Fault ride-through 요구를 고려한 풍력발전단지 연계선 보호 거리계전 알고리즘

강용철(Yong-Cheol Kang),강해권(Hae-Gweon Kang),정태영(Tai-Ying Zheng),김연희(Yeon-Hee Kim),이영귀(Young-Gui Lee) 대한전기학회 2010 전기학회논문지 Vol.59 No.6

A large modern wind farm should satisfy the requirements for a grid and accomplish the optimization of the wind farm system. The wind farm intertie protection system should consider a Fault Ride-Through (FRT) requirement for more reliable protection. The wind farm should keep connected to the grid in the case of a grid fault whilst it should be isolated for an intertie fault. This paper proposes a distance relaying algorithm suitable for wind farm intertie protection considering the FRT requirement. The proposed algorithm estimates the impedance based on a differential equation method because the frequency of the voltage and current deviates the nominal frequency. The algorithm extends the reach of Zone 1 up to 100 % of the length of the intertie to implement the FRT requirement. To discriminate an intertie fault from a grid fault, the algorithm uses a voltage blocking scheme because the magnitude of the voltage at the relaying point for an intertie fault becomes less than that for a grid fault. The performance of the algorithm is verified using a PSCAD/EMTDC simulator under various fault conditions. The algorithm can discriminate successfully the intertie fault from grid fault and thus helps to implement the FRT requirement of a wind farm.

Imbalanced Fault Detection using Real Time Symmetrical Coordinate Calculation with Memorized Data

Noriyuki Kimura,Xiao-xiao Yu,Koji Niijima,Toshimitsu Morizane,Hideki Omori 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a real time symmetrical coordinate transformation applied for detection of imbalanced fault in utility power system. The power conditioner of the photovoltaic system in Japan is required to remain connected when the utility power system fault occurs under certain condition. The most popular fault is 1 line-to-ground fault. The next is 2 line-short fault. Both cause the imbalance voltages and currents in 3-phase power system. To optimize the output from the power conditioner of the photovoltaic system, the detection of the imbalanced condition is important factor. In this paper, new development of the signal processing method by using the complex number algebra in real time system is shown. The fast detection of the imbalanced condition is verified by the computer simulations.

Investigation of a Hybrid HVDC System with DC Fault Ride-Through and Commutation Failure Mitigation Capability

Guo, Chunyi,Zhao, Chengyong,Peng, Maolan,Liu, Wei The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

A hybrid HVDC system that is composed of line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) in series with LCC at the inverter side is studied in this paper. The start-up strategy, DC fault ride-through capability, and fault recovery strategy for the hybrid HVDC system are proposed. The steady state and dynamic performances under start-up, AC fault, and DC fault scenarios are analyzed based on a bipolar hybrid HVDC system. Furthermore, the immunity of the LCC inverter in hybrid HVDC to commutation failure is investigated. The simulation results in PSCAD/EMTDC show that the hybrid HVDC system exhibits favorable steady state and dynamic performances, in particular, low susceptibility to commutation failure, excellent DC fault ride-through, and fast fault recovery capability. Results also indicate that the hybrid HVDC system can be a good alternative for large-capacity power transmission over a long distance byoverhead line.

Investigation of a Hybrid HVDC System with DC Fault Ride-Through and Commutation Failure Mitigation Capability

Chunyi Guo,Chengyong Zhao,Maolan Peng,Wei Liu 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

A hybrid HVDC system that is composed of line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) in series with LCC at the inverter side is studied in this paper. The start-up strategy, DC fault ride-through capability, and fault recovery strategy for the hybrid HVDC system are proposed. The steady state and dynamic performances under start-up, AC fault, and DC fault scenarios are analyzed based on a bipolar hybrid HVDC system. Furthermore, the immunity of the LCC inverter in hybrid HVDC to commutation failure is investigated. The simulation results in PSCAD/EMTDC show that the hybrid HVDC system exhibits favorable steady state and dynamic performances, in particular, low susceptibility to commutation failure, excellent DC fault ride-through, and fast fault recovery capability. Results also indicate that the hybrid HVDC system can be a good alternative for large-capacity power transmission over a long distance by overhead line.

