High level of delivered power quality (PQ) is becoming one of the key performance indicators for both contemporary and future power networks. The increased proliferation of converter connected generation and load in power networks, increased sensitivity to network disturbances of some of these new types of devices and requirements for more flexible operation of power networks led to the revision of some of PQ standards and introduction of modified or in some cases new requirements for PQ compliance. Although almost all PQ phenomena, with exception of voltage transients, are well defined and appropriate thresholds for individual phenomena are set in international standards, there is no standardised nor commonly accepted way to describe and evaluate the overall PQ performance at buses. This study presents an analytic hierarchy process (AHP) inspired methodology for assessing the overall PQ performance at a bus based on several different PQ phenomena considered simultaneously. Compound bus PQ index is defined using AHP to present the overall PQ performance at the bus with respect to voltage sag, harmonics and voltage unbalance. The application of the methodology is illustrated on a 295 bus generic distribution network.