This paper listed the mathematic model of transmission line firstly, and PSASP was used to simulate the fluctuate voltage of transformer substation which affected by wind generate electric power capacity which combined to the grid changed and the power flow of XINJIANG sent into GANSU changed. At the end, the conclusion and construction of improve grid running state was presented.

A novel structure for CMOS four-quadrant analog multiplier is presented. The multiplier is based on the square law of MOSFET. To enlarge the input impedance and improve the linearity, CMOS source coupled pair was employed. Also active attenuator was used to enhance the input range. Compared with the traditional multipliers based on Gilbert cell, the proposed circuit features high linearity, high input range. Circuit simulation using HSPICE with 0.5μm CMOS technology shows that under ±2.5V supply the proposed multiplier provides linear range of more than 50% of the voltage supply, THD is 0.3% at 100kHz and 0.8% at 1MHz, -3dB bandwidth is 2.5MHz, and the power consumption is 5mW.