Power system harmonic state estimation

A new power system state estimation--Harmonic State Estimation is proposed which removes the following assumptions on which the current power system state estimation has relied on for the last 25 years: (1) all current and voltage waveforms are pure sinusoids with constant frequency and magnitude (2) the system operates under balanced three phase conditions (3) the power system is a symmetrical three phase system (4) the system operates under steady state conditions.; Confidence level and sensitivity analysis are used to evaluate the modeling issue. Two sensitivity indices are introduced. The sensitivity of state with respect to the asymmetry control variable provides a quantitative measure of approximating the effect of the three phase asymmetric model by a three phase symmetric model. The sensitivity of state with respect to the balance control variable is used to evaluate the effect of approximating the three phase measurements by single phase measurement and the implied balanced conditions assumption.; The importance of modeling is demonstrated with a simple high voltage transmission system. Both the confidence level and the sensitivities of state are used to quantify the modeling importance. Numerical experiments are performed. It is concluded that the modeling accuracy issue is critical for the harmonic state estimation.; The topological observability analysis method for the conventional state estimation is extended to the harmonic state estimation such that the observability analysis for the three phase system requires almost the same computational effort as the conventional state estimation.; The Harmonic State Estimation is extended to distribution systems. The major differences for distribution systems are: (1) Existing large number of single phase laterals (2) The electric load is distributed along distribution lines.; The total electric load for each distribution circuit is modeled by a voltage-controlled current source which is part of the system state. This voltage- controlled current source can be estimated without the requirement of knowledge of the individual load along the circuit. For topological observability analysis purpose, system topology was modified to handle the 'new' state variable-electric load current.