Shut-down control with energy feedback and energy dissipation for MMC-HVDC systems

Summary The modular multilevel converters (MMCs) are frequently preferred for medium and high power energy conversion systems thanks to their modular structure and high quality output waveform. The remarkable studies related to the MMC have been carried out in recent years, which are mainly focused on its topology, control, or application. In this paper, MMC circuit topologies consisting of traditional submodule cells and new proposed configurations are introduced, and their control process, modulation techniques, and application areas are discussed in order to provide the readers the current state of the art of MMC technology. A wide part of this article is devoted to demonstrate the recent contributions arising in MMC studies. In this context, this paper not only outlines the circuit topology, control objectives, and applications of the MMC but also presents a comprehensive review, principally in terms of the latest developments of it. Ultimately, detailed proposals and new possible topics are provided to drive future expectations of MMC technology.

“…NLM technique is known as noncarrier method, which is easy to implement and directly controls the output voltage . Basic principle of NLM is shown in Figure F.…”

Section: Control Conceptmentioning

confidence: 99%

Recent contributions and future prospects of the modular multilevel converters: A comprehensive review

Kurtoğlu

Eroğlu

Arslan

et al. 2018

“…It is easily seen that the overall area of the proposed system is 93.5% of the MMC-HVDC. [17][18][19][20][21][22] To maintain the completeness of the whole control structure, the capacitor voltage balancing method is introduced in this section. And then, the system control strategies are proposed.…”

Section: Footprint Analysesmentioning

confidence: 99%

Topology and control of a new line commutated converter-modular multilevel converter hybrid bipolar high-voltage direct current transmission system

Liang

Wang³

2017

Summary This paper presents a new line commutated converter (LCC) and modular multilevel converter (MMC)‐based hybrid bipolar high‐voltage direct current (HVDC) transmission system. In the proposed circuit, each polar consists of one 12‐pulse LCC (12P‐LCC) and 1 MMC; meanwhile, the two 12P‐LCCs and the 2 MMCs locate diagonally. In each polar, the 12P‐LCC regulates DC voltage, while the MMC regulates the transmitted active and reactive power. Moreover, the MMC functions as an alternating current active power filter and a DC active power filter at the same time. Therefore, the 11th and 13th alternating current harmonics and the 12th DC current harmonic can be suppressed by the MMC without any other filters. It saves both footprint and cost of the system. In addition, the performance of this proposed system is almost the same as that of the MMC‐HVDC, while the footprint and cost are smaller than those of both the LCC‐HVDC and MMC‐HVDC systems. It means that the proposed system combines the benefits of both the MMC‐HVDC system and the LCC‐HVDC system. At last, the topology and control strategies of the proposed system are verified by the Power Systems Computed‐Aided Design/Electromagnetic Transients including DC simulations.

“…Generally, the modulation methods can be classified into two kinds: pulse width modulation (PWM) and staircase modulation. Pulse width modulation is based on the control of every submodule capacitor voltages by means of different modulation approaches . Staircase modulation is based on sorting method to control submodule voltages .…”

Section: Introductionmentioning

confidence: 99%

An enhanced level-increased nearest level modulation for modular multilevel converter

Zhu

Lei

et al. 2018

Summary An enhanced level‐increased nearest level modulation (eNLM) method is proposed to improve the performance of modular multilevel converter (MMC) with relatively small number of submodules. The eNLM method can almost double the level number of ac output voltage, compared with conventional NLM. Consequently, the ac output voltage quality of the MMC using eNLM is significantly enhanced. The proposed method inherits the advantages of the conventional NLM such as simple implication and low switching loss and avoids the disadvantages of the existing improved NLM method such as increasing in submodule capacitor voltage ripple amplitude and voltage offset, arm inductor voltage peak, complexity in topology, etc. PSCAD/EMTDC simulation results confirmed the effectiveness of the proposed method.