Optimal Operations of Local Energy Market With Electric Vehicle Charging and Incentives for Local Grid Services

The development of a local energy market (LEM) in Thailand involves prosumers and electric vehicle (EV) owners in a low-voltage distribution system (LVDS). However, both maximizing social welfare through independent energy transactions and managing distribution network constraints (DNCs) remain challenging. Additionally, defining fair incentives and ensuring equitable participation in local grid service programs further add to these challenges. This paper proposes an optimal LEM operation incorporating participants’ selection of energy transaction partners and independent price negotiations to maximize social welfare. The distribution system operator provides grid service programs to address violations, define fair incentives, ensure equitable participation, and guarantee the resolution of DNC violations while participants maintain control over their power consumption. A novel penalty scheme is proposed to support these grid service programs. Numerical simulations on a 380-V LVDS in Thailand demonstrate that social welfare is maximized at 19.17 THB/h across all preference cases during the study period. The LEM trades electricity without violating DNCs while allowing self-management. Results show that EVs contribute 83.66% of the demand reduction required by the distribution system operator, while the penalty scheme discourages 100% of individual benefit pursuit. Revenue compensation covers 100% of all prosumers’ revenue before implementing the grid service programs for all periods.

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Increasing Light Load Efficiency in Phase-Shifted, Variable Frequency Multiport Series Resonant Converters

Multiport power conversion topologies provide the capability of multiple independent converters with a single transformer having multiple windings (i.e., ports) potentially increasing power densities and enabling flexible (and bidirectional) power routing. In automotive onboard charger (OBC), the multiport approach combined with symmetrical series resonant circuits, the so-called multiport series resonant converter (MSRC), allows for a galvanic isolated connection between all ports: the grid-side converter (i.e., usually an AC/DC power factor correction (PFC) stage), vehicle’s main and the auxiliary low-voltage (LV) battery. The variation of the battery voltage significantly affects the MSRC operation, particularly for light loads at a low state-of-charge, and high losses can be experienced since zero-voltage-switching (ZVS) conditions are lost. In addition to the conventional control approach of the MSRC, where the power flow is set with a phase-shift between the individual full bridges or by changing the switching frequency, this paper proposes a novel and coordinated approach, including the manipulation of both and the additional modulation of the duty cycle as a function of the DC-link voltages, aiming to introduce a zero-voltage interval on the full bridge output voltages. A full mathematical description of the adopted converter topology is provided, including accurate simulation models that allow a comparison between the proposed duty cycle mode and the conventional control strategy. A detailed description of achieving ZVS within the connected full bridges is also included. Experimental results validate the proposal and demonstrate significant efficiency improvements compared to standard control approaches.

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On the Cyber-Physical Needs of DER-Based Voltage Control/Optimization Algorithms in Active Distribution Network

With the increasing penetration of distributed energy resources (DERs) and extensive usage of information and communications technology (ICT) in decision-making, mechanisms to control/optimize transmission and distribution grid voltage would experience a paradigm shift. Given the introduction of inverter-based DERs with vastly different dynamics, real-world performance characterization of the cyber-physical system (CPS) in terms of dynamical performance, scalability, robustness, and resiliency with the new control algorithms require precise algorithmic classification and suitable metrics. It has been identified that classical controller definitions along with three inter-disciplinary domains, such as (i) power system, (ii) optimization, control, and decision-making, and (iii) networking and cyber-security, would provide a systematic basis for the development of an extended metric for algorithmic performance evaluation; while providing the taxonomy. Furthermore, a majority of these control algorithms operate in multiple time scales, and therefore, algorithmic time decomposition facilitates a new way of performance analysis. Extended discussion on communication requirements while focusing on the architectural subtleties of algorithms is expected to identify the real-world deployment challenges of voltage control/optimization algorithms in the presence of cyber vulnerabilities and associated mitigation mechanisms affecting the controller performance with DERs. Finally, the detailed discussion provided in this paper identifies the modeling requirements of the CPS for real-world deployment, specific to voltage control, facilitating the development of a unified test-bed.

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Published in the IEEE Power & Energy Society Section within IEEE Access

Novel Universal Power Electronic Interface for Integration of PV Modules and Battery Energy Storages in Residential DC Microgrids

This paper introduces the novel concept of a highly versatile smart power electronic interface for fast deployment of residential dc microgrids. The proposed approach has bidirectional power flow control capabilities, wide operating voltage range, and high efficiency resulting from the topology morphing control utilization. This enables universal compatibility with the majority of the commercial 60- and 72-cell photovoltaic modules, as well as the efficient charge/discharge control of the 24 V and 48 V battery energy storages using the same hardware platform. The proposed concept features fully autonomous operation where switching between the photovoltaic and battery interfacing modes is automatically done using the input source identification algorithm. Moreover, the proposed universal interface converter employs droop control and solid-state protection, making it fully compatible with the emerging standards and requirements for power electronic systems used in dc microgrid environments. A 350 W prototype was developed and tested in the residential 350 V dc microgrid with droop control to validate the proposed concept experimentally.

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