Abstract:
A method of controlling a full-scale converter system in which both the grid-side inverter unit and the generator-side inverter unit have a series-connection of parallel inverters and form a generator-side and grid-side voltage-center-point at a voltage level between the inverters connected in series. The voltage-center-points are electrically connected by a center-line conductor. Conversion operation with a de-rated maximum active power-output is performed in response to at least one of (i) the grid-side inverter and (ii) the generator-side inverter of the first converter-string being disabled, by disabling active power production of at least one of (i) the grid-side inverter and (ii) the generator-side inverter of the second converter-string, or correspondingly reducing active power production of the second converter-string, thereby preventing a compensation current along the center-line conductor.
Abstract:
The present invention relates to a method for operating a wind power facility in order to provide reactive power support to a power grid, the method comprising the step of increasing an amount of reactive power injected into the power grid, decreasing an amount of active power injected into the power grid by a certain amount, and dissipating and/or storing essentially said certain amount of active power in power dissipation and/or power storage means. The wind power facility may comprise a wind turbine or a wind power plant.
Abstract:
A wind turbine is provided. The wind turbine comprises a generator, a power converter for converting at least a portion of electrical power generated by the generator, an energy dissipating unit and a controller. The power converter comprises a generator-side converter, a grid-side converter and a DC (direct current) link there between. The energy dissipating unit is operatively coupled to the DC-link. The controller is adapted to activate the energy dissipating unit to dissipate energy from the DC-link in response to a shutdown request.
Abstract:
A method for controlling a wind turbine system including an electrical generator, a power converter system, a DC-link, and at least a grid-side breaker arrangement controllable between open and closed states, wherein the method comprises monitoring for the presence of a shutdown event and, in response to identifying the presence of a shutdown event, controlling the wind turbine into a production-ready state, comprising: i) controlling the grid-side breaker arrangement in the closed state; ii) disabling one or more drive signals to the power converter system; and iii) controlling the DC-link of the power converter system in a charged state. Advantageously, this approach reduces the frequency of use of the grid-side breaker arrangement which extends serviceable life considerably, and also allows the wind turbine system to be transitioned rapidly between an operating state and a production-ready state.
Abstract:
A method of setting a reference DC-link voltage of a wind-turbine converter system is provided. At least at least one DC voltage demand from at least one generator-side inverter and at least one DC voltage demand are received from at least one grid-side inverter. A generator-side DC voltage demand value on the basis of the at least one DC voltage demand received from the at least one generator-side inverter. Also a grid-side DC voltage demand value is determined on the basis of the at least one DC voltage demand received from the at least one grid-side inverter. The highest DC voltage demand value out of the generator-side and grid-side DC voltage demand values is chosen. This chosen value corresponds to the set reference DC-link voltage.
Abstract:
A wind turbine generator 1 supplies three-phase a.c. current of variable voltage and variable frequency to two pairs of rectifiers 4a, 4b and 4c, 4d which generate respective d.c. outputs connected to positive, negative and neutral d.c. conductors 6, 7, 8. The outputs from each pair of rectifiers are connected together, and the outputs from the two pairs are connected in series to create a high-voltage d.c. output. Inverters 10a, 10b, 10c, 10d then convert the d.c. power to a.c. at a fixed frequency and voltage suitable for In connection to the mains grid. To reduce the effect of common-mode noise, a capacitor is connected between the 1 neutral conductor 7 and earth, and a respective filter circuit 30 is connected between each of the a.c. outputs of the inverters 10a, 10b, 10c, 10d and earth. To reduce the effect of voltage surges during lightning, a surge protection device is also connected between the neutral d.c. conductor 7 and earth. Any imbalance in the current in the positive and negative conductors 6, 8 is compensated by detecting the presence of current flowing in the neutral conductor 7. Power supplied to auxiliary circuits from the output of one of the inverters, e.g. 10a, of the wind turbine is measured, and any resulting imbalance between the current in the positive and negative conductors is compensated. In the event of an earth-leakage fault in the conductors connecting the a.c. outputs of the inverters to the grid, when isolated, isolation detection relays 25 are provided.