Optimal Operation of Network-Connected Combined Heat and Powers for Customer Profit Maximization
Abstract
:1. Introduction
2. Modelling of Network-Connected Combined Heat and Power
2.1. Schematic Diagram of Network-Connected Combined Heat and Power System
2.2. Technical Model of Combined Heat and Power
2.3. Profit Model for Combined Heat and Power
3. Optimization Model of Combined Heat and Power
3.1. Profit Model for Different Operation Modes
3.1.1. C1: PE,CHP > PE,L, PH,CHP > PH,L
3.1.2. C2: PE,CHP > PE,L, PH,CHP < PH,L
3.1.3. C3: PE,CHP < PE,L, PH,CHP > PH,L
3.1.4. C4: PE,CHP < PE,L, PH,CHP < PH,L
3.2. Optimization Model
3.2.1. Operation Mode Identification
3.2.2. Optimization Interval Identification
- (1)
- In Mode C1
- (2)
- In Mode C2
- (3)
- In Mode C3
- (4)
- In Mode C4
4. Demonstration Examples
5. Conclusions
- •
- There mainly exist four operation modes for network-connected CHP, determined by the relationship between the energy demand and supply. Based on the OI determined by operation modes and real-time prices, the operation of CHP can be optimized in a discrete way.
- •
- The profit is determined by electric prices because it is usually high or much higher than that of heat. Thus, in the daytime, the CHP is operated at a high loading level to gain a low value of HTER to produce more electricity. At night, the CHP is operated at a low loading level to gain a higher value of HTER for more heat production.
- •
- A high loading level or high output does not always mean high profits. The loading level affects the HTER and overall efficiency of CHP tremendously. Under different load conditions and energy price scenarios, the CHP should use different optimal operation strategies.
Acknowledgments
Author Contributions
Conflicts of Interest
Nomenclature
ECHP | kJ | The electric energy produced by the CHP |
HCHP | kJ | The heat energy produced by the CHP |
QU | kJ | The sum of heat and electricity produced by a CHP |
GIN | kJ | The energy of input natural gas |
η | % | The CHP efficiency converting gas energy to heat and electricity |
ζ | % | Heat to electricity ratio (HTER) |
VG | m3 | The volume of natural gas consumed by the CHP |
q | kJ/m3 | The energy contained in a cubic meter of natural gas |
CG | € | The fuel cost of CHP |
PROCHP | € | The profit of the community |
ILH | € | The equivalent heat income earned through consuming heat from CHP instead of heat network |
ILE | € | The equivalent electric income earned through consuming electricity from CHP instead of electric network |
INH | € | The income earned by selling surplus heat to the heat network |
INE | € | The income earned by selling surplus electricity to the grid |
€ | The heat purchasing cost during peak loading hours | |
€ | The electricity purchasing cost during peak loading hours | |
pLE | €/kJ | The real-time prices of buying electricity |
pLH | €/kJ | The real-time prices of buying heat |
pG | €/kJ | The real-time price of natural gas |
pNE | €/kJ | The real-time prices of selling electricity to the grid |
pNH | €/kJ | The real-time prices of selling heat to corresponding networks |
EL,CHP | kJ | The consumed electricity energy supplied by CHP |
HL,CHP | kJ | The consumed heat energy supplied by CHP |
