# An Integrated Testbed for Power System Cyber-Physical Operations Training
## 4 CPS Testbed Applications
### Module 1: Power Distribution System SCADA Operator Training  
Power distribution systems are responsible for delivering power from transmission systems to end customers through high-, medium-, and low-voltage lines. A co-simulation between Survival SCADA and the power distribution system was performed in this module to primarily study the protection performance in HIL testbeds. The power network simulated in OPAL-RT is based on an integrated sub-transmission and distribution network from Lubbock, TX, USA. It consists of 3 voltage levels--345 kV, 69 kV, and 12.47 kV--and has 24 substations and 41 lines. Figure 3 shows the CPS testbed and system models. For simulation efficiency, only 4 of the 24 substations were modeled in detail: Hurld Wood (HW), Wolffforth (WF), Vicksburg (VB), and Northeast (NE). These substations have a proper bus arrangement configuration, measurements, and controllable breakers and switches, whereas others only have bus connections. Figure 4 shows the NE substation modeling; similar modeling was conducted for HW, WF, and VB but with different bus configurations. NE has a sectionalized bus on its HV side (69 kV) and a double-bus single-breaker configuration on its MV side (12.47 kV). This substation is responsible for four MVA feeders. There are measurements on both high- and low-voltage sides of the transformers and each feeder output. For each of the detailed substations, virtual IEDs were created as DNP3 slaves. These IDEs are responsible for collecting and organizing all of the analog and status points from the substation, such as breaker status, three-phase voltage, and current magnitude and angle. All of the available points from the substations' IED are mapped and organized in Survalent SCADA. The SCADA GUI is responsible for providing an operator's interface with the electrical system. When the simulation is initialized, it is possible to visualize the real-time information for each bus, breaker, and switch on the four detailed substations. The green color indicates that the switch/breaker is open, and red indicates that it is closed. In addition, red lines represent 345 kV, green 69 kV, and purple 12.47 kV, whereas de-energized lines are shown in white. With this system setup, the module's test case is based on a short-circuit and protection analysis. A protection study was developed for the first feeder of the NE substation, where instantaneous (ANSI 50) and temporized (ANSI 51) overcurrent settings were computed along with reclosing (ANSI 79) shots and temporizations for two real SEL relays [53]. Figure 3: Distribution system testbed topology. The protection study starts with the feeder's current levels, presented in Table 2, where \(I_{maxload}^{bus}\) is the maximum load current, \(I_{3\phi S\text{C}}^{bus}\) is the three-phase short-circuit current, and \(I_{1\phi S\text{C}}^{bus}\) is the single-phase short-circuit current for each relay's bus. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Bus** & \(I_{maxload}^{bus}\) [**A**] & \(I_{3\phi S\text{C}}^{bus}\) [**kA**] & \(I_{1\phi S\text{C}}^{bus}\) [**kA**] \\ \hline A & 115 & 17.5 & 2.7 \\ B & 90 & 10.5 & 2.5 \\ C & 43 & 2.7 & 1.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Relay buses’ current levels. Figure 4: Northeast substation: (**a**) one-line diagram; (**b**) HYPERSIM modeling; (**c**) Survalent GUI. The CTs are dimensioned based on Equation (1), considering a secondary level of 5A. The obtained value is rounded up to the closest commercial value. \[CTR^{bus}=\frac{\frac{1_{3\phi SC}^{bus}}{20}} \tag{1}\]  
Equations (2) and (3) show the element 50 pick-up, \(I_{pickup}^{50-bus}\), a calculation based on the current levels for buses A and B, respectively. \[I_{pickup}^{50-A}>1.25.\frac{I_{3\phi SC}^{B}}{CTR^{A}} \tag{2}\]  
\[I_{pickup}^{50-B}>1.25.\frac{I_{3\phi SC}^{C}}{CTR^{B}} \tag{3}\]  
Equations (4) and (5) show the pickup current for element 51 of buses A and B, respectively.