Power Research

K. S. Meera ¹, R. A. Deshpande ², R. S. Shivakumara Aradhya ³

Affiliations
1 Joint Director Power Systems Division,Central Power Research Institute, Bangalore - 560 080, IN
2 Joint Director Distribution Systems Division, Central Power Research Institute, Bangalore - 560 080, IN
3 Ex Director, Central Power Research Institute, Bangalore - 560 080, IN

Abstract

Circuit breakers are an important element in a substation, which is used for coupling of busbars, transformers, transmission lines, switching of shunt reactors, capacitor banks etc. The most important task of a circuit breaker is to interrupt fault currents and thereby protect various power system components. This task requires operation of the circuit breaker under different making and breaking conditions such as - faults in the vicinity of the circuit breaker, short-line faults, out-of-phase closing/ opening, switching of - capacitor /shunt reactor banks, no-load transformers/lines etc. During opening operation, after the arc extinction, the insulating medium between the breaker contacts has to withstand the rapidly increasing recovery voltage. This recovery voltage has a transient component (transient recovery voltage, TRV) caused by the system when current is interrupted. The TRV of the Circuit Breaker is a decisive parameter that limits the interrupting capability of the Circuit Breaker. The TRV to be adopted for system voltages of 1200 kV, towards which our country is migrating, needs to be estimated by transient studies as they cannot be extrapolated from lower voltage systems. This paper deals with the modeling and study results of TRV for typical 1200 kV networks and a sample 1200 kV Indian system using Electromagnetic Transient Programs (EMTP).

Keywords

Transient Recovery Voltage (trv ), Rate of Rise of Recovery Voltage (rrrv ), Electromagnetic Transient Program (EMTP), Circuit Breaker (cb).

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C. Prabhakar ¹, T. S. Prasanna ², R. A. Deshpande ¹

Affiliations
1 Distribution Systems Division, Central Power Research Institute, Bangalore - 560080, IN
2 Associate Professor, Department of Electrical Engineering,University Visveswaraya College of Engineering, Bangalore - 560001, IN

Abstract

During earlier days, due to conventional loads power quality did not cause any problem as there was no effect on majority of the loads connected to the electrical distribution system. But in modern power systems, power quality is certainly a major concern. With the use of sophisticated devices, the performance is very sensitive to the quality of power supply. The most common type of power quality disturbance in the present days are voltage sags and swells. Among various devices proposed for this purpose for mitigation, VSC technology was considered as it has fast responses. This paper is intended to mitigate voltage sag using Distribution Static Compensator (D-STATCOM) for a test system. The simulation is carried out for a 9 bus test system using PSCAD^TM/EMTDC^TM to illustrate the use of D-STATCOM in mitigating the voltage sag in a distribution system.

Keywords

D-STATCOM, voltage sag, power quality, PSCADTM/EMTDCTM

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P. Chandhra Shekar ¹, R. A. Deshpande ¹, V. Sankar ²

Affiliations
1 Distribution Systems Division (DSD), Central Power Research Institute, Bangalore-560080, IN
2 Jawaharlal Nehru Technological University, Anantapur, A.P. - 515 002, IN

Abstract

Reliability assessment of distribution network is an important subject due to increasing demand for more reliable service with less interruption frequency and duration. An effective way to solving this issue is by the use of quantitative assessment of reliability, measure the reliability indices to find out the probability of availability and unavailability of supply. This paper describes the energy not supplied to the customers in terms of customer kWh loss and revenue loss to the customers and the revenue loss to the utility in profit making areas is presented for two practical networks by calculating the reliability indices. The software module CYMDIST Reliability Assessment Module (RAM) is used for the simulation and analysis.

Keywords

Distribution system, customer cost of interruption, reliability indices, CYMDIST-RAM.

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P. Chandhra Shekar ¹, R. A. Deshpande ¹, V. Sankar ², P. Manohar ²

Affiliations
1 Distribution Systems Division (DSD), Central Power Research Institute, Bangalore-560 080, IN
2 Jawaharlal Nehru Technological University, Anantapur, A. P. - 515 002, IN

Abstract

Reliability assessment is of primary importance in designing and planning distribution systems that operate in an economical manner with minimal interruption of customer loads. Distributed Generation (DG) is expected to play an increasing role in emerging power systems because they use different type of resources and technologies to serve energy to power systems. DG is expected to improve the system reliability as its backup generation. Since DG units are subject to failures like all other generation units, the random behavior of these units must be taken into account in the analysis. Existence of DG units in a distribution system will effect on restoration time of load points. The algorithm for restoration time assessment of load point is developed when DG unit is installed. In this paper, the reliability performance of distribution system is analyzed in terms of SAIFI, SAIDI, CAIDI, ASAI, ASUI, ENS and AENS. The algorithm to calculate the reliability indices for simple 9-bus radial distribution feeder with and without DG is developed. The improvement in the reliability of the feeder is studied for different locations of DG with respect to fault point. All the above analysis is carried out by developing MATLAB software.

Keywords

SAIFI, SAIDI, CAIDI, ASAI, ASUI, ENS and AEN.

