Study on group key update method for distributed photovoltaic terminal control based on the SM9 algorithm

In the era of green energy development, distributed photovoltaics (PV) are experiencing rapid growth. Currently, distributed PV has become a crucial force in national energy transition and power supply security. However, the largescale integration of numerous uncontrollable PV devices poses significant challenges to grid security, which has drawn substantial attention at the national level. At present, the group scheduling and group control mechanism is widely recognized as an effective solution for integrating low-voltage distributed PV into the grid. Nevertheless, due to practical limitations such as resource constraints and difficulties in upgrading, the secure and efficient transmission of control instructions to devices has become an urgent challenge. This study proposes an innovative lightweight dynamic group key management method for a hybrid network of public and private systems, supporting dynamic group formation, on-demand group joining, and flexible group leaving of devices. This method reduces communication and computational overhead within PV device groups, achieves efficient and secure group key updates, ensures the forward and backward security of keys, addresses the challenge of efficient and secure authentication for large-scale terminals, and significantly enhances the network security level of the digital power grid.