Method for protecting steam-electric generating set shafting through modality divergence criterion of torsional oscillation protection

Abstract

The present invention relates to a technique for measuring and protecting the shafting torsional oscillation of the 300MW, 600MW and 1000MW turbine generator of the large-scale heat power plant, and discloses a core protecting criterion comprising the shafting torsional oscillation protection of the turbine generator. The criterion obtains the modality time sequence by real-time measuring the acceleration of the rotary speed of the generator set shafting, real-time calculates the time sequence of the modality amplitude of each torsional oscillation, uses the observing windows with different lengths for calculating the relative variation trend of the modality amplitude itself, judges the torsional oscillation divergence according to the statistics of the modality variation trend in a certain time, and sends out the tripping operation command to disconnect the generator set from the electric network thereby protecting the generator set.

Description

technical field [0001] The invention relates to electric power systems, thermal power plants, industrial fields requiring various types of steam turbine generator sets and industrial fields requiring large electric motors, in particular to the measurement and protection technology of the shaft system torsional vibration of the steam turbine generator sets. Background technique [0002] Large-scale turbogenerator technology is one of the key equipment of major equipment in my country and the core equipment of thermal power plants. The safe operation of the steam turbine generator set is the basis and premise of the safe production of thermal power plants. The steam turbine generator set completes the conversion from thermal energy to mechanical energy to electrical energy. The power of large-scale units is usually 300MW, 600MW, and 1000MW. Such huge power produces huge torque on the shafting of the generating set. The operation of the generating set requires the shafting of t...

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Problems solved by technology

[0003] In order to improve the power transmission capacity, the power system adopts large-scale power electronic equipment and adopts the series compensation capacitor technology of the transmission line, so that there are many kinds of resonance or oscillation in the power system. The mechanical natural frequency of the shafting of the turbogenerator is usually within the range of this subsynchronous oscillation frequency, which makes the natural parameter model of the power system and the turbogenerator have the possibility of resonance. Once the subsynchronous oscillation occurs in the power system, it will The shafting of the steam turbine generator set at the factory end produces serious resonance between mechanical energy and electrical energy, which will have a destructive effect on the shafting of the generator set. loss, will also bring great harm to the safe operation of the transmission network

[0004] In addition to subsynchronous oscillation, some electrical operations of the power grid and power plant will also cause mechanical fatigue of the shafting of the generator set due to the proximity of the natural frequency of the shafting to the resonance frequency of the power grid. The long-term accumulation of mechanical fatigue will lead to damage to the shafting and even twist off

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