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power-line-Slide3

Each power phase is represented by a current transformer (CT) and a voltage transformer (VT). This complete system comprises three such pairs. The average power in the system at any instant is calculated by rapidly taking a number of samples of the output of each transformer, performing a discrete Fourier transform (DFT) on the sampled data, and performing the necessary multiplications and summations. AC is converted to DC for transmission and then back to AC at the point of use. The transmitting power at high voltage DC reduces loss. Ploss = I2R, keeping the current low is the most efficient method. As I = P/V, the power loss in the lines Ploss =  I2R = (P/V)2*R = RP2/V2. This means that the power loss is proportional to the resistance and inversely proportional to the square of the voltage. Improved signal processing technologies make it possible to achieve better than 0.1% accuracy in next-generation systems, as compared to present system’s typical 0.5% accuracy levels. This improvement is mainly achieved with the use of high-performance simultaneous–sampling ADCs (analog-to-digital converters), which provide the resolution and performance that will be needed for future systems.

PTM Published on: 2009-07-27