Frequency Management Based On The Coordination Between Dispatching And Control In Microgrid

Currently, the global energy crisis and the environmental crisis are increasingly serious.Besides, the shortcoming of bulk power grid is continually prominent. Thus, distributedgeneration is paid more attention. Microgrid is a new type of power grid, which canintegrate and coordinate various distributed generations. The effective utilization ofmicrogrid is helpful for making full use of distributed generation, exploring the value ofdistributed generation at maximum and relieving the contradiction between distributedgeneration and bulk power grid. When a microgrid is operated in island, the frequencyshould be completely maintained by the microsources. However, there are many uncertainfactors in microgrid. What’s more, the inertia of microgrid and the controllability of mostsources are relatively weak. All these raise a big challenge for the frequency management inmicrogrid. Therefore, this paper studys the frequency management based on thecoordination between dispatching and control in microgrid. Research work can besummarized as follows.Firstly, the basic theory of the coordination between dispatching and control inmicrogrid is studied. The reason why the current coordination mode in bulk power grid isnot suitable in microgrid is analyzed, and based on that the concept and framework of thecoordination between dispatching and control in microgrid are proposed. As well as manymeasures to increase the coordination between dispatching and control in microgrid arepresented. Besides, many key issues on management and technology which should besolved during the realization of the coordination between dispatching and control inmicrogrid are proposed respectively.Secondly, an evaluation method used for reserve capacity requirement in microgrid isproposed for the coordination between dispatching and control. As the reserve capacityrequirement is closely related to the uncertain factors in microgrid, the paper analyzes theinfluence factors on reserve capacity requirement, and then optimizes the reserve capacityrequirement of each period considering the power supply reliability, microsource failure,forecasting error of load and renewable generation output in detail. The case study indicatesthat the method proposed by this paper can improve the power supply reliability greatly.Finnaly, a method to allocate the reserve in microgrid is proposed. As there are manydifferences between microgrid and the bulk power grid, the indexes of the unit in microgridused for frequency adjustment and their calculation methods are put forward. At the same time, a normalization method is presented to evaluate the performance of each index. Thecomprehensive performance is obtained through Analytic Hierarchy Process and theperformance price ratio of a unit used for frequency adjustment is caluated based on theprice. The performance price ratio is set as the standard of the priority method and the unitsshould be selected by the priority list until the capacity and rate are all satisfied.The research in this paper exerts a reference value to microgrid operation andmanagement. Besides, the research in this paper when promoted may be used for bulkpower grid with high penetration of volatile renewable generation.