Thermal power unit primary frequency modulation control system and method

Abstract

The invention discloses thermal power unit primary frequency modulation control system and method. The system comprises a steam turbine high-pressure steam control valve, a steam turbine connected with the steam turbine high-pressure steam regulation valve, a synchronous generator connected with the steam turbine through a rotary shaft, and a generator end ampere-voltage meter connected with the synchronous generator, wherein one exit of the synchronous generator is connected with a power grid through a high-voltage transformer, and the other exit is connected with the in-plant electric equipment through an auxiliary power transformer; a high-voltage side ampere-voltage meter is mounted on the high-voltage side of the high-voltage transformer and, after inducing a three-phase current / voltage signal, is connected with a high-precision frequency meter which is connected with a primary frequency modulation instruction conversion module; the generator end ampere-voltage meter outputs a three-phase current / voltage signal and is connected with a high-precision power meter; the high-precision power meter and the primary frequency modulation instruction conversion module are sequentially connected with a deviation calculation module, a primary frequency modulation controller and a steam turbine high-pressure steam control valve. The invention also discloses a control method of the system. Asynchronous deviation in a dynamic process is avoided, and the primary frequency modulation performance index of the unit is further improved.

Description

Technical field [0001] The invention relates to the field of automatic control of thermal power plants, in particular to a primary frequency modulation control system and method for thermal power plants. Background technique [0002] The core function of the power grid is to ensure the real-time dynamic balance of power load and power generation. Before the advent of large-scale cheap energy storage technology, the continuous changes in power load required various power sources in the power grid to participate in the frequency modulation of the power grid. Primary frequency regulation means that the generator set automatically adjusts the power according to the change of the grid frequency to maintain the stability of the grid frequency. [0003] At present, the primary frequency regulation control loop commonly used in thermal power units in my country generally follows the traditional hydraulic control unit mode, using the steam turbine speed as the direct signal source. Because ...

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Problems solved by technology

Although the steam turbine speed has a good correlation with the grid frequency, on the one hand, due to the change of the generator angle of attack and the influence of the transformer inductance in the dynamic process, a layer of dynamic deviation between the unit speed and the grid frequency will be formed. It is also the moment when the primary frequency modulation loop needs to be activated and evaluated, which will have a certain adverse effect on the performance of the primary frequency modulation response of the unit; It is not high (generally ±1rpm), and the frequency modulation dead zone required by the power grid is ±2rpm, that is, the speed needs to be activated when the speed exceeds ±2rpm near the rated 3000rpm. Immediate action and certain indicators must be met, which actually requires extremely high signal accuracy for the selected primary frequency modulation, otherwise it is easy to cause misoperation and refusal due to insufficient signal accuracy

In recent years, some units have switched to the high-precision frequency table at the machine end to generate a frequency modulation command, but there is still a deviation between the low-voltage side electrical signal and the high-voltage side frequency in the dynamic process. In addition, the amplitude and speed indicators of a frequency modulation action need The power coordination of the unit requires accurate power signals as feedback for whether the action is in place, and the power meter commonly used in the unit control system often cannot meet the needs of high-precision index measurement, and often has a certain static deviation from the power signal obtained from the grid side. , which has a negative impact on the realization of the primary frequency regulation performance index of the unit

[0006] Based on the analysis of the above existing technologies, it can be seen that the primary frequency regulation control of the existing high-power thermal power units has obvious deficiencies, and it is difficult to improve the primary frequency regulation performance indicators of the units.

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