Figure 1.
Unipolar (a) and bipolar (b) DC microgrid.
Table 1.
Microgrids and bus characteristics
| Topology | Unipolar DC microgrid | Bipolar DC microgrid |
|---|---|---|
| Bus parameters | Single positive rail and ground | Positive, neutral and negative rails |
| Bus voltage | Single voltage (positive to ground) | Three-wire voltage (positive, neutral and negative) |
| Bus complexity | Simpler, with fewer components | More complex, with more components for balancing |
| Protection | Simple overcurrent/short-circuit protection | More complex, requiring balancing and fault detection for both rails |
| Voltage levels | 300 V | ±200 V |
| Power of sources | Pv (2 kW), wind (1 kW) | Pv (2 kW), wind (1 kW) |
| Load options | One voltage level per load, Load 1 (2 kW) | Load 2 (1 kW), load 3 (1 kW) |
Figure 2.
Microgrid resilience classification.
Figure 3.
Resilience curve.
Table 2.
Cost component comparison (Eskander and Silva, 2023; Jena et al., 2021)
| Component | PV | Wind (1 kW) | Boost | Buck | AC/DC | Bid- conv | Balancer converter | Circuit breaker | Cables (3 kW) | Total cost |
|---|---|---|---|---|---|---|---|---|---|---|
| Topology | ||||||||||
| Unipolar DC MG (3 kW) | €2,000 (CS6K-300) | €2,500 (Bergey Excel) | €350 (Energy Skylla) | €200 (MeanWell) | €800 (SMA Sunny Island) | €800 (SMA Sunny Island) | Not required | €150 (ABB S202) | €200 (Sola Cable) | €6,150 |
| Bipolar DC MG (3 kW) | €2,000 (CS6K-300) | €2,500 (Bergey Excel) | €350 (E. Skylla) | €200 (MeanWell) | €800 (SMA Sunny Island) | €800 (SMA Sunny Island) | €600 (Victron Energy BMV-702) | €150 (ABB S202) | €200 (Solar Cable) | €11,07 |
Figure 4.
NPC and COE comparison. COE, cost of energy; NPC, net present cost.
Figure 5.
AHP technique process. AHP, analytic hierarchy process.
Table 3.
Microgrids in the literature (Kumar and Prabha, 2022; Punitha et al., 2024)
| Topology | Type | Characteristics | Usage frequency (%) |
|---|---|---|---|
| AC microgrid | AC | Standard, widely used, less efficient for DC systems | 25 |
| Unipolar DC microgrid | DC | Simple, low-cost, suitable for small-scale systems | 13 |
| Bipolar DC microgrid | DC | More reliable, reduces losses compared to unipolar | 12 |
| Multi-terminal DC | DC | Connects multiple sources and loads, modular | 11 |
| Multi-bus DC | DC | Flexible load distribution and efficient control | 10 |
| Ring DC | DC | High resilience, continuous power supply | 10 |
| Radial DC | DC | Simple, but vulnerable to faults; low redundancy | 5 |
| Mesh DC | DC | High reliability, but complex control | 4 |
| Star DC | DC | Centralised, best for small systems | 3 |
Figure 6.
AHP technique (Siksnelyte et al., 2018; Yildiz et al., 2025). AHP, analytic hierarchy process.
Table 4.
Alternatives and criteria
| Alternatives | A1 | Unipolar microgrid | Figure 1 |
| A2 | Bipolar microgrid | Figure 2 | |
| A3 | Ring topology | Wang et al. (2023) | |
| A4 | Multi-terminal topology | Bouchekara et al. (2023) | |
| A5 | Multi-bus topology | Dali et al. (2022) | |
| Criteria | C1 | Cost | |
| C2 | Protection | ||
| C3 | Resilience |
Table 5.
Consumer scenarios
| Scenarios | S1 | S2 | S3 | S4 | 5S | S6 | S7 |
|---|---|---|---|---|---|---|---|
| Combined criteria | C1 = C2 = C3 | C2 > C3 > C1 | C2 > C1 > C3 | C3 > C2 > C1 | C3 > C1 > C2 | C1 > C2 > C3 | C1 > C3 > C2 |
Table 6.
Saaty’s comparison note (Saaty and Vargas, 2012)
| Significance level | 1 | 3 | 5 | 7 | 9 | 2, 4, 6, 8 |
|---|---|---|---|---|---|---|
| Definition | Equally important | Moderate important | Strong important | Very strong important | Extreme important | Moderate values |
Figure 7.
Criteria’s pair-wise comparison from the expert.
Figure 8.
Cost pair-wise comparisons from all alternatives.
Figure 9.
Protection pair-wise comparisons from all alternatives.
Figure 10.
Resilience pair-wise comparisons from all alternatives.
Figure 11.
Microgrid scores for scenario 5.
Figure 12.
All scenario results.
Figure 13.
Overall score for each microgrid topology.
Figure 14.
Performance sensitivity of the alternative.
Figure 15.
Protection gradient sensitivity.
Figure 16.
Cost gradient sensitivity.
Figure 17.
Resilience gradient sensitivity.
Table 7.
Data from scientific articles
| Criterion alternatives | Cost (20%) | Short-circuit resilience (40%) | Protection complexity (30%) |
|---|---|---|---|
| Unipolar DC MG | Economical for basic setups | Limited | Low |
| Bipolar DC MG | Moderate | Enhanced redundancy (20%) | Moderate |
| Ring topology | Moderate | Self-healing capabilities (30%) | Moderate |
| Multi-terminal | High | Adaptive energy management (20%) | High |
| Multi-bus | High | Fault isolation and modular replacement (30%) | High |
Figure 18.
Pairwise comparison matrix from scientific articles.
Figure 19.
Flowchart of sensitivity improvement. AHP, analytic hierarchy process.
Figure 20.
Frobenius norm evolution.
Figure 21.
Rank of decision vector.