Study On Restraining Measures And Characteristics Of Secondary Arc In Uhv Systems

Developing UHV transmission power technology effectively not only fits to China's actual conditions, but is an excellent way to adapt to the fast growth of power, to optimize the allocation of resource, environment protection, and lack of land resource of these such economic development and social problems. With the improvement of voltage level, the secondary arc phenomenon is becoming more serious, if we do not adopt effective measures, the secondary arc will be difficult to extinguish, which directly affects the successful implementation of single-phase automatic reclosure. So, it is necessary to deeply study on the characteristics of secondary arc and what measures to restrict the secondary arc occurrence.On the point of system, by using frequency-dependent model and the theory of phase-mode transformation, the the forming mechanisms of secondary arc, the dynamic characteristics,the influential factors and restrictions on secondary current and recovery voltage, refering to the UHV single-circuit, multi-circuit transmission lines, are calculated in detail and analyzed completely according to the actual situation of UHV alternative current transmission power project.Firstly, the single-phase arc ground fault and double circuit line fault occurred in the UHV alternative current transmission line on the same pole, and then the secondary current and recovery voltage are calculated, High Speed Grounding Switches (HSGS) limit effect for the secondary arc is analyzed. The paper mainly studies the effect of ground resistance of the HSGS on the secondary arc restriction. Considering the distance is small between interphase and intercircuit wiring, the large induced voltage and the large induced current is produced, the induced voltage and induced current are calculated under the different transposition and the different load, and the situation of influence on line outage under transient over-voltage which produces by the running operation of circuit breaker are analyzed. The result of calcuation refer reference value for line mainenance, operation and equipment selection. Secondly, considering the parameters of shunt reactors and small reactors are difficult to configuration on extra high voltage and ultra high voltage transmission lines, an optimization method is provided to solve the parameters of reactors, as an example of four-circuit transmission lines on 220kv/500kv same tower, the electromagnetic transient calculation model is established to obtain the parameter values of shunt reactors and small reactors when secondary current and recovery voltage are limited to the minimum value. The results show that secondary current and recovery voltage can be effectively limited by using the parallel reactor with different parameters to compensate in different ways, which the successful rate of single-phase automatic reclosing is ensured.Finally, based on the characteristics of secondary arc harmonic on UHV transmission line, by using total harmonic distortion rate of voltage and current on the fault position, this paper proposes a method that diagnosis the artificial neural network model input to distinguish the transient faults and permanent faults. Theoretical analysis and simulation results show that the method has high sensitivity, which can effectivity distinguish transient faults and permanent faults under different faults condition, independent of fault location, power supply phase angle and the impact of transient resistance, eliminating the systerm in the risk of permanent fault to achieve the purpose of reclosing.