TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The profile form of the wing is symmetric or asymmetric. The wing profile has two leading edges mirrored. The wing has attachment means which allow the wing surface angle of attack to be adjustable by turning it around support axis. The wing has a profile in which a flowing water causes reaction forces that are larger than action forces. The converter has: either the cover or shaft rotationally fixed and the other part rotating; connection for the underwater wing for using water movement to cause rotating force to the hinge-type energy converter; means for turning the wing to a preferred position; hydraulic transmission comprising a high pressure accumulator without pipe-work built into the shaft to enable receiving high energy peaks and to regulate power production; hydraulic transmission comprising low pressure accumulator keeping positive pressure in the system; and mechanical transmission, which comprises at least one epicyclic gear stage. The converter is autonomous and has a bilge pump, a sealing flushing pump and/or a hydraulic fluid return pump. The converter is tethered and has external hydraulic fluid recirculation with filtering and leak removal. The converter is remote controlled. The housings will be fixed together for coupling the connectors. The connector is rated for higher frequency than main frequency. The energy plant comprises several adjacent production units which have underwater wings with asymmetric profiles, where the profiles are installed right handed or left handed in relation to the water flow direction, and the underwater wings of two successive production units are opposite handed. The converters of the production units are attached to a non-rotating foundation giving support to the stationary part of hinge unit at the bottom, submerged or above the water surface. The actuator surface angle of attack can be adjustable by turning it around support axis. The wing profiles of the plant are in such a position that the wing profile forces are caused by pressure differences caused by velocity differences on different sides of the profile. The wing profiles of the plant have such forms and are in such positions that the force component caused by the water flow on the wing profile is smaller in the direction of the water flow than the force component in the direction which is orthogonal to the direction of the water flow.