Experiences on Usages of State Estimation in Indian Power System

State estimation is an indispensable tool for the grid operator to ensure reliable and economic operation of the power system at all times. State estimation enables accurate determination of the current operating conditions of the system, which is the starting point for all subsequent network applications in a control center, such as operator load flow, contingency, and sensitivity analysis, determining the transfer capability of any part of the network, and optimal decision-making processes. The Indian power system is one of the largest synchronous grids in the world, comprising multiple regional grids with thousands of transmission lines, several hundred generators, and other elements like transformers, shunt reactors, and FACTS devices, including HVDC links. At any point in time, out of the total analog and status measurements necessary to correctly model the power network and get valid estimates of all the state variables, a redundant set of measurements must be available so that deficiencies due to incorrect measurements and unavailability of measurements can be overcome for proper state estimation. State estimation is employed to estimate the real-time values of system variables (voltage and angle), followed by estimation of line flows and generator outputs based on the available measurements. With converged results of state estimation, the estimated state variables are fairly close to the actual voltages and angles and therefore serve as valuable inputs for real-time monitoring and decision-making in the Indian power system. They provide essential information for load flow analysis, contingency analysis, optimal power flow, and voltage stability assessment, enabling operators to take appropriate actions to maintain system stability and reliability. State estimation in the Indian power system is also integrated with WAMS, which consists of synchronized phasor measurement units (PMUs) placed at strategic locations across the grid. PMU measurements, along with traditional SCADA measurements, further enhance the accuracy and speed of state estimation, facilitating enhanced situational awareness and dynamic system monitoring.