# Using a state estimation scheme as a means of collecting data in real time from a digital device,

To monitor and control modem power systems effectively, the introduction of state estimation in power systems plays a crucial role. As in the case of load flow analysis, power system state estimation has the same objective of obtaining the most accurate bus voltage magnitudes and angles possible by analysing the data available within the network. It has been decided to make two modifications now to achieve a higher degree of accuracy in the solution at the expense of a few additional computations.

First of all, the numerical values to be processed for state estimation tend to be noisy due to the errors in the data. It is also important to note that in addition to the variables that can be measured in the system, a large number of variables cannot be utilised in the analysis of load flow. A statistical criterion is used to power system state estimation of the true value of the state variables to minimise or maximise the selected criterion to minimise or maximise the selected criterion in estimating the system states.

In many cases, a commonly used criterion is minimising the difference between the estimated value and a function’s “true” value, in other words, the sum of squares of the difference. It is usually the case that State Estimation in Power System programs is formulated as overdetermined systems of non-linear equations, which are then solved using weighted least-squares (WLS) methods.

A static-state estimator can be either static or dynamic. Both have been developed for power systems. This chapter describes the basic principles of a static-state estimator because the state variables in a power system are the magnitude and phase angles of the voltages across the buses. The power system’s imperfect (noisy) measurements are input into an estimator.

As part of the design of the estimator, the system voltage and phase angle are estimated in the best possible manner, taking into account that there will be errors in the measured quantities and the possibility of redundant measurements. These output data are then used at the energy control centres to conduct several real-time or online system studies, such as economic dispatch or security analysis.

Digital processing is a method that provides a real-time database for many of the central control and dispatch functions of a power system by using state estimation as a data processing scheme. The estimator processes the imperfect information available to produce the best possible estimate of the system’s true state. The theory and computational requirements of static state estimation are presented in detail, and their impact on the evolution of the data acquisition, processing, and control subsystems is discussed.