Operational Security Region Analysis And Optimal Regulation Of Multi-Factor Coupling Renewable Distribution Systems

In the context of China’s carbon peaking and carbon neutrality goals,ensuring the secure operation and efficient consumption of renewable energy in the distribution system is an important task of the renewable distribution system.However,the current research on the operational security region of distribution systems has problems such as analytical solution difficulty,low calculation efficiency,and difficulty in adapting to high-penetration renewable energy and largerscale distribution systems.In addition,multiple factors such as renewable energy consumption,electricity market price,source-network-load-storage coordination,and operational security are increasingly closely coupled in the renewable distribution system.Then the optimal regulation of multi-factor coupling renewable distribution systems is also facing severe challenges.To deal with these issues,this thesis conducts research on the operational security region analysis and optimal regulation of multi-factor coupling renewable distribution systems,which includes the four aspects: optimal power flow modeling,operation security region analysis,optimal operation,and voltage regulation.The integrated modeling,analysis,and regulation methodologies are proposed in the thesis to support the secure operation of renewable distribution systems and the efficient consumption of renewable energy.The main contributions of this thesis are summarized below:(1)A generalized linear-constrained optimal power flow(GLOPF)model is proposed for distribution systems.Using the Taylor expansion point-based iterative method,the GLOPF model is constructed for distribution systems as a series of linear-constrained convex quadratic suboptimizations.The objective function of the GLOPF model is only added with a second-order penalty on state variables,which is at least positive semi-definite and easy to calculate.This avoids the complex calculation of quasi-Hessian or Hessian matrices in traditional sequential programming methods,and guarantees the convexity of the quadratic optimization to obtain the globally optimal solution at each iteration.The converged solution to the GLOPF model is proved to satisfy the Karush–Kuhn–Tucker(KKT)conditions of the original optimal power flow problem,and a sufficient condition is given for solution convergence.The proposed GLOPF model is adapted to both radial and mesh distribution systems and has high computational efficiency and fast convergence speed.Besides,the convergent solution satisfies AC power flow constraints,which also can provide multiple precision operational approximate solutions for distribution systems.(2)An analytical operational security region(AOSR)model is proposed for renewable distribution systems.Facing the issue of the secure operation of distribution systems with renewable energy and the influence of demand-side resources,this thesis introduces the concept,definition and linearization of AOSR for renewable distribution systems.A boundary point solving model of AOSR is established to obtain the boundary point on the line connecting the given interior and exterior points.Then,an n-dimensional boundary hyperplane solving model is constructed based on boundary points,which efficiently solves the boundary hyperplane expression and ensures its accuracy.A point-hyperplane iterative algorithm is developed to efficiently generate the complete expression of the AOSR of distribution network with highpenetration renewable energy.This thesis also quantitatively evaluates the impact of demand-side flexibility on the security region of renewable energy,which provides important support for the optimal regulation of renewable distribution systems.(3)A bi-level transactive control model is proposed to integrate the distribution locational marginal price(DLMP)pricing of the distribution system and the decision-making of users.The lower-level DLMP-driven demand response model enables each nodal agent to minimize its expenditure under the DLMP.A linearized optimal power flow problem is constructed for the distribution system operator,whose dual form is used to build a DLMP-pricing model.Then the DLMP can be directly integrated into the upper-level optimization model in the form of variables.With the integration of DLMP-pricing and demand-side decision-making,a bi-level transactive control model is proposed for renewable distribution systems,which is converted into a singlelevel mixed-integer linear programming problem by using linearization methods and replacing the lower-level optimizations by KKT conditions.The proposed transactive control model realizes the integration of DLMP-pricing and demand-side decision-making,which promotes the secure and economic operation of renewable distribution systems under multiple factor couplings such as source-load-network-storage coordination,power pricing,and demand-side decision-making.(4)A voltage-price coupling(VPC)mechanism is proposed for price-driven voltage regulation in renewable distribution systems.The voltage sensitivity coefficient and voltage impact factor models are constructed to quantify the influence of the nodal power on the voltage deviation of the renewable distribution system.In the proposed VPC mechanism,the spatiotemporal coupling relationship between nodal voltage and nodal price is characterized by price allocation rules at different nodes and horizons.Based on the VPC mechanism,a fair and adaptive nodal pricing method is formed for distribution systems,which considers the voltage-price spatiotemporal coupling relationship,the impact on the existing pricing mechanism,and the effect of voltage regulation.By integrating demand-side energy management,voltage regulation and nodal pricing,a price-driven voltage regulation approach is constructed for renewable distribution systems,which significantly improves the voltage security of renewable distribution systems with multi-factor coupling.