Baoming Ge

Bio: Baoming Ge is an academic researcher from Beijing Jiaotong University. The author has contributed to research in topics: Maximum power point tracking & Photovoltaic system. The author has an hindex of 31, co-authored 93 publications receiving 2948 citations. Previous affiliations of Baoming Ge include Michigan State University.

An Energy-Stored Quasi-Z-Source Inverter for Application to Photovoltaic Power System

Abstract: The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load, but its existing topology has a power limitation due to the wide range of discontinuous conduction mode during battery discharge. This paper proposes a new topology of the energy-stored qZSI to overcome this disadvantage. The operating characteristic of the proposed solution is analyzed in detail and compared to that of the existing topology. Two strategies are proposed with the related design principles to control the new energy-stored qZSI when applied to the PV power system. They can control the inverter output power, track the PV panel's maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. An experimental prototype is built to test the proposed circuit and the two discussed control methods. The obtained results verify the theoretical analysis and prove the effectiveness of the proposed control of the inverter's input and output powers and battery power regardless of the charging or discharging situation. A real PV panel is used in the grid-tie test of the proposed energy-stored qZSI, which demonstrates three operational modes suitable for application in the PV power system.

Modeling, Impedance Design, and Efficiency Analysis of Quasi- $Z$ Source Module in Cascaded Multilevel Photovoltaic Power System

Abstract: The quasi- $Z$ source (qZS) cascaded multilevel inverter (CMI) (qZS-CMI) presents attractive advantages in application to photovoltaic (PV) power system. Each PV panel connects to an H-bridge qZS inverter (qZSI) to form a power generation module. The distributed maximum power point tracking and all modules' dc-link peak voltage balance can be achieved. However, it is the same with the conventional CMI that the second-harmonic ( $2\omega$ ) voltage and current ripples exist in each qZSI module. It is crucial for a qZS-CMI to design the reasonable qZS network parameters to limit the ripples within a desired range. This paper proposes an analytic model to accurately calculate the $2\omega$ voltage and current ripples of each qZSI module. A qZS impedance design method based on the built model is proposed to limit the $2\omega$ ripples of dc-link voltage and inductor current. Simulated and experimental results through using the designed 1.5-kW prototype validate the proposed analytic model and the design method. Furthermore, this paper analyzes all of the operating states for a qZSI module and calculates the power loss. The measured efficiency from the prototype verifies the theoretical calculation, and the qZS-CMI-based grid-tie PV power system is tested in practical.

Overview of Space Vector Modulations for Three-Phase Z-Source/Quasi-Z-Source Inverters

Abstract: Three existing and one extended space vector modulations (SVMs) for the three-phase Z-source/quasi-Z-source inverter (ZSI/qZSI) are investigated. The different switching control patterns, the available maximum shoot-through duty ratio, the maximum voltage stress across the switch versus voltage gain, and efficiency are compared in detail. A total average switch device power taking into account the shoot-through current stress is proposed to evaluate the total stress of power switches. Simulation and experimental results of the prototyped qZSI verify the theoretical analysis. The six parts of shoot-through time intervals will reduce the inductor current ripples, and improve the qZSI efficiency. Also, the maximum voltage stress and total average switch power will benefit from the shoot-through division. However, the division method impacts these performances of qZSI.

Z-Source\/Quasi-Z-Source Inverters: Derived Networks, Modulations, Controls, and Emerging Applications to Photovoltaic Conversion

Abstract: The current and emerging investigations on Z-source/quasi-Z-source inverters (ZSIs/qZSIs) are presented. The ZSI/qZSI fulfills buck/boost capability in single-stage topology and overcomes the limits of traditional voltage source inverters (VSIs). Hence, high reliablity, high efficiency, and low cost can be achieved. The recently derived impedance networks with improved voltage gain are discussed. The classic and newly proposed modulations and feedback controls for ZSIs/qZSIs are compared. Finally, the emerging applications and trends of ZSIs/qZSIs to photovoltaic (PV) power generation are discussed. This study offers a comprehensive and systematic reference for the future development of the high-performance ZSI/qZSI.

