UNIVERSITY PARK, Pa. — In power grids, oscillations — or fluctuations in voltages, currents and frequency — can negatively impact equipment life, degrade the quality of service provided to end users and destabilize the grid. When oscillations happen, operators reduce or disconnect the power output from renewable sources, forcing the demand to be supplemented by generators at short notice, which are typically non-renewable, high-polluting and costly. When this happens, consumers can experience large-scale power cuts or even blackouts.
Nilanjan Ray Chaudhuri, associate professor of electrical engineering, was awarded a three-year, $450,000 grant from the National Science Foundation to address these oscillations through modeling the cyber-physical power grid using novel approaches and identifying ways to damp the oscillations in the face of anomalies in sensor measurements, such as cyber-attacks. Constantino Lagoa, professor of electrical engineering, will collaborate on the project as co-principal investigator.
Chaudhuri spoke with Penn State News about the problems power grids face today and the potential solutions the proposed research can address.
Q. Has it been difficult to introduce renewable energy into existing power grids? How so?
Chaudhuri: Unlike conventional power generation driven by fossil fuels, renewable generation depends on the variability of sources like solar irradiance and wind speed. Power electronic converters, often called inverters, are used to help interface such generators with the grid and control them. Large-scale integration of inverter-based renewable resources (IBRs) in the grid with simultaneous retirement of “traditional" synchronous generators decreases the system’s strength and poses new challenges in terms of the operation and stability of the grid. In particular, sub- and potentially super-synchronous oscillations have been observed, which can cause significant disruptions. Operators have only dealt with these problems in a reactive manner — including reducing the output power or even temporarily shutting down the renewable plants — and a proper systematic approach in solving such problems during network operation is lacking.
Q: How will this project seek to minimize the number of oscillations in power grids?
Chaudhuri: The proposed innovations in modeling the cyber-physical power grid will help analyze the root cause of such oscillations even for a large-scale power grid in offline planning stages. This can help take preventive actions like controlling a redesign to avoid oscillations. When oscillations appear, we will use the wide-area measurement systems — a sensor network used in power systems — to detect the oscillations and their source in the control center. Once detected, we will use new algorithms to increase or reduce the power output of the IBRs to dampen the oscillations.
Another approach is to use advanced control algorithms, which do not require any intervention from a control center, to modulate the power output in response to oscillations. Both approaches will use the sensor and communication network of the power grid.
Q. Are the sensors vulnerable to cyberattacks? Does the project help in this regard?
Chaudhuri: The sensors and communication network of the power grid may become vulnerable to cyberattacks. The project proposes methods to choose appropriate locations to install the sensors and create a dynamic grouping of those sensors to facilitate the detection of crafty cyberattacks. Novel approaches are proposed to detect data anomalies and correct those anomalies before the data is used for oscillation monitoring and control.
Q. Are there any other broader impacts of the project?
Chaudhuri: The proposed research is timely and important because it directly addresses the challenge of stabilizing oscillations in grids. Beyond publishing, engaging with students and informing curricula at Penn State, we plan to engage the important stakeholders facing the challenge of oscillations at the interconnection level. We also plan to interface with the Energy Systems Integration Group, an industry consortium focusing on the changing power grid.
The proposed research will be integrated into the one-week summer camps offered by Penn State’s School of Electrical Engineering and Computer Science called Anything is POssible for Girls in Electrical Engineering. In addition, the proposed project outcomes will be incorporated into high school outreach activities via high school lectures at Penn State.