Research On Parallel Coordination Restoration Of Power Systems Considering Large Scale Wind Power Participation

Due to the human factors and external environmental factors such as natural disasters,large-scale blackouts are still difficult to avoid for modern power systems,as evidenced by the many large-scale blackouts that have occurred around the world in recent years.Practical experience has shown that safe,orderly and rapid recovery of power systems will help to reduce the negative impact of blackouts.Thus,the research on power system restoration has significant and far-reaching practical significance.Under the strong guidance of sustainable development policy,coupled with the rapid development of manufacturing technology and control technology of wind turbine,the capacity and permeability of wind power integration are increasing year by year,and they have great impact on power system operation control.In this context,the development of an efficient and safe restoration plan is a real problem that must be faced and urgently addressed after blackouts occurred.Based on comprehensive study and analysis on existing research work about the power system restoration,the key issues of parallel coordination restoration of power systems considering large-scale wind power integration have been studied systematically.The main contents of this thesis include the following aspects.1.Generation and comprehensive assessment of black-start zone partitioning schemes.As the introduction of virtual network flow,the explicit expressions of connectivity constraints of each subsystem are given.Based on them,an iterative integer linear programming model is established for obtaining multiple black-start zone partitioning schemes.Then,the evaluation indexes of schemes are extracted from multiple perspectives,which construct the synthetic evaluation index system.And a multi-attribute decision making method is applied to determine the comprehensive optimal scheme.The proposed method can provide a general and efficient decision support for black-start zone partitioning.At the same time,from the practical requirements of black-start zone partitioning,the lossless simplification method based on cut points and the lossy simplification method based on swing nodes are proposed to improve the possibility of applying the proposed method to large-scale power systems.2.Optimization decision for unit partitioned restoration considering wind power participation.The method of optimizing unit partitioned restoration sequence for coordinating wind power with conventional synchronous generators is proposed under the general idea of time-step modelling.The uncertainty of wind power output is described in the form of the scenario set,and a chance-constrained programming model is developed.The deterministic transformation of the model is achieved by applying the sampling average approximation method and solved efficiently with the help of commercial solver.The proposed method enables the coordination of the unit restoration sequence and black-start zone partitioning schemes,and the trade-off between safety and speed of restoration.The results of case system show that the design scheme can give full play to the value of wind power,weaken the negative impact of wind power integration,which lays the foundation for follow-up safe and fast restoration process.3.Optimal control of standing phase angle under wind power integration.The impact of uncertain wind power output on the standing phase angle is analyzed using the interval power flow algorithm.Therefore,the necessity of considering the uncertainty of wind power output when regulating the standing phase angle is pointed out.The interval of wind power output is represented by uncertainty set.Then,by adjusting the output and terminal voltage of synchronous generators and restoring some load as the control measures,a two-stage robust optimization model is established to reduce the standing phase angle.In order to solve the model efficiently,the original model is transformed into a mixed integer linear programming model,which is solved iteratively by the combination of the dichotomy method and column-and-constraint generation method.The proposed method can minimize the control cost and ensure the reliability of the standing phase angle adjustment scheme in complex wind power output environment,and provide a guarantee for safe and reliable network parallel operation,which has strong practical significance.4.Optimization of load recovery schemes considering source-load uncertainties.Based on time-step modelling framework,the continuous load recovery process is discretized into multiple progressive time steps.Then,a robust optimization model of the load recovery scheme is established for each time step considering the source-load multiple uncertainties.The original model is decomposed into the main problem of scheme optimization in prediction scenario and the subproblem of scheme checking in error scenario by applying the decoupling idea.And the column and constraint generation algorithm is used to solve it efficiently,which provides a powerful support for online safety-aided decision making for load recovery under large-scale wind power participation.The linear polyhedral set and the adjustable box set are utilized to describe the wind power prediction errors with certain correlation and the load prediction error respectively,which facilitates operators to regulate the conservatism of the scheme.