Übersetzung für "Load rejection" in Deutsch

The rail pressure pCR rises after the load rejection.

During load rejection, for instance, the control servo motor reaches the safe position in less than 300 ms.

This bypass system is also employed if, after a load rejection (for example when the mains circuit-breaker is opened) or in the case of a rapid shut-down of the turbine, the steam generated cannot be completely accepted by the turbine or cannot be accepted at all.

The present invention achieves this object in that characteristic curves for the required value of the reheater pressure are used for controlling the low-pressure bypass valve during run-up, during (partial) load rejection procedures or during idling, which characteristic curves depend on the load applied to the installation, and/or on the pressure before the high-pressure turbine blading and/or on the reheater steam flow, and also on the high-pressure turbine exhaust steam temperature, and/or on the temperature and/or on the pressure of the live steam introduced into the high-pressure turbine, and/or on the reheater pressure.

Because the high-pressure exhaust steam temperature T HD has, in certain operating conditions (run-up, part-load operation, load rejection), the tendency to exceed critical values and to give rise to material damage, particular attention must be paid to this process parameter.

The present invention relates to a method for controlling a low-pressure bypass system for a steam turbine installation having a reheater, in particular for run-up from the cold condition, for idling and low-load operation and after load rejection procedures.

If, for example, an internal combustion engine is being operated in a steady state at a constant rail pressure of 1800 bars, and a complete load rejection occurs, the time until the pressure control valve responds is 37.5 ms.

The method just described has proven effective for a complete load rejection, i.e., a reduction of the generator load from 100% to 0%.

This makes dealing with transient operating states, such as for example network short circuit, dropout and return of the network voltage, load rejection, almost impossible despite an overdimensioning of the components.

As a result of the limited switching frequency of the HV-IGBT of the network-side converter 26 and the associated, restricted dynamics, dealing with transient operating states, such as load rejection, short circuit in the on-board network, network restoration etc. is difficult and inevitably leads to an overdimensioning of the components of this voltage source inverter.

At point in time t A, a load rejection takes place and the generator speed increases to a value above the nominal speed.

Since the speed limitation in the second operating state, as in the prior art, is realized by an open-loop control system, optimization of the speed controller parameters for the load rejection is not necessary.

Since the industry standards for the load rejection preset a speed increase of, for example, a maximum of 10% of the rated speed, in practice, the DBR curve is selected in such a way that this criterion is guaranteed to be maintained.

At point in time t 1, a load rejection takes place and the generator speed increases to a value considerably above the nominal speed.

If, in a load reduction, a large load is rejected, the result is a very high negative gradient GRAD (GRAD