Resonance Issues and Damping Techniques for Grid-Connected Inverters With Long Transmission Cable

Abstract: An infinite source with series inductance is usually employed as a grid emulator in grid-connected distributed generation systems. Thus, high capacitance of a transmission cable (i.e., underground cable) is too significant to be neglected. As a result, the capacitance and inductance may cause system resonance, which, in turn, challenges system stability. This paper takes offshore wind farm as an example to investigate the resonance issues caused by the submarine transmission cable of the grid-connected generation system. Based on the submarine cable model, a series of considerable resonant peaks is found in the open-loop transfer function of the grid-connected system because of the high-order LC configuration. The resonant peaks are sensitive to the system setup, which is clearly investigated. To overcome the resonances, this paper proposes a cascaded notch-filter-based active damping method to guarantee a good system stability and robustness. Furthermore, the proposed controller employs a proportional-resonant component to reduce the steady-state error of the output current. The simulation and experimental results have validated the findings of resonances and the effectiveness of the proposed controller.

A review of energy storage technologies for wind power applications

Abstract: Due to the stochastic nature of wind, electric power generated by wind turbines is highly erratic and may affect both the power quality and the planning of power systems. Energy Storage Systems (ESSs) may play an important role in wind power applications by controlling wind power plant output and providing ancillary services to the power system and therefore, enabling an increased penetration of wind power in the system. This article deals with the review of several energy storage technologies for wind power applications. The main objectives of the article are the introduction of the operating principles, as well as the presentation of the main characteristics of energy storage technologies suitable for stationary applications, and the definition and discussion of potential ESS applications in wind power, according to an extensive literature review.

Review of energy system flexibility measures to enable high levels of variable renewable electricity

Abstract: The paper reviews different approaches, technologies, and strategies to manage large-scale schemes of variable renewable electricity such as solar and wind power. We consider both supply and demand side measures. In addition to presenting energy system flexibility measures, their importance to renewable electricity is discussed. The flexibility measures available range from traditional ones such as grid extension or pumped hydro storage to more advanced strategies such as demand side management and demand side linked approaches, e.g. the use of electric vehicles for storing excess electricity, but also providing grid support services. Advanced batteries may offer new solutions in the future, though the high costs associated with batteries may restrict their use to smaller scale applications. Different “P2Y”-type of strategies, where P stands for surplus renewable power and Y for the energy form or energy service to which this excess in converted to, e.g. thermal energy, hydrogen, gas or mobility are receiving much attention as potential flexibility solutions, making use of the energy system as a whole. To “functionalize” or to assess the value of the various energy system flexibility measures, these need often be put into an electricity/energy market or utility service context. Summarizing, the outlook for managing large amounts of RE power in terms of options available seems to be promising.

An Overview of Recent Research and Emerging PV Converter Technology

Abstract: Photovoltaic (PV) energy has grown at an average annual rate of 60% in the last five years, surpassing one third of the cumulative wind energy installed capacity, and is quickly becoming an important part of the energy mix in some regions and power systems. This has been driven by a reduction in the cost of PV modules. This growth has also triggered the evolution of classic PV power converters from conventional singlephase grid-tied inverters to more complex topologies to increase efficiency, power extraction from the modules, and reliability without impacting the cost. This article presents an overview of the existing PV energy conversion systems, addressing the system configuration of different PV plants and the PV converter topologies that have found practical applications for grid-connected systems. In addition, the recent research and emerging PV converter technology are discussed, highlighting their possible advantages compared with the present technology. Solar PV energy conversion systems have had a huge growth from an accumulative total power equal to approximately 1.2 GW in 1992 to 136 GW in 2013 (36 GW during 2013) [1]. This phenomenon has been possible because of several factors all working together to push the PV energy to cope with one important position today (and potentially a fundamental position in the near future). Among these factors are the cost reduction and increase in efficiency of the PV modules, the search for alternative clean energy sources (not based on fossil fuels), increased environmental awareness, and favorable political regulations from local governments (establishing feed-in tariffs designed to accelerate investment in renewable energy technologies). It has become usual to see PV systems installed on the roofs of houses or PV farms next to the roads in the countryside. Grid-connected PV systems account for more than 99% of the PV installed capacity compared to