Three-Phase Equivalent Circuit And Asymmetric Component Analysis Of Three-phase Power Grid

With the development of power system, more and more prominent characteristics power network parameters asymmetry, and power system operation requirements, leading to traditional symmetrical component method does not applied in some respects. Phase component method is abc phase coordinate calculation, it does not require symmetry network parameters and meet the needs of power system operation. In recent years, phase component method has been greatly developed in three-phase asymmetric power flow, Power network failure analysis, Distribution network analysis, DC/AC electromagnetic and transient simulation and Distribution network analysis with distributed generations and so many respects to get a very wide range of applications. The approach for asymmetric parameters of mutual inductance components are inadequate, but also failed effectively taking into account neutral grounding and other information.In this paper, with the basic principles of the circuit, starting from the basic physical phenomena, the author establishes the equivalent circuit of the phase component of the three-phase components which conforming the physical significance and it is convenient in forming circuit. At first’the principle of eliminating the mutual inductance’is applied to the three-phase asymmetric transmission line and transformer and the double circuit lines on the same tower, and their phase component equivalent circuit whit no mutual inductance are deduced, and thus the formation of the entire network without mutual inductance equivalent circuit can be given out. There are a variety of forms of power grid failure, and they have their own characteristics. Based on the different failure modes, this paper gives the equivalent circuit of any fault types, and lists the three-phase node voltage equation of the different fault types and fault node, and conducts failure analysis and calculation. This paper uses small current grounding systems and high-current grounding system and including a double-circuit line systems, respectively, compared with PSCAD simulation to verify the correctness of the proposed method.Phase component equivalent circuit used in this paper takes into account the information of the parameters of asymmetry factor and neutral grounding, and its physical meaning is clear, simple and intuitive, and it is convenient for forming circuit, and it is very easy to get the node voltage equation of the system. Phase component equivalent circuit takes into account the phase shift introduced by the transformer, so the calculation results is the actual voltage for the network.The examples in this paper contain a ring network and multi-power supply, showing that this method can be used for the ring network system, and multiport power supply situation.lt is not only able to calculate a simple fault but also the complex failure.So this study may provide the basis for power system analysis,and it has practical value.