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T. R. Jyothsna ¹, B. Ramya Sree ¹, V. Ramya ¹, R. A. Deshpande ²

Affiliations
1 Department of Electrical Engineering, AU College of Engineering, Andhra University, Visakhapatnam, IN
2 Central Power Research Institute, Bangalore, IN

Abstract

The analysis of small-signal stability of conventional power systems is well established, but for inverter based microgrids there is a need to establish how circuit and control features gave rise to particular oscillatory modes and which of these have poor damping. This paper develops the modeling and stability analysis of autonomous operation of inverter based microgrids. Each sub-module is modeled in state-space form and all are combined together on a common reference frame. The model captures the detail of the control loops of the inverter but not the switching action. Some inverter modes are found at relatively high frequency and so a full dynamic model of the network (rather than an algebraic impedance model) is used. The complete models linearized around an operating point and the resulting system matrix is used to derive the eigenvalues. The eigenvalues (termed “modes”) indicate the frequency and damping of oscillatory components in the transient response. A sensitivity analysis is also presented which helps identifying the origin of each of the modes and identifies possible feedback signals for design of controllers to improve the system stability. With experience it is possible to simplify the model (reduce the order) if particular modes are not of interest as is the case with synchronous machine models. Transient stability results have been obtained from a microgrid of three 10-kVA inverters.

Keywords

Inverter, inverter model, microgrid, power control, small-signal stability, transient Stability

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K. Devender Rao ¹, M. Venugopal ¹, R. A. Deshpande ²

Affiliations
1 Engineering OfficerGrade-4, UHV Research Laboratory, Central Power Research Institute, Hyderabad - 500098, IN
2 Joint Director, Distribution Systems Division, Central Power Research Institute, Bangalore - 500080, IN

Abstract

High Voltage Distribution System (HVDS) is being implemented in many utilities across our Nation. In rural areas, loads particularly agricultural consumers are widely dispersed and low tension lines of 433 V run for long distances to feed a small load. Two or three low tension spans are to be laid to fetch a load of one pump set and such 30 to 40 pump sets are connected on each distribution transformer of 63 kVA or 100 kVA. These transformers are generally overloaded due to long LT lines and more number of consumers connected. This paper describes about the various aspects in preparing HVDS scheme on an overloaded 100 kVA transformer and its Cost Benefit Analysis (CBA).

Keywords

HVDS, LVDS, Distribution transformer (DTR), Low tension (LT)line – 433 V, High tension (HT)line – 11 kV.

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K. V. Harikrishna ¹, V. Ashok ¹, P. Chandrasekhar ¹, T. Raghunatha ¹, R. A. Deshpande ¹

Affiliations
1 Distribution Systems Division, Central Power Research Institute, Bangalore - 560 080, IN

Abstract

The electrical utilities are facing market conditions and therefore have to plan and operate their distribution systems in a cost effective way. This implies that the customer’s requirement on reliability i.e. availability has to be balanced towards the cost for obtaining the same. An effective way to solving this issue is by the use of quantitative assessment of reliability, i.e. reliability indices, which is based on probability theory. However these methods require input data that defines the condition for the system and its components. is to predict the future behaviour based on collected data and measured performance.

The reliability assessment is normally used to evaluate performance of the distribution system network. The reliability of power Distribution system can be calculated by different reliability indices.This paper describes the reliability indices for two feeders of one is an industrial feeder and another one is an urban feeder. A software module (Reliability Assessment Module-RAM) has been used and the results of two practical distribution feeders are compared to benchmark the performance and operation of the power distribution system.

Keywords

Distribution System, Reliability Indices, Reliability Sassements Module

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R. Sudhir Kumar ¹, R. A. Deshpande ², D. Kavitha ³

Affiliations
1 Engineering Officer Grade IV, Distribution Systems Division, CPRI, Bangalore - 560080
2 Joint Director (HOD), Distribution Systems Division, CPRI, Bangalore - 560080, IN
3 JRF, Distribution Systems Division, CPRI, Bangalore - 560080, IN

Abstract

Vehicles running on oil have to change over in next few decades to alternatives which could be hydrogen, electricity. World over, almost all the major players in the automobile industry have introduced electric vehicles (EV) or Plug-in Hybrid Electric vehicle (PHEV) in the market. This is rather in response to their commitment to a green environment, reducing carbon footprints and reducing the emission rates. With the unveiling of the National Electric Mobility Mission Plan 2020, by the government of India manufacturers are urged to adopt electric vehicles in an attempt to reduce our dependence on imported oil. The ambitious plan aims to produce 6–7 million electric vehicles by 2020 with an estimated fuel saving of 2.2–2.5 million tonnes of oil. Electric vehicles when utilized for feeding back the energy to the grid play a very important role in Demand response in Smart grid environment. This will play a major role in the Power sector scenario. Though this technology is yet to pick up in India, it has become popular in the western countries. Lot of Research work has been carried out and research work has been published, which is reviewed in this paper.

Keywords

Plug-in hybrid electric vehicle (PHEV), Battery chargers, Vehicle to grid integration (V2G) and Grid to vehicle (G2V)

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