# Smart Grid Protection, Automation and Control: Challenges and Opportunities
## 3 Evolution of Substation Architectures and Digital Modernizations for Smart Substations
### Virtualization of Protection, Automation and Control (VPAC)
\begin{table}
\begin{tabular}{p{85.4 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Aspect** & \multicolumn{1}{p{113.8 pt}}{**Traditional Protection Systems**} & \multicolumn{1}{p{113.8 pt}}{**CPAC Systems (e.g., SSC600)**} & \multicolumn{1}{p{113.8 pt}}{**VPAC Systems**} \\ \hline Network Dependencies & Less reliant on complex networks; simpler communication protocols. & Highly dependent on robust network infrastructure; requires redundancy in communication paths. & Strong dependency on network reliability; latency and bandwidth can impact performance. \\ \hline Software Vulnerabilities & Limited software components reduce the risk, but a lack of updates can expose vulnerabilities. & Regular software updates and rigorous testing are essential to prevent failures. & Increased risk due to the complexity of the virtual environment; robust management of the software lifecycle is critical. \\ \hline Maintenance and Testing & Maintenance-intensive; testing can be cumbersome due to multiple devices. & Simplified maintenance with fewer devices; regular testing in simulated environments is crucial. & Virtualized testing environments allow for extensive testing but require careful management. \\ \hline Scalability and Flexibility & Limited scalability; difficult to adapt to new requirements. & Highly scalable and flexible; easy to reconfigure and expand. & Maximum scalability means it can quickly adapt to new demands and integrate new applications. \\ \hline \hline \end{tabular}
\end{table} 
Table 9: _Cont._assumed that the VPAC system satisfies the criteria to operate in digital substations. Such an application of standards thus allows VPAC systems to be validated toward their effective performance in real-world situations, hence offering some level of confidence to their stakeholders regarding their reliability and performance [50]. Figures and Data: The graphical figures in the technical documentation [53], such as white papers, support the illustration of performance requirements provided by IEC 61850. These figures provide the reference point, enhancing the understanding of the benchmarks needed to be reached by VPAC systems. They make it very clear and concise how the levels of performance are to be attained; this makes it much easier for the engineer or decision-maker to assess whether VPAC solutions will satisfy their needs. Challenges in the Implementation of VPAC: VPAC systems offer significant advantages but face challenges in integration with legacy infrastructure, requiring complex and costly adaptations. A common misconception is their internet connectivity; in reality, they use private networks, enhancing cybersecurity but still requiring strict protection measures. A lack of hardware standardization leads to interoperability issues, as vendors develop different specifications. Future efforts should focus on defining universal standards for seamless integration and real-time performance across vendors. Additionally, dedicated hardware resources must be efficiently managed to ensure reliability. Despite these challenges, VPAC systems hold great potential for modernizing substations while maintaining security and performance. Nevertheless, the engineering of a dedicated hardware resource would also call for managing such shared resources efficiently without compromising on system reliability [55; 56; 57]. The implementation cost varies by region and market demands: European substations can use simpler overcurrent relay arrangements, whereas in ANSI markets, which are generally more advanced and complex, with up to 20-30 control panels and multiple functions, the cost-benefit analysis may be clearly seen, hence justifying such deployments. These regional differences affect initial investment costs as well as operational costs. The migration from legacy protocols like C37.94 line differential or pilot wire to modern IEC 61850-90-5 R-SV requires greater bandwidth and adaptation to specifications in accordance with the relevant standards. Please be advised that VPAC servers do not currently support C37.94 NICs.