Virtual Internships in Southern California Edison
By Matthew Gomez, Adam Pham, and Manuel Avendaño
Southern California Edison Company (SCE) serves a population of approximately 15 million in a 129,500-square-kilometer service area within Central, Coastal, and Southern California, USA. SCE is building the grid of the future to support more clean energy, make way for more electric vehicles, and to protect against the impacts of extreme weather. Creating this clean energy future takes all kinds of talent and people. From craft workers to engineers, data scientists to environmental and cyber experts, and everything in between. SCE increases its talent pipeline through internships and offers these programs with the belief that learning, and development are important parts of building upcoming leaders. With COVID-19, SCE has had to work quickly to find new, innovative, and safe ways to handle its internship program. This article provides an overview of SCE’s internship program in 2020 and discusses two recent projects led by SCE interns.
SCE’s Summer Internship program is a ten- or twelve-week paid opportunity to gain hands-on experience with meaningful work, while developing skills, and building networks. Typically, interns also can participate in intern mixers, executive speaker series, site tours, community volunteer events, and cross-company networking. In 2020, due to evolving changes related to the COVID-19, SCE decided to run its entire internship program virtually for the first time. As a result, interns have been asked to leverage digital tools such as video interviewing and other formats. SCE recently kicked off its annual summer internship program and more than 150 interns are gaining real-life experience through virtual internships. Highlights of the virtual internship program include:
- Maintained the tradition of meaningful work and a robust event engagement experience virtually
- Intern orientation was conducted via Adobe Connect to educate interns about critical SCE information
- A dedicated team within SCE team planned a variety of virtual educational and various networking events, for example, speaker events, Ally 101 training, résumé review, brown bags, and so forth
- An Intern Expo was conducted live via Microsoft Teams, giving interns the opportunity to present the projects they worked on throughout the summer company-wide
Intern Project #1 – Maximum Flows Study
One of the intern projects was to analyze the reliability of a major transmission path connecting SCE’s system and a large municipal facility by means of maximum flows study. Computer models of the bulk electric system forecasted to the summer of 2025 were used to stress the transmission path to its rated maximum and observed the impact on the overall reliability of the system. The performance of the system was analyzed under both steady state and transient conditions using PowerWorld simulator. In steady state, the system must not experience thermal overloads on any lines or transformers above 100% of their limits. Under transient conditions, bus voltages must recover to their pre-fault operating point after a fault is cleared and the system must settle around a new equilibrium for the system to be considered stable.
Once the power flow on the path of interest was increased to its maximum, a contingency analysis was performed. Several possible outages that could occur within the system were simulated to ensure that system performance meets regulatory standards. The contingency analysis revealed several voltage and line overload violations that needed to be addressed to maintain normal operating conditions. An additional voltage stability analysis was performed to determine the system response to large disturbances, i.e., line or bus faults followed by the opening of lines or transformers to clear the fault. The bus voltages at key buses of the US Western Interconnection were visualized and analyzed to determine whether the system is performing optimally.
The results of this study show the impact that the transmission path of interest has on the overall performance of the bulk electric system. For most of the transient contingencies, the voltages stabilize after faults are cleared. There are a few instances where the recovery of the bus voltages is delayed, however, this is to be expected with the use of new dynamic load models. Overall, bus voltages reach their pre-fault operating point after several seconds and all transient stability performance violations were investigated and mitigated.
Intern Project #2 – Bulk Power System Limit Study
Another intern project was a study of a major transmission path that consists of a group of facilities within the Western Interconnection. The purpose of the study was to maximize the flow across the major transmission path and determine potential system limits during single and multiple contingency events (i.e., unplanned outages). Although operators have a regulatory obligation to intervene (i.e., secure the system by making necessary system adjustments) within 30 minutes following contingency events, the study assumes the operator does not have adequate time to adjust the system within 30 minutes of the event.
The study particularly focused on overlapping single contingencies, where two unrelated outages (e.g., loss of two separate transmission lines) occur within 30 minutes of each other and the operator fails to intervene. The operator’s inability to adjust the system in-between overlapping single contingencies can impact the overall transmission system reliability and can cause instability, uncontrolled separation, or cascading outages. As such, the system may not be able to regain a state of equilibrium after being subjected to such a disturbance. The study, therefore, identified potential bulk power system limits that can be provided to real-time operators for situational awareness. Ultimately, awareness of system limits is crucial to ensuring the safe and reliable operation of the grid during real-time conditions.
The study was conducted using PowerWorld to process simulated contingencies in the form of steady state and transient stability analyses. The initial conditions of the bulk system computer models were based on the forecasted load and generation of the chosen study year. Steady state analysis was performed to identify what issues may arise for simulated contingency events. Contingencies that resulted in thermal loadings above 100% of the associated transmission line emergency ratings were identified. This approach is carried out for all elements above 100kV within SCE’s planning area. Transient stability analysis was performed to see how the power system stabilizes after a large disturbance, such as a fault. Finally, the path was stressed up to 5% above its rating, before voltage stability simulations were performed during contingency events.
The results of the study indicate whether a potential cascading event will occur when a major transmission path flow is maximized, and system adjustments in-between unplanned outages are not made quickly by the operator. The results and findings are subsequently documented in a report and shared with the California Independent System Operator, who oversees the operation of California's bulk power system.
This article edited by Mehrdad Rostami
For a downloadable copy of the October 2020 eNewsletter which includes this article, please visit the IEEE Smart Grid Resource Center.
Manuel earned a bachelor’s degree and a master’s degree in Electrical Engineering in Mexico and a PhD in Electrical Engineering in United Kingdom. Manuel, a Senior Member of IEEE, currently serves as the Chair of the IEEE Distribution Subcommittee and Chair of the R&D Committee of IEEE Smart Grid.