Research On Three-phase Unbalance Improvement Of Power Supply And Distribution In Airport Substation

As an important navigation aid at the airport,the substation is closely related to the safe take-off,landing and taxiing of the aircraft.Influenced by its main electrical equipment — the constant current regulator(CCR),the asymmetric load using line voltage power supply and various non-linear elements can easily cause the three-phase load unbalance(TPLU)in the power distribution network,which would affect the quality of power supply and the operation of aeronautical ground light(AGL),thus result in potential safety hazards to navigation substations and aircraft during takeoff and landing.Moreover,the additional line loss caused by TPLU will also increase the energy consumption and bring economic losses to the airport.In this study,a TPLU improvement system is designed on the basis of two proposed optimization strategies such as the CCR light level adjustment(LLA)and the phase sequence adjustment(PSA)optimized using an intelligent algorithm,which should be useful for fundamentally solving the TPLU problem,and have a good practical value.Aiming at the TPLU problem of the airport navigation substation and its improvement,and based on a full summary and review of relevant research progresses,this thesis mainly addressed the corresponding research subjects as follows.(1)The power supply structure and its operation principle of civil airport navigation light control system were briefly introduced at first.The generation mechanism,evaluation method and calculation method of line loss of TPLU in the lowvoltage distribution network of the substation were presented and the process of TPLU was simulated and analyzed as well.Then the overall structure and function of the TPLU improvement system were planned,and the design principle and ideas for controlling TPLU were put forward through the strategy of taking LLA as the first choice and PSA as the last alternative.(2)Focusing on the control strategy of LLA to improve TPLU in the substation of airport,the relationship between LLA,current change and TPLU was analyzed,and the LLA method and its control procedure were proposed.Then the on-site observed current data from a domestic airport were applied to test the feasibility of the method.The results showed that the proposed LLA method and corresponding control procedure with current increase adjustment coupled and based on decrease adjustment,although simple and easy to implement,were able to be used to formulate effective TPLU improvement strategy.(3)As for the PSA method,a TPLU model was established taking the minimum TPLU degree and the minimum number of commutation switches as the objective functions.The elite adaptive hybrid genetic algorithm(EAHGA)was applied to solve the model for optimizing the PSA strategy also through the aforementioned case study,and compared with a few other commonly used intelligent algorithms.The comparisons demonstrated that less number of commutation switches was required and obtained through a stronger search ability and a faster convergence speed when using the PSA method based on the established TPLU model and the chosen EAHGA.(4)Finally,based on the above two proposed TPLU improvement methods and related procedures,models and algorithms,the overall hardware of the TPLU improvement system for the airport substation was designed on the basis of the selection of the main control chip,the commutation switch and devices,and the design of each hardware circuit.The research results should be useful to provide scientific basis and technical support for improving the power supply quality of airport substations,ensuring airport safety,and reducing their energy consumption and operating costs.