This article proposes a method for optimal placement of phasor measurement units (PMUs) to improve measurement redundancy distribution in a system under normal operating condition or in presence of contingency. The minimum number of PMUs is determined using integer linear programming method, after which the measurement redundancy is optimized using a novel model to represent the redundancy level of each bus. Weight parameters are assigned to auxiliary variables, which enables control of priority of different redundancy level. The impact of zero injection bus is integrated into the model, as well as the channel limitation of PMUs and existing measurements. Besides, contingency is modeled in a generalized form, which enables N-1 or N-2 contingency analysis. The proposed method is tested on various IEEE systems, and the results show that the number of PMUs obtained by the proposed method is further reduced comparing with other methods, while with a highly improved measurement redundancy.

The increased focus on sustainability in response to climate change has given rise to many new initiatives to meet the rise in building load demand. The concept of distributed energy resources (DER) and optimal control of supply to meet power demands in buildings have resulted in growing interest to adopt microgrids for a precinct or a university campus. In this paper, a model for an actual physical microgrid has been constructed in OPAL-RT for real-time simulation studies. The load demands for SIT@NYP campus and its weather data are collected to serve as input to run on the digital twin model of DERs of the microgrid. The dynamic response of the microgrid model in response to fluctuations in power generation due to intermittent solar PV generation and load demands are examined via real-time simulation studies and compared with the response of the physical assets. It is observed that the simulation results match closely to the performance of the actual physical asset. As such, the developed microgrid model offers plug-and-play capability, which will allow power providers to better plan for on-site deployment of renewable energy sources and energy storage to match the expected building energy demand.

A medium/high-power conversion system using power electronic (PE) converter along with a medium/high-frequency transformer, offers many desirable features that are beneficial for present-day power system topologies. Leakage inductance is identified to be one of the key parameters to characterize performances of such a medium-frequency (MF) high-power (HP) transformer. In this paper, existing analytical method to calculate leakage inductance of a concentric winding is further refined employing mean turn length of individual layer and winding porosity factor. Impact of interleaving to reduce leakage inductance is studied. Consequently different winding dispositions (normal and interleaved) and conductor geometries (foil, round) are investigated for a 10 kW, 0.5/2.5 kV, 1 kHz transformer design. Finally generalized method to deduce leakage inductance of fractional-interleaved winding is introduced in scope of this paper. Analytical calculations are corroborated with PEMag simulation results. With proper selection of wire and core geometry, good agreement between analytical and PEMag results is achieved at medium switching frequency, which substantiates aptness of presented methodology.

The conventional active neutral-point-clamped (ANPC) multilevel inverters are popular for single-phase applications owing to their advantage of mitigating high-frequency common-mode voltage. With the ac neutral connected to the midpoint of dc-link, their voltage gain is restricted to only half. For boosting output voltage, a two-stage structure by adding a frontend dc-dc boost converter is commonly used. This paper investigates the performance of the conventional two-stage 5-level ANPC inverter and proposes an improved topology by splitting the dc-link midpoint and cross clamping them to the dc-link capacitors. While using the same number of power devices and retaining the advantages of the conventional two-stage 5-level ANPC topology such as high-frequency common-mode voltage mitigation and continuous dc source current, the proposed 5-level split-midpoint cross-clamped (5L-SMCC) inverter achieves several advantages such as higher voltage gain, lower voltage across dc-link capacitors, lower inverter voltage stress, and natural voltage balancing for all capacitors without requiring any balancing controller or sensor. In addition, it saves one capacitor by eliminating the flying capacitor of the conventional 5-level ANPC inverter. The operation of the proposed 5L-SMCC inverter is thoroughly analyzed. For validation, simulation and experimental results are presented.

The latest single-stage boost inverter has many advantages such as continuous input or dc source current, high-frequency common-mode voltage mitigation and generation of three-level boosted ac voltage. However, it requires a dedicated circuit design, which cannot be implemented using commercial power modules such as half-bridge. To resolve this drawback, this letter proposes an improved topology designed using three half-bridges. While retaining the advantages of the latest boost inverter, the proposed topology reduces the number of conducting switches for load current during positive voltage level that enhances efficiency. The proposed three-level boost inverter can be extended to generate five levels by merely adding a half-bridge and a capacitor. The derivation of the proposed single-stage boost inverters and their operation are analyzed. Simulation and experimental results are presented for verification.

This paper presents a new triple phase shift (TPS) closed-loop control scheme of a dual active bridge (DAB) LCC resonant DC/DC converter to improve wireless charging power transfer efficiency. The primary side inverter phase shift angle regulates the battery charging current/voltage. The secondary side rectifier phase shift angle regulates the rectifier AC load resistance to match its optimized setting. The inverter-to-rectifier phase shift angle is set to achieve unity power factor operation of the DAB rectifier and inverter. The mathematical formulation of the TPS shift control is given for each phase shift angle. The analytical calculation, circuit simulation, and experimental test are carried out in a power scaled-down DAB LCC resonant wireless charging converter laboratory hardware setup to validate the proposed TPS close-loop control scheme. The PLECS circuit simulation shows that DAB LCC resonant SiC MOSFET operates at zero-voltage-switching (ZVS) with a unity power factor in emulated constant current (CC) mode battery charging. In constant voltage (CV) mode operation, one inverter/rectifier Leg does not operate at ZVS switching when Sic MOSFET is switched on near zero current. The experimental results show that the efficiency is greatly improved for CV mode charging with large DC load resistance connected if rectifier AC load resistance matching control is enabled. The measured efficiency matches well with the analytical calculation. The estimated efficiency improvement will be much more significant for EV applications in the kW power range with greater winding loss. The challenges and possible solutions to implement TPS PWM modulation in two separate inverter and rectifier control hardware are explained for future TPS control algorithm development in practical wireless charging products.