Optimal Sizing Method For Power Source Of Microgrids With Hydro-Wind-Solar Energy

In order to alleviate the energy crisis and respond to climate change,the large-scale application of new energy has become a trend.With the increase of the proportion of renewable energy power generation,the problems of power grid operation safety and power quality have become more serious.Microgrid technology is an effective method to solve the grid connected problem of distributed generation.Microgrid planning is the foundation of microgrid technology,and its capacity configuration of power source will directly affects the technical indicators such as the utilization rate of renewable energy,power supply reliability and power quality.So this article will focus on the optimal sizing method for power source of microgrid.The main work is summarized as follows:(1)In order to make full use of various types of renewable energy and ensure that the microgrid is effectively connected to the grid,an optimal sizing method for power source of hydro-wind-solar microgrid is proposed.Considering the technical constraints such as grid-connected operation constraint and installation constraint of power source,the objective functions are constructed from the aspects of economy and environmental protection.The multi-objective optimization model for the power source sizing of hydro-wind-solar microgrid is established,and the Non-dominated Sorting Genetic Algorithm(NSGA-II)is used to solve this model.The results show that hydro-wind-solar microgrids is superior to hydro-wind microgrid and hydro-solar microgrid in various performance indicators.The maximum voltage offset rate of the proposed model is reduced by 0.12% compared with the hydro-solar microgrid.The maximum fluctuation rate of the power in hydro-wind-solar microgrid is reduced by 4.59% compared with the hydro-wind microgrid.The power supply reliability of the proposed model is increased by 6.19% compared with the hydro-wind microgrid.(2)Considering the influence of hydro-wind energy and load power uncertainties on microgrid planning,an optimal sizing method for power source of hydro-wind-diesel microgrid based on bi-level robust programming is proposed.The upper layer is the optimal sizing model for power source.The lower layer is the optimal operation model for microgrid,which takes into account the uncertainties of small hydro-power,wind power and load power.The robust linear optimization theory(SCK-type robust linear optimization)proposed by Seng-Cheol Kang is used to transform the uncertainty model into a deterministic model.Simulation results show that in the severe dry season scenario,the power supply reliability of the bi-level robust programming model is 18.72% higher than the model without considering uncertainties.In terms of energy utilization,the power curtailment rate of the proposed model is 8.08% lower than the model without considering uncertainties.It is verified that the optimal sizing model for hydro-wind-diesel microgrid based on bi-level robust programming is more robust.(3)Considering the problem of the consumption of renewable energy,the configuration capacity of power source are too small to make full use of renewable energy.This paper proposes an optimal sizing model for power source of microgrid based on the coordination of power source and load.A variety of technical constraints are combined to build a bi-level linear programming model.The inner linear model is an optimal operating layer for power source and load,which takes into account the uncertainties of power source and load.The outer linear model is an optimal sizing layer for power source and load,which coordinates global optimization.Then,the complex max-min model of the inner layer is transformed into a simple max model by the strong dual theory.Simulation results show that the annual equivalent incomes of the proposed model is 541000 yuan higher than the model without taking into account the coordination of power source and load.The capacity of renewable energy power source has also increased by 69.06%.It can be seen that the optimal sizing model for power source of microgrid based on the coordination of power source and load has better economy and environmental protection.