MMC‑modified sub‑module structure with double reverse blocking IGBTs

Yiqi Liu,Zhaoyu Duan,Qichao Chen,Bingkun Li,Mingfei Ban,Zhenjie Li 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.3

In high-voltage direct current (HVDC) systems, among the voltage source converters (VSCs), the modular multilevel converter (MMC) is a popular choice for power transmission. Unfortunately, the conventional half-bridge sub-module (SM) cannot deal with DC faults by itself. Thus, improved SM topologies enabling DC fault ride-through are significant. With this in mind, an MMC-modified SM structure is presented with double reverse blocking IGBTs (DRBSM). When all of the IGBTs in an MMC are blocked, the DRBSM can insert two capacitors in series to the fault circuit to rapidly overcome the DC fault. First, the DRBSM topology and working principle are analyzed. Second, the DRBSM control strategy is illustrated. Third, the device withstand voltage, DC fault ride-through, cost, and loss performance of the DRBSM are presented in detail. Finally, according to simulation results, the DRBSM fault ride-through speed is shown to be as fast as the full-bridge SM, and faster than the clamp double SM. In addition, experimental results validate the feasibility of the proposed DRBSM structure.

분산전원의 Fault Ride Through를 고려한 방향성 과전류 계전기 최적 정정법에 관한 연구

송진솔(Jin-Sol Song),조규정(Gyu-Jung Cho),김지수(Ji-Soo Kim),신재윤(Jae-Yun Shin),김동현(Dong-Hyun Kim),김철환(Chul-Hwan Kim) 대한전기학회 2018 전기학회논문지 Vol.67 No.8

Fault Ride Through(FRT) requirement prevents disconnections of distributed generations during the specific time on disturbance condition for system stability. However, since there is a limitation to the FRT capability of distributed generation, and the protection system needs to clear the fault quickly before the distributed generation is disconnected. Therefore, this paper proposes a novel optimal setting method of directional overcurrent relay considering FRT of distributed generation. The proposed method reduces the probability of disconnections of the distributed generation in disturbance without additional equipment considering the FRT capability of the distributed generation by calculating the optimal relay setting through the Genetic Algorithm(GA).

PMU를 사용한 FRT 검출시스템 설계 및 분석

권대윤(Dae-Yun Kwon),문채주(Chae-Joo Moon),정문선(Moon-Seon Jeong),유도경(Do-Kyeong Yoo) 한국전자통신학회 2021 한국전자통신학회 논문지 Vol.16 No.4

송·배전시스템에서 사고나 장애는 결코 완벽하게 피할 수 없으며, 단락 및 지락사고는 계통운영자의 노력에도 불구하고 발생한다. 최근 대용량 신재생 분산전원의 송·배전계통에 연계가 급증하여 계통 운영에 다양한 영향을 주고 있어, 이를 최소화하기 위해 FRT(Fault-Ride-Through)와 같은 연계기준을 마련하여 풍력터빈 또는 태양광 인버터가 계통의 중대 장애 시 연계유지 또는 신속한 계통분리 등을 원활히 수행하여 운영자가 안정적으로 계통을 운영할 수 있도록 지원을 하여야 한다. 본 논문에서는 대표적인 신재생 분산전원의 계통연계 기준인 FRT 조건의 충족여부를 적절하게 판단하기 위하여 동기페이저 측정을 하는 PMU(Phasor Measurement Unit)를 사용한 검출 시스템을 설계 및 구축하고 발전기 탈락으로 인한 계통사고 사례를 기반으로 제시한 시스템을 분석하고 평가한다. Accidents or faults in the transmission and distribution system are never completely avoidable, and short-circuit and earth faults are occurs despite the efforts of the TSO and DSO. Recently, the connection to the transmission and distribution system of large-capacity new and renewable distributed power has increased rapidly and has various effects on the operation of the system. In order to minimize this, connection standards such as FRT (Fault-Ride-Through) have been established to provide wind turbines or solar inverters. In the event of a major faults of the power system, the operation support shall be provided so that the operator can stably operate the system by smoothly performing connection maintenance or rapid system separation. In this paper, in order to appropriately determine whether the FRT condition, which is the grid connection criterion for a representative DERs, is sufficient, a detection system using a PMU (Phasor Measurement Unit) that measures a synchro-phasors was designed and deployment and a system accident due to a generator step-out to analyze and evaluate the proposed system based on the case.

