This is the final defense presentation by me and my project team on An Active Power Control Strategy for Hybrid Micro-hydro and Photovoltaic Microgrid Using Battery Energy Storage System (BESS).

1. Final Presentation
On
Final Year Project - II
TEAM MEMBERS:
Dinesh Pradhan (073BEL318)
Ram Baral (073BEL331)
Shristi Shrestha (073BEL342)
Suiksha Gautam (073BEL344)
AN ACTIVE POWER CONTROL STRATEGY
FOR
HYBRID MICRO-HYDRO AND PHOTOVOLTAIC
MICROGRID USING BESS
PROJECT SUPERVISOR:
Prof. Dr. Indra Man Tamrakar
1

2. PRESENTATION OVERVIEW
•Introduction
•Project Objective
•Theory
•Methodology
•Simulations and Results
•Conclusion
•References
2

3. INTRODUCTION
3

4. 4
Introduction:
-Trend of inter-connecting of various renewable energy generating sources to form
a Micro-Grid is getting popular for supplying power to isolated rural area, where
there is no presence of national grid.
-- One of the major challenge in such system is to maintain voltage magnitude and
frequency within acceptable values at varying load condition.
-- There shall be balance between active power generation and consumption for
frequency control and there shall be balance between reactive power generation and
consumption for voltage control.
--This project deals with the frequency control in a Micro-Grid consisting of MHP
plant and PV-plant.

5. Proposed System Components:
Fig 1. Block Diagram of the Proposed System
• A Micro-hydro Plant (15 KW)
• A 10 KW PV Plant
• A 25 KW Discrete Electronic Load Controller (D-ELC) at
Point of Common Coupling (PCC)
• A Battery Energy Storage System (BESS) Connected to
PCC
• Load
5
Introduction:

6. Modes of Operation of the system:
Mode I [Pgen > Pload]
The excess power is smaller than the power that battery is capable of
consuming. Hence, no power is dumped to the D-ELC.
Mode II [Pgen > Pload]
The excess power is greater than the power that battery is capable of
consuming. Hence, excess power that can not be stored in BESS is
dumped into the D-ELC.
Mode III [Pgen < Pload]
The battery discharges to supply the deficit power to the load.
6

7. PROJECT OBJECTIVE
7

8. To develop simulation model of MHP-PV micro-grid with BESS for active
power control to maintain constant frequency
8
OBJECTIVE

9. RELATED THEORY
9

10. Discrete-ELC
• Parallel resistance banks are turned on
and off according to the requirement to
adjust the power at the PCC rather than
chopping the voltage across the dump
load
• D-ELC does not have the problems of
harmonics and reactive power
consumption.
10
Fig 2. Schematic Diagram of D-ELC connected to a Synchronous Generator and load
RELATED THEORY
Load

11. Resistive Load Banks in D-ELC
Numbers of resistor banks in D-ELC and their
power rating are determined from the
frequency-droop characteristic and tolerable
frequency deviation
If ∆f is the tolerable frequency deviation, then
the allowable step-change in dumped load is
estimated as:
∆P = KP
∆f
Where, Kp = inverse of slope of frequency
droop line
And the minimum number of dumped load in
each phase is estimated as:
Nmin = ?????????
Where PSG
= Full load rating of the synchronous
generator.
11
Fig 3. Frequency Droop Characteristics
∆f
∆P

12. DC-DC Boost Converter for PV system
When the switch is on, the inductor stores energy
and the load gets power from the previously
charged capacitor.
When the switch is off, the inductor releases
energy (stored in the previous cycle) and supplies
power to the load and charging current to the
capacitor.
The switch is controlled by PWM signals to
control the duty cycle (D) such that the voltage
from input source is converted to desired voltage
level at the output side.
It is used to extract Maximum power from PV
panel at a given value of irradiance.
12
Fig 4. DC-DC Boost Converter

13. Maximum Power Point Tracking (MPPT)
A technique used with photovoltaic (PV)
solar systems to maximize power extraction
under all conditions.
P & O Algorithm is used for MPPT.
● When minor perturbation is introduced in
voltage, it causes power variation ΔP.
● If ΔP is positive, perturbation is
continued.
● If ΔP is negative, perturbation is returned
to previous point.
● Thus, power generated hovers around the
point of maximum power.
13
Fig 5. MPPT Logic and multiple irradiances

