Control and Design of Microgrid Components - Power Systems ...

More documents

Recommendations

Info

instantaneous calculation of the radius of the ellipse (the magnitude of the voltage) will yield a quantity pulsating at twice the nominal system frequency. If the unbalance is less than 3 percent, the magnitude of the pulsation can be very small. The active power measure will have the same issue, showing a small amplitude ripple at twice the system frequency superimposed over the traditional value. Filtering the signals of voltage magnitude and power is the solution that can eliminate the presence of the small ripples. In the hardware realization measures are brought in by sensing equipment and translated to digital values. These values are plagued by noise coming from the sensing devices and from the connecting cables that carry those measurements. The digital values inside the DSP environment need to be filtered to minimize the effect of these noises. It turns out that those filtering levels may also be enough to eliminate the 120Hz ripples in the measures due to low levels of unbalance present in the system. In the hardware laboratory setup the voltage supply is rather well balanced, showing a 0.2 percent level of unbalance at the 480V point of common coupling. The values of P,Q and regulated voltage magnitude, V are filtered before being introduced in the controller. The filter is a low pass, single time constant transfer function: 1 H ( s) = 1+τ s The time constant τ is worth 30ms, for P, Q and V. Figure 5.1 shows the frequency response of this filter. Figure 5.1 Filter Gain as a Function of Frequency. The test system is one microsource in island connected to an unbalanced load. The load is unbalanced by removing the connection at one of the three phases. As a consequence, the current in that particular phase will be zero. The resulting unbalance in the voltage is 5.12%. 66
Figure 5.2 shows the plots for P,Q and V as the unbalance is applied. It is possible to notice the 120Hz component superimposed to the balanced value on each of the three quantities. The voltage magnitude, V, shows a very small magnitude in the double frequency component, that is because the unbalance driving it is 5.12%. The values of P and Q show a relatively larger magnitude in the double frequency component because they are calculated using voltage and as well as the current, which has a 100% unbalance. Figure 5.3 shows the three line to line voltages at the load terminals (upper traces) and the currents (lower traces). Figure 5.4 shows the same quantities with a longer time division (1s/div) to make the point that there are no lower frequency oscillations in the envelope of the voltages or currents. Figure 5.2 P, Q and Magnitude of V. [50ms/div] 67
Page 1 and 2:
PSERC Control and Design of Microgr
Page 3 and 4:
Information about this project For
Page 5 and 6:
Executive Summary Economic, technol
Page 7 and 8:
Table of Contents Chapter 1. Introd
Page 9 and 10:
List of Figures Figure 1.1 Microgri
Page 11 and 12:
List of Figures (continued) Figure
Page 13 and 14:
Chapter 1. Introduction Distributed
Page 15 and 16:
1.2.2 Operation and Investment The
Page 17 and 18:
Figure 1.1 Microgrid Architecture D
Page 19 and 20:
Chapter 2. Static Switch The static
Page 21 and 22:
ω ωo ω1 Preq Pgrid P Pload Figur
Page 23 and 24:
2.3 Synchronization Conditions The
Page 25 and 26:
droop. The issue is that it is poss
Page 27 and 28: This synchronizing behavior is unac
Page 29 and 30: Figure 2.12 shows on the upper plot
Page 31 and 32: Chapter 3. Microsource Details This
Page 33 and 34: with different size. This control i
Page 35 and 36: u + _ K F ω o + _ ω o s P u ω o
Page 37 and 38: Q versus E Droop E req Q m Q _ + E
Page 39 and 40: currents from the microsources incr
Page 41 and 42: inverter ratings limits (in kVA) ca
Page 43 and 44: A 16 DG B 22 DG Static Switch C 8 D
Page 45 and 46: ω Unit 2 Max Unit 2 ω o Unit 1 ω
Page 47 and 48: Unit 1 Min Unit 2 ω Unit 1 ΔPmin
Page 49 and 50: positive value. When this value has
Page 51 and 52: needs of power. This solution would
Page 53 and 54: This expression is very similar to
Page 55 and 56: Li-Pmax < Fi < Li for unit ‘i’
Page 57 and 58: ω ω ω o Fo ω o Fo F F Unit Powe
Page 59 and 60: This control has been implemented i
Page 61 and 62: characteristic will coincide with t
Page 63 and 64: ating on the voltage output, establ
Page 65 and 66: Prime Mover DC Storage Voltage Sour
Page 67 and 68: linearity. A value of 30 degrees pr
Page 69 and 70: Figure 4.8 P and Q Plane Capability
Page 71 and 72: 4.4 System Ratings The inverter per
Page 73 and 74: Switching Sequence 145 146 136 236
Page 75 and 76: generated by the inverter: the VA r
Page 77: % of voltage unbalance = 100 maximu
Page 81 and 82: Figure 5.5 shows the measures of P
Page 83 and 84: Figure 5.7 One Unit Connected to th
Page 85 and 86: Microsources are connected to the l
Page 87 and 88: The transformer impedance can be se
Page 89 and 90: o r 1 = 0.3277 Ω = 0.0547 Ω x x 1
Page 91 and 92: Table 6.3 Load Data Summary. Rated
Page 93 and 94: The worse case scenario is represen
Page 95 and 96: The filtering is achieved by a low
Page 97 and 98: works with an internal voltage leve
Page 99 and 100: terminals to achieve each of the th
Page 101 and 102: Table 6.5 Lookup Table for Switchin
Page 103 and 104: Chapter 7. Microgrid Tests There ar
Page 105 and 106: Table 7.1 Summary of Experiments fo
Page 107 and 108: Table 7.2 Series Configuration Cont
Page 109 and 110: Figure 7.6 Control of F1 and F2, Fe
Page 111 and 112: Figure 7.10 Control of P1 and F2, F
Page 113 and 114: pu, but when it is fed from a remot
Page 115 and 116: Unit 1: P, Q, F, Frequency, Voltage
Page 129 and 130:
Unit 1: P, Q, F, Frequency, Voltage
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
7.4.1 Unit 1 (F), Unit 2 (F), Impor
Page 209 and 210:
Import From Grid, Setpoints are 10%
Page 211 and 212:
Page 213 and 214:
Island, Setpoints are 10% and 90% o
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
7.4.2 Unit 1 (F), Unit 2 (F), Expor
Page 223 and 224:
Export to Grid, Setpoints are 10% a
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
7.4.3 Unit 1 (F), Unit 2 (P), Impor
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
7.4.4 Unit 1 (F), Unit 2 (P), Expor
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Chapter 8. Conclusions This work sh
Page 257:
[14] Lasseter, R.,” Microgrids,
show all

Control and Design of Microgrid Components - Power Systems ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?