Antilock braking system (ABS) has been designed to attain maximum negative acceleration and prevent the wheels from locking. Many efforts had been paid to design controller for ABS to improve the brake performance, especially when road condition changes. In this paper, an adaptive fuzzy fractional-order sliding mode controller (AFFOSMC) design method is proposed for ABS. The proposed AFFOSMC combines the fractional-order sliding mode controller (FOSMC) and fuzzy logic controller (FLC). In FOSMC, the sliding surface is PDα, which is based on fractional calculus (FC) and is more robust than conventional sliding mode controllers. The FLC is designed to compensate the effects of parameters varying of ABS. The tuning law of the controller is derived based on Lyapunov theory, and the stability of the system can be guaranteed. Simulation results demonstrate the effectiveness of AFFOSMC for ABS under different road conditions.
Accurate timestamping with 1 µs precision is required by power system monitoring and control equipment, including: Phase Measurement Units (PMU) for real-time measurement and control; travelling wave detectors for fault location, protection and control; and sample value measurement techniques associated with the IEC 61850 process bus. The conventional way of achieving this is to transmit 1-PPS or IRIG-B timing signals using dedicated cables but such an approach is expensive and difficult to update as secondary control systems evolve. IEEE 1588 precision time protocol (PTP) allows the transmission of time information with submicrosecond accuracy in an Ethernet network. However, a comprehensive study is required to enhance the confidence of the power industry in using PTP in present and future IEC 61850 based substations. This paper delivers a design and experimental validation of the real-time time synchronisation characteristics achievable with IEEE 1588. Several factors which can potentially affect the synchronisation accuracy in delivering a time reference from the master clocks to the end devices during both steady-state and transient changes were investigated. The objective is to increase the understanding of the real-time performance of a complete IEEE 1588 timing system applied in transmission substations, and identify the limitations of commercially-available devices.
This paper introduces an analytical method, based on the Complex Network Theory (CNT), to assess the risk of the Smart Grid failure due to communication network malfunction, associated with latency and ICT network reliability. Firstly, the communication architecture is modelled using a two-step CNT frameworkan Operation Graph (OG) in step one and a Reliability Graph (RG) in step two. Secondly, the latency of data packets and the reliability of each communication device are incorporated into the model to identify the reliability of all operational communication paths for successful power system control purposes. Then, the risk of Smart Grid failure due to the communication network malfunction is quantified using a System Reliability Index (SRI). Next, sensitivity analysis is performed to assess the importance of each communication network component using two innovative Importance Measures (IM), namely System Reliability Advancement Worth (SRAW) and System Reliability Deterioration Worth (SRDW). Finally, the proposed approach is demonstrated on a laboratory-scale communication network.
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