高压换流场分区靶向送风研究

电力已经成为我们生活的基本保障,随着电力需求侧的迅猛扩张,供给侧的规模和容量也在不断加大,高压输电系统的室内热环境保障成为一项至关重要的任务。高压换流场是功能目标明确的能源站建筑,与普通办公、商场等商业建筑相比,换流场不仅对温度要求高,而且对于工作区域的温度分布均匀性要求也高,因此需对其进行精准的空间环境控制,保障直流场设备高效运行。从高压换流场环境研究着手,针对其设备环境的要求,提出分区靶向送风系统设计,并对高压换流场进行分区方案设计。靶向送风针对换流场内散热设备降温,分区主要考虑降低空调系统能耗,相比于传统方案更精准、更高效、更节能。以某一高压换流场为例,将研究空间分为电抗器区域内和电抗器以外空间,针对两个区域环境的不同特点,对其进行不同的方案设计,与传统方案进行比较,分析其在高压换流场内的环境调节效果;利用FLUENT,模拟出研究空间运用分区靶向送风方案的温度分布效果,分区靶向送风方案能够将特高压直流场内环境温度降至平均温度33.4℃,远低于要求温度40℃,由此可见分区靶向送风方案能够有效降低温度,均匀空间分布温度场,对高压换流场内环境起到很好的调节作用,从而保障电力设备不间断安全稳定运行。

PIV Investigations of Flow Patterns in the Entrance Configuration of Plate-fin Heat Exchanger

Flow characteristics in the entrance of plate-fin heat exchanger have been investigated by means of particle image velocimetry (PIV). The flow field was measured using the two-frame cross-correlation technique. Streamline and velocity contour graphs at different cross-sections were obtained in the experiment. The experimental results indicate that flow maldistribution in the conventional header is very serious, while the improved header configuration with punched baffle can effectively improve the uniformity. The flow maldistribution parameter in plate-fin heat exchanger has been reduced from 1.21 to 0.21, and the ratio of the maximum velocity to the minimum is reduced from 23.2 to 1.8 by install-ing the punched baffle. The results suggest room for the optimum design of plate-fin heat exchanger.

±800kV换流站通用设计研究与应用

介绍了±800 kV换流站通用设计编制的目的、输入条件和主要技术原则,并按照换流站功能区划分为换流场、直流场、交流滤波器场、站用电、接地极5个基本模块。重点分析了±800 kV换流站设计的主要技术方案,对电气主接线形式、布置方案及优化要点等进行了详细的说明,提出了适应不同外部条件的15个标准化模块方案,为后续特高压换流站设计工作提供参考。

Damping controller design based on FO-PID-EMA in VSC HVDC system to improve stability of hybrid power system

Wind energy sources have different structures and functions from conventional power plants in the power system.These resources can affect the exchange of active and reactive power of the network.Therefore,power system stability will be affected by the performance of wind power plants,especially in the event of a fault.In this paper,the improvement of the dynamic stability in power system equipped by wind farm is examined through the supplementary controller design in the high voltage direct current(HVDC)based on voltage source converter(VSC)transmission system.In this regard,impacts of the VSC HVDC system and wind farm on the improvement of system stability are considered.Also,an algorithm based on controllability(observability)concept is proposed to select most appropriate and effective coupling between inputs-outputs(IO)signals of system in different work conditions.The selected coupling is used to apply damping controller signal.Finally,a fractional order PID controller(FO-PID)based on exchange market algorithm(EMA)is designed as damping controller.The analysis of the results shows that the wind farm does not directly contribute to the improvement of the dynamic stability of power system.However,it can increase the controllability of the oscillatory mode and improve the performance of the supplementary controller.

Anti-flooding of polymer electrolyte membrane fuel cell with in-plate adverse-flow flow-field

The stoichiometric ratios and related regimes, which can promote anti-flooding of polymer electrolyte membrane fuel cell （PEMFC） with in-plate adverse-flow flow-field （IPAF）, were investigated. Two flow combinations, which are the simple and complex adverse-flow between plates （ABP） that can be realized by IPAF, were employed. Constant stoichiometric ratios examination indicates that the complex ABP could improve anti-flooding of PEMFC better in the medium （greater than 200 mA/cm2 and less than 1 000 mA/cm2） and high （greater than 1 000 mA/cm2） current densities than the simple ABP. More stoichiometric ratios were introduced to find the cathode critical stoichiometry. Under the condition of cathode critical stoichiometry, the maximal local relative humidity of both electrodes of complex ABP is equal to 100% and below while the anti-flooding of the cathode of simple ABP is not satisfactory in the medium and high current densities. Further study shows that the mechanism of fuel cell, which is the imerdependence between the electrodes effect, can make significant contribution to anti-flooding.

Flexible HVDC Transformer for Next Generation Renewable Energy Industry

The growing demand on non-fossil fuel energy has escalated the desire for mega-scale renewable energy power generation, which can no longer be satisfied solely by relying on onshore renewable energy power plants. Outcomes from a recent project funded by the Sixth European Union Framework Programme （FP6）, Project ＂Upwind＂ concluded that larger offshore wind turbines （i.e., 〉 10 MW） are feasible and cost effective. It will be beneficial for such future large scale renewable energy power generators （i.e., large offshore turbines） and plant （i.e., large offshore wind farms） to have a dedicated high efficiency, robust, flexible and low cost power collection, transmission and distribution technology. Proposed in this paper is a compact and effective hybrid HVDC （high voltage direct current） transformer that allows realisation of a highly robust and financially rewarding next generation multi-terminal HVDC system for future offshore renewable energy power plant. This concept, potentially, allows the elimination or minimisation of the need for a centralised local offshore HVDC platform or substation in each wind farm, solar farm, or tidal farm. This paper discusses the study outcome of the proposed hybrid HVDC transformer and the application of a multi-terminal HVDC system in the renewable energy industry, compared to the existing HVAC and VSC （voltage source converters） type HVDC systems.