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This paper illustrates a study on HVDC light for its enhancement of AC/DC hybrid transmission system and multi-infeed HVDC system. In the sense of the realizing independent controlling of active and reactive power, HVDC light is more effective compared to the conventional HVDC system. An AC/DC parallel transmission system and a three-infeed HVDC system are modeled using PSCAD/EMTDC. Simulations corresponding...
Fast diagnosis of commutation failure in HVDC systems can improve the level of operation in the power systems. It is also the base to realize the prevention of commutation failure. By application of wavelet transform, the rapidity and correctness of faults diagnosing are enhanced. AC voltage and DC voltage in inverter side are taken as the signals for wavelet analysis. Wavelet coefficient d6 changed...
Representation of high voltage direct current (HVDC) transmission links in power system stability studies requires special attention. A detailed model, while very precise, requires considerable time for modeling and calculation. Simplified models, on the other hand, do not always provide sufficiently accurate results. In this paper, simplified and detailed HVDC simulation models are described and...
The objective of this paper is to propose a new method of identification and protection for commutation failure in HVDC system. The technique of wavelet entropy is introduced by combining wavelet transform with entropy principles. It is used to decompose the transient signal of HVDC system into different resolution levels and extract the feature of the signal. According to the calculation of wavelet...
The mechanism of UHVDC Emergency DC Power Support (EDCPS) to enhance transient stability of multi- machine system is analyzed briefly based on EEAC (Extended Equal Area Criteria), and the influence of load model characteristic including ZIP static load model and IM (Induction Motor) model on UHVDC EDCPS effect after heavy disturbance is further studied, and the corresponding UHVDC EDCPS Strategies...
The behaviors of transient phenomena in HVDC systems, including DC line faults, commutation failures caused by AC faults and missing firing are difficult to be identified automatically by the control systems, while the effective protection control for commutation failures depends on the rapid and correct identification of such faults. This paper proposes a method to identify different causes leading...
The study of commutation failures requires more detailed and accurate simulation of HVDC systems. Hypresim is an integrated digital simulator, which could provide reliable, extensible and high-speed electromagnetic transient simulation for power systems. Its special characteristics are introduced in this paper. A HVDC system is established based on Hypersim. Modeling details of the ac system, dc lines,...
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