| To realize energy revolution,it is necessary to develop high penetration of wind and solar power generation.One question comes up: should wind and solar photovoltaic(PV)power generation be developed in areas near the load centres with extensive distributed wind and solar PV systems,i.e.,the ?local consumption?(LC)scheme,or should large-scale wind and solar PV bases be developed in areas far away from the load centers and then transmitting the electricity generated there to the load centers by long distance transmission lines,i.e.,the ?large-scale and long-distance transmission?(LSLDT)scheme? Choosing which way in developing wind and solar power generation will make a big difference to the energy transition and industry distribution of China.Nevertheless,there is a lack of valuable research on the macroscopic and strategic issue,especially lacking in the methods of assessment and optimization.In view of above issues and based on a lot of investigations on practical engineerings,following work was carried out.Firstly,the key technical points about the LSLDT scheme and the nature bebind the argument about the LC and LSLDT schemes were analyzed.Based on the philosophy of interconnected power systems,a qualitative analysis about the restriction of the LSLDT scheme on the development of wind and solar power generation was done from the following 3 perspectives: renewable energy electricity ratio,system operation and available regulation capacity.Secondly,mathematical models were developed on the assessment of the maximum renewable energy electricity integration ratios that could be achieved by the two development schemes.Among which,the combination of the model of the sending-side system and that of the receiving-side system makes up the integral mathematical model of the LSLDT scheme.The constraints of peak regulation and renewable energy electricity curtailment ratio were given special attention in above models.To solve the model proposed,a two-stage strategy was proposed to search for feasible solutions to unit commitment.And then,it is able to conduct timing simulation to the system with unit commitment instrument.It is the first time to find that the LSLDT scheme makes a ?negative leverage effect? on the development of wind and solar power generation,i.e.,whenever one unit of wind and solar electricity of the LSLDT scheme is integrated into a power system,two units of wind and solar electricity of the LC scheme that could have been developed in the power system are reduced.Also,the simulation results show that it is able to realize the long-term target of high penetration of wind and solar power when only the LC scheme is adopted.Thirdly,a mathematical model of total social cost consisting of 6 major items or 13 minor items was proposed.Among which,some cost items ignored in existing research were considered here,e.g.,the ancillary service cost.Also,an optimal planning was done to the bundling scheme of the sending-side system of the LSLDT scheme.Based on this,the power supply costs and their variations in the near future of 4 specific schemes were compared in the light of investigation data.The 4 specific schemes were developing wind power by centralized wind-thermal bundling with long-distance transmission,developing solar PV power by centralized solar-thermal bundling with long-distance transmission,developing wind power with the distributed wind power generation,and developing solar PV power with the distributed solar PV power generation.It is found that the power supply costs of the LC scheme are already or will be soon lower than those of the LSLDT scheme.Then,based on the limited data provided by Lawrence Berkeley National Laboratory,a calculation method of costomer interruption cost was proposed to make up the shortcomings in reliability cost calculation.The method is with explicit physical meaning and easy to use.It made the calculation done by 4 steps which considering the following 4 key factors respectively,i.e.,customer type,customer size,interruption occurrence time,interruption duration.Case studies were done and the calculation results indicated that the method could be used into the assessment of reliability cost in smart distribution grid easily with the premise of calculation accuracy.Lastly,standalone PV and energy storage system is a special form of the LC scheme solar PV power generation.An optimal planning method of standalone PV and energy storage system was proposed.Minimizing the sum of the expectation of customer interruption cost and investment cost was set the objective function.A novel control strategy with timing prospective was put forward,and it could reduce the costomer interruption cost as far as possible.Case studies were done and the results showed that the method proposed in the paper could reduce the total cost of standalone PV and energy storage system. |
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