A cost-effective retrofit architecture for integration of legacy digital meters into advanced metering infrastructure

Advanced metering infrastructure (AMI) is critical for improving the efficiency and reliability of smart grids. However, large-scale implementation of AMI remains challenging due to high costs and logistical constraints, particularly in developing economies. This paper proposes a solution that addresses these challenges while ensuring the utilization of the remaining useful life of existing digital meters. To achieve this, a low-cost solution comprising retrofit modules, a Data Concentration Unit (DCU), and radio communication is developed. A Retrofit Module (RM) is designed to extract measurement data from digital meters through an optical or serial port. The module features firmware supporting the universal metering data exchange protocol DLMS/COSEM (IEC 62056-21) as well as the conventional Modbus protocol. The extracted meter data is wirelessly transmitted to a DCU via an onboard radio module using LoRaWAN and stored on a central storage server. The RM is tested on two different scenarios: (i) integration with single-phase meters, (ii) integration with three-phase meters. Furthermore, multiple test cases are executed using single-phase and three-phase meters from different manufacturers. The test results demonstrate the module’s efficacy in extracting digital meter data, and its power consumption profile indicates low energy usage across various operating modes. An NS-3-based LoRaWAN simulation study is conducted to evaluate the scalability of the proposed solution under varying numbers of RMs, spreading factors, and communication distances. The results demonstrate reliable data delivery with acceptable latency for large-scale deployments. Finally, a cost comparison with conventional smart meter replacement highlights the better economic prospects of the proposed solution.