# An Integrated Testbed for Power System Cyber-Physical Operations Training
## 3 CPS Testbed Architecture  
The proposed CPS testbed is designed to be flexible enough to provide interactive training to industry professionals and be as reliable as possible compared to real-world applications. Figure 1 presents the testbed structure, which is divided into four different layers: the power layer, the hardware layer, the communication layer, and the application layer. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Literature** & **Year** & **Research Topic** & **Novelty** & **Co-Simulation** & **Real Time** & **IDS** \\ \hline \multirow{4}{*}{[11]} & \multirow{4}{*}{2015} & The impact of cyberattacks on & \multirow{4}{*}{Reconfigurable testbed} & No & No & No \\  & & power grids was studied in a & & & & \\  & & simulated power network and an & & & & \\  & & emulated communication network. & & & & \\
[39] & 2015 & Development and application of & \multirow{4}{*}{Real-time simulation} & No & Yes & No \\  & & real-time testbed for CPS & & & & \\  & & ICS for the deployment of & \multirow{4}{*}{Emphasizes the optimal} & \multirow{4}{*}{No} & \multirow{4}{*}{No} & \multirow{4}{*}{No} & \multirow{4}{*}{No} \\
[18] & 2016 & cybersecurity methods was studied & & & & \\  & & using different attack scenarios. & & & & \\  & & & ICSs & & & \\
[40] & 2018 & Detection of stealthy cyberattacks in & \multirow{4}{*}{Study of hybrid and} & \multirow{4}{*}{Yes} & \multirow{4}{*}{Yes} & \multirow{4}{*}{Yes} \\  & & the smart grid & & & & \\  & & CPS testbed for wind energy & \multirow{4}{*}{HIL simulation} & \multirow{4}{*}{Yes} & \multirow{4}{*}{Yes} & \multirow{4}{*}{No} \\
[41] & 2020 & & systems & & & \\
[42] & 2021 & CPS testbed studying MITM attack & \multirow{4}{*}{FDIA and MITM attacks} & \multirow{4}{*}{No} & \multirow{4}{*}{No} & \multirow{4}{*}{Yes} \\  & & detection and defense & & & & \\  & & & layer & & & \\
[43] & 2021 & Real-time co-simulation testbed for & \multirow{4}{*}{Use of SEL-3530 with} & \multirow{4}{*}{Yes} & \multirow{4}{*}{Yes} & \multirow{4}{*}{No} \\  & & inverter-based microgrids & & & & \\
[44] & 2021 & A real-time CPS testbed to study & \multirow{4}{*}{Use of EXata CPS for} & \multirow{4}{*}{Yes} & \multirow{4}{*}{Yes} & \multirow{4}{*}{No} \\  & & cyber threats and risk assessments & & attack simulation in real & & \\  & & time & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Most recent studies on CPS testbeds for power system applications. Figure 1: Cyber–physical testbed topology. Within the OPAL-RT real-time digital simulator, both the network and physical layers are modeled. At the bottom level, the power network is modeled through lines, loads, generators, switches, and transformers. Above it, there are virtual IED models responsible for measuring the point of connection. In equipment such as switches, the IED is also responsible for controlling the opening and closing of that device based on its internal logic or external commands. On a third level, the communication for each of these IEDs is defined by MODBUS and DNP3 protocols. Even though still inside the OPAL-RT, the simulator has the capabilities to model IP addresses and communication protocols and use simulated values as data points. Besides virtual modeling, the OPAL-RT is also integrated into real IEDs. The hardware layer is based on the connection between the simulator and the IEDs, which is achieved by analog and digital wires, which provide voltage and current measurements to the IED inputs. From a real IED point of view, its measurements are coming from an actual real system, as they would be installed in the field. It is worth highlighting that the IEDs are protective relays and automation controllers from the SEL manufacturer, which are widely used worldwide for power system monitoring, protection, and control. The application layer is primarily compounded by the SCADA software, along with physical and cyber models of the system. USA power utilities commonly use the Survalent system to provide visibility and control power system networks and substations.