Abstract: A bipolar DC power transmission scheme including first and second DC poles, each including a respective DC power transmission medium extending between first and second ends; a plurality of converters wherein each end of the transmission medium of each of the poles is operatively connected to at least one of the converters to form a rectifier and an inverter at opposite ends of the DC power transmission media; and a controller to operate at least one converter of one of the rectifier and inverter in a control mode and at least one converter of the other of the rectifier and inverter in a second control mode in response to a fault occurring on either of the poles. Additionally, the first control mode decreases and the second control mode increases the operating DC voltage of the or each corresponding converter from a normal operating voltage value.

Abstract: Methods and apparatus for controlling a voltage source converter to energise a DC link. A voltage order generating module generates a voltage order for controlling the voltage source converter to generate a DC voltage on the DC link. the voltage order is based on a time varying voltage reference signal. A voltage reference module, which may include a ramp generator generates the time varying voltage reference signal such that the rate of change of the voltage reference signal changes over time. The rate of change of the voltage reference signal may decrease over time, to become more gradual as the nominal operating voltage is reached to avoid over-voltages.

Abstract: An assembly including a converter including first and second DC terminals connectable to the DC network and between which extends a converter limb. Each converter limb includes first and second portions separated by an AC terminal. Each portion includes a switching element for normal operation and a switching element and energy absorber for a bypass mode. The bypass mode causes current to bypass the energy absorber in the limb portion and flow through the energy absorber. The assembly also includes an AC circuit breaker which is openable to isolate the converter from the network. The electrical assembly includes a control unit that is a programmed to operate the energy absorption module within the converter in its bypass mode and following a DC fault to initiate opening of the AC circuit breaker then to operate in absorption mode to remove DC fault current within an augmented current path.

Abstract: A power transmission network comprises, an AC electrical system AC transmission link from the AC electrical system to at least one AC-DC converter which includes: an AC connecting point connected to the AC transmission link and a DC connecting point for connection to a DC transmission link and a control system configured to operate each AC-DC converter in an AC voltage control mode as an AC slack bus to control a magnitude and/or a frequency of an AC voltage of the AC transmission link at a or a respective steady-state value and facilitating a power transfer between its connecting points to accommodate power generated or supplied to the AC electrical system. The control system is further configured to operate each first AC-DC converter in a protection mode to protect each AC-DC converter from an overvoltage and/or an overcurrent.

Abstract: A method and apparatus for controlling a voltage source converter to energise a DC link. A voltage order generating module generates a voltage order for controlling the voltage source converter to generate a DC voltage on the DC link. An oscillation damping module monitors the DC current flow to determine an indication of current oscillation and the voltage order is based on a voltage reference signal which is modulated by the indication of current oscillation to provide oscillation damping.

Abstract: A method and apparatus for controlling a fault blocking voltage source converter apparatus which is, in use, connected to an AC system and a DC system for power transmission, in the event of a DC side interruption operating the voltage source converter apparatus after identification of a need for a DC side interruption based on a voltage order, so as to extract at least some electrical energy stored in the connected DC system to the voltage source converter apparatus.

Abstract: The present invention relates to method for operating a power plant, with at least one wind turbine generator arranged for supplying power to an electrical grid, at least one energy storage device arranged for supplying power to the electrical grid, and a power plant controller, the method comprises, measuring repetitively measurement sets of at least one electrical parameter from the electrical grid, and calculating, in respect the measurement sets of the at least one electrical parameter, a change in active and/or a required change in reactive power at a point of common coupling, and calculating and dispatching of a first control reference signal to the at least one wind turbine generator and a second control reference signal to the at least one energy storage device, for providing ancillary service functionalities to the electrical grid.

Abstract: A power transmission network includes a plurality of converters. Each converter includes first and second electrical terminals, each first electrical terminal being connectable to an electrical network, each second electrical terminal being operatively connected to at least one other second electrical terminal. A first converter includes a first controller, the first controller configured to selectively operate the first converter to modulate a power flow at its first or second electrical terminal, and a second converter includes a second controller, the second controller being configured to selectively operate the second converter to modulate a power flow at its second electrical terminal to generate a power to compensate for an imbalance in power within the power transmission network caused by the modulation of power flow by the first converter, and thereby inhibit the modulation of power flow by the first converter from modifying a power flow in a third converter.

Abstract: A voltage limiter includes first and second DC terminals connectable to a DC power transmission medium and ground, respectively. The voltage limiter further includes: (1) a current transmission path including two portions connected in series between the terminals and each including a non-linear resistive element; (2) a current bypass limb connected in parallel with the second portion and including at least one switching element; and (3) a control unit configured to control switching of the or each switching element to selectively switch the current bypass limb, during a fault condition, from a first mode to a second mode. In the first mode, current flows through the current bypass limb and bypasses the second current transmission path portion. In the second mode, current between the DC terminals is inhibited from flowing through the current bypass limb and thereby permits the current to flow through the second portion.

Abstract: A power transmission network includes a plurality of converters. Each converter includes first and second electrical terminals, each first electrical terminal being connectable to an electrical network, each second electrical terminal being operatively connected to at least one other second electrical terminal. A first converter includes a first controller, the first controller configured to selectively operate the first converter to modulate a power flow at its first or second electrical terminal, and a second converter includes a second controller, the second controller being configured to selectively operate the second converter to modulate a power flow at its second electrical terminal to generate a power to compensate for an imbalance in power within the power transmission network caused by the modulation of power flow by the first converter, and thereby inhibit the modulation of power flow by the first converter from modifying a power flow in a third converter.

Abstract: The present invention relates to method for operating a power plant, with at least one wind turbine generator arranged for supplying power to an electrical grid, at least one energy storage device arranged for supplying power to the electrical grid, and a power plant controller, the method comprises, measuring repetitively measurement sets of at least one electrical parameter from the electrical grid, and calculating, in respect the measurement sets of the at least one electrical parameter, a change in active and/or a required change in reactive power at a point of common coupling, and calculating and dispatching of a first control reference signal to the at least one wind turbine generator and a second control reference signal to the at least one energy storage device, for providing ancillary service functionalities to the electrical grid.

Abstract: Apertures with inclined sidewalls are produced in a dielectric layer by exposing a photoformable dielectric layer through a mask having a section without a sharp line of demarcation between opaque and transparent areas.