DC Microgrids

2 Chapter 2Figure 2.1 Simple representation of DC MGs.Figure 2.2 Classification of DC MG control strategies.Figure 2.3 Centralized control strategy.Figure 2.4 Decentralized strategy.Figure 2.5 Distributed strategy.Figure 2.6 Higher-level control strategy.Figure 2.7 Droop control characteristics for DC MGs.Figure 2.8 Improved droop control characteristics for DC MGs.Figure 2.9 Droop control algorithm for DC MGs.Figure 2.10 Timing diagram for three levels.Figure 2.11 Three-level control strategy.Figure 2.12 Control loop for a solar system in DC MGs.Figure 2.13 Control loop for wind energy system in DC MGs.Figure 2.14 Control loop for fuel cells in DC MGs.Figure 2.15 Control loop for battery-based storage systems in DC MGs.

3 Chapter 3Figure 3.1 Constant power load characteristics.Figure 3.2 Internal circuit diagram of the PPU.Figure 3.3 PPU equivalent circuit during fault.Figure 3.4 DC MGs equivalent circuit.

4 Chapter 4Figure 4.1 Typical EMS architecture.Figure 4.2 Power forecast from the solar farm.Figure 4.3 Power output forecast from the wind farm.Figure 4.4 Cost of power for transaction with the utility.Figure 4.5 Step-by-step pseudocode lines of GA.Figure 4.6 Flowchart of heuristic based Genetic Algorithm.Figure 4.7 Step-by-step pseudocode lines of PSA.Figure 4.8 Flowchart of heuristic-based Pattern Search Algorithm.Figure 4.9 Single-line diagram of 380V DC Microgrid.Figure 4.10 Load demand of the microgrid.Figure 4.11 Power transaction from/to utility using GA and PSA.Figure 4.12 Economic dispatch of DERs using GA.Figure 4.13 Economic dispatch of DERs using PSA.

5 Chapter 5Figure 5.1 Management in microgrid.Figure 5.2 Various approaches for EMS.Figure 5.3 Residential microgrid.Figure 5.4 Day-ahead PV power generation and load demand.Figure 5.5 Hourly energy price of the grid and natural gas.Figure 5.6 Day operating cost with respect to day initial charging level of BESS...Figure 5.7 Hourly OC for 20% day initial charging level of BESS.Figure 5.8 Hourly OC for 100% day initial charging level of BESS.Figure 5.9 Hourly SOC of BESS in ISM for various day initial charging level.Figure 5.10 Hourly SOC of BESS in GCM for various day initial charging level.Figure 5.11 Hourly power sharing in ISM for 20% day initial charging level.Figure 5.12 Hourly power sharing in GCM for 20% day initial charging level.Figure 5.13 Day operating cost with respect to capacity of BESS.Figure 5.14 Cost with respect to capacity of BESS.

6 Chapter 6Figure 6.1 Trends in production of energy by non-renewable in India. Source: [2]...Figure 6.2 Schematic diagram of a DC microgrid.Figure 6.3 Schematic of hybrid renewable energy system.Figure 6.4 A schematic of methodology adopted.Figure 6.5 Schematic of ANN architecture.Figure 6.6 The proposed architecture of the artificial neural network.Figure 6.7 Training data regression plot for the superlative architecture 5/48/1...Figure 6.8 (a-d). Derived discharge series at Sundri site.Figure 6.9 Discharge flow curve with percentile dependability.

7 Chapter 7Figure 7.1 Residential/Commercial DC microgrid structure.Figure 7.2 DC bus Equivalent Thevenin Circuit (Reprinted with permission from 50...Figure 7.3 Converter static behavior considering the line resistance effect.Figure 7.4 Approaches for ps and cs, DC bus voltage restoration.Figure 7.5 Secondary control implementation in the embedded local controller.Figure 7.6 Implementation of consensus-based secondary control on local control.Figure 7.7 Hybrid secondary control diagram (Reprinted with permission from 5052...Figure 7.8 Fully connected communication network (Adapted from [8] and reprinted...Figure 7.9 δRd (t) Convergence (Reprinted with permission from 5052471151140/IEE...Figure 7.10 δRd (t) Convergence under communication delays (Reprinted with permi...Figure 7.11 Closed-loop secondary control diagram (Reprinted with permission fro...Figure 7.12 Output signals from the complete μG model and the stability analysis...Figure 7.13 Closed-loop root locus under parameter variations (Reprinted with pe...Figure 7.14 Simulated and experimental system used for performance validation.Figure 7.15 Experimental setup.Figure 7.16 Simulation results considering load disturbances and communication f...Figure 7.17 Experimental result with load disturbances and communication failure...Figure 7.18 Simulation results considering constant power loads and communicatio...Figure 7.19 Unique vs control diagram (Adapted from [7] and reprinted with permi...Figure 7.20 Assessment of the power sharing behavior. In (a) and (b), varies f...Figure 7.21 Evolution of δvV and its effect on bus voltage and power imbalance (...Figure 7.22 Closed-loop control diagram for stability analysis (Reprinted with p...Figure 7.23 Output voltage and current behavior of the switched and stability an...Figure 7.24 Stability analysis of two converters (Reprinted with permission from...Figure 7.25 Simulated DC bus diagram. (Reprinted with permission from 5052471360...Figure 7.26 Simulation of control unique vs secondary control performance. (Adap...Figure 7.27 Experimental performance of unique vs secondary control. (Adapted fr...Figure 7.28 Secondary control cycle time frame for the hybrid control technique ...Figure 7.29 Experimental analysis of one communication cycle.Figure 7.30 Phasor representation of information sent by CAN converters.Figure 7.31 Auto-synchronization of timers.

