# Smart Grid Protection, Automation and Control: Challenges and Opportunities
## 4 Time Management and Synchronization  
In IEC 61850-9-3:2016 [58, 59], for the electrical systems design phase, the calculation of timing inaccuracy has to be done to ensure the proper processing and synchronization of time, particularly where communication utilizing sample values (SV) is used. The proper configuration of GMC will be needed with prioritized standards such as IEC 61588 and UNE-EN IEC 62439-3:2022 [23], among others, for proper synchronization [60]. The implementation of PTP is a challenging task in virtualized environments because virtualization latency occurs. However, such difficulties can be reduced by the application of different solutions, such as hardware support for PTP or passthrough [55, 61]. For less critical applications, the alternative could be NTP. Precise time synchronization, which depends on proper network configuration and validation, is an important factor in modern electrical systems' reliability and effectiveness [62]. The verification of GNSS-related requirements, such as multi-GNSS support and spoofing and interference detection, significantly improves the reliability of the system, and such considerations are critical for the stability and security of the power grid. The main aspects can be seen in Table 12. This at least challenges the latency and consistency of implementation for the Precision Time Protocol in virtualized environments. IEC 61850-90-4 itself provides the essential time synchronization for the VPAC system, but even this in practice requires a lot of careful planning and thorough validation to impart the required precision and reliability within the critical infrastructure. Precise time synchronization is required for protection systems to perform optimally in electrical networks, mainly in applications that involve more than one input of sampled values, such as differential protection functions of transformers and buses. Different methods for time synchronization have specific characteristics and applications [56, 63, 64], as given in Table 13. Each of these timing methods has a different relative accuracy, and is thus suited for different applications. GPS and PTP are the most accurate methods and are necessary for critical applications. The IRIG-B is less accurate but is appropriate for a lot of the substation applications; NTP is appropriate where a very accurate time is not needed. Precision Time Protocol PTP, as defined in IEEE 1588 [65], is a key enabler of high-precision synchronization for distributed systems, in particular for a critical infrastructure like electrical grids. This would mean the careful consideration and proper implementation of PTP, more so in virtual environments where accurate time would have to be distributed across all network elements. The best practices and key considerations that shall form the basis for the successful implementation of PTP, taking into consideration network configuration, latency management, consistency across virtualized environments, and strict testing and validation procedures, are summarized in Table 14. Such considerations are fundamental to maintaining the high level of precision and reliability required by today's modern electrical systems.