Patent application number | Description | Published |
20080258559 | Electric Power Flow Control - An apparatus for controlling power flow in a high voltage network. A phase shifting transformer includes a tap changer. | 10-23-2008 |
20080265848 | Electric Power Flow Control - An apparatus for controlling a power flow in a high voltage network. A phase shifting transformer includes a tap changer. | 10-30-2008 |
20090134850 | CONTROL OF POWER FLOW IN A TRANSMISSION LINE - A method for controlling the power flow in an ac transmission line including prompt handling of voltage recovery and only thereafter thermal constraints. | 05-28-2009 |
20090218993 | DEVICE AND A METHOD FOR CONTROL OF POWER FLOW IN A TRANSMISSION LINE - A device for control of power flow in a three-phase ac transmission line. The device includes a series transformer unit, a shunt transformer unit, and a reactance unit. | 09-03-2009 |
20100088048 | Method And Device To Predict A State Of A Power System In The Time Domain - A method to predict a state of a power system and a device to perform the method are presented, where the method includes the step of performing a Fast Fourier Transform on samples of a periodic waveform signal in order to determine a frequency spectrum of the signal, where the signal was derived from at least one measurable electric quantity of the power system and is representative for the state of the power system. Frequencies and related complex amplitudes at selected peaks in the frequency spectrum are determined and stored together with a time stamp. Afterwards, a predicted value of the periodic waveform signal in the time domain is determined at a prediction time by calculating a sum of sinusoidal signals at the prediction time, where each of the sinusoidal signals is characterized by one of the determined frequencies and its related complex amplitude as well as the time stamp. | 04-08-2010 |
20100094477 | DETERMINATION AND USE OF POWER SYSTEM SENSITIVITIES - The present disclosure relates to power system sensitivities as computed from power flow parameters and control parameters of a Power Flow Control Device (PFC). To this end, control parameter variations are applied to or generated by a PFC, and comprise variations in a control input u, a control effort e (injected series voltage, inserted series reactance), or a control effect q (power flow, active power transfer, phase-shift, current). A power flow response measuring unit measures a variation of a power flow response such as current, active or apparent power, in a way sufficiently synchronized with the control parameter variation to allow establishing an unambiguous causal relationship or correspondence in the form of a power system sensitivity. The latter may be on-line adapted to continuously reflect an updated aspect of the power system behaviour, and thus enable an improved, fast and reliable power flow control in power systems comprising a meshed power network with two parallel flow paths or corridors connecting two areas or sub-systems. | 04-15-2010 |
20110093124 | INVESTIGATING TIMING RELIABILITY IN RELATION TO CONTROL OF A POWER TRANSMISSION SYSTEM - The disclosure is related to a method, power control device and computer program product for evaluating accuracy of timing provided by time generating equipment in relation to wide area control in a power transmission system, where the wide area control is performed based on time stamped measurements of system data. The power control device can include a timing deviation handling unit that investigates timing used in relation to time based measurements, determines if the timing is reliable or not based on the investigation, and aborts wide area control if the timing is deemed unreliable. | 04-21-2011 |
20110126038 | TIME DELAY COMPENSATION IN POWER SYSTEM CONTROL - A method and controller are provided for the compensation of time delays in remote feedback signals in power system control. The method includes converting the time delay into a phase shift and calculating four compensation angles from the phase shift. The optimal compensation angle is determined and applied to the remote feedback signals. A technique of equipping a controller with a global clock is also disclosed. | 05-26-2011 |
20120200166 | Power Or Voltage Oscillation Damping In A Power Transmission System - A method, device and computer program product for providing improved control of power or voltage oscillation damping in a power transmission system. The device includes a magnitude obtaining element configured to obtain an instantaneous magnitude of a signal representing a deviating oscillation in at least one element of the power transmission system, a slope investigating element configured to determine the rate of change of the signal, and a first processing block including an integrating element configured to integrate the instantaneous magnitudes with an integrating factor that is based on the determined rate of change. The first processing block is further configured to form a phase compensation angle based on the integrated instantaneous magnitude for use in a damping control signal generating unit in order to provide power or voltage oscillation damping of the system. | 08-09-2012 |
20120201059 | FAULT CURRENT LIMITATION IN DC POWER TRANSMISSION SYSTEMS - A method, voltage source converter and computer program product for limiting the current in a DC power transmission system are disclosed. The voltage source converter has an AC side and a DC side and a fault current path between these sides. It furthermore includes a control unit and at least one switching unit of a first type provided in the fault current path and that includes a primary switching element together with an anti-parallel secondary controllable rectifying element. Based on a fault being detected in the DC power system when the primary switching elements of the converter are blocked, the control unit changes the control of the controllable rectifying element from acting as a non-controllable rectifying to acting as a controllable rectifying element. | 08-09-2012 |
