Research On The Allocation Of Harmonic Pollution Responsibility

The problem of harmonic pollution in power grid becomes more and moreserious, acquiring more attention than before, with the widely use of powerelectronic equipments and nonlinear equipments. The reasonable harmonicpollution responsibility allocation is not only the basis of harmonic suppression,but also the key of evaluation of harmonic treatment effect. Firstly, thequantitative allocation of every harmonic source’s responsibility in system mustbe accurate, and then the harmonic treatment can be carried out by the users.Secondly, the effect of harmonic treatment can be evaluated exactly only whenthe uses responsibility allocation is accurate. In one word, the firstly solvedproblem of harmonic treatment is to get an exact responsibility allocation.Harmonic source identification and location have been studied by otherpapers. Harmonic source identification is defined as determining whether a loadis harmonic source or not, and harmonic source location is to determine theharmonic sources’ positions in the electrical power network. Any of them can dowell to the local compensation and improve the power quality of power grid.The present location algorithms can only determine whether the harmonicsource is located at supply-side or load side without further quantitative analysisand be adaptable in single harmonic source rather than multi-harmonic sources.Responsibility allocation is to identify the ratio of responsibility betweenvarious harmonic source and those between load harmonic pollution andbackground harmonic pollution.The oriented research of harmonic source based on harmonic voltage orharmonic current are summarized in this paper，whose inherent shortcoming isthat the voltage distortion and current distortion are neglected. So the weightedcoefficient method and the harmonic power method for responsibility allocationare proposed based on comprehensive considered of voltage and current.Weighted coefficient method and the harmonic power method for responsibilityallocation are proposed. The weight coefficients of weighted coefficient method reflect the requirement of power quality. Harmonic power method is based onthe assumption that more harmonic power provided by the load, moreresponsibility should be taken by the load. The responsibility allocatingapproach for multi-harmonic source system is further studied in this paper. Thesimulation results verify the feasibility and correctness of the above method.In the harmonic treatment, the basic principle of the passive filter banks isto set specific resonant branch to absorb the load harmonic current. Theoperating resonance circuit of filters can not distinguish whether the harmoniccurrent is from user or external load and attracting all of them, probably causingmisjudgment of invalid treatment and damage of filters. By simulation andanalysis of the running condition of the intermediate frequency furnace in caseof outside harmonic pollution sources，the paper proposes a new method whichcan derive harmonic current of customer and the interference level of the outsideharmonics is also estimated from two working conditions of passive filters,without the data of outside harmonic source.