1. Metering Center of Yunnan Power Grid Co., Ltd., Kunming 650200, China
2. Department of Automation, Lublin University of Technology, Nadbystrzycka 38D, 20-618 Lublin, Poland
3. Department of Measuring-Information Technologies, Lviv Polytechnic National University, 79013 Lviv, Ukraine
4. Department of Automatics and Metrology, Lublin University of Technology, Nadbystrzycka 38D, 20-618 Lublin, Poland