Search

Updating the road infrastructure requires the potential mass adoption of the road studs currently used in car detection, speed monitoring, and path marking. Road studs commonly include RF transceivers connecting the buried sensors to an offsite base station for centralized data management. Since traffic monitoring experiments through buried sensors are resource expensive and difficult, the literature detailing it is insufficient and inaccessible due to various strategic reasons. Moreover, as the main RF frequencies adopted for stud communication are either 868/915 MHz or 2.4 GHz, the radio coverage differs, and it is not readily predictable due to the low-power communication in the near proximity of the ground. This work delivers a reference study on low-power RF communication ranging for the two above frequencies up to 60 m. The experimental setup employs successive measurements and repositioning of a base station at three different heights of 0.5, 1 and 1.5 m, and is accompanied by an extensive theoretical analysis of propagation, including line of sight, diffraction, and wall reflection. Enhancing the tutorial value of this work, a correlation analysis using Pearson’s coefficient and root mean square error is performed between the field test and simulation results.

The increased penetration of large-scale renewable energy sources may result in ac grids with low inertia, where a sudden generation shortfall could lead to a high rate-of-change-of-frequency (RoCoF). Under such conditions, high-voltage direct-current (HVdc) links are expected to provide fast frequency support to contain frequency deviations within statutory limits. This may be achieved by introducing supplementary loops to the conventional controllers of HVdc converters. However, the response time of typical frequency support schemes is limited by the ramp rate and magnitude of the additional active power through the converters. To overcome these limitations, a temporary overproduction with droop (TOD) control scheme is presented. TOD provides fast frequency support to disturbed ac grids through the injection of additional active power by HVdc converters. A three-terminal meshed HVdc grid implemented on a hardware-in-the-loop test-rig and modeled in Simulink is used to demonstrate the effectiveness of the scheme. Experimental and simulation results exhibit good agreement.