A Linear Formulation for Power System State Estimation including RTU and PMU Measurements

Abstract

In this paper, a novel linear formulation for power system state estimation that simultaneously treats conventional and synchrophasor measurements is proposed. A linear circuit model for conventional measurements is introduced to enable a fully linear equivalent circuit representation of the power system. The estimated system state is then obtained by formulating the optimization problem to minimize the measurement errors and solving the resulting linear set of optimality conditions. To evaluate the accuracy of the proposed method, simulations are performed on several test cases of various sizes and the results are presented and discussed.

Enhanced Modelling Framework for Equivalent Circuit-Based Power System State Estimation

“…Then, each branch current is represented as a parallel connection of a current source and a conductance. Therefore, all possible sets of PMU data are covered by the appropriate circuit models that were already introduced in [20], [21].…”

“…The variables in this model are the values of the current sources. More details on the derivation of this circuit model can be found in [21].…”

“…The terms that are minimized are the currents flowing through the PMU conductances, I G , the V P M U dif f and I P M U dif f terms that represent the weighted difference between PMU voltage and current variables and their corresponding measured values, as well as I RT U dif f that represents the weighted difference between RTU current variables and their respective linear measurement functions. For more details, the reader is referred to [21]. Since the entire system along with the measurements is modelled by an equivalent linear split-circuit, the problem is subject to a set of linear equality constraints (4b), i.e.…”

“…I 2 G , must be minimized, which is added as an additional term in the objective function of the SE algorithm. As current flowing through a conductance is proportional to its value, a large value is selected for G, same as for G P M U in the PMU circuit model [21], to ensure that a sufficiently large weight factor is VR VI…”

“…The PMU circuit models that were used in [20] and [21] can represent any configuration of phasor measurements observed at a bus. However, the RTU circuit models that were derived can only capture the relation between bus voltage magnitude and injected active and reactive power, i.e.…”