The development of renewable energy sources can help optimise energy structures and alleviate environmental problems. However, the integration of large-scale distributed renewable energy sources into power distribution systems may lead to reverse power flows and over-voltage. In addition, the simultaneous charging of numerous electric vehicles may result in under-voltage. To address this issue, a collaborative voltage regulation algorithm for regulating the operating power of aggregated air conditioners is developed in this study. First, a thermal model of a room is developed for analysing the dynamic operation processes of an air conditioner. Based on the thermal model, the regulation power provided by the aggregated air conditioners can be calculated, by temporarily resetting the set temperatures. Furthermore, the node voltages can be regulated by increasing/decreasing the operating power of the air conditioners. In addition, a participation priority algorithm is proposed for selecting the most suitable air conditioners for regulation. The numerical test results show that the proposed method can control the node voltage fluctuation within the permissible limits, and can maintain the room temperature within a suitable range. Thus, using thermal modelling and the proposed collaborative algorithm, voltage regulation services can be provided by utilizing the air conditioners, without affecting occupant comfort.