20130054035 | Control Of A Power Transmission System - The invention provides improved control of a power transmission system having a first group of measurement units in a first geographical area providing a first set of phasors and a second group of measurement units in a second geographical area providing a second set of phasors, where the phasors in the sets are generated at the same instant in time. In this system the power control device includes a phasor aligning unit that time aligns the first and second sets of phasors and a control unit that compares each set of phasors with a corresponding phasor number threshold, determines that a first control condition is fulfilled if each phasor number threshold has been exceeded and enables the provision of a common signal if the first control condition is fulfilled. The common signal is based on the obtained phasors in the first and second sets. | 02-28-2013 |
20130077204 | BREAKER FAILURE PROTECTION OF HVDC CIRCUIT BREAKERS - A breaker failure protection system for a high voltage direct current, HVDC, circuit breaker is provided. The circuit breaker is arranged for interrupting a DC circuit upon reception of a trip signal. The protection system includes a current sensor, at least one inductor, and a breaker failure detection unit. The current sensor is arranged for measuring a current I(t) through the DC circuit. The at least one inductor is connected in series with the DC circuit. The breaker failure detection unit is arranged for assessing, whether the circuit breaker has failed, and sending, if the circuit breaker has failed, a trip signal to an adjacent circuit breaker. The assessment is based on the measured current. The stability of HVDC grids may be improved by sending, in case of a breaker failure, a trip signal to adjacent circuit breakers. Further, a method of breaker failure protection for an HVDC circuit breaker is provided. | 03-28-2013 |
20130088802 | FAULT PROTECTION OF HVDC TRANSMISSION LINES - A protection system for high voltage direct current, HVDC, transmission lines is provided. The protection system includes a direct current, DC, bus, a device configured to connect an HVDC transmission line to the bus, at least one DC circuit breaker arranged for disconnecting the transmission line from the bus upon reception of a trip signal, current and voltage sensors, an inductor arranged such that the current through the transmission line passes the inductor, and a fault detection unit. The fault detection unit is arranged for assessing, on the basis of current and/or voltage measurements, whether a fault exists on the transmission line, and sending, if a fault is detected on the transmission line, a trip signal to the circuit breaker. The additional inductance limits the rise in fault current and facilitates a selective fault detection. Further, a method of fault protection for an HVDC transmission line is provided. | 04-11-2013 |
20130106184 | HVDC SWITCHYARD AND AN HVDC SWITCHYARD SYSTEM | 05-02-2013 |
20130127426 | METHOD AND CONTROL DEVICE FOR CONTROLLING POWER FLOW WITHIN A DC POWER TRANSMISSION NETWORK - A method for controlling power flow within a DC power flow within a DC power transmission network includes two or more interconnected converter stations. The method includes the steps of: establishing a common feedback signal (U | 05-23-2013 |
20130307331 | INVESTIGATING TIMING RELIABILITY IN RELATION TO CONTROL OF A POWER TRANSMISSION SYSTEM - The disclosure is related to a method, power control device and computer program product for evaluating accuracy of timing provided by time generating equipment in relation to wide area control in a power transmission system, where the wide area control is performed based on time stamped measurements of system data. The power control device can include a timing deviation handling unit that investigates timing used in relation to time based measurements, determines if the timing is reliable or not based on the investigation, and aborts wide area control if the timing is deemed unreliable. | 11-21-2013 |
20140002943 | DC GRID AND A METHOD OF LIMITING THE EFFECTS OF A FAULT IN A DC GRID | 01-02-2014 |
20140022680 | CURRENT LIMITATION SYSTEM FOR LIMITING THE EFFECTS OF A FAULT IN A DC GRID AND A METHOD OF OPERATING A CURRENT LIMITATION SYSTEM - A current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part is provided, as well as a method of operating a current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part. | 01-23-2014 |
20140313641 | USING THE TRANSFER SWITCH OF A HYBRID CIRCUIT BREAKER AS SELECTOR SWITCH - A high voltage direct current (HVDC) switchyard is provided. The switchyard is arranged for interconnecting three or more sections of an HVDC power network, such as transmission lines, converters, or any other type of HVDC equipment. The switchyard comprises at least one main circuit breaker and at least four transfer switches. The at least one main circuit breaker and the at least four transfer switches are arranged so as to enable to individually disconnect any one of the at least three sections of the HVDC power distribution network. In an embodiment of the invention, the transfer switches which usually are comprised in direct current (DC) hybrid circuit breakers are used as selector switches, thereby reducing the number of main breakers in the switchyard. | 10-23-2014 |