# Computer Aided Power System Analysis

The present day power systems are characterized by large highly interconnected network. Extensive system studies are required at almost all stages of its planning, operation and control.

Simulation and analysis of such a large system is possible only with the help of digital computers. Most of the time, a power system, theoretically, remains under steady state.

Load flow or power flow study is the most frequently carried out steady state analysis, which determines system voltage profile and line flows/losses. The ever growing concern towards secure

operation of power systems requires security analysis to be carried out at planning as well as operation stage, which involves analyzing system states following contingencies.

A fault in the power system network results in excessive current flowing through its various components. Fault analysis is important in determining the short circuit levels, which is utilized

in proper selection of equipments and determining the protection requirements. A disturbance in the system, including a fault, may sometimes lead to unstable operation of the system.

Different types of stability phenomena have been observed in the power systems, which need to be critically analyzed, utilizing appropriate dynamic model of the system.

This course will cover the modeling issues and analysis methods for the power flow, short circuit, contingency and stability analyses, required to be carried out for the power systems. Necessary

details of numerical techniques to solve nonlinear algebraic as well as differential equations and handling of sparse matrices will also be included.

- General Introduction
- AC power flow analysis
- Introduction, modeling of power system components and formation
- Formation of YBUS matrix in the presence of mutually coupled
- Basic power flow equations and Gauss-Seidel load flow
- Example of Gauss-Seidel load flow technique
- Newton-Raphson (polar) load flow technique
- Example of Newton-Raphson (polar) load flow technique
- Newton-Raphson (rectangular) load flow technique
- Example of Newton-Raphson ( rectangular ) load flow
- Fast decoupled load flow technique
- Example of Fast decoupled load flow technique
- A.C.-D.C. load flow technique
- Example of A.C.-D.C. load flow technique

- Sparse Matrices
- Analysis of faulted power system
- ZBUS matrix formulation without mutual impedance
- ZBUS matrix formulation without mutual impedance (continued)
- Example of ZBUS matrix formulation
- ZBUS matrix formulation considering mutual coupling between
- Example of ZBUS matrix formulation in the presence of mutual
- Symmetrical Fault analysis & introduction to symmetrical
- Sequence networks of power system components
- LG, LL,LLG fault analysis using sequence networks
- Unbalance fault analysis using of ZBUS matrix
- Example of fault calculations for three-phase and LG
- Example of fault calculations for LL and LLG faults
- Open conductor fault analysis
- Example of Open conductor fault analysis

- Security Analysis
- Stability Analysis
- Classification of power system stability, equation of motion of
- Basics of transient stability analysis with Partitioned
- Techniques for numerical integration with modified Euler’s
- Example of transient stability analysis using modified Euler’s
- Example of transient stability analysis using Runge-Kutta 4th
- Basics of Small signal analysis and linearization of network
- linearization of network equations at load buses
- Formation of system state matrix and example of small signal
- Introduction to voltage stability
- Relation between PL, QL and V
- Criteria for assessing voltage stability
- Appendix-A System Data