Optimization Configuration And Operation Research Of On-load Capacity And Voltage Regulating Distribution Transformers After Electric Energy Substitution

In order to reduce air pollution,increase the proportion of electric and coal,and optimize the energy layout,China has vigorously promoted the electric energy substitution in the whole country,that is,in the terminal of energy consumption,the energy consumption modes of loose burning coal,oil and gas are replaced by electric energy.However,while electric energy substitution brings us economic and environmental benefits,it will increase the peak-to-valley difference of power supply load of distribution network,resulting in the problem of voltage over-limit and large distribution transformer no-load loss.The on-load capacity and voltage regulating distribution transformer is an energy-saving distribution transformer.It can realize the capacity switching and voltage adjustment without power failure through the on-load capacity and voltage regulating switch,which not only effectively reduces the distribution transformer no-load loss,but also helps to improve the voltage pass rate.Therefore,in order to support the urban electric energy substitution,this paper studied the optimization configuration method of on-load capacity and voltage regulating distribution transformers in urban distribution network after electric energy substitution and the energy-saving and loss-reduction optimization operation method of urban distribution network with on-load capacity and voltage regulating distribution transformers.The main contents of this paper are as follows:(1)Aiming at the problem of distribution network voltage over-limit and large distribution transformer no-load loss caused by the change of load characteristics after electric energy substitution,an optimization configuration method of on-load capacity and voltage regulating distribution transformers in urban distribution network after electric energy substitution was proposed.Through analyzing the relationship between conventional distribution transformer loss and on-load capacity and voltage regulating distribution transformer loss,a criterion of replacing with on-load capacity and voltage regulating distribution transformers was derived.And the on-load capacity and voltage regulating distribution transformer replaceable point set was obtained,realizing preliminary judgment of replacing conventional distribution transformers with on-load capacity and voltage regulating distribution transformers.Then after studying the cost-benefit of replacing with on-load capacity and voltage regulating distribution transformers,the optimization configuration model of on-load capacity and voltage regulating distribution transformers in urban distribution network after electric energy substitution was established.The model was solved by branch and bound method within on-load capacity and voltage regulating distribution transformer replaceable point set,so as to obtain the optimization configuration scheme of distribution transformers in urban distribution network after electric energy substitution.(2)Considering the influence of DGs and the uncertainties of load on the load forecasting during the planning period,an optimization configuration method of on-load capacity and voltage regulation distribution transformers considering DGs and load uncertainties was proposed.According to the probability models of load,wind power and photovoltaic,the Monte Carlo method was used to sample the nodal effective load.Then based on the aforementioned optimization configuration method of on-load capacity and voltage regulating distribution transformers,the optimization configuration scheme of distribution transformers in urban distribution network considering DGs and load uncertainties was obtained.(3)Aiming at the problem that the theoretical critical capacity regulating load of on-load capacity and voltage regulation distribution transformers don’t consider the influence of voltage regulating on the loss of distribution transformers,an energy-saving and loss-reduction optimization operation method of urban distribution network with on-load capacity and voltage regulating distribution transformers was proposed.The load flow calculation equivalent circuit and active loss calculation formula of on-load capacity and voltage regulating distribution transformers were studied.The active loss of on-load capacity and voltage regulating distribution transformers under different critical capacity regulating loads was analyzed.Then,taking the minimum power loss of the whole network as the objective function,critical capacity regulating loads,on-load tap changer gears and reactive power compensations as optimization variables,an energy-saving and loss-reduction optimization operation model of urban distribution network with on-load capacity and voltage regulating distribution transformers was proposed.IPCCD-EA was used to solve the model to obtain the operation schemes of equipment such as on-load capacity and voltage regulation distribution transformers.