the frequency is related to the inductor and the input voltage (max) and the duty cycle you need to get the boost ratio...to go from 30 to 200volts requires a high duty cycle and this means a very high current ripple in a 100uH choke at 1kHz, to get 200V from 30v requires a step up ratio of 6.6667, and a duty cycle on a std booster of 0.85 (i.e. the on time is 85% and the off time is 15%) at 1kHz this is 850us, 30v across 100uH for 850uS gives a current rise of 255 amps, which likely cannot be supplied by your source and would saturate your inductor - and melt the mosfet.
At 35kHz the duty cycle is still 85%, but this is now 24.3uS, and the di in the choke is now 7.3 amps - much more acceptable (2.55 amps rms approx)
Regards, Orson Cart.