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Wind energy is being used extensively in various areas as an economically and environmentally friendly type of energy. The number of wind farms is continuously developing and it is foreseen a three time increase in contribution of wind energy to European electricity consumption for next twenty years. A complementary trend, of large potential and expectations, is the revival of the small wind turbines (SWT) (<100 kW), suitable for operating in rural areas with moderate winds. In the case of SWT one may use the hydraulic system to convey energy to the ground. When one consumer is used only, the structure of the hydraulic system may be conventional one meaning with impressed flow. For the case of two or more consumers with different loads, the secondary control concept is proposed which means a system with impressed pressure. In this paper, a model for the simulation of the hydraulic system with impressed flow was tested and the step response is presented. The proposed model may be used as an instrument for the design of a hydraulic system with impressed flow.

Abstract. Among the properties of working fluid, viscosity is the most important as it regards especially to pumps. In order to study the behavior of hydrostatic transmission it is important to create a reliable research instrument for dynamic simulation. Our research expertise being in SimHydraulics consequently this instrument is the suitable block diagram. The purpose of this paper is to present the possible ways to customize the properties of the working fluid in the block diagram.

In fluid power systems, flow control may be done either with variable displacement pump or using variable orifice. In this paper is considered the second method for flow control. In a hydraulic system, working pressure is frequently variable and therefore the use of the method does not provide constant flow rates in all operating conditions. In order to keep a constant flow, if this is important in a certain case, the flow control must be accomplished using a pressure compensated flow control valve. In this paper are analyzed possible structural diagrams, mathematical model, block diagram and functional diagram for this kind of equipment. The influence of the spring compression is analyzed also. The diagrams proposed in the paper will be used for the study of a hydraulic system designated for applications with strict flow control. It will represent an important research instrument for such cases.