The specific types of loads such as cranes, in particular, ship to shore (STS), rubber tyred gantry (RTG), rail mounted gantry (RMG) and cold ironing system in the ports present a distinctive load profile, due to their sudden peak load demand. To deal with the problem and avoid extra costs, it is possible to apply a delay time management to cranes operation and/or to implement energy storage systems (ESSs) to take benefit of regenerative energy. At this aim, the load profile characteristics require both energy storage with high power and energy densities and fast response time. Peak shaving can optimize the load demand and facilitate the participation of small power generation units based on renewable energy resources. In this regard, many approaches are introduced such as energy management strategies, modern technologies, and installing high-tech devices such as battery energy storage (BES), ultracapacitors (UCs), and flywheel energy storage (FES) acting as ESS. Therefore, the goal of this paper is to deal with an investigation for an integrated vision and a combination of ESSs application in the ports loads. Since the ports cannot persist to have independent and uncontrolled power systems, hence, the paper proposes the organization of their global design in a microgrid approach and the coordinated management for all the services such as cranes, reefers, col ironing, trucks, offices to increase the operation and energy performance. The statistical results show that the integration of ESSs can provide peak shaving, energy saving, and cost reduction in ports.

This paper investigates the stability of a modular multi-level converter (MMC)-based HVDC system connected to a weak ac grid. Impedance analysis is used to study the interactions between the weak ac grid and the converter. For this, the impedance of the MMC is first derived considering various outer- and inner-loop controllers. The Nyquist-stability criterion is then used to analyze the stability of the MMC connected to the weak ac grid for various case studies. The impact of circulating current controller on the stability of the MMC connected to the weak ac grid is also validated for two different types of outerloop controllers. Finally, time-domain simulations are carried out using MATLAB/Simscape Power System toolbox to validate the analytical results

The aim of this paper is to investigate the risk for subsynchronous control interaction (SSCI) in Type 4 based wind farms connected to series-compensated transmission lines. For this purpose, the frequency-dependent input admittance of the turbine is derived and the power-dissipation properties of the turbine are used to identify those control parameters and operating conditions that mainly impact the behavior of the wind turbine in the subsynchronous frequency range. It is shown that the Type 4 wind turbine presents a non-dissipative behavior in the subsynchronous frequency range, which is mainly dependent on the speed of response of the synchronization loop, the reactive power controller and the active-power output. For a radial connection, a high series-compensation level also negatively impacts the risk for SSCI. The generalized Nyquist criterion is used to assess the stability of the system and the theoretical findings are verified using detailed time-domain simulations.

The properties of complex space-vector models for asymmetric three-phase systems are investigated in this article. Most importantly, three alternative methods for the stability analysis of the asymmetric closed-loop systems are presented. The end results avoid the usage of matrix manipulations. It is shown how the theory can be applied to modeling and stability analysis of a grid-connected voltage-source converter (VSC). The methods are compared using numerical examples.

In this paper, two types of filter capacitors of varying capacity were connected to the battery packs of a cascaded H-Bridge single-star multilevel vehicle traction inverter, and their influence on the battery losses has been analyzed. The battery and capacitor simulation models used are experimentally verified in a downscaled system. Different capacitor configurations were simulated for four-drive cycle scenarios to determine the potentials for the mitigation of current pulse stresses and battery loss reduction with respect to the added weight. By adding capacitors corresponding to a weight of 4% of the initial battery storage, the peak current is reduced by 5%-20%, depending on the operating point from dc to a few kilohertz, and the battery losses are reduced by 10%. In comparison, it is demonstrated that adding supercapacitors is more beneficial for lower output frequencies, while adding electrolytic capacitors is better for higher output frequencies. Furthermore, the low-order voltage harmonics of the dc-rails between the converter and battery were reduced by 10%-30% for frequencies above 9 kHz, which decreases the potential of electromagnetic disturbances. In addition, during cold battery temperatures, when it is very important to avoid heavy cyclings, the loss reduction using the capacitors was 2.5 times larger than for nominal temperature.