High penetration of solar energy can result in voltage rise in midday, while growth in residential air conditioning is the main contributor of overloading and voltage drop issues during peak demand time. This paper provides a hierarchical control scheme to coordinate multiple groups of aggregated thermostatically controlled loads to regulate network loading and voltage in a distribution network. Considering the limited number of messages that can be exchanged in a realistic communication environment, an event-triggered distributed control strategy is proposed in this paper. Through intermittent on and off toggling of air conditioners, the required active power adjustment is shared among participating aggregators to solve the issue. A case study is conducted and simulation results are presented to demonstrate the performance of the proposed control scheme.