Research On Flexible Frequency Modulation Characteristics Of Double Reheat Coal-Fired Power Generation Unit

In order to ensure the safe operation of the power grid and smooth the impact of new energy on the power grid,coal-fired power generation units need to adapt to the new environment and improve their frequency modulation flexibility.In this paper,Ebsilon simulation soft is used to build the model a 660 MW ultra-supercritical double reheat unit.Based on this model,the frequency modulation characteristics of different frequency modulation modes,such as high pressure feeding water heater bypass frequency modulation,steam make up valve adjustment and condensate throttle frequency modulation,are studied respectively to obtain their effects of each frequency modulation mode on the unit load and thermal performance.Their advantages and disadvantages of are compared and ranked respectively.Finally,some valuable suggestions for the use of the frequency modulation methods are given.The results show that:it is better to use the whole high pressure feeding water heater bypass frequency modulation when the load demand for the unit is higher,to use the condensate throttling frequency modulation when the economic performance requirement is higher,and use 1/2 mixed high pressure feeding water heater bypass or the whole bypass when simultaneously considering both the load demand and the economic performance demand.At the initial response of the unit,the steam make up valve can be opened to realize the fastest response.On the basis of the established model,the following coupling frequency modulation characteristics are further studied:coupling of high pressure feeding water heater bypass with steam make up valve adjustment frequency modulation,coupling of high pressure feeding water heater bypass with condensate throttle frequency modulation,coupling of condensate throttle with steam make up valve adjustment frequency modulation,coupling of high pressure feeding water heater bypass with steam make up valve adjustment with condensate throttle frequency modulation.Their effects of each frequency modulation mode on the unit load and thermal performance are obtained and their respective advantages and disadvantages for ranking are compared.Suggestions are given as follows:it is better to use NO.1 high pressure feeding water heater bypass frequency modulation or coupling three ways together when the load demand for the unit is higher,to use the coupling of condensate throttle with steam make up valve adjustment frequency modulation when the economic performance requirement is higher,and use coupling of three ways together when simultaneously considering both the load demand and the economic performance demand.As coupling of high pressure feeding water heater bypass with steam make up valve adjustment frequency modulation is low in both rankings,so it is not recommended.