| 摘要 |
PURPOSE:To calculate an accurate effective value regardless of variation in system frequency by calculating the effective value, active power, and reactive power from two sampling data in time series. CONSTITUTION:Multiplication parts 301 and 302 calculates the products of sampled values i1 and v2, and v1 and i2 of a current and a voltage respectively, and a block 303 subtracts the output of the multiplication part 302 to find v2i1-i2v1. A division part 304, on the other hand, divides a variation DELTAf in frequency by a reference value f0 of frequency and multiplication parts 305-307 halve the outputs of the division part 304 and multiplication parts 305 and 307. Further, an addition part 308 adds the outputs of the multiplication parts 305-307, an addition part 309 adds '1' to the output of the addition part 308, and a block 310 halves the output of the addition part 309 to obtain sinomegaDELTAt. A division part 311, on the other hand, divides the output of the block 303 by the output of the block 310 to obtain the reactive power Q. Thus, the accu rate effective value is calculated. |
