Power System State Estimation: Part 1

Introduction

Power system state estimation is defined as the act of estimating the state of the network from the redundant telemetry measurements. Static state estimation refers to the procedure of obtaining the voltage phasors at all of the system buses at a given point in time. This can be achieved by direct means which involve very accurate synchronized phasor measurements of all bus voltages in the system. However, such an approach would be very vulnerable to measurement errors or telemetery failures. 

Instead,state estimation procedure makes use of a set of redundant measurements in order to filter out such errors and find an optimal estimate.The measurements may include not only the conventional power and voltage measurements, but also those others such as the current magnitude or synchronized voltage phasor measurements as well. Simultaneous measurement of quantities at different parts of the system is practically impossible, hence a certain amount of time skew between measurements is commonly tolerated. This tolerance is justified due to the slowly varying operating conditions of the power systems under normal operating conditions..

Data for State Estimation

1. Network data

2. Measured Data

(i) Real Power (P)

(ii) Reactive Power (Q)

(iii) Real Line Flow (P_ij)

(iv) Reactive Line Flow (Q_ij)
(v)Magnitude of Line current( [I_ij] )

(vi) Voltage magnitude ([V])