14. Reference Current Generator to transfer Max power to grid
The voltage at which maximum power
occurs is set as Vref
.
Volatge across the capcitor is sensed and
compared with Vref.
PI controller is tuned to generate reference
current Id
corresponding to maximum power.
The reference current Id
is converted ia
,ib
,ic
using a dq0-abc transformation.
Inverter shall be controlled to track these
reference current to ensure maximum power
transfer from Inverter to Grid.
14
Fig 6. Schematic diagram of reference current generator

15. Three Phase Inverter
The three-phase inverter has six IGBTs as switching
devices to convert DC to three phase AC.
It has an inductor and a resistor in series to track the
current signal.
It acts as a power controller between the DC link
capacitor of the DC side (PV or Battery) and the
three-phase side (PCC).
The Hysteresis Band current controller provides the
generation of the switching signals for the inverter.
15
Fig 7. Three Phase Inverter

16. Three Phase Bi-directional Converter
The bidirectional AC/DC converter consists of six IGBT
Diode switches.
Operated in two modes of operation:
● Inverter Mode [DC to AC]
Control system maintains the battery current to be of
sinusoidal waveform and in phase with the generated
voltage.
Reference d-axis current is positive and abc reference
currents are in phase with generated voltages. Thus,
the power flow occurs from dc side to ac side.
● Rectifier Mode [AC to DC]
The battery current is displaced 180o from the
generated voltage.
Reference d-axis current is negative and abc reference
current are out of phase with generated voltages. Thus,
the power flows from ac side to dc side.
16
Fig 8. Three Phase Bi-directional Converter

17. Hysteresis Band Current Controller
Hysteresis band current control technique is used to control
the inverter output current.
A zone is set around the reference current to keep the output
current of the inverter within this zone.
Control action:
● If the output current of the inverter reaches the upper limit
of the zone, then the upper switch is OFF and the lower switch
is ON.
● If the output current of the inverter reaches the lower limit
of the zone, then the upper switch is ON and the lower switch
is OFF.
17
Fig 9. Hysteresis Band Pulse Width Modulation

18. METHODOLOGY
18
Following steps are followed to in this project to get results as per objectives set:

19. 19
STEP 1
Modelling and
simulation of a 15 kW
Micro-Hydro Plant
connected to a resistive
load with D-ELC
STEP 2
Modelling and
simulation of a 10 kW
PV Plant connected to
grid
STEP 3
Modelling and
simulation of parallelly
connected 15 kW
Micro-Hydro Plant and
10 kW PV Plant with
D-ELC
STEP 5
PI tuning of the
BESS-VSC using
conventional PI tuning
method
STEP 4
Modelling and
simulation of a
Microgrid consisting
of 15 kW MHP Plant,
10 kW PV Plant with
D-ELC and BESS
Simulation Progression

20. SIMULATION AND RESULTS
20

21. SIMULATION OF PROPOSED SYSTEM (HYBRID MHP - PV MICROGRID WITH D-ELC AND BESS)
21
Fig. 10 Simulation of proposed system

22. SOURCE: 15 kW MICRO-HYDRO POWER PLANT
22
Fig. 11 Synchronous Generator with excitation system

23. SOURCE: 10 kW PHOTOVOLTAIC POWER PLANT
23
Fig. 12 10 kW photovoltaic plant

24. DC- DC BOOST CONVERTER BETWEEN PV PLANT AND THREE PHASE INVERTER
24
Fig. 13 DC-DC Boost Converter

25. THREE PHASE INVERTER BETWEEN PV AND PCC
25
Fig. 14 Three Phase Inverter

26. CONTROL CIRCUIT FOR THREE PHASE INVERTER
26
Fig. 15 Control circuit for controlling the switched of three phase inverter

27. 25 kW DISCRETE ELECTRONIC LOAD CONTROLLER
27
Fig. 16 25 kW D-ELC

28. INTERNAL STRUCTURE OF DISCRETE LOAD CONTROLLER
28
Fig. 17 Internal Connection of D-ELC
Fig. 18 Resistive banks of D-ELC

