Holomorphic Embedding State Estimation Method Using Phasor Measurement Units

The HELM (Holomorphic Embedding Power Flow Method) is a recently developed technique used for solving algebraic power flow equations providing an exact and unique solution using a deterministic non-iterative method. Due to all their advantages and applicability for power systems analysis, this paper presents a new technique for power systems state estimation (PSSE) based on the HELM formulation, called Holomorphic Embedding State Estimation Method (HESEM). In the proposed approach, different measurement types can be used for the PSSE including PMU (Phasor Measurement Unit) measurements, nodal voltages, currents, active and reactive power flows. Their corresponding algebraic equations are calculated as function of the voltages to be estimated for each system bus being transformed in holomorphic expressions. Then, all the system bus voltages are written as a sum of multiple terms of a Maclaurin series, being determined recursively based on the use of an analytical continuation methodology using Padé approximants. The state variables are composed of voltage phasors expressed in rectangular coordinates. The main advantage of the HESEM is its ability to constructively solve the PSSE equations by a non iterative technique ensuring the uniqueness of the solution and requiring a lower computational time when compared with traditional techniques. Computational simulations are carried out using different test systems to prove the viability and effectiveness of the proposed HESEM. The well known 14 and 33 bus test systems are used to demonstrate the applicability of the proposed HESEM and an equivalent of the Brazilian transmission system is used to test the performance of the algorithm in a larger system.