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In order to ensure the rapid application of Communication-Based Train Control (CBTC) system interconnection in urban rail transit in China, it is necessary to construct a complete indoor cross-test case system for CBTC system interconnection. Firstly, this paper introduces the development status of interconnection in China, combines the technical route of interconnection, analyzes the defects of the existing test case design methods, and puts forward the idea of case design from the overall perspective of the system. Then, this paper analyzes the test contents of interconnection cases in detail and elaborates the relevant contents of function test, interface test, and data test from two aspects of collinear and cross-line. By summarizing the actual problems in the process of Chongqing interconnection cross-testing, this paper puts forward two suggestions on strengthening the safety awareness and standardization of interconnection test.

A 100% renewable energy system (RES) satisfies a user’s energy demand using only renewable energy, which is an important energy supply in China given that the government aims to realize carbon neutrality by 2060. The design and operation of 100% RESs in different areas would vary significantly due to the impacts of climates and geographical features. This study aimed to investigate the economic and environmental performance of 100% RESs for residential communities in different areas of China. In total, 30 typical cities were chosen based on the climate characteristics and the availability of renewable energy resources. The genetic algorithm was selected to obtain the optimal design of the 100% RES in each area by taking the minimum total annual cost and the minimum CO2 emissions as optimization objectives. The results showed that 100% RESs were dominated by solar energy and biomass. The investment could be recovered in 8 years if the economic performance was optimized in most areas, but the payback period became longer when the 100% RES was optimized when considering environmental performance. The emissions could be reduced by 86–99% for CO2 and 64–97% for NOx. The results of this study would provide data support for the investment of 100% RESs in rural or suburban areas of China.

This paper presents a modified back-to-back starting (M-BBS) method with virtual synchronous generator (VSG) technology for starting a large-capacity synchronous condenser (SC). An M-BBS system is built first, including the cascaded H-bridge converter (CHB) controlled as a VSG, and an SC. The control structure containing a VSG model, a speed controller, and a current feed-forward controller, is then established to access of the influence of critical factors, such as the field excitation and the initial relative angle between the machines, on the starting process. Also, a principle how to start a large-capacity SC by regulating the mechanical torque and the damping torque is proposed. Finally, the simulation results are presented validating the theoretical analyses.

In view of the short comings of traditional synchronous machine transient model, in this paper, an accurate equivalent circuit modeling and parameter identification method is proposed. In this new modeling method, the phenomenon of unequal mutual reactance of different windings and the eddy current during transient process on solid rotor are taken into consideration and thus derive a model that better reflects the actual physic phenomenon inside the motor. Then, dynamic parameters of this accurate model are identified using a DC step signal test. In this process, a chaotic simulated annealing particle swarm algorithm is used to obtain the values of dynamic parameters. Finally, the presented method in this paper is applied on a 300 MVA solid rotor synchronous machine and validated by finite element analysis.

The short-time high capacity reactive power output and quick dynamic response performance are two key performances of new large synchronous condenser. In this paper, the effect of load condition on transient response capability of synchronous condenser by finite element analysis (FEa) model. A 300/-150Mvar prototype synchronous condenser is provided for modeling analysis at a group of different steady state operating conditions. Then the suddenly three-phase short circuit is carried out to compare the inrush current in different load condition.

To improve the ability of reactive power support at Ultra High Voltage Direct Current (UHVDC) project sending and receiving terminals, State Grid Corporation will install large synchronous condensers which gives high requirements in transient and dynamic characteristics. Some performance indexes of large synchronous condenser are very different from traditional turbo-generator. The change of performance index will have great influence on equipment design, production, operation and manufacture. And there is contradiction between the higher transient, dynamic characteristics and equipment safety. The paper analysised the performance index, technical requirements, equipment characteristics of large synchronous condenser for UHVDC project. Compared with the 412MVA synchronous turbo-generator. Mainly analyzed the differences and influences of leading phase operation capability, short-circuit-ratio, direct-axis transient time constant, direct-axis subtransient reactance and forced excitation ability. Finally the paper gives some advices on improving the design of large synchronous condenser for UHVDC project to ensure the quality of performance index and the safety of equipment.

Niushan Lake (114°32′E, 30°19′N), situated in Hubei Province of China, is a shallow macrophyte lake in the middle reaches of the Changjiang (Yangtse) River, with a total surface area of 40 km 2 . Age, growth and reproduction of Rhodeus ocellatus from the lake were studied during April to June 1999. Annuli on scales were clear and could be used as valid indicators of age. The population of the bitterling comprised only one age group, and the maximum of life span for both sexes may be less than 2 years. The sex ratio of males to females was 1.59:1 (n= 332) with significant difference from 1:1 (X 2 test, X c 2 =16 94,p 0.01). The relationship between total length ( TL , mm) and body weight ( W , g) for sexes was expressed by the equation ln W =-11.945 + 3.163 ln TL (n= 238, r= 0.98, p 0.0001). Slope of the equation was significantly greater than 3 (p 0.01). This may suggest an allometric growth. The bitterling were multiple spawners reaching maturity in the second year. During spawning, both sexes exhibited secondary sexual characters. Minimum size was 26 mm in total length and 0.216 g in weight for males, and 32 mm and 0.393 g for females. Mature eggs were cucurbit like form with mean size of 3.31 mm long (n= 23, SD= 0.14). Fecundity per female averaged 61 eggs (n= 46, SD= 18) with a range of from 28 to 119. In addition to that, There wassignificantly correlation of fecundity ( F , eggs) to total length ( TL , mm) or body weight ( W , g) (p 0.0001), and the relationships were expressed by the equations F = 26.1 + 83.2 W (n= 52, r= 0.73) F = 4.78 10 -3 TL 2.537 (n= 52, r= 0.78).

1. 1. Comparisons were made on the growth and energy budgets of six teleost fishes fed ad libitum at 25°C. 2. 2. In the six species, the proportion of assimilated energy allocated to metabolism ranged from 60 to 77%, and that to growth ranged from 23 to 60%. 3. 3. Difference in food consumption was most important in causing the interspecific growth differences among the six species; difference in the proportion of food energy allocated to feeding metabolism was also important in causing the growth differences between some species.