Generation And Transmission Optimal Expansion Planning Considering Large-scale Wind Power Integration

Renewable energy,which is represented by wind power,is regarded as an effective substitute for traditional fossil fuels.However,given the randomness,intermittence,and volatility of wind power,planners face the challenge of dealing with it in power system expansion planning with large-scale wind farm integration.The traditional single-time section planning model based on maximum load can not take the intermittent and volatility of wind power into consideration,and can not meet the requirements of generation and transmission expansion planning method with large-scale wind power integration.Unit commitment(UC),generation expansion planning(GEP),transmission expansion planning(TEP),and joint generation and TEP(G&TEP)with large-scale wind power integration are investigated in this study on the basis of the analysis of wind power characteristics.This research coordinates the planning issues and economic dispatch problems of generation sources,transmission networks,and loads by improving the regulation capability and flexibility of the power supply side.This study aims to promote large-scale wind power consumption and solve the economic and reliability problems caused by the change of wind power output.The findings of this work are as follows:(1)A multi-area UC considering tie-line operation modes was presented.Intermittence and fluctuation of large-scale wind power lead to increased demand for peak shaving capacity of the system,and tie lines were used to achieve inter-regional peak shaving resources mutual benefit.Detailed mathematical models for operation modes and power flow inversion times and power flow fluctuation degrees on tie lines were also established.Artificial variables were introduced to transform the models into mixed-integer linear programming formulations.A multi-area and multi-scenario UC model considering tie-line operation modes was proposed on the basis of the theory of multi-scenario based stochastic optimization method to minimize annual comprehensive costs.A total of three worst case scenarios were defined on the basis of the size and the change rate of the net load and the degree of dispersion of the load and the wind power to balance solution efficiency and accuracy.(2)A short-term operation constrained multi-area GEP model was introduced.The wind power time series data and load were sampled by employing the sequential Monte Carlo simulation,and the typical daily scenarios were filtered by using the Gauss mixture clustering method.A multiarea GEP model considering the short-term operation constraints of conventional generators and BESSs was built to minimize the annual investment of conventional units and BESSs and generating costs.(3)A TEP model considering optimal transmission switching was constructed.By dynamically adjusting network topology,optimal transmission switching was introduced into TEP in this work to improve the economy of planning schemes.A novel TEP model with optimal transmission switching to minimize the sum of the annual investment and the operation cost was proposed.(4)A joint G&TEP model considering the systematic regulation ability was presented.The requirement of system flexibility with large-scale wind power integration should be proceeded from two aspects,namely,conventional generators and transmission networks.In addition,the regulation characteristics of different power sources should be considered.Wind power can be consumed by turning conventional generators on or off,and generators can provide sufficient spinning reserve.Optimal transmission switching was proposed for the transmission network to introduce a flexible topology.A joint G&TEP model considering the system regulation capacity was established on this basis to minimize the annual comprehensive cost.(5)A coordination of multi-objective,multi-area G&TEP model considering short-term operation constraints was developed.A planning model with different operation modes of tie lines were established,taking tie lines as the set of candidate lines.On this basis,a multi-objective and multi-area joint G&TEP model considering economic(i.e.,investment and operation costs),reliability(i.e.,load shedding),and environmental indicators(wind curtailment and carbon dioxide emissions),was developed.Short-term operation issues and long-term planning problems in typical day scenarios were combined.Case studies on the modified IEEE RTS system and a real 301-bus system were proposed to verify the effectiveness and applicability of the presented methods.