Abstract: A static synchronous compensator for use in reactive power compensation, the static synchronous compensator comprising at least one primary compensator limb including first and second DC terminals, and an AC terminal for connection in use to an AC network, the or each primary compensator limb defining first and second limb portions, each limb portion-including at least one switching element connected in series with a chain-link converter-between a respective one of the first and second DC terminate and the AC terminal, the switching elements of the first and second limb portions being operable to switch the respective chain-link converters in and out of circuit between the respective DC terminal and the AC terminal and the chain-link converters being operable to generate a voltage waveform at the AC terminal; and a secondary compensator limb including at least one DC link capacitor connected between the first and second DC terminals, the secondary compensator limb being connected in parallel with the or each