METHOD AND APPARATUS FOR DIAGNOSING A HYDRAULIC MACHINE, POWER GENERATING APPARATUS OF RENEWABLE-ENERGY TYPE, AND METHOD OF DIAGNOSING THE SAME

A method is for diagnosing a hydraulic machine including a rotation shaft, a high-pressure line, a low-pressure line, cylinders, pistons guided by the respective cylinders, a cam configured to reciprocate the pistons in conjunction with rotation of the rotation shaft, high-pressure valves provided for respective working chambers formed by the cylinders and the pistons, for switching a communication state between the high-pressure line and the respective working chambers, and low-pressure valves provided for the respective working chambers, for switching a communication state between the low-pressure line and the respective working chambers. The method includes a step of detecting a failure of the hydraulic machine, the failure including at least one of sticking of the high-pressure valves in an open state, sticking of the low-pressure valves in a closed state, or sticking of the pistons, on the basis of at least one of a standard deviation of a torque of the rotation shaft in a no-load state of the hydraulic machine, or a fluctuation component of a specific frequency from among a torque fluctuation of the rotation shaft, a pressure fluctuation in the high-pressure line, and an output fluctuation of the hydraulic machine, the specific frequency being determined by a rotation speed É of the rotation shaft and a cam-lobe number m of the cam.