Active Power analysis of a Smart Grid- Using MATLAB/SIMULINK Approach

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Active Power analysis of a Smart Grid- Using MATLAB/SIMULINK Approach

Vikash Kumar Prof. Pankaj Rai

Asstt. Professor/ EEE Deptt, Department of Electrical Engg.

BACET, Jamshedpur BIT Sindri, Dhanbad

Abstract: In this paper, a Smart Grid has been designed by MATLAB/SIMULINK approach for analysis of Active Power. Analysis of active power gives the exact idea to know the range of maximum permissible loads that can be connected to their relevant bus bars. This paper presents the change in the value of Active Power with varying load angle in context with small signal analysis. The Smart Grid, regarded as the next generation power grid, uses two-way flow of electricity and information to create a widely distributed automated energy delivery network.

Index: SIMULINK, Smart Grid, Active Power, Load Analysis

I. INTRODUCTION

The smart grid is a modern electric power grid infrastructure which smoothly integrates automated control, advanced sensing and metering technologies, modern communication infrastructure and modern energy management techniques into the electricity power grid. The Smart Grid, regarded as the next generation power grid, uses two-way flows of electricity and information to create a widely distributed automated energy delivery network. [1]. Smart grid is technically classified in three categories namely Smart Infrastructure System, Smart Management System and Smart Protection System [2]. The simulation works of this paper is done under the Smart Power generation [3] technique which is a part of Smart Infrastructure System. Active power is the main parameter to show the stability of any power system network like conventional power grid, micro grid or any virtual power plant.

These distributed generators along with local loads and storage constitute micro grids. [4]. Active power control of smart grid using plug-in hybrid vehicle has already done [5]. One of the essential components in a smart grid is energy storage. A Plug-in Hybrid Electric Vehicle (PHEV) can be used as a smart storage in smart grids. PHEV is a vehicle that provides its forward propulsion from a rechargeable storage to save fuel [6], [7].Different rating of storage and integrating devices are used to control the frequency can creates a very complex situation. Since micro grids are a low voltage network which is generally not the case of modern power system network [8].

In present scenario of power system network, conventional and distributed generation are combinedly used to control the power flow in order to get a highly stable network. The smart grid model includes 4 units of Thermal power plant (conventional generation) and 6 units of Wind power plant (distributed generation). Wind power plant is connected to major load side to control the power flow and this connecting point is treated as smart grid. Power generated in Thermal power plant is done by Synchronous generated and in Wind power plant Doubly Feded induction generator (DFIG) [9]. The rating of each thermal power plant is 900 MW where as wind power plant rating is 12 MW. 13.8 KV is generated by synchronous generated which is then step-up to 230 KV of voltage level and 575 V is generated by DFIG which is again step-up to 230 KV because transmission voltage is 230 KV. The overall Frequency of system is controlled by controlling the frequency of both synchronous generator and DFIG independently.

The model simulates the power system network with two area system control where each area is characterized with two conventional thermal power plant each having 900 MW capacity.

II. ACTIVE POWER ANALYSIS METHOD

Active power is the real power which flows in electrical network viz. transmission and distribution networks. Depending upon the load angle gradient the flow of active power takes place from source to load or from one area to another area.

Fig. 1. Single line diagram of the power source connected to the load via a transmission line.

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From Fig. 1 the active power flowing from sending end to the receiving end. For small “δ”, active power can be controlled by changing the angle “δ” between the sending end and receiving end voltages, V^Sand V^R respectively. Moreover reactive power can be controlled by controlling the difference between voltage magnitudes of VS and VR. For a two area system, during normal operation the real power transferred over the tie line is given by

12 12

2 1

12

sin 

X E P  E

Where X₁₂



X₁



X_tie



X₂ and



₁₂

 

₁

 

₂

For a small deviation in the tie-line flow

12 12

12 12 12

12



_

^  ^ ^





P_s

d P dP



₁ ₂



12

     



P P_s

Fig.2 Tie Line Power Representation

In an interconnected power system, different areas are connected with each other via tie-lines. When the frequencies in two areas are different, a power exchange occurs through the tie-line that connected the two areas. In case of Wind power plant DFIG is used. Doubly-fed electric machines are basically electric machines that are fed ac currents into both the stator and the rotor windings. Doubly-fed induction generators when used in wind turbines is that they allow the amplitude and frequency of their output voltages to be maintained at a constant value, no matter the speed of the wind blowing on the wind turbine rotor. Because of this, doubly-fed induction generators can be directly connected to the ac power network and remain synchronized at all times with the ac power network.