8 Chapter 8Figure 8.1 DC microgrid.Figure 8.2 Annals of publication on the modeling of DC-DC converter.Figure 8.3 Different analysis derived from modeling techniques.Figure 8.4 Positions of roots in the pole-zero map for stability analysis.Figure 8.6 Circuit diagram of DCL-QB converter.Figure 8.7 Step response of DCL-QB converter.Figure 8.8 Types of controller used in power converters.

9 Chapter 9Figure 9.1 Classification of modulation schemes for MC.Figure 9.2 Circuit configuration of three-to-n phase (a) direct MC (b) indirect ...Figure 9.3 Switch configuration of sparse MC.Figure 9.4 Switch configuration of very sparse MC.Figure 9.5 Switch arrangement of the ultra-sparse MC.Figure 9.6 Shortened high-frequency model of (a) a five-phase IM (b) phase ‘A’ o...Figure 9.7 Drive system fed from Three-five phase MC.Figure 9.8 Switching combinations of three-to-five phase MC.Figure 9.9 Three-phase input filter.Figure 9.10 Equivalent circuit of a MC.Figure 9.11 Clamp circuit to protect the MC switches.Figure 9.12 Schematic of electrical power requirements in the aircraft.Figure 9.13 Application of matrix converters in the wind energy systems.

10 Chapter 10Figure 10.1 Basic inverter Topology.Figure 10.2 Two inverters connected in series.Figure 10.3 Stepped waveform of multilevel inverter.Figure 10.4 Advantages of multilevel inverters.Figure 10.5 Basic classification of multilevel inverters (MLIs).Figure 10.6 One leg of a bridge of diode clamped MLI.Figure 10.7 Output voltage waveform of diode clamped MLI.Figure 10.8 THD analysis of diode clamped MLI.Figure 10.9 Flying capacitor multilevel inverter (one leg of a bridge).Figure 10.10 Output voltage waveform of flying capacitor MLI.Figure 10.11 THD analysis of flying capacitor MLI.Figure 10.12 Cascaded H bridge multilevel inverter.Figure 10.13 Output voltage waveform of cascaded H bridge multilevel inverter.Figure 10.14 THD analysis of cascaded H bridge multilevel inverter.Figure 10.15 Formation of seven-switch five-level ANPC topology (a) Circuit I (b...Figure 10.16 Proposed seven-switch five-level topology.Figure 10.17 Output voltage waveform of proposed ANPC MLI.Figure 10.18 THD analysis of proposed ANPC MLI.Figure 10.19 Comparison of various parameters in different types of MLIs.

11 Chapter 11Figure 11.1 Proposed step-up topology.Figure 11.2 Equivalent circuit of proposed converter in CCM, during a) mode I, b...Figure 11.3 Key waveforms of proposed converter during CCM operation.Figure 11.4 Comparison of the proposed structure in terms of (a) gain, (b) numbe...Figure 11.5 The equivalent circuit of the proposed converter during DCM operatio...Figure 11.6 The theoretical waveform of inductor currents in DCM.Figure 11.7 The separator curve of the CCM and DCM regions, related to the induc...Figure 11.8 Waveforms of (a) load voltage, (b) load current, (c) voltage ripple ...Figure 11.9 Voltage waveform of capacitors (a) C1, (b) C2, (c) C3, (d) Co.Figure 11.10 The voltage waveform of inductors (a) L1, (b) L2, (c) L3.Figure 11.11 The current waveform of inductors (a) L1, (b) L2, (c) L3.Figure 11.12 The waveforms of the capacitor currents (a) C2, (b) C3.Figure 11.13 The voltage stress waveforms of switches (a) S1, (b) S2, and diodes...Figure 11.14 The real gain of the proposed converter versus Ideal gain.Figure 11.15 The efficiency curve of the proposed converter in terms of (a) Duty...Figure 11.16 Block diagram of control mechanism to better utilization of the pro...Figure 11.17 Variation of (a) output voltage and (b) duty cycle versus reference...Figure 11.18 Dynamic behavior of the proposed converter due to the changes of (a...Figure 11.19 (a) P-V characteristic, and (b) P-I characteristic of a 120 [W] sol...Figure 11.20 The connection between a photovoltaic panel and proposed structure ...Figure 11.21 The simulation results for MPP tracking by the converter.