A method for identifying a system anomaly in a power distribution system is described herein. The system anomaly may indicate a non-technical loss or a topology error, including schematic entry errors and component modelling errors in the power distribution system. The method includes a) selecting a common coupling point in the power distribution system, wherein downstream branches are connected to the common coupling point; b) determining voltage estimates of the common coupling point according to electrical measurements from the downstream branches; and c) identifying the system anomaly by determining whether a detection criterion is satisfied using the voltage estimates.