Energy Management System for DC Micro Grid Presented By : Rajeev Kumar Chauhan School of Computing & Electrical Engineering Indian Institute of Technology Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India  India is running shortage of 11% peak demand.  Power losses in transmission and distribution system are more than 24% [2].  The energy consumption in commercial and residential is increased by 20% and 40% in developed countries [3]. 29-12-2014 R.K. Chauhan, IIT Mandi, India Generation  Conventional Power Plant  Renewable Energy Source (RES) Line Losses  Transmission and Distribution System  Conversion Losses Energy Efficient Buildings Demand Management 29-12-2014 R.K. Chauhan, IIT Mandi, India Why Microgrid Energy? Improve Reliability & Security Increase Availability of Energy from Renewable Energy Sources  Creates an Open Horizontal Environment for Energy Innovation and Application 29-12-2014 R.K. Chauhan, IIT Mandi, India • Nano- Grid An electrical power system as described in the two universal points of agreement that serves a defined space in one building. • Micro- Grid A micro-grid consists of interconnected distributed energy resources capable of providing sufficient and continuous energy to a significant portion of internal load demand. Or An electrical power system as described in the two universal points of agreement that serves one building • Mini-Grid An electrical power system as described in the two universal points of agreement that serves more than one building. 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India DC Energy Sources  Energy Storage  Battery Electrical Vehicles  Renewable Energy Sources  Solar Photovoltaic  Wind  Small Hydro Power Plant DC Appliances Lighting  LEDs, 10 to 100 times more efficient as compared to tungsten bulb, use only DC power  CFL is neutral to AC or DC power Motor  The micro-grid applications utilizes BLDCs  Conventional DC machines need brush replacement – but not anymore 29-12-2014 R.K. Chauhan, IIT Mandi, India  Fan is primarily a motor  A dc fan also allows better speed control  Refrigerator is essentially a motor  Air-Conditioner is primarily a motor  Washing-Machine / grinder is a motor  Electronics  All electronics (Mobiles/TV/Computers) use low voltage DC  Need a ac/dc power adaptor to charge Note: These appliances power supplies with small transformers , which have only 60-70% energy efficiency. 29-12-2014 R.K. Chauhan, IIT Mandi, India • A DC system requires only two conductors as compared to three for AC system. • A DC system has no inductance as a result the voltage drop in DC system is less than that of AC system for same load and hence a better voltage regulation. • A DC system has no skin effect so we can utilize entire cross section area of the line conductor. • A DC system requires less insulation than an AC system because of less potential stress for same working voltage. 29-12-2014 R.K. Chauhan, IIT Mandi, India  Absence of capacitance in DC system leads to less power loss because there is no need for charge and discharge of capacitance.  DC system reduces the amount of resistance in the line.  Use of non-conventional energy like wind and solar reduce the carbon emission in the atmosphere.  The Power Quality is not a issue. 29-12-2014 R.K. Chauhan, IIT Mandi, India • It is easier to enhance the capacity of the system by adding additional DC power generating sources like PV, fuel cell, wind turbine and the integration is much easier than the integration in AC bus. • System reliability is higher. In AC bus system, if any power generating source like an alternator fails, there is a good chance of circulating current to flow though the alternator and there is a big impact on the system. • DER ability to inject fault current contributions and power into the utility system, a dc approach is an interesting way to prevent such injections. 