Machine type communications are ubiquitous in electrical power systems. From the perspective of performance analysis for LoRa and NB-IoT systems of low power wide area network(LPWAN), this paper provides comparison results of service capabilities between LoRa and NB-IoT systems by wireless coverage and BER transmission performance simulations of 230 MHz, 900 MHz multi-bands, and urban area, suburban area multi-scenarios. Furthermore, parameter configuration and optimization design for LPWAN to enable QoS transmission of smart grid applications are given in this paper. The proposed results and scheme could effectively guide communication technology selection and network optimization for power Internet of Things.