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Many cyclone detection and tracking methods (CDTMs) have been developed in the past to study the climatology of extratropical cyclones. However, all CDTMs have different approaches in defining and tracking cyclone centers. This naturally leads to cyclone track climatologies with inconsistent physical characteristics. More than that, it is typical for CDTMs to produce a non-negligible number of tracks of weak atmospheric features, which do not correspond to large-scale or mesoscale vortices and can differ significantly between CDTMs. Lack of consensus in CDTM outputs and the inclusion of significant numbers of uncertain tracks therein have long prohibited the production of a commonly accepted reference dataset of extratropical cyclone tracks. Such a dataset could allow comparable results on the analysis of storm track climatologies and could also contribute to the evaluation and improvement of CDTMs. To cover this gap, we present a new methodological approach that combines overlapping tracks from different CDTMs and produces composite tracks that concentrate the agreement of more than one CDTM. In this study we apply this methodology to the outputs of 10 well-established CDTMs which were originally applied to ERA5 reanalysis in the 42-year period of 1979-2020. We tested the sensitivity of our results to the spatiotemporal criteria that identify overlapping cyclone tracks, and for benchmarking reasons, we produced five reference datasets of subjectively tracked cyclones. Results show that climatological numbers of composite tracks are substantially lower than the ones of individual CDTMs, while benchmarking scores remain high (i.e., counting the number of subjectively tracked cyclones captured by the composite tracks). Our results show that composite tracks tend to describe more intense and longer-lasting cyclones with more distinguished early, mature and decay stages than the cyclone tracks produced by individual CDTMs. Ranking the composite tracks according to their

Many critical five-phase permanent-magnet synchronous machine drive systems require operation after a single open-phase fault. The single dc supply open-end winding inverter topology allows for the injection of four unbalanced phase currents to better optimize the postfault machine torque after this fault. However, all previously published field-oriented control schemes send varying current references to the proportional-integral (PI) current controllers when controlling four unbalanced phase currents. This makes the design of the PI controllers considerably difficult as each machine operating point will require a different gain to accurately track the varying reference with minimum ripple. Consequently, this paper proposes a new postfault transformation matrix that obtains constant current references for any given set of four unbalanced sinusoidal phase currents. This facilitates easy design of the PI current controllers as the steady-state error can be reduced to zero in a user-defined response time for all operating points. This current control technique is the first to be designed specifically for the case of an open-phase fault to a five-phase open-end winding system.

The deployment of distributed generation contributes to the facilitation of the microgrid concept and grid modernization on a global scale. An increasing number of workforces are required for further development of microgrid systems. However, the mismatch between the University education and industry expectation places a negative impact on workforce development for future energy infrastructure. This paper introduces the implementation of a microgrid virtual laboratory for a design course. The key elements of this developed course are described in detail and the reflections from the students are investigated. This contribution also provides a statistical analysis of the students' knowledge gap in the field of microgrids. The curricula design outlined in this study can be proposed in future power engineering education to offer competent students for the microgrid industry.

Nitrous acid (HONO) is a key determinant of the daytime radical budget in the daytime boundary layer, with quantitative measurement required to understand OH radical abundance. Accurate and precise measurements of HONO are therefore needed; however HONO is a challenging compound to measure in the field, in particular in a chemically complex and highly polluted environment. Here we report an intercomparison exercise between HONO measurements performed by two wet chemical techniques (the commercially available a long-path absorption photometer (LOPAP) and a custom-built instrument) and two broadband cavity-enhanced absorption spectrophotometer (BBCEAS) instruments at an urban location in Beijing. In addition, we report a comparison of HONO measurements performed by a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) and a selected ion flow tube mass spectrometer (SIFT-MS) to the more established techniques (wet chemical and BBCEAS). The key finding from the current work was that all instruments agree on the temporal trends and variability in HONO (r(2) > 0.97), yet they displayed some divergence in absolute concentrations, with the wet chemical methods consistently higher overall than the BBCEAS systems by between 12% and 39 %. We found no evidence for any systematic bias in any of the instruments, with the exception of measurements near instrument detection limits. The causes of the divergence in absolute HONO concentrations were unclear, and may in part have been due to spatial variability, i.e. differences in instrument location and/or inlet position, but this observation may have been more associative than casual.

Open-phase faults in multiphase PMSMs could occur either through an electrical failure or by selective isolation of one or a higher number of phase windings. In such cases, post-fault currents are injected into the remaining healthy windings to maintain an average torque. However, considerable torque ripple may be present if the post-fault currents are not properly designed. Accordingly, a generic approach is proposed in this paper for designing post-fault currents including non-fundamental harmonics that lead to maximum post-fault average torque with suppressed torque ripple in open-end multiphase PMSMs. The proposed scheme is not restricted by the number of open-phase faults. In the proposed algorithm, the post-fault currents are parameterized, based on which the instantaneous post-fault torque is exhaustively formulated. An optimization algorithm is then used to obtain the optimal parameters of the post-fault currents. Experimental tests on a prototype open-end five-phase PMSM under different fault scenarios are used validate the torque ripple suppression capability of the proposed approach.

The five-phase open-end winding inverter topology has a low-impedance zero-sequence current path when a single dc supply is used. As a result of this, any source of common-mode voltage in the circuit can lead to an uncontrolled low-frequency zero-sequence current. This is an issue for permanent magnet machine systems as they can possess zero-sequence components in the back electromotive force, which will couple with the generated zero-sequence current to produce undesired torque pulsations. One possible solution for reducing these torque pulsations is to use a zero-sequence proportional-integral current controller to actively suppress the zero-sequence current to zero. This requires a modulation technique, which can independently control the common-mode voltage. However, there is currently no reported space-vector modulation technique, which can independently control common-mode voltage while operating in the overmodulation region. Consequently, this paper develops a novel space-vector modulation technique for the five-phase open-end winding topology to address this issue. Experimental open-loop results prove that the proposed technique can accurately control common-mode voltage at any operating point with the tradeoff of producing increased switching band harmonics. Experimental closed-loop results prove that this modulation technique can be combined with a zero-sequence proportional-integral controller to actively suppress low-frequency zero-sequence current to zero in the overmodulation region.