EN,CHP | kJ | The electricity energy sold to the corresponding networks |
HN,CHP | kJ | The heat energy sold to the corresponding networks |
kJ | The bought electricity from corresponding networks | |
kJ | The bought heat from corresponding networks | |
EL | kJ | The electric demand of the community |
HL | kJ | The heat demand of the community |
PE,CHP | kW | The output electricity power of the CHP |
PH,CHP | kW | The output heat power of the CHP |
PE,CHP_ahead | kW | The output electricity power of the CHP the day ahead |
PH,CHP_ahead | kW | The output heat power of the CHP the day ahead |
PE,L | kW | The electric power demand of the community |
PH,L | kW | The heat power demand of the community |
€ | The profit of the community in Mode C1 | |
€ | The profit of the community in Mode C2 | |
€ | The profit of the community in Mode C3 | |
€ | The profit of the community in Mode C4 | |
HCHP,min | kJ | The minimum heat energy produced by the CHP |
HCHP,max | kJ | The maximum heat energy produced by the CHP |
ECHP,min | kJ | The minimum electric energy produced by the CHP |
ECHP,max | kJ | The maximum electric energy produced by the CHP |
PH,CHP,min | kW | The minimum output heat power from the CHP |
PH,CHP,max | kW | The maximum output heat power from the CHP |
PE,CHP,min | kW | The minimum output electricity power from the CHP |
PE,CHP,max | kW | The maximum output electricity power from the CHP |
VG,min | m3 | The minimum volume of natural gas consumed by the CHP |
VG,max | m3 | The maximum volume of natural gas consumed by the CHP |
Appendix
Typical Overall Efficiency | Loading Level | HTER | Loading Level | ||
---|---|---|---|---|---|
η1 | 80% | 40% | ζ1 | 0 | 0%–40% |
η2 | 85% | 65% | ζ2 | 2.83 | 40%–60% |
η3 | 86.7% | 78% | ζ3 | 2.2 | 60%–80% |
η4 | 87.5% | 90% | ζ4 | 1.4 | 80%–90% |
ηN | 87.8% | 100% | ζ5 | 0.8 | 90%-100% |
Nominal capacity SN (MW) | 1 | |
Ramp capacity (kW/min) | 15 | |
Electricity output PE,CHP (MW) | 0.7 (max) | 0.4 (min) |
Heat output PH,CHP (MW) | Pramp 0.6 (max) | 0.3 (min) |
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Time | Modes | Time | Modes | Time | Modes | Time | Modes |
---|---|---|---|---|---|---|---|
0:00–0:30 | C3 | 6:00–6:30 | C2 | 13:00–13:30 | C3 | 19:00–19:30 | C2 |
0:30–1:00 | C3 | 6:30–7:00 | C2 | 13:30–14:00 | C3 | 19:30–19:50 | C2 |
1:00–1:15 | C3 | 7:00–7:10 | C2 | 14:00–14:30 | C3 | 19:50–20:00 | C4 |
1:15–1:30 | C2 | 7:10–7:30 | C4 | 14:30–15:00 | C3 | 20:00–20:30 | C4 |
1:30–2:00 | C2 | 7:30–8:00 | C4 | 15:00–15:30 | C3 | 20:30–20:45 | C4 |
2:00–2:30 | C2 | 8:00–8:30 | C4 | 15:30–16:00 | C3 | 20:45–21:00 | C3 |
2:30–3:00 | C2 | 8:30–9:00 | C4 | 16:00–16:30 | C3 | 21:00–21:30 | C3 |
3:00–3:30 | C2 | 9:00–9:30 | C4 | 16:30–16:45 | C3 | 21:30–21:50 | C3 |
3:30–3:40 | C2 | 9:30–10:00 | C4 | 16:45–17:00 | C2 | 21:50–22:00 | C1 |
3:40–4:00 | C3 | 10:00–10:30 | C4 | 17:00–17:30 | C2 | 22:00–22:15 | C1 |
4:00–4:30 | C3 | 10:30–11:00 | C4 | 17:30–17:50 | C2 | 22:15–22:30 | C2 |
4:30–5:00 | C3 | 11:00–11:30 | C4 | 17:50–18:00 | C4 | 22:30–22:45 | C2 |
5:00–5:30 | C3 | 11:30–12:00 | C3 | 18:00–18:20 | C4 | 22:45–23:00 | C3 |
5:30–5:50 | C3 | 12:00–12:30 | C3 | 18:20–18:30 | C2 | 23:00–23:30 | C3 |
5:50–6:00 | C2 | 12:30–13:00 | C3 | 18:30–19:00 | C2 | 23:30–24:00 | C1 |
