Abstract: A hydraulic system employing an electronically commutated fluid working machine having working chambers, each having one or more electronically controllable valves actively controlled by a controller to regulate the net displacement of working fluid into or out of low- and high-pressure manifolds on a cycle by cycle basis to meet an indicated demand. The high-pressure manifold has an additional outlet, regulated by a controllable outlet valve. If the demand indicated by a demand signal is expected to cause pulsatile flow or vibrations which may excite resonant modes, the controller causes the displacement of working fluid by the working chambers to exceed the demand indicated by the demand signal, and the controller simultaneously opens an electronically controllable outlet valve to allow some of the excess flow to leave, such that the net displacement of fluid meets the demanded displacement of fluid, while mitigating the pulsatile flow or undesirable vibrations.