Shubha Pandit

Object-oriented design for power system applications

A sound design method is based upon a sound theoretical foundation, yet it offers degrees of freedom for artistic innovation. In the object oriented paradigm, the world is viewed as a collection of objects interacting with each other to achieve a meaningful behavior. The design perspective provided in this article can be used for many applications, such as power system state estimation and optimal power flow (OPF), and the sparse matrix class can be developed further to include eigenvalue analysis. As such, the architecture presented in this article is scalable.

Design of Generic Direct Sparse Linear System Solver in C++ for Power System Analysis

This article presents the design of the generic linear system solver (LSS) for a class of large sparse symmetric matrices over real and complex numbers. These matrices correspond to one of the following: (1) symmetric positive definite (SPD) matrices, (2) complex Hermitian matrices, or (3) complex matrices with SPD real and imaginary matrices. Such matrices arise in various power system analysis applications like load flow analysis and short circuit analysis. A template facility of C++ is used to write a generic program on float, double, and complex data types. The design of the algorithm guarantees numerical stability and efficient sparsity implementation. A reusable class SET is defined to cater to graph theoretic computations. LSS problems with matrices up to 20,000 nodes have been tested. Another feature of the proposed LSS is the implementation of associative array, which allows subscripting an array with character strings, such as bus names. This helps in making the four power system analysis software user friendly. The proposed LSS reflects an important development towards a truly object-oriented four power system analysis software.

Computational Methods for Large Sparse Power Systems Analysis

Preface. Acknowledgments. 1. Introduction. 2. Object Orientation for Modeling Computations. 3. Data Structure for Sparse Matrix Computation. 4. Sparse Symmetric Linear System Solver. 5. Sparse QR Decomposition. 6. Optimization Methods. 7. Sparse LP and QP Solvers. 8. Load Flow Analysis. 9. Short Circuit Analysis. 10. Power System State Estimation. 11. Optimal Power Flow. 12. Power System Dynamics. Appendices. References. Index.

Object-oriented network topology processor [power system automation]

Modern power systems have grown both in size and complexity. Various constraints, such as security, economy and environmental regulations, are forcing power systems to operate closer to their design capabilities and security margins. Here, the authors describe a system where a network topology processor groups physical buses at the substation into electrical buses, builds connectivity from electrical buses to the network branches, and analyzes electrical network connectivity for islands.

Experimental evaluation of current transformer performance under saturation

Current transformers form an integral part of protective systems. Ideal current transformers (CTs) are expected to reproduce the primary current faithfully on the secondary side. Often, during fault conditions an important component of current is exponentially decaying DC offset current. Under such conditions the CT saturates, and hence it cannot reproduce the primary current faithfully. This paper deals with experimental methods for determining CT performance under saturation. A laboratory setup has been developed to observe CT response under steady state and fault conditions. Thus, it is now possible to experimentally evaluate the CT performance under fault conditions

An OOP based real time reactive power control algorithm for large power systems

Voltage and reactive power control is essential for secure and optimal real time operation of power systems. The problem is of special significance in case of stressed power systems, where bad reactive power management can lead to excessive MW loss in the system. This can cause reduction in load bus voltages and active load, changes in system frequency and voltage stability problem, all being detrimental to system operation. This paper proposes an object oriented programming (OOP) based reactive power/voltage control algorithm for large scale power systems which tries to improve system voltage with curtailed number and reduced controller movements, so that the decisions can be implemented in real time. The algorithm is specially suitable for use in energy control centers.

Optimal Power Flow

In the load flow analysis problem, generator voltage magnitudes, active power generation (except for the slack bus), and P and Q loads at all the busses is known beforehand. Consequently, to determine the power system state, we have to solve 2n - g - 1 equations in as many unknowns, where n is the number of busses in the system and g is the number of generators. Therefore, the resulting system of equations is neither underdetermined nor overdetermined. In contrast, in the state estimation problem, to filter noise, we deliberately work with an overdetermined system (more measurements than unknowns). In both of the above scenario, controller settings, like generator voltages, MW injections, transformer taps, reactive power compensation etc have been decided beforehand. The criteria used for setting these controllers is not relevant to the problem. However, the next logical question that arises is how best to choose the controller settings for a given load condition. Clearly, there exist multiple choices. If the controller settings are also made variable, then a computational problem on the lines of load flow analysis will have to deal with an underdetermined system of equations. For example, if generator voltage magnitudes are not fixed in load flow analysis, as many additional columns (g) will appear in the load flow Jacobian while the number of rows or equations will remain unchanged.

Discussion and closure of "Design of generic direct sparse linear system solver in C++ for power system analysis"

This article presents the design of the generic linear system solver (LSS) for a class of large sparse symmetric matrices over real and complex numbers. These matrices correspond to one of the following: (1) symmetric positive definite (SPD) matrices, (2) complex Hermitian matrices, or (3) complex matrices with SPD real and imaginary matrices. Such matrices arise in various power system analysis applications like load flow analysis and short circuit analysis. A template facility of C++ is used to write a generic program on float, double, and complex data types. The design of the algorithm guarantees numerical stability and efficient sparsity implementation. A reusable class SET is defined to cater to graph theoretic computations. LSS problems with matrices up to 20,000 nodes have been tested. Another feature of the proposed LSS is the implementation of associative array, which allows subscripting an array with character strings, such as bus names. This helps in making the four power system analysis software user friendly. The proposed LSS reflects an important development towards a truly object-oriented four power system analysis software.

Emerging issues in Indian power sector

Indian power sector is facing the challenges in the area of fuel, policy issues and cost effectiveness. Thus country needs a sweeping reform to tackle these new challenges. Green Building scenario, peaking power plant and cost of the power served in Indian scenario are considered to address theses challenges. A regional approach for policy and innovative finance schemes is proposed and discussed for Green Building promotion. A need for peaking power plant and selection criterion for gas based stations and a captive power plant is proposed. The structure for cost of the power and various new steps that will lead to the reduced cost is put forth.

Load Flow Analysis

The starting point of any analysis of power system will be the computation of complex voltages at all the busses. Load flow analysis is a computational tool for this purpose.