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Simulation model of smart grid

Simulation result table:

III. RESULT AND DISCUSSION:

Initial load values are taken from problem of [10] and simulation has been done. Some of the results are discussed here with their graph data are as:

CASE I

Load at BUS 3

Inductive Active Capacitive

130 MVAR 1050 MW 200 MVAR

Load at BUS 6

The graph of Active power obtained form this SIMULINK model at this load values has shown below:

Sl No Load at Bus 3 Load at Bus 6 Frequencies( Hz)

Inductive (MVAr)

Active (MW)

Capacitive (MVAr)

Inductive (MVAr)

Active (MW)

Capacitive (MVAr)

Minimum Maximum

1. 150 1100 200 120 1900 350 49.90 50.292

2. 180 1030 200 190 1950 350 49.72 50.105

3. 190 1200 200 210 2100 350 49.81 50.06

4. 130 1050 200 140 1850 350 49.87 50.03

5. 120 1000 200 120 1800 350 49.96 50.33

6. 100 960 200 100 1760 350 49.78 51.23

7. 80 900 200 80 1700 350 49.72 50.24

8. 70 800 200 65 1600 350 49.70 50.34

9. 60 700 200 50 1500 350 49.63 50.55

10. 50 650 200 40 1400 350 49.20 50.8

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Fig. 3 Graph of Active power for case-I

Hence this is observed from above graph that the active power values are:.B1- 620.4 MW , B2- 458.7 MW , B3- 748.3 MW, B4- 674.2 MW , B5- 673.5MW

CASE II

Load at BUS 3

Load at BUS 6

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CASE III

Load at BUS 3

Load at BUS 6

The graph of Active power obtained form this SIMULINK model at this load values has shown below:

Fig.5 Graph of Active power for case-III

Hence this is observed from above graph that the active power values are : B1- 489.7 MW , B2- 213.2 MW , B3- 887.9 MW, B4- 527.1 MW , B5- 568.1 MW

CASE IV

Load at BUS 3

Load at BUS 6

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Fig.6 Graph of Active power for case-IV

Hence this is observed from above graph that the active power values are : B1-588.4 MW, B2- 420.4 MW, B3- 576.1 MW, B4- 643.2 MW, B5- 640.3 MW

In load analysis of above simulation model, Inductive and Active loads are varied in RL series load which is taken at both load buses i.e. B3 and B6. Whereas capacitive load kept as it is with the initial value taken in series load. The value of capacitive load at bus bar B3 is 200 MVAR where as 350 MVAR of capacitive value is taken at bus bar B6. Initially active and inductive load at B3 is taken as 1050MW and 130 MVAR respectively and at B6 the value of active load is 1850 MW and the value of inductive load is 140 MVAR. The maximum and minimum measured frequency values on these loads are 50.252 Hz and 49.90 Hz respectively. The active power values at this load condition is measured by the obtained graph is B1- 620.4 MW , B2- 458.7 MW , B3- 748.3 MW, B4- 674.2 MW , B5- 673.5MW

Inductive and Active loads at both buses has increased simultaneously and this is found that when inductive and active load values at bus B3 is 180 MVAR and 1030MW and load value at bus B6 is 190 MVAR and 1950 MW then active power measured at all buses namely B1, B2, B3, B4 and B5 are not constant. Active power values at B1 has changed to 639.2 MW from 620.4 MW, at B2 it is found that active power values changed from 458.7 MW to 473.2 MW and likewise active power values changes at all buses like B3, B4 and B5.

The maximum values of load has already taken to check the maximum limit of this smart grid network .To know these load ranges, value of inductive load on bus bar B3 is decreased to 60MVAR from their initial value which is 130 MVAR and value of active load is decreased to 700 MW from their initial value of 1050 MW where as at bus bar B6, inductive load is decreased from 140 MVAR to 50 MVAR and active load is decreased from 1850 MW to 1500 MW. At these load values, the values of maximum and minimum frequencies are measured to 50.80 Hz and 49.20 Hz.The active power values at this load condition are calculated from the simulation graph is B1-588.4 MW, B2- 420.4 MW, B3- 576.1 MW, B4- 643.2 MW, B5- 640.3 MW.

IV. CONCLUSION

In this paper, load analysis has been done on this smart grid to check the stability in terms of active power flow. Active power values at all buses has been changed with respect to changes in active and inductive load values at bus bar B3 and B6 keeping capacitive load constant. Frequency has been also measured and keeping values of both active power and frequency , magnitude of inductive and active load has been deduced while maintaining synchronism of the proposed smart grid model.

REFERENCES

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using service oriented architecture”. IEEE PECon’08, pages 1212–1217, 2008.

[4]. P. B. Andersen, B. Poulsen, M. Decker, C. Træholt, and J. Østergaard. “Evaluation of a generic virtual power plant framework using service oriented architecture”. IEEE PECon’08, pages 1212–1217, 2008

[5]. Andisheh Ashourpouri,S.A.Nabavi Niaki,”Active power control of smart grid using plug in Hybrid electric vechile”

[6]. Palo Alto, Comparing the Benefits and Impacts of Hybrid ElectricVehicle Options, EPRI, CA: 2001. 1000349

[7]. Palo Alto, Comparing the Benefits and Impacts of Hybrid ElectricVehicle Options for Compact Sedan and Sport Utility Vehicles, EPRI,CA: 2002. 1006892

[8]. G.Lalor, “Frequency control on an isolated power system with evolving plant mix,” Ph.D. dissertation, School of electrical and mechanical Engineering, University College Dublin, September 2005.

[9]. Suryanarayana Doolla, Jayesh Priolkar, “Analysis of Frequency Control in Isolated Microgrids ” IEEE PES Innovative Smart Grid Technologies – India, 2011

[10]. P Kundur, ”Power system stability and control “

Active Power analysis of a Smart Grid- Using MATLAB/SIMULINK Approach