System configuration, fault detection, location, isolation and restoration: a review on LVDC Microgrid protections

Low voltage direct current (LVDC) distribution has gained the significant interest of research due to the advancements in power conversion technologies. However, the use of converters has given rise to several technical issues regarding their protections and controls of such devices under faulty conditions. Post-fault behaviour of converter-fed LVDC system involves both active converter control and passive circuit transient of similar time scale, which makes the protection for LVDC distribution significantly different and more challenging than low voltage AC. These protection and operational issues have handicapped the practical applications of DC distribution. This paper presents state-of-the-art protection schemes developed for DC Microgrids. With a close look at practical limitations such as the dependency on modelling accuracy, requirement on communications and so forth, a comprehensive evaluation is carried out on those system approaches in terms of system configurations， fault detection, location, isolation and restoration

Power Flow Control and Current Ripple Minimization of HVDC Converter System by Using Zero-Sequence Voltage Injection Control

This paper introduces the Zero_Sequence Voltage_Injection(ZSVI) based Model Predictive_Control (MPC) to minimize the ripples in dc current & voltage and concurrently regulate the power_flow & dc_current. This paper takes the benefits to calculate and inject best possible zero_sequence_voltage_components to Parallel_Hybrid Modular Multilevel_Converter (PHMMC) dc bus voltage. Dc line current has been derived by discrete_time_dynamic model and also it expands the predictive_model. Required amount of zero sequence voltage is injected to reference voltage of dc bus by using predictive model. Compared to triplen_harmonic injection_method, the proposed scheme improves the PHMMC_performance by minimizing the ripples of dc_voltage ¤t. Execution of the proposed methodology of PHMMC-based HVDC system is done using SIMULINK/MATLAB

The Essential Role and the Continuous Evolution of Modulation Techniques for Voltage-Source Inverters in the Past, Present, and Future Power Electronics

The cost reduction of power-electronic devices, the increase in their reliability, efficiency, and power capability, and lower development times, together with more demanding application requirements, has driven the development of several new inverter topologies recently introduced in the industry, particularly medium-voltage converters. New more complex inverter topologies and new application fields come along with additional control challenges, such as voltage imbalances, power-quality issues, higher efficiency needs, and fault-tolerant operation, which necessarily requires the parallel development of modulation schemes. Therefore, recently, there have been significant advances in the field of modulation of dc/ac converters, which conceptually has been dominated during the last several decades almost exclusively by classic pulse-width modulation (PWM) methods. This paper aims to concentrate and discuss the latest developments on this exciting technology, to provide insight on where the state-of-the-art stands today, and analyze the trends and challenges driving its future