29-12-2014 R.K. Chauhan, IIT Mandi, India • However, in common DC bus, every power-generating source can be isolated using diodes and they are able to share the power independently. • The dc approach is able to avoid almost all of the key complications of interconnection because they isolate the generation from the grid. • The blocking diode prevents power injection into the ac system during both steady state and transient system conditions. • No fault contributions, or reverse power injection from the dc system into the ac power system. • Ripple management can be accomplished by adding more capacitors in the DC bus. 29-12-2014 R.K. Chauhan, IIT Mandi, India  Single phase system: V = 2×Vac Volt dc =3 3 Vp Volt dc  Three phase system: V  Current I= P Ampere V  Power Loss p=I2R Watt DC Voltage AC Voltage Reduction in Current Rating Reduction Power losses 325 230 29.24% 50.07% 325 110 66.15% 88.54% Where Vdc = DC system voltage, Vac = AC System Voltage; I = System Current ; R= Line resistance; P = Power transfer; Vp = peak value of the phase (line to neutral) input voltages 29-12-2014 R.K. Chauhan, IIT Mandi, India k   Ampere hour  TDL with DC System for Fixed Load:   vdc  TDL with DC System for Variable Load:    TDL with DC System for AC Load:=  = Total Daily Load ;  1 ,  2 ,...  μ×       v ac 1 v dc ηinv Ampere hour  Ampere hour  = Number of operating hours per day, k = Load rating in kW vdc = DC System voltage , v ac = Rated voltage of AC Load, ηinv = Inverter efficiency μ = AC Load in ampere at rated 29-12-2014 = DC Loads in Ampere system voltage ,  = Number of Loads R.K. Chauhan, IIT Mandi, India Load AC DC Load Power Rating (kW) 1. - 24 2.4 - 2400 2. - 48 2.4 - 1200 3. 120 V - 2.4 92% 2608.7 4. 220 - 2.4 92% 2608.7 5. 110 - 2.4 95% 2526.32 S.N 29-12-2014 R.K. Chauhan, IIT Mandi, India Inverter Total Daily Efficiency Load (Ah) 29-12-2014 R.K. Chauhan, IIT Mandi, India  PV Panel ratings  Voltage :24 Volt DC  Power rating: 1.8kW  Battery Details  Battery Bank: 4*150=600AH  Voltage Level: 12 Volt  Power ratings of Converters:  AC-DC :1.5kW  DC-DC : 1.5kW 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India 29-12-2014 R.K. Chauhan, IIT Mandi, India  Number of conversion stages becomes less in DCDS over ACDS.  The power consumption in DCDS is less over ACDS.  The converter losses in ACDS are approximately 6 times higher than DCDS.  DCDS required small size of PV panel and Battery Bank than ACDS. 29-12-2014 R.K. Chauhan, IIT Mandi, India • • • • • • • • • K. W. E. Cheng: Overview of the DC Power Conversion and Distribution,” Asian Power Electronics Journal, Vol. 2, No. 2 (2008), p. 75-82 T. Gruzs: Powering Telecom and Info Technology Systems, Power Quality Assurance (2001), p. 22–29 J. Ciezki and R. Ashton: Selection and Stability Issues Associated with a Navy Shipboard DC Zonal Electric Distribution System, IEEE Trans. Power Delivery, Vol. 15, No. 2 (2000), p. 665–669 R. Hill: Electric Railway Traction Part 3 Traction Power Supplies, Power Engineering Journal, Vol. 8 (1994), p. 275–286. P. Savage, R. R. Nordhaus, and S. P. Jamieson: DC microgrids: Benefits andbarriers, in REIL (Ed.) From Silos to Systems: Issues in Clean Energy and Climate Change, New Haven, CT: Yale Publications (2010). D. J. Hammerstrom: AC versus DC Distribution Systems. Did We Get it Right, IEEE Power Engineering Society General Meeting (2007), p. 1-5 P. Paajanen, T. Kaipia, and J. Partanen: DC Supply of Low-Voltage Electricity Appliances in Residential Buildings, 20th International Conference and Exhibition on Electricity Distribution (2009), p.1-4 P. W. Lee, Y. Z. Lee, and B. T. Lin: Power Distribution Systems for Future Homes, IEEE International Conference on Power Electronics and Drive Systems, Vol. 2 (2009), p. 1140-1146Z. Gershony, PE, and T. McCalmont: Optimal DC Cable Selection in PV Designs, Solarpro (2012), p. 64-73. Information on http:// www.solarprofessional.com K. Engelen, E. L. Shun, P. Vermeyen, I. Pardon, R. D. Hulst, J. Driesen, and R Belmans: The Feasibility of Small-Scale Residential DC Distribution Systems”, IEEE Conference on Industrial Electronics (2006), p. 2618-2623 29-12-2014 R.K. Chauhan, IIT Mandi, India Thanks! 29-12-2014 R.K. Chauhan, IIT Mandi, India