Study on Asynchronous Sampling in Digital Electrical Energy Metering Based on IEC61850

Technical issues regarding asynchronous sampling for digital electrical energy metering based on IEC 61850 are studied. Asynchronous sampling is inevitable when the power network frequency fluctuates. The additional metering error caused by asynchronous sampling is simulated and discussed. The additional error can be as big as 2% under typical conditions, which is unacceptable. Quasi-synchronous sampling algorithm is employed to reduce the error. Simulation result shows that it can reduce the error to an ignorable level. The error under extreme conditions is also simulated and discussed.