Grid-integrated Solar PV Optimization With Consideration Of Demand Side Flexibility Techniques

Global concerns on the sustainability of the exponentially growing human energy needs have created fertile grounds for the penetration of solar PV into the modern power system.Thus,solar PV has achieved tremendous growth in the recent global energy mix.However,variation in the solar resource is a major barrier to the utilization of solar PV in power systems as it adversely affects the operation,control and planning of the modern power system.Among the various solar variation mitigation methods,demand side grid flexibility techniques have great potential to alleviate some of the operation and control challenges posed by solar resource variation.Thus,this study investigated the optimization of solar photovoltaic-integrated power systems using demand side flexibility techniques.This study focused on improving consumer load profiles through demand response programs using peak load clipping,valley load filling and load shifting methods to enhance the performance of the grid-integrated solar photovoltaic system.In the study,the main performance indexes of interest were power generation cost,solar power absorption,generation system ramping and other system constraints that should be observed during power demand and supply process.In this regard,methodical research has been carried out through numerical analyses and the implementation of the proposed optimization model in an existing microgrid power station facility.Some achievements that can enhance the operation and control of photovoltaic-integrated power systems are as follows:1.A dynamic economic dispatch model with integrated solar photovoltaic and demand side management was proposed to optimize the generation cost of solar integrated power system.The Matlab platform was the main computational software considered for the numerical simulations using several load demand profile improvement techniques in thermal generation unit test systems under varying solar resource conditions.Besides,PVsyst and PVWatts software were also used in the solar power generation analyses whereas the SPSS software was used for solar-load correlational analyses.The validation of the proposed power generation cost optimization model revealed that it was effective.2.Using the proposed model,the generation cost performances of two main load profile improvement methods: conventional load profile flattening and the solar-load alignment,were investigated using an evolving load profile.The results showed that both the conventional load profile flattening and solar-load alignment techniques improved the generation costs of solar photovoltaic-integrated power systems at low and high solar penetrations,respectively.However,load profiles with very high positive solar-load correlation may not effectively reduce the generation costs even under high solar penetration conditions.Moreover,the results revealed that generator ramping down could be a limitation to the load flattening technique under high solar penetration condition whereas generator ramping up could be a limitation on the solar-load alignment technique under low solar penetration condition.3.In a generation system with inadequate flexibility,positive solar-load correlation conditions exhibited higher solar power absorption capability than the negative and weak solar-load correlation conditions.The high solar power absorption capability of the positive solar-load correlation could have adverse effects on the total cost of generation which can be mitigated through implementation of demand side management.Moreover,in a generation system where solar power absorption is not a challenge due to adequate generation system flexibility,the daytime load characteristics of the load demand profile affected the capability of the solar power absorbed to improve the generation cost of the power system.4.Also,the impact of financial incentive levels for peak load clipping and load shifting demand side management on the power generation cost of solar photovoltaic-integrated power systems were investigated.For all incentive levels of the load shifting program relative to the threshold incentive of the peak clipping program,peak clipping exhibited a higher capability of reducing the power generation cost than load shifting.However,high solar penetration and priority given to solar power could significantly reduce the generation cost gap between the peak clipping and load shifting programs.Moreover,the results showed that similar incentives levels for both the load shifting and peak clipping programs had an adverse impact on the generation cost under system conditions in which the peak solar power generation occurred during low-load periods.5.The load shifting demand response program was employed to vary the degrees of daytime peak loads of the load profiles under varying penetration and solar resource conditions.The result showed that improving the daytime peak load management could reduce the generation costs at high levels of solar penetration.However,this solar variation mitigation technique may pose operational challenges with consequential adverse effects on power generation costs in generation systems with inadequate ramping capabilities.6.The proposed optimization model was implemented in the Shaoxing microgrid power station.The result revealed that aligning the consumer load demand profile with the solar resource improved the on-site consumption of renewable energy generated and subsequently reduced power importation from the central grid more than flattening the consumer load demand profile.With respect to generation cost,it was observed that the impact of the load profile to improve the generation cost depended on the economic value placed on the excess renewable power exported to the central grid.The results implied that,the solar-load alignment technique favoured the independent operation of the Shaoxing microgrid more than the conventional load profile flattening technique.