• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.9
• /
• pp.434-440
• /
• 2005

This paper describes an optimized Scheme of reactive-power compensation for the low short-circuit-ratio AC system interconnected with the HVDC system. An HVDC system interconnected with tile low SCR AC system is vulnerable to the ac voltage variation, which brings about the commutation failure of the converter. This problem can be solved using optimized compensation of reactive power. In this study, a benchmark system for HVDC system interconnected with low SCR AC system is derived using PSS/E simulation. Then an optimized srheme for reactive power compensation was derived using integer programming. The feasibility of proposed scheme was analyzed through silnulations with PSS/E and PSCAD/EMTDC. The proposed scheme can compensate the reactive power accurately and minimize the number of switching for harmonic filters and shunt reactors.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.3
• /
• pp.393-401
• /
• 2013

This paper deals with the operation strategy of the Cheju AC network included MIHVDC system (Multi-Infeed HVDC system). In case that where several HVDC systems are located in the vicinity of each other, there are interactions between the different HVDC systems in such network configurations. The interactions which could be generated in multi-infeed HVDC are voltage stability, power stability and inertia stability, to analyze such systems in a systematic way to ensure that there are no risks of adverse interactions is very important. The developed method until now to analyze MIHVDC interaction is extended from MAP(Maximum Available Power) method for analyzing the power stability of the single-infeed HVDC system, this method is to solve the eigenstructure using the identified factors influencing the interactions. Finally, the algorithms which are introduced in this paper, to determine the operation strategy are applied to Cheju island network which is supplied by two HVDCs.

• Proceedings of the KIPE Conference
• /
• 2013.07a
• /
• pp.516-517
• /
• 2013

신재생 에너지의 비중 확대와 보급이 늘어남에 따라, 국가 간, 도시 간의 송전이 중요한 이슈로 대두 되고 있다. 위와 같은 요구 조건을 만족시키기 위해서 초고압 직류 송전의 개발이 필요하다. 초고압 직류송전(HVDC)에는 전류형과 전압형으로 나뉘는데. 각 HVDC에서 사용되는 Valve는 실제 운전 전에 여러 가지 방법으로 검증이 필요하다. 합성 시험회로 설비(Synthetic Test Circuit = 이하 STC)는 전류형 HVDC에서 사용되는 주요 전력변환 장치로, Thyristor Valve의 동작을 실제 동작 조건에 맞추어 동작을 시켜, 동작의 신뢰성을 검증하는 시험 설비이다. 본 논문에서는 전류형 HVDC Valve의 Operational Test를 위한 STC의 보호기능에 대해 기술하고 있다. 합성시험회로는 2상 초퍼와 6 펄스 사이리스터 컨버터를 사용하였고 설계된 보호기능은 PSCAD를 사용하여 검증하였다. HVDC Valve Operational Test시 합성시험회로 내에서 발생할 수 있는 사고 상황을 상정하고 그에 따른 보호 기능을 모의하였다.

• Journal of Power Electronics
• /
• v.7 no.3
• /
• pp.233-237
• /
• 2007

This paper deals with the new HVDC interaction which was observed in the Jeju-Haenam HVDC system. The interaction is not from a system malfunction or controller loop problem but from the change of AC network scheme and the network operating condition. We have found that the interaction is caused by the voltage oscillation between synchronous compensator and HVDC shunt reactor. We analyzed the cause of the interaction and suggested a solution.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.9
• /
• pp.1232-1241
• /
• 2012

The ac side current of an high voltage direct current (HVDC) converter is characterized by highly non-sinusoidal waveform. If the harmonic current is allowed to flow in the connected ac system, it may cause unacceptable levels of distortion. Therefore, ac side filters are required as part of the total HVDC converter station, in order to reduce the harmonic distortion of the ac side current and voltage to acceptably low levels. The ac side filters are also employed to compensate network requested reactive power because HVDC converters also consume substantial reactive power. Among different types of filters, double-tuned filters have been widely utilized for HVDC system. This paper presents two design methods of double-tuned filter; equivalent method and parametric method. Using a parametric method, in particular the paper proposes a new design algorithm for a realistic system. Finally, the performance of the design algorithm is evaluated for a 80kV HVDC system in Jeju island with PSCAD/EMTDC program. The results cleary demonstrate the effectiveness of proposed design method in harmonics elimination and steady-state stability.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.6
• /
• pp.431-440
• /
• 2000