29. BATTERY ENERGY STORAGE SYSTEM WITH BI-DIRECTIONAL CONVERTER
29
Fig. 19 BESS with bi-directional controller

30. HYSTERESIS BAND PULSE WIDTH MODULATION CONTROL CIRCUIT FOR BIDIRECTIONAL CONVERTER
30
Fig. 20 Hysteresis band PWM control circuit for bidirectional controller

31. TRIGGERING CIRCUIT FOR BATTERY AND D_ELC
31
Fig. 21 D-ELC trigger generating circuit Fig. 22 Battery trigger generating circuit

32. LOAD SYSTEMS CONNECTED TO THE MICROGRID WHEN BATTERY SOC STARTS AT 50%
32
Fig. 23 Load connected to the micro-grid for
charging at initial SOC 50%(Case I)
Fig. 24 Load connected to the micro-grid for
discharging at initial SOC 50%(Case II)

33. RESULT: Power Plot for Initial Battery SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 21 kW (Battery is charging)
33
Fig. 25 Active power injected by MH and PV , consumed by load, consumed by D-ELC and supplied or consumed by battery at the PCC (Case I)

34. 34
Fig. 26 Waveform of voltage at PCC (Case I)
Fig. 27 Waveform of voltage at PCC magnified (Case I)
Time (s)
RESULT: Waveform of voltage at PCC for Initial Battery SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 21 kW (Battery is charging)

35. 35
Fig. 28 Plot of frequency at PCC (Case I)
RESULT: Frequency Plot for Battery Initial SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 21 kW (Battery is charging)

36. 36
Fig. 29 Waveform of HBPWM I(ref) and I(act) (Case I)
Fig. 30 Waveform of HBPWM I(ref) and I(act) magnified (Case I)
time(sec)
time(sec)
Current
(A)
Current
(A)
RESULT: Waveform of actual current and reference for Battery Initial SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 21 kW (Battery is charging)

37. RESULT: Plot of Battery SOC for Battery Initial SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 21 kW (Battery is charging)
37
Fig. 31 Waveform of BESS SOC (Case I)

38. 38
Fig. 32 Active power injected by MH and PV , consumed by load, consumed by D-ELC and supplied or consumed by battery at the PCC (Case II)
RESULT: Power Plot for Initial Battery SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 28 kW (Battery is charging and discharging)

39. 39
Fig. 33 Waveform of voltage at PCC (Case II)
Fig. 34 Waveform of voltage at PCC magnified (Case II)
RESULT: Waveform of voltage at PCC for Initial Battery SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 28 kW (Battery is charging and discharging)

40. 40
Fig. 35 Plot of frequency at PCC (Case II)
RESULT: Frequency Plot for Battery Initial SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 28 kW (Battery is charging and discharging)

41. RESULT: Waveform of actual current and reference for Battery Initial SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 28 kW (Battery is charging and discharging)
41
Fig. 36 Waveform of HBPWM I(ref) and I(act) (Case II)
Fig. 37 Waveform of HBPWM I(ref) and I(act) magnified (Case II)
time(sec)
time(sec)
Current
(A)
Current
(A)

42. 42
Fig. 38 Waveform of BESS SOC (Case II)
RESULT: Plot of Battery SOC for Battery Initial SOC = 50% and
Load is connected in steps of 7 kW, 14 kW and 28 kW (Battery is charging and discharging)

43. LOAD SYSTEMS CONNECTED TO THE MICROGRID WHEN BATTERY SOC STARTS AT 96%
43
Fig. 39 Load connected to the micro-grid for
charging at initial SOC 96%(Case III)

44. RESULT: Power Plot for Initial Battery SOC = 96% and
Load is connected in steps of 12 kW, 20 kW and 22 kW (Battery is trickle charging)
44
Fig. 40 Active power injected by MH and PV , consumed by load, consumed by D-ELC and supplied or consumed by battery at the PCC (Case III)
Time(s)
Active
Power
(W)

