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High voltage DC grid is developing towards more terminals and larger transmission capacity, thus the requirements for DC circuit breakers (DCCB) will rise. The conventional methods only use the faulty line DCCB to withstand the fault stress, while this paper presents a coordination method of multiple DCCBs to protect the system. As many adjacent DCCBs are tripped to interrupt the fault current, the fault energy is shared, and the requirement for the faulty line DCCB is reduced. Moreover, the adjacent DCCBs are actively controlled to help system recovery. The primary protection, backup protection, and reclosing logic of multiple DCCB are studied. Simulation confirms that the proposed control reduces the energy dissipation requirement of faulty line DCCB by around 30–42 %, the required current rating for IGBTs is reduced, and the system recovery time reduced by 20–40 ms.

The development of DC grids faces challenges from DC fault protection. The conventional DC circuit breaker (DCCB) employs metal-oxide varistor (MOV) to isolate the faulted line, in which the fault isolation process is coupled with the energy dissipation process. In this study, a clamping type DCCB (CTCB) uses internal capacitors to clamp the converter voltage is proposed. Thanks to the proposed configuration, fault isolation and energy dissipation are decoupled, resulting in a fast fault isolation and low energy dissipation compared to the conventional DCCB. The working principle of the proposed CTCB is presented and verified in a DC grid simulation model. A comparison is made with the traditional DCCB. The fault isolation time can be reduced by 34.5 %. The dissipated energy can be reduced by 17.4 %. The energy dissipation power can be reduced by 76.2 %.

Aiming at the impulse noise generated in capturing the images of insulator on power lines, a denoising method based on peer groups is proposed. The center pixel variance

One motivation of wireless technology is the ubiquitous wireless access abilities, which provide the automatic handovers for any moving devices at any place and any time in the heterogeneous networks combining different access technologies. TD-SCDMA is a very advanced 3G standard with global coverage, but bandwidth is its weakness. WiMAX offers higher bandwidth with low operational costs but its maximum mobility is at about 120km/h. A WiMAX & TD-SCDMA interworking approach can make best use of advantages of both technologies and can eliminate their stand-alone defects. In this paper, we present a possible interworking architecture for WiMAX and TD-SCDMA based on the WiMAX Forum and 3GPP standards. Handover is an essential part of interworking .The proposed handover scheme is based on IEEE 802.21 media independent handover functions (MIHFs) and the key component to support mobility management is Mobile IP.

Worldwide interoperability for microwave access (WiMAX) is standardized in the IEEE 802.16e-2005/802.16d-2004, the physical layer of WiMAX is based on orthogonal frequency division multiplexing (OFDM) modulation which is particularly sensitive to the timing synchronization. This paper gives a new method based on the idea of cross-correlation and difference which can confront frequency-offset when it is in the moment of the symbol timing synchronization. In the new method, the sequences of the receiver and the second OFDM sign sequence of the local reference long preamble are made difference respectively; then the two difference sequences are made cross-correlation. Finally the peak value is judged. The new method is simulated which show a good performance.

The physical layer of IEEE802.16e is based on orthogonal frequency division multiplexing (OFDM) modulation which is particularly sensitive to the timing synchronization. This paper gives a new method based on the idea of difference. The new method can confront frequency-offset when it is in the moment of the symbol timing synchronization and reduce the computation complexity. In the new method, the sequences of the receiver and the sequence of the local reference short preamble are made difference respectively; Then the two difference sequences are made cross-correlation. Finally the peak value is judged. The new method is simulated which show a good performance.

In this paper, a new improved production algorithm of patterns based on other past methods is presented. This method combines iteration of fractal matrix and evolution of fuzzy cellular automata, makes iteration and evolution to process interactively by setting times of iteration and evolution, then produces a lots of fractal patterns. Finally, experiments are put forward, this algorithm can produce plenty of complex beautiful fractal patterns by the simple initial patterns, and it is a promising and applied production algorithm of patterns.

In order to resolve the problems of edge detection algorithm of images based on fuzzy seasoning or cellular automata, a new improved edge detection algorithm of images based on cloud model cellular automata is presented. This method uses direction information and edge order information as edge characteristic information, uses cloud model to inference these information, then gives accurate feedback information got from inference results to direction information measure and direction edge order measure, and detects edge by automatic evolution of cellular automata. Finally, experiments are put forward, this algorithm has powerful ability in exiguous edge detection, and it is a promising and applied image processing algorithm.