Suman Bhowmick

An Advanced IPFC Model to Reuse Newton Power Flow Codes

Complexities of computer program codes for Newton-Raphson load flow (NRLF) analysis are usually enhanced during power flow modeling of an interline power flow controller (IPFC). This is due to the fact that the contributions of the series converters of the IPFC are needed to be accounted for while computing bus power injections and Jacobian matrix elements. Also, the IPFC real power injection term along with its associated Jacobian matrix call for new codes to be written. In this paper an advanced IPFC model is proposed to address this issue, wherein an existing power system installed with IPFC(s) is transformed into an augmented equivalent network without any IPFC. To obtain the solution of the original network containing IPFC(s), the augmented network can easily be solved by reusing the existing NRLF codes, as this network is now devoid of any IPFC. Consequently, the complexities of the computer program codes are reduced substantially. Various practical device limit constraints of the IPFC can also be taken into account by the proposed model.

An Indirect UPFC Model to Enhance Reusability of Newton Power-Flow Codes

Power-flow modeling of a unified power-flow controller (UPFC) increases the complexities of the computer program codes for a Newton-Raphson load-flow (NRLF) analysis. This is due to the fact that modifications of the existing codes are needed for computing power injections, and the elements of the Jacobian matrix to take into account the contributions of the series and shunt voltage sources of the UPFC. Additionally, new codes for computing the UPFC real-power injection terms as well as the associated Jacobian matrix need to be developed. To reduce this complexity of programming codes, in this paper, an indirect yet exact UPFC model is proposed. In the proposed model, an existing power system installed with UPFC is transformed into an augmented equivalent network without any UPFC. Due to the absence of any UPFC, the augmented network can easily be solved by reusing the existing NRLF computer codes to obtain the solution of the original network containing UPFC(s). As a result, substantial reduction in the complexities of the computer program codes takes place. Additionally, the proposed model can also account for various practical device limit constraints of the UPFC.

An Advanced Static Synchronous Compensator Model to Reuse Newton and Decoupled Power Flow Codes

Abstract To reduce the complexities of the computer program codes for a Newton Raphson load flow analysis of a network containing static synchronous compensators (STATCOM), a Newton power flow model of a STATCOM is proposed, which transforms an existing power system installed with one or more STATCOM into an augmented equivalent network without any STATCOM. The absence of STATCOM(s) enables the existing Newton Raphson load flow codes to be reused to solve the original network containing STATCOM(s). Consequently, the complexities of the computer program codes are reduced substantially. Subsequent application of decoupling techniques renders the elements of the Jacobian matrices constants, which are known a priori. This enables the original network containing STATCOM(s) to be solved by reusing the existing fast decoupled load flow codes. As a result, drastic reduction in the complexities of the computer program codes takes place. Both of the proposed models—the Newton and the decoupled power flow models—can handle multiple control functions, STATCOM converter switching losses, losses in the coupling transformer, and various practical device limit constraints of the STATCOM. The feasibility of the proposed models has been validated on the IEEE 118- and 300-bus systems.

Load compensation with DSTATCOM and BESS

This paper deals with modeling & control of Distribution Static Compensator (DSTATCOM) and Battery Energy Storage System (BESS) using Simulink and SimPower System in MATLAB environment. The results are presented for a test system with/without DSTATCOM for a wide variety of system disturbances. The modeled DSTATCOM is also tested for load compensation of linear and non-linear loads in both steady state and dynamic conditions. Battery Energy Storage System (BESS) is also modeled, controlled & tested for compensation of load. Simulation results justify enhanced power quality of system with DSTATCOM and BESS under different tested conditions.

Small signal stability improvement of a single machine infinite bus system using SVC

FACTS (Flexible AC Transmission Systems) controllers are used to enhance power transmission capability of existing transmission corridors. Shunt FACTS controllers achieve this by improving the bus voltage profile of the system. The Static Var Compensator (SVC) is a shunt FACTS controller which is used to improve the system bus voltage profile by providing reactive power compensation. In addition, SVC firing angle modulation using a damping controller can achieve the additional objective of power oscillation damping. It is observed that SVC with only voltage controller increases the small signal stability marginally. However, when a damping controller is added, a marked increase in the system small signal stability is achieved. A damping controller can use a variety of auxiliary or supplementary signals to improve the power oscillation damping. Usually, at the SVC location, electrical power, synthesized frequency, line current etc. are used as auxiliary signals. This paper presents the small signal stability improvement of a single machine infinite bus (SMIB) system with a SVC connected at the mid-point of the transmission line. Line current signal is used as a supplementary signal for the SVC damping controller. Multiple case studies are carried out to validate the results.

Newton-Raphson power flow models of static VAR compensator

This paper presents two Newton power flow models - the variable shunt susceptance model and the firing-angle model of the static VAR compensator (SVC). Both these models depict the SVC as a variable shunt susceptance. Here, the SVC state variables are combined with the nodal voltage magnitudes and angles of the network for Newton power flow solution. Both these models possess very strong convergence characteristics. Studies carried out on IEEE 14-Bus Test Network are used to compare both the SVC models and to validate their convergence characteristics.

Modelling of neutral point clamped based VSC-HVDC system

This work shows the performance of Voltage Source Converter (VSC) based High Voltage DC (HVDC) transmission system. A 200 MVA, ±100 kV link is modeled between two identical asynchronous AC systems. The system studies are based on three level neutral point clamped (NPC) converters. Current controlled scheme is used for active and reactive power control. One converter is operated in DC voltage control mode, while the other operated in Active and Reactive power (PQ) control mode. The results are carried out in MATLAB software. The smoothness of DC voltages shows the feasibility of the work.

Potential of distributed generation resources in India

With increasing stress over transmission lines and non-availability of electricity at remote locations; Distributed Generation (DG) has emerged as the best option for utilities. DG includes conventional and non-conventional energy resources. This paper presents the various factors concerning the integration of DG in electrical power systems. These include environmental; commercial and technical issues. In this paper; the main focus has been given to the Indian power sector and the initiatives taken by the government to increase the penetration of DG based on renewable energy. The role of various technical institutes/centres; which work under the Ministry of Renewable Energy (MNRE) for resource assessment and different financial institutions which provide monetary assistance to set up non-conventional based DGs; are discussed in this paper. This paper also highlights the various schemes launched by the government to promote DG. It will benefit the academia and the industry to systematically understand the scope; potential and the government commitment to promote various available non-conventional energy resources in India.

A novel sequential power-flow model for hybrid AC-DC systems

This paper represents the study of integrated AC-DC Newton Raphson power flow modelling of Multi-terminal HVDC (M-HVDC) systems. Some electrical parameters are specified to control the HVDC system in Power Flow Modelling. A set of specified parameters is known as the control strategy. The number of control strategies increases with the increase in the number of DC terminals. It is observed that the power flow convergence is affected by the control strategy. In this paper, sequential method is used for integrated AC-MTDC power flow analysis. Numerous case studies are conducted with the IEEE-30 bus test system in MATLAB software.

A Fuzzy TCSC Controller for transient stability improvement

This paper discusses a Fuzzy Logic Controller for a Thyristor Controlled Series Compensator (TCSC) to improve power system transient stability. A TCSC is a series FACTS controller which is used to improve the power transmission capability of a line. It is also used for power system transient and small signal stability improvement along with mitigation of SSR. Conventional TCSC damping controllers are not robust as their parameters have to be changed as per the operating condition. In this respect, Fuzzy Logic based damping controllers adjust themselves automatically. In this paper, a Fuzzy Logic based TCSC damping controller is used in a Single Machine Infinite Bus (SMIB) system to enhance the power system transient stability improvement.