Abstract: Methods and systems for detecting systemwide service issues by using anomaly localization. In an example, a method includes receiving time-series monitoring data for multiple services, the time-series monitoring data including multiple dimensions and an error metric; for the monitoring data from each service, evaluating scopes within the monitoring data based on an objective function for a time-series of the error metric to identify at least one anomalous scope, each scope including at least one dimension and a value for the dimension; based on evaluating the scopes, generating a ranked list of scopes for each service based on objective function scores for the scopes; correlating the ranked lists of scopes across the multiple services to identify a cross-service anomaly; and generating an alert for the services based on the cross-service anomaly, the alert indicating at least one scope as a potential root cause for the cross-service anomaly.

Abstract: A voltage source converter having first and second DC terminals for connection to a DC network is provided. The voltage source converter includes at least one converter limb that extends between the first and second DC terminals and first and second limb portions that are separated by a respective AC terminal for connection to a corresponding phase of an AC network. Each limb portion includes a chain-link converter which is defined by a plurality of series-connected switching modules which operate in combination to provide a stepped variable voltage source. The voltage source converter includes a control apparatus configured to coordinate operation of the chain-link converters to cause an exchange of power between the DC and AC networks, evaluate the performance of one of the pluralities of series-connected switching modules, and modify the operation of the respective chain-link converter when the performance becomes degraded to a predetermined amount.

Abstract: There is provided an electrical assembly comprising a converter (20) for connection to an electrical network (40), the converter (20) comprising at least one module (44) including at least one switching element (46) and at least one energy storage device (48), the or each switching element (46) and the or each energy storage device (48) in the or each module (44) arranged to be combinable to selectively provide a voltage source, the electrical assembly including a controller (54) configured to selectively control the switching of the or each switching element (46) in the or each module (44), wherein the electrical assembly includes a sensor (56a) configured for measuring a current of the electrical network (40), wherein the controller (54) and sensor (56a) are configured to operate in coordination to carry out a characterisation of an electrical parameter of the electrical network (40) so that, in use: the controller (54) selectively controls the switching of the or each switching element (46) in the or ea

Abstract: In the field of high voltage direct current (HVDC) transmission, a voltage source converter comprises first and second DC terminals that are for connection to a DC network. The voltage source converter also includes at least one converter limb. The or each converter limb extends between the first and second DC terminals and includes first and second limb portions that are separated by a respective AC terminal for connection to a corresponding phase of an AC network. Each first limb portion extends between the first DC terminal and a corresponding AC terminal, and each second limb portion extends between the second DC terminal and the corresponding AC terminal. Each limb portion includes a respective chain-link converter which is defined by a plurality of series-connected switching modules which are operable in combination to provide a stepped variable voltage source.

Abstract: There is provided a method of configuring a closed-loop control system, the control system comprising a controller and a plant, the controller configured to provide an actuator signal to the plant, the controller configured to receive a reference signal (r) and a feedback signal (y), the feedback signal (y) derived from a state (x) of the plant, wherein a first state space representation of the control system includes at least one system delay, the method comprising the steps of: transforming the first state space representation of the control system into a second, augmented state space representation of the control system; configuring a control law (uT) based on the augmented state space representation of the control system, wherein the control law (uT) is configured to include at least one control term configured to compensate for at least one disturbance (d) to the control system, wherein the control law (uT) is configured to include a time-advanced or predicted reference signal (r) configured so that the

Abstract: A voltage source converter for interconnecting first and second electrical networks, including first and second terminals for connection to the first electrical network, and a primary converter limb extending between the first and second terminals including first and second primary limb portions separated by a third terminal connectable to the second electrical network. The converter further including a second chain-link converter connected to the third terminal and a control unit configured to selectively operate one or more chain-link modules to generate a discontinuous pulse width modulation voltage waveform. The converter further including a controller configured to selectively operate each chain-link converter to control the configuration of a discontinuous pulse width modulation voltage waveform at the third terminal.

Abstract: A synthetic test circuit, comprising: a device under test including a chain-link converter under test, comprising a plurality of test modules, each test module including module switches connected with an energy storage device; a terminal connected to the device under test; at least one injection circuit operably connected to the terminal, the injection circuit including a source, the source including a source chain-link converter, which includes a plurality of source modules, each source module including a plurality of module switches connected with at least one energy storage device; a controller being configured to operate each source module to selectively bypass the corresponding energy storage device and insert the corresponding energy storage device into the corresponding source chain-link converter so as to generate a voltage across the source chain-link converter and thereby operate the injection circuit to inject a current waveform and/or a voltage waveform into the chain-link converter under test.

Abstract: A synthetic test circuit, for performing an electrical test on a device under test, is provided. The circuit includes a terminal connectable to the device under test; a voltage injection circuit-operably connected to the terminal, the voltage injection circuit including a voltage source, the voltage source including a chain-link converter, the chain-link converter including a plurality of modules, each module including a plurality of module switches connected with at least one energy storage device; and a controller-configured to operate each module of the voltage injection circuit to selectively bypass the or each corresponding energy storage device and insert the or each corresponding energy storage device into the chain-link converter so as to generate a voltage across the chain-link converter and thereby operate the voltage injection circuit to inject a unidirectional voltage waveform into the device under test.

Abstract: A method is provided for controlling a converter including at least one converter limb corresponding to a respective phase of the converter, the or each converter limb extending between first and second DC terminals and including first and second limb portions separated by an AC terminal, each limb portion including a converter arm, at least one of the limb portions including at least one director arm, the or each director arm including a director switch. The method comprises the steps of obtaining a respective AC current demand phase waveform for the or each converter limb, and a DC current demand, both of which the or each converter limb is required to track; determining a limb portion current; timing the current ramp profile of the determined director arm current for the director arm or the one of the director arms; and providing a limb portion voltage source for each limb portion.

Abstract: A voltage source converter for interconnecting first and second electrical networks, including first and second terminals for connection to the first electrical network, and a primary converter limb extending between the first and second terminals including first and second primary limb portions separated by a third terminal connectable to the second electrical network. The converter further including a second chain-link converter connected to the third terminal and a control unit configured to selectively operate one or more chain-link modules to generate a discontinuous pulse width modulation voltage waveform. The converter further including a controller configured to selectively operate each chain-link converter to control the configuration of a discontinuous pulse width modulation voltage waveform at the third terminal.