Research On The Influence Of Cabling Distribution Line On Electric Network And Its Countermeasure

With the advancement of urbanization in China,cable landing process overhead lines are also accelerating,a large amount of energy distributed by the cable access,lead to a large increase in distribution cable outlets.It brings two main problems: the first problem is the cable capacitance current is much higher than the overhead line,the capacitor current of the small current grounding system(the neutral point is not grounded or grounded via the arc suppression coil)increases sharply;the second problem is: due to the large capacitance of the cable,the capacitive reactive power is reversed when the line is lightly loaded.For a series of problems such as capacitance current exceeding the standard for small current grounding system,but difficult to increase capacity of substation arc suppression coils in actual work,the dissertation proposes several solutions such as new planning area and full cable outlet substation use neutral low resistance grounding,expanding the capacity of arc suppression coils according to local conditions and arc suppression coil distributed compensation.And compensation scheme for distributed arc suppression coil,demonstrated by Simulink.Simulation results show: capacitor current compensation of arc suppression coil has regional effect,it can be suppressed centrally in the substation,or it can be suppressed distributively in other places in the same distribution area,such as substation outlets and substations.For the problem of increased charging power for cable outlets,reactive power backflows badly in light load period,the dissertation changes the IEEE33 node distribution network to cable line,and simulate the reactive power backflow in light load period.Meanwhile,generalize some features and conclusions of reactive power backflow in cable line.Under the premise of meeting the power quality,aiming at reducing the cost,innovatively break through the traditional perceptual reactive power compensation principle,and adopt selective compensation scheme for the corresponding nodes by PSO.The results show that the cost of the inductive reactive compensation scheme obtained by the optimization method is significantly lower than the traditional local compensation.And it is proposed that centralized inductive compensation should be used when the power grid line loss can be ignored and decentralized inductive compensation should be used when the power grid line loss is much larger than the compensation equipment cost.