Enhancing fault ride through capability via diesel generator control in dynamic positioning vessels

김성일,성병철,이덕수 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.6

The current trend in dynamic positioning vessels involves using closed-bus tie systems, which aim to be more efficient by using fewer generators. However, this new setup brings challenges due to the potential for a single fault to disrupt the entire power systems. To address these challenges, the paper presents a strategy to control diesel generators and meet strict requirements for handling faults. Using extensive factory test data, simulation models are developed for individual governor and exciter systems. These models have an error margin of about 2.1%, showing their good alignment with real-world situations. With these simulation models, a thorough analysis of system stability is conducted. This analysis checks if the governor and automatic voltage regulator settings, validated by factory tests, can restore the system to normal operation. The investigation reveals that the frequency response remains stable even with short-circuit faults. However, the voltage response does not meet the ship's requirements. The paper investigates the reason behind this voltage problem due to an excessive integral controller gain value and implements changes to rectify it by adjusting controller parameters. By explaining the critical aspects of the voltage issue, the paper contributes to our understanding of strengthening closed-bus tie systems on dynamic positioning ships. The findings emphasize the importance of careful generator control to maintain a reliable power system, especially during faults.

Hybrid-Mode Cuk Inverter with Low-Voltage Ride-Through Capability under Grid-Faults

Byeongcheol Han,Minsung Kim,Jih-Sheng Lai 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a hybrid-mode Cuk inverter with low-voltage ride-through (LVRT) capability under grid-faults. It operates as an unfolding-type inverter during normal grid condition and two-stage inverter during abnormal grid condition. Thus, it normally transfers the energy to the utility grid highly efficiently, and also has the LVRT ability under grid-faults. Moreover, two types of inverters share the full-bridge circuit on the gridside and so the proposed circuit can be developed with low cost and reduced size. This paper outlines operation principles and control methods for the proposed inverter. The prototype of the proposed converter was implemented and experimental tests were carried out to demonstrate its practical feasibility.

Low voltage ride-through control strategy for virtual synchronous generators based on virtual self-inductive flux linkage

Shi, Kai,Li, Tong,Ren, Mingwei,Xu, Peifeng The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.5

Virtual synchronous generators (VSGs), with the operational characteristics of synchronous generators (SGs), have been employed in renewable energy generation grid-connected systems to solve the problem of insufficient equivalent inertia, which is caused by the high permeability of distributed generation systems in the grid. However, a VSG does not possess low voltage ride-through (LVRT) capability. A novel LVRT control strategy for a VSG based on virtual self-inductive flux linkage is proposed in this paper. First, the electromagnetic transient response mechanism of a SG under grid faults is analyzed in detail. Then, a memory and retention strategy are proposed to simulate the effect of the switch law. Furthermore, the virtual q-axis armature self-inductance is introduced into the VSG and a virtual self-inductive magnetic chain is utilized to block the change of the transient fault current. This helps the inverter adjust the output voltage quickly. In addition, under the premise of meeting the reactive power margin, the reactive power compensation strategy is optimized to achieve a quick response in terms of the reactive power compensation of grid faults, which is helpful for realizing the LVRT of a VSG. Finally, the feasibility and effectiveness of the proposed LVRT method are verified by thorough simulation results.