Erieke Weitenberg

Claudio De Persis, Erieke Weitenberg, Florian Dorfler

A novel power consensus algorithm for DC microgrids is proposed and analyzed. DC microgrids are networks composed of DC sources, loads, and interconnecting lines. They are represented by differential-algebraic equations connected over an undirected weighted graph that models the electrical circuit. A second graph represents the communication network over which the source nodes exchange information about the instantaneous powers, which is used to adjust the injected current accordingly. This give rise to a nonlinear consensus-like system of differential-algebraic equations that is analyzed via Lyapunov functions inspired by the physics of the system. We establish convergence to the set of equilibria consisting of weighted consensus power vectors as well as preservation of the weighted geometric mean of the source voltages. The results apply to networks with constant impedance, constant current and constant power loads.

Thomas Rooijakkers, Anne Nijsten, Cristian Daniele et al.

Many business processes currently depend on web services, often using REST APIs for communication. REST APIs expose web service functionality through endpoints, allowing easy client interaction over the Internet. To reduce the security risk resulting from exposed endpoints, thorough testing is desired. Due to the generally vast number of endpoints, automated testing techniques, like fuzzing, are of interest. This paper introduces WuppieFuzz, an open-source REST API fuzzer built on LibAFL, supporting white-box, grey-box and black-box fuzzing. Using an OpenAPI specification, it can generate an initial input corpus consisting of sequences of requests. These are mutated with REST-specific and LibAFL-provided mutators to explore different code paths in the software under test. Guided by the measured coverage, WuppieFuzz then selects which request sequences to send next to reach complex states in the software under test. In this process, it automates harness creation to reduce manual efforts often required in fuzzing. Different kinds of reporting are provided by the fuzzer to help fixing bugs. We evaluated our tool on the Petstore API to assess the robustness of the white-box approach and the effectiveness of different power schedules. We further monitored endpoint and code coverage over time to measure the efficacy of the approach.

Erieke Weitenberg, Claudio De Persis, Nima Monshizadeh

We investigate the performance and robustness of distributed averaging integral controllers used in the optimal frequency regulation of power networks. We construct a strict Lyapunov function that allows us to quantify the exponential convergence rate of the closed-loop system. As an application, we study the stability of the system in the presence of disruptions to the controllers' communication network, and investigate how the convergence rate is affected by these disruptions.