The thermoelectric power (TEP) for (Y1-xCax)Ba2Cu3sO6.1 and (Pb0.5Cd0.5)Sr2 (Y1-xCax)Cu2O7 have been measured. The temperature dependence of TEP for these two series show very similar characteristic curves, which may be associated with the 0102 plane contributions. By comparing the data of these two different compound systems, we have shown that (Pb,Cd)O layers have negligible contribution to TEP in underdoped region. And, by comparing our results with those of Zn-doped Y-123 compounds, we suggest that the suppression of interlayer coupling may be the reason for the disappearance of a hump in the normal state TEP.