This paper analyses the dynamic performance of HVDC System connected to a weak AC system for various exciter characteristics of synchronous machines connected at the converter bus. Conventionally capacitors are used to supply reactive power requirement at a strong converter bus. But the installation of synchronous machine is essential in a isolated weak network to re-start after a shutdown of HVDC and to increase system strength. The dynamic performance of a synchronous machine depends on the characteristics depends of its exciter. In this paper, several exciter types are used to investigate their effect on the dynamic performance of the HVDC system and modifications to standard exciter topologies are suggested to mitigate observed problems.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.3
• /
• pp.247-256
• /
• 1999

In this paper, a methodology for optimal design of PID controller using the modified genetic algorithm has been proposed to improve the transient stability at system fault in HVDC transmission system, mathematical model preparation for stability analysis, and supplementary signal control by an optimal PID controller using the modified genetic algorithm(MGA). The propriety was verified through computer simulations regarding transient stability. It means that the application of MGA-PID controller in HVDC transmission system can contribute the propriety to the improvement of the transient stability in HVDC transmission system and the design of MGA-PID controller has been proved indispensible when applied to HVDC transmission system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.1
• /
• pp.132-140
• /
• 2008

Power system of Jeju is interconnected to the mainland using HVDC and that is also interconnected two wind farms. Control of Jeju power system will be difficult if HVDC is disconnected or HVDC is overhauled under large scale wind farms interconnected. We measured and analysed the power quality of two substation and two wind farms to assess that wind farms and HVDC overhaul have an effect on Jeju system or not during the HVDC overhaul. We found that the frequency of Jeju system is very unstable and the voltage distortion excess the limitation. Harmonic currents of wind farms flew into Jeju system in proportion to the power of wind turbine. And the voltage of nearby distribution line was distorted by power of wind turbine when the amount is more that 3,000[kW].

• Journal of Electrical Engineering and Technology
• /
• v.5 no.1
• /
• pp.54-60
• /
• 2010

This paper presents a new algorithm for determining generator operation point for maintaining stability considering generator faults in Jeju-Haenam HVDC system. As the HVDC system consumes reactive power for the transmission of active power substantially, compensation of reactive power is essential. And the HVDC system is operated on frequency control mode. That is to say, the HVDC system almost manages system frequency. Therefore, we recognized that the Jeju system could be unstable if the reactive power consumed by the HVDC is insufficient when out-of-step occurs with large generators. When the solution of power flow analysis does not converge due to the unstable system phenomenon, we have difficulty in establishing countermeasures as the post-fault information is not available. In this paper, for the purpose of overcoming this difficulty in establishing countermeasures, we introduce the CPF(Continuation Power Flow) algorithm. This paper suggests an algorithm for calculating the output limitation of the generator to maintain the stability in case of generator fault in the Jeju system.

• Proceedings of the KIPE Conference
• /
• 2012.11a
• /
• pp.185-186
• /
• 2012

본 논문에서는 HVDC C&P(High Voltage Direct Current Control and Protection) 시스템의 네트워크 이중화 방법을 제안한다. 본 논문에서 제안하는 HVDC C&P 시스템 네트워크 이중화 방법은 2개의 이더넷 라인을 제어기에 직접 연결하고, 연결된 라인으로 동시에 정보를 송신하여, 제어기에서 정보를 필터링하여 사용하는 방법을 사용한다. 또한 네트워크 라인의 효과적인 결선 체크를 위해 제어기간 송수신을 통해 네트워크 라인의 결선을 체크하는 방법을 사용한다. 위와 같은 방법은 HVDC C&P 시스템의 네트워크 안정성을 향상시키는 효과를 기대할 수 있다.