Time | Profit (Euro) | Time | Profit (Euro) | Time | Profit (Euro) | Time | Profit (Euro) |
---|---|---|---|---|---|---|---|
0:00–0:30 | 2.04 | 6:00–6:30 | 4 | 13:00–13:30 | −149.2 | 19:00–19:30 | 7.55 |
0:30–1:00 | 2.19 | 6:30–7:00 | 4.48 | 13:30–14:00 | −119.9 | 19:30–19:50 | 12.07 |
1:00–1:15 | 0.83 | 7:00–7:10 | 4.3 | 14:00–14:30 | −110.2 | 19:50–20:00 | 0.78 |
1:15–1:30 | 0.01 | 7:10–7:30 | −11.2 | 14:30–15:00 | −80.78 | 20:00–20:30 | −9.95 |
1:30–2:00 | 0.4 | 7:30–8:00 | −28 | 15:00–15:30 | −50.6 | 20:30–20:45 | −0.92 |
2:00–2:30 | −0.77 | 8:00–8:30 | −43.46 | 15:30–16:00 | −27.61 | 20:45–21:00 | −7.14 |
2:30–3:00 | 0.86 | 8:30–9:00 | −58.01 | 16:00–16:30 | −21.15 | 21:00–21:30 | −14.13 |
3:00–3:30 | 0.56 | 9:00–9:30 | −73.26 | 16:30–16:45 | −1.71 | 21:30–21:50 | −0.85 |
3:30–3:40 | 0.29 | 9:30–10:00 | −95.82 | 16:45–17:00 | 1.91 | 21:50–22:00 | 1.75 |
3:40–4:00 | 0.15 | 10:00–10:30 | −119.3 | 17:00–17:30 | 2.63 | 22:00–22:15 | 2.01 |
4:00–4:30 | −0.56 | 10:30–11:00 | −99.92 | 17:30–17:50 | 1.63 | 22:15–22:30 | 0.54 |
4:30–5:00 | −0.67 | 11:00–11:30 | −79.91 | 17:50–18:00 | 1.69 | 22:30–22:45 | 0.12 |
5:00–5:30 | −1.51 | 11:30–12:00 | −76.96 | 18:00–18:20 | 0.59 | 22:45–23:00 | 0.52 |
5:30–5:50 | −2.51 | 12:00–12:30 | −72.01 | 18:20–18:30 | 2.06 | 23:00–23:30 | 1.61 |
5:50–6:00 | 1.22 | 12:30–13:00 | −153.8 | 18:30–19:00 | 8.91 | 23:30–24:00 | 0.65 |
Time | Profit (Euro) | Time | Profit (Euro) | Time | Profit (Euro) | Time | Profit (Euro) |
---|---|---|---|---|---|---|---|
0:00–0:30 | 1.97 | 6:00–6:30 | 3.98 | 13:00–13:30 | −157.00 | 19:00–19:30 | 7.54 |
0:30–1:00 | 2.10 | 6:30–7:00 | 4.48 | 13:30–14:00 | −123.67 | 19:30–19:50 | 12.02 |
1:00–1:15 | 0.81 | 7:00–7:10 | 4.28 | 14:00–14:30 | −113.83 | 19:50–20:00 | −1.42 |
1:15–1:30 | −0.03 | 7:10–7:30 | −11.82 | 14:30–15:00 | −83.68 | 20:00–20:30 | −18.40 |
1:30–2:00 | 0.34 | 7:30–8:00 | −29.11 | 15:00–15:30 | −52.71 | 20:30–20:45 | −2.15 |
2:00–2:30 | −0.81 | 8:00–8:30 | −55.05 | 15:30–16:00 | −28.64 | 20:45–21:00 | −7.52 |
2:30–3:00 | 0.81 | 8:30–9:00 | −71.85 | 16:00–16:30 | −21.99 | 21:00–21:30 | −14.33 |
3:00–3:30 | 0.50 | 9:00–9:30 | −97.61 | 16:30–16:45 | −1.78 | 21:30–21:50 | −0.96 |
3:30–3:40 | 0.27 | 9:30–10:00 | −124.17 | 16:45–17:00 | 1.88 | 21:50–22:00 | 1.75 |
3:40–4:00 | 0.08 | 10:00–10:30 | −147.73 | 17:00–17:30 | 2.57 | 22:00–22:15 | 2.01 |
4:00–4:30 | −0.68 | 10:30–11:00 | −121.56 | 17:30–17:50 | 1.59 | 22:15–22:30 | 0.51 |
4:30–5:00 | −0.69 | 11:00–11:30 | −96.42 | 17:50–18:00 | 1.65 | 22:30–22:45 | 0.10 |
5:00–5:30 | −1.66 | 11:30–12:00 | −79.65 | 18:00–18:20 | 0.45 | 22:45–23:00 | 0.51 |
5:30–5:50 | −2.68 | 12:00–12:30 | −74.90 | 18:20–18:30 | 2.04 | 23:00–23:30 | 1.61 |
5:50–6:00 | 1.20 | 12:30–13:00 | −159.90 | 18:30–19:00 | 8.90 | 23:30–24:00 | 0.66 |
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Xie, D.; Lu, Y.; Sun, J.; Gu, C.; Yu, J. Optimal Operation of Network-Connected Combined Heat and Powers for Customer Profit Maximization. Energies 2016, 9, 442. https://doi.org/10.3390/en9060442
Xie D, Lu Y, Sun J, Gu C, Yu J. Optimal Operation of Network-Connected Combined Heat and Powers for Customer Profit Maximization. Energies. 2016; 9(6):442. https://doi.org/10.3390/en9060442
Chicago/Turabian StyleXie, Da, