• Title/Summary/Keyword: MMC-HVDC

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New Topology for Valve Performance Test Equipment of MMC based STATCOM (MMC 기반 STATCOM 용 밸브의 성능시험 장치를 위한 새로운 토폴로지)

  • Bae, Jongwoo;Jung, Jae-Hun;Nho, Eui-Cheol;Chung, Yong-Ho;Baek, Seung-Taek;Lee, Jin-Hee;Kim, Young-Woo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.1
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    • pp.82-88
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    • 2017
  • This study proposes a new topology for the performance test of a valve consisting of a modular multilevel converter (MMC)-based static synchronous compensator (STATCOM). The conventional valve performance test equipment requires high-voltage AC source of several kV rating because the number of submodules to be tested in a valve should be at least six or eight. However, the power source of the proposed scheme is DC and not AC source. The DC power source voltage range of the proposed test circuit is from several volts to several tens of volts. Therefore, the size and cost for the performance test equipment can be reduced considerably compared with the conventional method. The proposed scheme satisfies the requirements of the IEC 62927 standard. Simulations are conducted for a valve of 50[MVA] MMC-based STATCOM. Experimental results with a scale-downed setup show the validity of the proposed performance test topology.

Control Strategy of MMC-HVDC under Unbalanced Grid Voltage Conditions

  • Zhang, Jianpo;Zhao, Chengyong
    • Journal of Power Electronics
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    • v.15 no.6
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    • pp.1499-1507
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    • 2015
  • High voltage direct current transmission based on modular multilevel converter (MMC-HVDC) is one of the most promising power transmission technologies. In this study, the mathematical characteristics of MMC-HVDC are analyzed in a synchronous rotational reference frame. A hybrid current vector controller based on proportional integer plus resonant is used to uniformly control the DC and double-base frequency AC currents under unbalanced grid voltage conditions. A corresponding voltage dependent current order limiter is then designed to solve the overcurrent problems that may occur. Moreover, the circulating current sequence components are thoroughly examined and controlled using a developed circulating current suppressor. Simulation results verify the correctness and effectiveness of the proposed control schemes.

Development of simulation model for offshore wind power generation with MMC for HILS application (HILS 적용을 위한 해상풍력 계통 연계 MMC 모델 개발)

  • Shin, Dong-Cheol;Yoon, Jin-Woo;Lee, Dong-Myung
    • Proceedings of the KIPE Conference
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    • 2018.07a
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    • pp.372-373
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    • 2018
  • HVDC(High Voltage Direct Current)전력망은 발전소에서 생산한 교류를 직류로 변환한 이후 송전하여 부하에 가까운 전력변환기를 이용하여 교류로 변환한 후에 사용하는 방식이며, 전압형 HVDC에 MMC(Modular Multilevel Converter)가 널리 사용되고 있다. 본 논문에서는 MMC가 적용된 HVDC를 이용한 해상 풍력 계통 제어 성능을 테스트하기 위해 실시간 시뮬레이션 툴인 RT-Lab에 적용한 모델에 대해 설명하고자 한다.

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Development of the Phase Controller for MMC STATCOM (MMC STATCOM용 Phase 제어기 개발)

  • Yeo, Sang-Min;Seo, Jae-Jin;Choi, Jong-Yun;Yang, Hang-Jun
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.414-415
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    • 2015
  • 최근 대용량 전압형 컨버터 분야에서는 기존 전압형 컨버터에 비해 용량 증대, 고조파 저감 등이 용이한 Modular Multi-level Converter 토폴로지가 주요 관심사가 되고 있다. 이러한 새로운 컨버터 토폴로지는 대용량 컨버터가 요구되는 HVDC 기술을 시작으로 여러 분야에 적용되고 있으며, 전압형 컨버터를 사용하는 STATCOM에서도 이 토폴로지를 적용한 MMC STATCOM이 전력 시장에 등장하고 있다. MMC STATCOM을 제어하기 위한 제어 시스템은 기존 MMC HVDC와 유사하게 기능 및 제어 수준에 따라 계층적으로 구성된다. 이중 Phase 제어기는 실제 컨버터를 동작하기 위한 Valve Based Electronic (VBE)로써 MMC를 구성하는 각 submodule들이 어떻게 동작해야 하는지에 대한 지령을 생성하는 제어기이다. 본 논문에서는 당사에서 개발하고 있는 MMC STATCOM에 적용하기 위한 Phase 제어기를 소개하고 H/W 개발, F/W 개발 등에 대해 기술하였다.

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Capacitance Value Analysis of Sub-module Test Circuit for MMC-based HVDC System (MMC 기반 HVDC 시스템용 서브모듈 시험회로의 커패시터 용량 분석)

  • Seo, Byuong-Jun;Park, Kwon-Sik;Jo, Kwang-Rae;Nho, Eui-Cheol;Kim, Heung-Geun;Chun, Tae-Won;Kim, Tae-Jin;Lee, Jong-Pil
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.6
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    • pp.433-439
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    • 2018
  • This study considers the design of a submodule test circuit for the modular multi-level converter (MMC)-based HVDC systems. A novel submodule test circuit is proposed to provide not only an AC but also a DC component to the submodule current. However, the current waveforms depend on the capacitor voltages. Therefore, determining the capacitance value of the test circuit is important. Finding a proper capacitance value is easy when the proposed analysis method is used. Simulation and experimental results show the usefulness of the proposed method.

Power Loss Modeling of Individual IGBT and Advanced Voltage Balancing Scheme for MMC in VSC-HVDC System

  • Son, Gum Tae;Lee, Soo Hyoung;Park, Jung-Wook
    • Journal of Electrical Engineering and Technology
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    • v.9 no.5
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    • pp.1471-1481
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    • 2014
  • This paper presents the new power dissipation model of individual switching device in a high-level modular multilevel converter (MMC), which can be mostly used in voltage sourced converter (VSC) based high-voltage direct current (HVDC) system and flexible AC transmission system (FACTS). Also, the voltage balancing method based on sorting algorithm is newly proposed to advance the MMC functionalities by effectively adjusting switching variations of the sub-module (SM). The proposed power dissipation model does not fully calculate the average power dissipation for numerous switching devices in an arm module. Instead, it estimates the power dissipation of every switching element based on the inherent operational principle of SM in MMC. In other words, the power dissipation is computed in every single switching event by using the polynomial curve fitting model with minimum computational efforts and high accuracy, which are required to manage the large number of SMs. After estimating the value of power dissipation, the thermal condition of every switching element is considered in the case of external disturbance. Then, the arm modeling for high-level MMC and its control scheme is implemented with the electromagnetic transient simulation program. Finally, the case study for applying to the MMC based HVDC system is carried out to select the appropriate insulated-gate bipolar transistor (IGBT) module in a steady-state, as well as to estimate the proper thermal condition of every switching element in a transient state.

Performance Evaluation of AC Controllers (MMC HVDC AC 전류 제어기 성능 비교 분석)

  • Park, Seung Hee
    • Proceedings of the KIPE Conference
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    • 2015.11a
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    • pp.111-112
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    • 2015
  • MMC HVDC(Multi-level Modular Converter High Voltage Direct Current)는 현재 차세대 전력망으로써 각광을 받고 있고 그에 대한 연구가 활발하게 진행 중이다. 본 논문에서는 모듈형 멀티레벨 컨버터를 이용한 전압형 HVDC 시스템의 AC 전류제어기에 대하여 기술하고자 한다. 일반적으로 사용되는 회전변환을 통한 DQ전류제어와 PR제어를 사용하여 응답특성을 PSCAD/EMTDC를 통하여 비교 검증하고자 한다.

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A Strategy of Increasing the Wind Power Penetration Limit with VSC Type MMC-HVDC in Jeju Power System (전압형 MMC-HVDC에 의한 제주계통의 풍력한계용량 증대 방안)

  • Lee, Seungmin;Kim, Eel-Hwan;Kim, Ho-Min;Chae, Sang-Heon;Quach, Ngoc-Thinh
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.6
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    • pp.550-557
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    • 2015
  • The Jeju Special Self-Governing Province is currently promoting the "Carbon-free Island by 2030" policy, which requires the use of renewable energy instead of fossil fuel so that the island will have no carbon gases generated by 2030. To implement this policy, the island plans to build a wind power plant capacity of 1.09 GW in 2020; this wind power plant is currently ongoing. However, when wind power output is greater than the power demand of the island, the stability of Jeju Island power system must be prepared for it because it can be a problem. Therefore, this study proposes a voltage source-type MMC-HVDC system linked to mainland Korea to expand the wind power penetration limits of Jeju Island under the stable operation of the Jeju Island power system. To verify the effectiveness of the proposed scheme, computer simulations using the PSCAD/EMTDC program are conducted, and the results are demonstrated. The scenarios of the computer simulation consist of two cases. First, the MMC-HVDC system is operated under variable wind power in the Jeju Island power system. Second, it is operated under the predicted Jeju Island power system in 2020.

Level Selection Algorithm with Fixed Sampling Frequency for Modular Multilevel Converter (고정 샘플링 주파수에서의 모듈형 멀티레벨 컨버터 레벨 선택 알고리즘)

  • Kim, Chan-Ki;Park, Chang-Hwan;Kim, Jang-Mok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.6
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    • pp.415-423
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    • 2018
  • This study uses a level selection algorithm with fixed sampling frequency for modular multilevel converter (MMC) systems. Theoretically, the proposed method increases the level infinitely while the sampling time remains the same. The proposed method called cluster stream buffer (CSB) consists of several clusters, wherein each cluster is composed of 32 submodules that depend on the level of the submodules in the MMC system. To increase the level of the MMC system, additional clusters are used, and the sampling time between clusters is determined from the sampling time between levels needed for utilizing the entire level from the MMC system. This method is crucial in the control of MMC-type HVDC systems because it improves scalability and precision.

Analysis of Internal Energy Pulsation in MMC System According to AC -Side Output Voltage Synthesis Methods (AC단 출력 전압 합성 방법에 따른 MMC 시스템 내부 에너지 맥동 분석)

  • Kim, Jaemyeong;Jung, Jae-Jung;Kim, Heung-Geun
    • Proceedings of the KIPE Conference
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    • 2019.07a
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    • pp.183-185
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    • 2019
  • 최근 대용량 전력 전송 시스템에서 모듈형 다단 컨버터(Modular Multilevel Converter; MMC)를 이용한 고압 직류(high voltage DC; HVDC) 송전 시스템이 각광받고 있다. 일반적으로, 전압형 컨버터는 AC 단출력전압 합성 방법에 따라 AC 단 전압 사용률이 달라지며, MMC 시스템에 있어서도 마찬가지이다. 따라서, HVDC 송전시스템의 DC 단의 용량이 정해져 있는 경우에도 출력전압 합성 방법에 따라 AC 단으로 공급 가능한 최대 무효전력의 크기를 변화시킬 수 있다. 본 논문에서는 대표적인 전압 변조 방식에 따른 암 에너지 맥동을 수학적으로 분석하였으며, 이를 MMC의 실제 스케일의 시뮬레이션으로 검증하였다.

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