HVDC transmission systems are mostly used in long distance or cross-regional transmission and trans-region interconnections.Yet in hydro power sending provinces the load increase rapidly and the transmission routes are more and more difficult to choose.In order to increase the transmission capacity,it's an important option to choose the regional HVDC schemes within the province in transmission planning of hydro power stations.The installed capacity of the power stations on the middle reach of the Yalong River totaled 11560 MW and the distance to load center of Sichuan province is 400~500km.During the transmission system planning of the stations,the regional HVDC transmission schemes within Sichuan province or SichuanChongqing area were studied.The technical and economical comparisons between HVDC and 500kV/1000kV AC transmission schemes were made.In consideration of the present situation and planning characteristic of the Sichuan power grid,the studies focused on the transmission route problems,the increase of transient stability power limit margin and the reduction of short-circuit current level.The research came to the conclusion that it's applicable to choose the regional HVDC transmission scheme within Sichuan province.

There are about 200 GW hydropower resources for exploitation in Southwest China,especially in Yunnan Sichuan Province.It is the important hydropower resources base for West-East electricity transmission project in the future.The primary energy resource is very short in Henan,Hubei,Hunan Jiangxi Provinces of the east of Central China(abbreviation east four Provinces of Central China),and the pressure of carriage is very hard for those areas,which will be the important markets for hydropower resources of Southwest China,and receiving the hydropower resources will be the energy strategy for Central China in the future.A few avenues were put forward for satisfying the east four provinces of Central China’s electrical requirement in the future based on analyzing the power supply demand.Combined with the development of electricity market and system features,the capability of east four provinces in Central China for receiving the hydropower resources of Southwest China was studied,and the capability of thermal power and hydropower regulating or receiving the hydropower from Three Gorges was analyzed.Based on the conclusion of the power receiving scale,the drainage area of the hydropower resources in Southwest China was also put forward,which can be as a reference for future power planning in related area.

In Sichuan province,most fossil fuel plants are located in the vicinity of load centers and auxiliary power sources are provided from the generator sides.The reactive power output variation of the plant affects the auxiliary power source voltage.Primary studies were conducted on the selection of voltage regulating mode for the high-voltage auxiliary transformer in the Sichuan Baima 600 MW CFB demonstration power plant.According to the status quo and planning characteristics of Sichuan power grid,the main electrical connection of the plantand the connecting method,the power flow,phase and voltage adjustment was calculated with a variety of operational modes.Technical and economic comparison was made between the on-load tap changing and off-circuit tap changing of the high-voltage auxiliary transformer.The preliminary conclusion proved that the off-circuit tap changing mode can be used in Sichuan power grid.

Energy resource in China totals 4000 gigaton of standard coal, ranking third in the world. China has a vast territory in north area, accounting for 57.8% of territory. 34.2% of the population is located in north area while the coal resource exceeds 81% of the total reserve in China. The coal reserve in China ranks third in the world, after USA and Russia. Hydropower resource in north area is lacking, however. As a whole, China has an imbalance between energy distribution and consumption. On one hand, nearly 2/3 of hydropower resources locate in Yunnan, Sichuan and Tibet while nearly 2/3 of coal reserve centralizes in Shanxi, Inner Mongolia and Shanxi province. On the other hand, the eastern developed regions, such as Beijing-Tianjin-Tangshan delta, Yangtze River delta and Zhujiang River delta, where energy consumption is most heavy, have a vital shortage of energy resources. According to the statistics, 88% of energy has to be imported from other provinces in these areas. The imbalance of energy production and consumption leads to the energy flow feature of power transmission from west to east and coal transportation from north to south in China. The coal is playing a leading role in energy production and consumption. Petroleum consumption exceeded production since 1995 and shortage of petroleum is growing year by year. Since 1992, China's energy consumption demand has exceeded its energy supply. The tendency of energy demand exceeding supply still persists until now. China has become the world's third largest region with heavy acid deposition after Europe and North America. It is predicted that China's primary energy consumption will reach around 4.1 billion tons of the standard coal by 2020, which is almost 25% of the worldwide. The energy supply will be the bottleneck of development. The Energy Saving and Pollution Reducing policy should be carried out without a moment to lose. This article discusses the energy status of China and its position in the world by analyzing and comparing a great deal of data. Energy demand for the year 2020 is predicted through analysis of energy production and consumption condition in China. The characteristics, consumption balance of energy resources and environment restriction in china determine that energy saving and pollution reducing is inevitable. Based on statistical information, the energy saving potential in energy-consuming industries, especially the electrical power industry, is analyzed in this paper.

There contains abundant hydropower resources in Southwest China,especially in Yunnan Sichuan Province.Many power-generation companies presently start to set foot in exploitation of hydropower resources.Combined with analyzing the prospect of receiving electric-market of hydropower and capability of mechanic-electric equipment manufacturing,the present situation and exploitation problems of hydropower resources in such regions were discussed and demonstrated in this paper.The important measures for reasonable and efficient exploitation of hydropower in Southwest China were presented.

The hydropower resources in China should be ranked first in the world,59% of which comes from the southwest,including the nearly 200 GW exploitable capacity in Yunnan and Sichuan provinces.These two provinces will become the major electric-energy base of Electricity Delivery from West to East in the future.In order to effectively utilize the southwest hydropower resources,the transmit-out scale,capacity of receiving electric-market and power delivery direction of the southwest hydropower were proposed in this paper,which can be as reference for power plannings.

The electric energy production of the Three Gorges Hydropower Station will exceed the prediction during the Eleventh Five-Year Plan.The study of excess electric energy consumption is important to realize the benefit of the Three Gorges Project.The current status of the Three Gorges power consumption and the Eleventh Five-Year Power Planning of the corresponding regions are primary conditions of the study.The recommended scheme of power consumption in future five years is proposed in this paper,which can be as reference for Three Gorges power dealing.