45. 45
Fig. 41 Waveform of BESS SOC (Case II)
RESULT: Plot of Battery SOC for Battery Initial SOC = 96% and
Load is connected in steps of 12 kW, 20 kW and 22 kW (Battery is trickle charging)
Time (s)
soc
(%)

46. RESULT SUMMARY FOR CASE I
46
The findings during operation of the micro-grid as per Case I can be summarized as per the following table:
Load = 7 KW Load = 14 KW Load = 21 KW
Time 0 to 3 sec 3 to 6 sec 6 to 10 sec
Frequency at the PCC 51.05 Hz 50.42 Hz 49.60 Hz
Voltage at the PCC 1 pu 1 pu 1 pu
Power injected by PV 9800 W 9800 W 9800 W
Power injected by micro-hydro 14800 W 14800 W 14800 W
Power injected to the PCC by
micro-hydro and PV
24000 W 24000 W 24000 W
Power supplied to/from BESS 8000 W (to) 8000 W (to) 4000 W (to)
Power consumed by D-ELC 9600 W 3000 W 0
Power consumed by Load 6600 W 13100 W 19800 W

47. 47
The findings during operation of the micro-grid as per Case II can be summarized as per the following table:
Load = 7 KW Load = 14 KW Load = 28 KW
Time 0 to 3 sec 3 to 6 sec 6 to 10 sec
Frequency at the PCC 51.05 Hz 50.42 Hz 49.60 Hz
Voltage at the PCC 1 pu 1 pu 0.9 pu (6 to 6.5 sec)
1 pu (6.5 to 10 sec)
Power injected by PV 9800 W 9800 W 9800 W
Power injected by micro-hydro 14800 W 14800 W 14800 W
Power injected to the PCC by
micro-hydro and PV
24000 W 24000 W 24000 W
Power supplied to/from BESS 8000 W (to) 8000 W (to) 2400 W (from)
Power consumed by D-ELC 9600 W 3000 W 0
Power consumed by Load 6600 W 13100 W 26200 W
RESULT SUMMARY FOR CASE II

48. RESULT SUMMARY FOR CASE III
48
The findings during operation of the micro-grid as per Case III can be summarized as per the following table:
Load = 12 KW Load = 20 KW Load = 22 KW
Time 0 to 3 sec 3 to 6 sec 6 to 10 sec
Frequency at the PCC 51.05 Hz 50.42 Hz 49.70 Hz
Voltage at the PCC 1 pu 1 pu 1 pu
Power injected by PV 9800 W 9800 W 9800 W
Power injected by micro-hydro 14800 W 14800 W 14800 W
Power injected to the PCC by
micro-hydro and PV
24000 W 24000 W 24000 W
Power supplied to/from BESS 8000 W (to) Almost 0 Almost 0
Power consumed by D-ELC 4200 W 5000 W 3000 W
Power consumed by Load 11800 W 19500 W 21300 W

49. CONCLUSION
49

50. The proposed addition of the BESS and D-ELC to the microgrid improves the power quality and
transient response of the microgrid. However, the system only balances the active power requirements
of the system and doesn’t deal with reactive power.
Future enhancement possibilities of the system include reactive power compensation nd harmonic
compensation to reduce the harmonic distortion in the voltage and current output of the microgrid.
50

51. 1. Hou, R., Nguyen, T., Kim, H., Song, H. and Qu, Y. (2017). An Energy-Based Control Strategy for Battery Energy Storage Systems:
A Case Study on Microgrid Applications.
2. Ranganadh, B., Prasad, A., & Sreedhar, M. (2013). Modelling and Simulation Hysteresis Band Pulse Width Modulated Current
Controller Applied To A Three Phase Voltage Source Inverter By Using Matlab. International Journal of Advanced Research in
Electrical Electronics and Instrumentation Engineering, 2(9), 4378-4387
3. Dipesh Shrestha, Ankit Babu Rajbanshi, Kushal Shrestha & Indraman Tamrakar (2014). Advance Electronic Load Controller for
Micro Hydro Power Plant.
REFERENCES
51

52. THANK YOU!
RAM
BARAL
073BEL331
SHRISTI
SHRESTHA
073BEL342
SUIKSHA
GAUTAM
073BEL344
DINESH
PRADHAN
073BEL318
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