The invention discloses an air-conditioning
system and a control method thereof. The air-conditioning
system comprises a controller, a frequency converter, a
circulating pump, a cold water
machine set, a hot water
machine set and a coil
pipe blower group of each user end, wherein the controller is provided with a frequency-conversion protecting device used for
refrigeration; the frequency converter is used for controlling the working frequency of the
circulating pump; the
circulating pump, the cold water
machine set, the hot water machine set and the coil
pipe blower group of each user end arepositioned on a circulating water loop, the coil
pipe blower groups are respectively connected and arranged on the circulating water loop in parallel, a flow rate automatic balance adjusting valve and a temperature sensor which outputs a temperature
signal to the flow rate automatic balance adjusting valve are respectively arranged on the connection pipelines of the coil pipe blower groups, the temperature
signal output by the temperature sensor is used for switching the maximum flow rate setting value of the flow rate automatic balance adjusting valve under a
refrigeration mode and a heatingmode, the controller controls the constancy of the
temperature difference of an inlet and an outlet of the cold water machine set or the hot water machine set by adjusting the working frequency of the circulating pump, and the frequency-conversion protecting device used for
refrigeration is switched to a bypass under the heating mode. The invention can correspondingly adjust the frequency of thecirculating pump according to the load change of the
system, save energy, lower consumption and control the flow rate in the circulating loop accurately.