| China's UHVDC transmission technology is booming in a higher,faster and stronger direction.Today,the highest voltage level of DC transmission and distribution around the world has climbed to ±1100KV.With the expansion of installed capacity and the improvement of electromagnetic performance,DC high-voltage equipment has higher and higher requirements for air quality.The DC field is called "safe haven" for a number of power equipment,the rational design of the airflow environment in this field plays a decisive role in the smooth operation of the DC transmission and distribution line.This paper takes guaranteeing the safety of power equipment as the most important.Firstly,it analyzed the reasonable value range of air physical parameters such as temperature,humidity and cleanliness in the DC field.Then it makes sure design points which need to be considered in the organization of on-site airflow with premeditating both the indoor DC field structure characteristics and the established environmental control parameters.Combined with the airflow law in the DC field,this paper individually analyzed and selected the relevant methods of each part about the numerical simulation,and establishes a simulation model of the indoor DC field in a true ±1100KV DC project.In this paper,a similar tall power station is selected as the measured object to verifying the feasibility of the selected simulation method.Considering the limitations of the traditional whole-room mixed ventilation method,“partitioning and targeting air supply system” dedicated to huge indoor DC field is proposed.Specific design method of the new air supply scheme in the example project is introduced.This paper also studies the realization method of the scale conversion of the core research area and the whole DC field,to achieve the balance between the overall airflow organization and the local environment optimization in the huge space and provides new ideas for airflow organizing of the same type big power equipment room.Aiming at the concentrated jetting's characteristics of high momentum airflow in targeted air supply,the highest ambient temperature of the smoothing reactor was selected as the index for judging air supply system's cooling effect and power equipment's safe level.In this case,the relationship between the supply air volume,the supply air temperature and the load should be eliminated,and conversely,The first two can be regarded as independent factors.Through the combination of single factor analysis and orthogonal simulation test,the influence laws of the airflow environment in the core with nozzle angle,air supply speed and air supply temperature are quantitatively discussed which can provide a method for the selection and control of the air supply parameters in the design of the uneven airflow.The results show that the targeted air supply effect is the best when the nozzle angle is 65°;the effect of the air supply speed increasing by 1m/s and the air supply temperature decreasing by 2K on the maximum ambient temperature is approximately equivalent when the temperature range is 293K~299K and the speed range is 6~9m/s;the recommended air supply scheme to meet the 3°C margin is: when the air supply temperature is 26°C?24°C?22°C and 20°C,the air supply speed corresponds to 7 m/ s?6 m/s?5 m/s and 5 m/s.The above results have certain reference value for the design and optimization of airflow environment in large space power station buildings. |
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