摘要:
A method for controlling the power flow in an ac transmission line including prompt handling of voltage recovery and only thereafter thermal constraints.
摘要:
A DC grid (100) comprising a plurality of AC/DC converters (105) which are interconnected via DC lines (115) is provided, wherein, in order to limit the effects of a fault in the DC grid, the DC grid is divided into at least two zones (200) by means of at least one current limiter (205) in a manner so that a current limiter is connected in each of the DC line(s) (115z) by which two zones are interconnected. A method of limiting the effects of a fault in a DC grid by dividing the DC grid into at least two zones is also provided.
摘要:
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.
摘要:
A DC grid (100) comprising a plurality of AC/DC converters (105) which are interconnected via DC lines (115) is provided, wherein, in order to limit the effects of a fault in the DC grid, the DC grid is divided into at least two zones (200) by means of at least one current limiter (205) in a manner so that a current limiter is connected in each of the DC line(s) (115z) by which two zones are interconnected. A method of limiting the effects of a fault in a DC grid by dividing the DC grid into at least two zones is also provided.
摘要:
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.
摘要:
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 (Ud,common, Ũd,common) to the converter stations, the common feedback signal (Ud,common, Ũd,common) being based on an overall voltage level in the DC transmission, power network; providing, in the converter stations, a control signal (S1, S2, S3, S4) based on the common feedback signal (Ud,common) and a drooped error signal (Pe, droop, Ue, droop); and controlling the power flow within the DC power transmission network towards set operating points (Udref, PCCref) by using the control signal (S1, S2, S3, S4). A control device and computer program product is also described.
摘要:
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.
摘要:
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.