Research On The Comprehensive Compensation Schemes Of Traction Substations Based On System Flow

The three main technic subjects of AC traction supply system origin the characters of rectification traction load: low power factor, abundant harmonics and negative sequence current for its single phase independence. Adverse influences of reactive power, negative sequence and harmonics on power system need to be solved by adopting technical measures.At present, the fixed parallel capacitor compensation devices have been adopped, but as the policy of "reactive power returning back as positive value" employed, it is difficult to conform to the limit standard of the traction load power factor set up by the power supply departments.This paper discusses the effectiveness of this mode of capacitor compensation and introduces simple and useful assessment methods for evaluation programs.For the traction supply system, the reactive power and negative sequence current appear at the same time following traction load. It is insignificant to compensate one of them, hence, we have to study the comprehensive compensation for reactive power and negative sequence.So, it is necessary to analyse the rule of negative sequence according to the character of traction load to find a type of optimizatonal capability allocating schemes, the destination is to decrease the negative sequence current to the min and increase the power factor at the same time.Apart from filtering, filters can provide some fundamental reactive power to the power system. Optimizatonal design methods of single-tuned passive filters which could be desiged to increase power factor and decrease the harmonic currents are introduced, The objective function is to minimize the total investment and the plant capability with qualified reactive power.The single-tuned passive filters with reducing transformer is introduced too and then according to its design idea, the compensation scheme of fixed filters and adjustable capacitor and reactor is put forward.The software Neharparcom2.0 is develoed to design parameters of device and calculate parameters of compensation branch of the compensationschemes for electrified railway traction substation. Neharparcom2.0 has a popular GUI, and has the characters of class's hierarchy and opening, which makes it easy to expand, maintain and replant. The functions of Neharparcom2.0 : the effectiveness of the fixed parallel capacitor compensation devices;the optimizatonal allocate scheme for negative compensation capability;optimizatonal designs for single-tuned passive filters;optimizatonal designs for single-tuned passive filters with reducing transformer;optimizatonal designs of fixed filters and adjustable capacitor and reactor;accomplishing the three-phase models of power system main elements,forming the topological structure of three-phase fundamnental wave and the three-phase nodal admittance matrices.Using Neharparcom2.0, dechang traction substation in the xichang electric network is implemented by compensation schemes. By calculating the qualifications of dechang traction substation and analyse of negative sequence and harmonic through implementing compencation schemes fore and after, the suitable compensation scheme for dechang traction substation is obtained.