Number of PWM pins on STM32F072
I don't think that ST has any microcontroller with 30 pwm outputs but with such low frequency you don't really need it. There's a 1 ms interrupt with systick that will provide you with 10 levels of brightness at 100Hz.

Each time the interrupt is triggered set or reset an io pin, you'll have to keep track of 30 variables, one for each pin. It's really easy and you are only limited by the chip pin count.