Once block fault occurs in high-capacity UHVDC transmission system, it brings large-capacity power supply loss to AC power system located at receiving end. If the reserve capacity in the disturbed control area is insufficient to fill up the gap,reserves in other areas of the interconnected system will be transferred to support the recovery of system frequency. Based on the analysis of the defects of existing control strategies when dealing with large-capacity power shortage, this paper presented a coordinated optimal dispatch strategy of emergency power support among provinces after block fault of UHVDC transmission system. Total power shortage was firstly allocated among provinces aiming at maximum remaining spare and inter-area available transfer capability with the constraints such as tie line power and reserve capacity taken into account. Then,allocation scheme among units according to generator units' type was raised. Cooperation among the regional grid dispatching system and provincial dispatching systems achieved emergency power support among provinces. Simulation results verify the effectiveness of the proposed approach.

The characteristics of satellite regular movements and the regular arrays of inter satellite links(ISL) were analyzed.A new optimal path routing algorithm based on division of two phases(OPRA-DTP) is presented.In this algorithm,routing choice was divided into two phrases: static routing strategy phrase and online routing correction phrase.In the first phrase,satellite networks′ topology variation is shielded by introducing logic nodes,and routing choice rules of the shortest path at the least hops are given with not considering network flow distribution;while in the second phrase the information of network flow distribution is supervised in real time,and once the information varies enough acutely,routing choice is corrected based on the results in the first phrase,which could maximize the throughout of network with certain quality of service(QoS).The validity of OPRA-DTP in decreasing computing complexity and routing spending was verified through simulation results.

A novel regional satellite navigation system design method is proposed based on the Flower constellation design scheme. A navigation Flower constellation (NFC) included 2 Flower constellations. Through the Flower constellation model, the six orbital parameters of each satellite are designed concretely. The deployment of the NFC is progressive, starting with eight satellites, more affordable capacity that can be increased in stages as necessary by launching additional six satellites. The simulation of the geometrical dilution of precision (GDOP) performance for china showed that the mean GDOP value of NFC is 2.113. Moreover, GDOP performance of NFC was compared with GPS, GLONASS, Galileo and some other navigation constellations proposed by national study groups. The results demonstrated that NFC was same with Galileo and was much better than the other satellite navigation systems. Therefore, the high navigation precision and economic performance proved that the regional satellite navigation system design method based on the Flower constellation design scheme was effective.

分析和确定了Flower星座的优化参数,从参数编码、适应度评价和算法流程设计三个方面进行讨论,给出了Flower星座的遗传算法优化模型.利用自行开发的卫星星座仿真软件SatSim (satellite simulation)和STK (satellite tool kit)工具包,设计了适合中国区域通信的三个Flower星座并进行了性能分析.仿真结果表明,4和5颗星的星座在最小仰角10°的条件下对中国的平均覆盖率分别为97.26 %和99.24 %;6颗星的星座在最小仰角15°的条件下对中国的平均覆盖率为99.88 %,基本实现对中国的连续覆盖,可以满足卫星移动通信的需求.

The architecture of satellite communication networks based on GEO/LEO constellations is presented considering the optimizationof network management.Management subnet and service subnet are separate physically in this architecture,which makes centralized routing strategy more adapted than that in terrestrial networks.In order to strengthen the reliability of the architecture,spare routing strategy decreasing computation load is constituted making use of the characteristics of satellites’ regular movement and regular array of Inter Satellite Links(ISL).At last the performances of two routing strategies are validated through simulations.

Focused on regional image surveillance,a novel surveillance satellite constellation design method based on the GA (genetic algorithm) is proposed.Through the GA model,the orbital elements of each satellite such as altitude,inclination,RAAN and mean anomaly are optimized.The optimal simulation of a constellation with 3 LEO satellites was made.The result shows that the optimized constellation can provide excellent performance of maximum access time interval in specified target region and have definite capability of global surveillance and reconnaissance.

Focused on regional reconnaissance, a novel reconnaissance satellite constellation design method based on the GA (genetic algorithm) is proposed in this paper. Through the GA module, the orbital parameters of satellite such as inclination, RAAN and mean anomaly are optimized. The interactions between orbit altitude and the maximum revisit time are analyzed. The optimized simulation of a 3 LEO satellites constellation for 7 different orbit altitudes is conducted. The results show that the optimized constellation could provide a great maximum revisit time performance for a certain target region and had a good capability for global surveillance and reconnaissance.

前言 在IP层实现数据加密具有密钥协商开销小、应用程序及上层协议透明等优点,通常采用在NDIS层与IP层之间插入一个垫片层来实现对发送数据的加密及接收数据的解密(其逻辑结构如图1所示);但当主机的负载加重,而且有大量的数据需要处理、发送或接收时,如上设计将明显影响系统效率.