consideration of this topic needs to be included in any Canadian-US effort concerning Smart Grid, especially given the interconnection between the two electrical systems.
Needless to say, this topic is still very much under discussion and only time will tell whether these or similar requirements will or will not be adopted.
08-10-2009 2:53 PM