Real Life Connections: Integrating Social Justice into the Elementary Mathematics Classroom

For this inquiry, I integrated social justice issues into the mathematics curriculum in a fourth grade classroom. My inquiry questions are: In what ways do children understand real life connections between math and social issues? How can I create meaningful learning experiences about specific social issues using mathematics? To answer these questions, I created lessons and held class discussions about three different social justice issues relevant to students\u27 lives: money, equality, and sweatshops. The data I collected included student work, my own written reflections on lessons I taught, and field notes of child observations. Preliminary findings indicate that students understand real life connections between math and social issues. I also found that the students had a better understanding of the mathematics concepts from the inclusion of social justice issues

Characterization of Interaction in an Offshore AC Grid with Large WPPs and VSC-HVDCs

© 2017 The Institution of Engineering and Technology. To exploit the full and flexible capability of offshore voltage-sourced converter high-voltage DC (VSC-HVDC) lines, interaction studies in the offshore AC grid are required but are not well understood or reported. This study examines the interaction dynamics of an offshore AC grid for interconnecting large wind power plants (WPPs). The conventional eigenvalue analysis method has limitations which make the interaction analysis of such systems difficult. Hence, in this study, an impedance-based analytical approach is employed to investigate the interaction phenomena. The impedance model of a VSCHVDC converter for both direct and vector control with outer and droop controls are derived along with the impedance model of the full-converter wind generator. The interaction dynamics of the offshore grid is predicted through the well-established Nyquist criteria and is validated using time-domain simulations. The analysis shows that the system stability is decidedly influenced by the control configurations and tuning of the VSC-HVDC lines

Dual-loop Primary Frequency Regulation Controller for VSC-HVDC System

This paper presents a frequency control mechanism for an AC system through the active and reactive power loops of a VSC-HVDC system. The proposed scheme makes use of the reactive power loop for inertia support by exploiting the voltage-power sensitivity of loads, and active power droop control has been used to provide governor-like support following the large-disturbance. The performance of the presented controller is evaluated through various simulation case studies in DIgSILENT Power Factory including small-perturbation to demonstrate the effect of the frequency controller in system electromechanical mode damping. From the set of case studies it can be found that the proposed dual-loop control has favorable effects on the frequency behaviour and the inter-area mode damping of the system. © 2017 IEEE