A modular power converter includes first and second terminals to connect to electrical networks and at least one module connected between the first and second terminals, the module(s) including at least one switching element and at least one energy storage device, the switching element(s) and the energy storage device(s) combining to selectively provide a voltage source, the switching element(s) being switchable to transfer power between the first and second terminals. The converter further includes a control unit configured to selectively control switching of the switching element(s) to store energy from or release energy to either or both of the first and second terminals so as to decouple respective power flows at the first and second terminals and thereby inhibit a modulation of power flow at one of the first and second terminals from modifying a power flow at the other of the first and second terminals.