Analysis Of Unit Frequency Characteristic And Research On Unit-Grid Coordinated Strategies

As access of large capacity units in power grid, expansion of power grid, and the formation of cross-regional interconnected power grid, the interaction relationship between the regional power grid and unit has been increasingly close, making the power grid complex. This also makes the system frequency characteristic more complex.Frequency stability of power system becomes vulnerable, which is not conducive to stable operation of power grid. Under the increasingly complex power grid environment,in order to effectively control the frequency, the power system needs to further improve its frequency regulation ability. So it is necessary for researchers to conduct thorough research tounit and system frequency characteristics, so as to provide reference to improve the performance ofsystem frequency regulation.At present, the research of unit frequency characteristic mainly focuses on the analysis of the influence of speed regulating system parameters, ignoring the impact of dynamic parts such as CCS, boiler, steam turbine, etc, on unit frequency characteristic. This has limitedthe unit frequency characteristic, making the unit not able to give full play to the frequency regulation function which is finally not conducive to the improvement of unit frequency characteristic, and effects the stability of the power grid frequency. In this paper, on the basis of the classical unit model, the equipments of unit are accurately modeled. The modelshave taken into account the frequency dynamic models such as devicesof the CCS coordinated control system, boiler, steam turbine, and the OPC overspeed protection control. Then the simulation analysis of influence of the parameters and the control strategies of those parts on unit frequency characteristic has been made, and the relationship of the speed control system parameters, the CCS frequency modulation control method, the dynamic characteristics of steam turbine and boiler and the unit frequency characteristic has been analyzed.By breakthrough of the past in the research content of the influence of frequency regulation parameters of the unit speed regulation system and control strategies on power system frequency characteristic, this paper analyses the influence of the speed regulation system, OPC overspeed protection on the unit side and load disturbance and low frequency load shedding on power grid side on power system frequency characteristic. What’s more, the influence of the coordination between unit side and grid side on power grid frequency stability is analyzed.Unit-grid coordinated control strategies have beenproposed for improving the frequency characteristic of power system. Finally, taking sanshui power grid in guangdong as an example, this paper simulates and analyzes the the stability of power grid frequency under different faults.With the combination of analysis and research above, this paper also puts forward the corresponding unit-grid coordinated control strategy, and verifies the effectiveness of the control strategy in the end.