This paper proposes an energy management system (EMS) for a fuel cell hybrid electric vehicle (FCHEV). The EMS is based on nonlinear model predictive control (NMPC) and employs a recurrent neural network (RNN) for modeling a proton exchange membrane (PEM) fuel cell (FC). The NMPC makes it possible the formulation of control objectives not allowed by a linear model predictive control (MPC), such as maximum efficiency point tracking (MEPT) of the FC, while the RNN can accurately predict the FC nonlinear dynamics. The EMS was implemented on a low-cost development board, and the experiments were performed in real-time on a hardware-in-the-loop (HiL) test bench equipped with a real 3 kW FC stack. The experimental results demonstrate that the NMPC EMS is able to meet the vehicle's energy demand, as well as to operate the FC in its most efficient region. Moreover, a comparative study is performed between the proposed NMPC, a linear MPC and hysteresis band control (HBC). The results of this comparative study demonstrate that the NMPC provides a better fuel economy and can reduce FC degradation.

This work proposes the Hybrid Control Converter (HCC), a new kind of VSC control. This method aims at having one single converter mimic the behavior of two individual, virtual converters working in parallel (one with grid-following and the other with grid-forming control). This way, the hybrid converter can show behavioral characteristics of both kinds of converter control at the same time. Two possible applications for the HCC are presented. The first one is related to synthetic inertia capability of wind turbines. Results show that the HCC presents superior performance when compared to conventional techniques based on grid following converters, resulting in a smaller grid frequency drop during transients. The second application shows that the HCC allows for autonomous connection of multiple distinct AC systems using a meshed DC transmission system. This enables automatic frequency support and generation and load sharing between the AC grids without requiring any specific action by the system operator.

This paper presents an analysis of a new high voltage DC (HVDC) transmission system, which is based on current and voltage source converters (CSC and VSC) in the same circuit. This proposed topology is composed of one CSC (rectifier) and one or more VSCs (inverters) connected through an overhead transmission line in a multiterminal configuration. The main purpose of this Hybrid HVDC (H²VDC), as it was designed, is putting together the best benefits of both types of converters in the same circuit: no commutation failure and system’s black start capability in the VSC side, high power converter capability and low cost at the rectifier side, etc. A monopole of the H²VDC system with one CSC and two VSCs—here, the VSC is the Modular Multilevel Converter (MMC) considered with full-bridge submodules—in multiterminal configuration is studied. The study includes theoretical analyses, development of the CSC and VSCs control philosophies and simulations. The H²VDC system’s behavior is analyzed by computational simulations considering steady-state operation and short-circuit conditions at the AC and DC side. The obtained results and conclusions show a promising system for very high-power multiterminal HVDC transmission.

In grid-connected power converters, active and reactive power references are typically provided for calculating current and/or voltage references. This is generally achieved by using the standard instantaneous power theory (IPT). However, when a converter is required to operate with different per-phase power levels, the IPT cannot be applied to fully describe this interphase power interaction. To address this limitation, this work presents an interpretation of the interphase power imbalance problem, which enables the representation of the system as a combined electrical interaction between the unequal per-phase active powers on the inverter side and balanced power on the grid side. To achieve this, a Clarke transformation based on sequence order rotation is proposed. Thus, per-phase quadrature $\alpha \beta$ -components can be obtained, allowing the instantaneous per-phase unbalanced power on the inverter side to be analytically derived. Based on this representation, an analytical expression of the instantaneous zero-sequence voltage (ZSV) is obtained. This ZSV allows one to extract unbalanced per-phase power on the inverter side while injecting balanced power on the grid side. A case study showing experimental results from a 10 kVA cascaded H-bridge converter applied to a scaled-down medium-voltage photovoltaic system are presented.