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Research On Control And Optimization Scheduling Strategy For Stand-alone Microgrid With Hybrid Energy Storage System

Posted on:2019-01-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:J F ChenFull Text:PDF
GTID:1362330590961651Subject:Power electronics and electric drive
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The microgrid system is a controllable power supply system that is tightly integrated by the load,distributed power supply and power electronic converter through the electrical network.It fully utilizes the wind/solar resources for stable local power supply,which not only promotes the local consumption of renewable energy power generation,but also improves the stability and economy of the local power supply system.It is an effective way to ensure stable power supply in remote areas such as islands,mountains and rural areas,and it is also an important supplementary means for the modern large-scale power systems.As a self-operating small power system,the primary task of the independent microgrid system is to maintain stable operation.Based on this,the second task is to optimize the energy scheduling of various types of power generation units and to improve the economy.The output of wind and photovoltaic power generation units of independent microgrid systems is greatly affected by natural conditions such as wind speed,solar radiationintensity and temperature,and is often volatile and intermittent.At the same time,the power load is also randomly fluctuating.The proportion of the fluctuating load to the total power of the whole microgrid system is relatively high,which brings great challenges to the operation of the microgrid.It is not only harmful to the stable operation of the system,but also causes great difficulties for the energy optimization scheduling of the whole system.Therefore,whether the independent microgrid system ensure its stable and economic operation under the condition of minimizing energy storage capacity,and whether it can improve the economics of the microgrid system are the keys to the large-scale application of the microgrid system.However,how to establish a scientific and reasonable microgrid system model to solve the stability problem and energy optimization scheduling problem of the microgrid system? This paper focuses on this key technical problem,and conducts in-depth research on the topology and mathematical modeling,coordinated stability control,optimization scheduling strategy and multi-time scale intraday optimization scheduling of independent microgrid systems.The main research contents of the thesis include the following parts:(1)The paper firstly describe the challenges of precision transient modeling for a typical microgrid system architecture,and then perform independent static and dynamic modeling of the typical power generation units,describing the characteristics of the different time responses for multiple power generation units in the microgrid system.The key problems encountered in the overall modeling of the microgrid system are proposed,and other issues such as random disturbance,multi-time scale characteristics and stability domain solving are also discussed.All the above contents lay down a foundation for the subsequent chapters to implement stable control of the microgrid system.(2)Based on the hierarchical control structure,considering the dynamic characteristics of the power consumption deviation in the independent microgrid system,a multi-timescale voltage/frequency control method for microgrid and a fast dynamic stabilization of renewable power fluctuations and a renewable energy consumption control strategy are proposed for the fast dynamic component of the energy deviation.According to the dynamic characteristics of the voltage/frequency of the independent microgrid,the strategy divides the voltage/frequency stability area into three zones: warning zone,emergency zone and qualified zone.The primary power control and the secondary power coordinated control can effectively compensate the net load power shortage in the millisecond time scale,quickly suppress the voltage/frequency fluctuation.Furthermore,the coordinated optimal control of the system is realized by the microgrid energy management system.(3)Based on the low-cost and stable control of the independent microgrid system,a day-ahead optimization scheduling strategy for independent microgrid systems with multiple energy storage is proposed for the slow dynamic component of the energy deviation.The constrains used in this strategy includes the system balance constraints,energy storage unit operating constraints,distributed generation unit system operating constraints,spare capacity constraints,and three-phase unbalance constraints.On this basis,the fuzzy theory and chaotic particle swarm optimization algorithm are combined to solve the day-ahead optimization scheduling of independent microgrid systems with multiple energy storage.(4)The randomness and intermittentness of the output of renewable energysource(RES)lead to the increasing regulation pressure of conventional controllableunit commitments,the increased risk of microgrid operation and the poor economic performance.To improve the benefits of microgrid operation,this study proposes a multi-time scale coordinated control scheme of “day-ahead optimization(DAO)+ intraday rolling(IDR)+ quasi-real-time correction(QRTC)+ real-time coordinated control(RTCC).”Considering the shortcomings of existing low prediction accuracy of distributed RES and loads,the soft constraints such as unit commitment scheduling errors and load switching scheduling errors are introduced in the intraday rolling model,allowing the correction of day-ahead unit commitment and load switching schedule.In the quasi-real-time coordinated control,an integrated criterion is introduced to decide the adjustment priority of the distributed generations.In the real-time coordinated control,the HESS adopts an improved first order low pass filtering algorithm to adaptively compensate the second-level unbalanced power.In order to further absorb the predicted deviation power of the system,the stable and economical operation of the microgrid system is finally realized.
Keywords/Search Tags:Autonomous microgrid, multi-type energy storage, multi-time scale, day-ahead optimal scheduling, intraday rolling optimization, real-time coordinated optimizatio
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