  A dynamic state estimation method of integrated natural gas and electric
power systems (IGESs) in proposed. Firstly, the coupling model of gas pipeline
networks and power systems by gas turbine units (GTUs) is established.
Secondly, the Kalman filter based linear DSE model for the IGES is built. The
gas density and mass flow rate, as well as the real and imaginary parts of bus
voltages are taken as states, which are predicted by the linearized fluid
dynamic equations of gases and exponential smoothing techniques. Boundary
conditions of pipeline networks are used as supplementary constraints in the
system model. At last, the proposed method is applied to an IGES including a
30-node pipeline network and IEEE 39-bus system coupled by two GTUs. Two
indexes are used to evaluate the DSE performance under three measurement error
conditions, and the results show that the DSE can obtain the accurate dynamic
states in different conditions.
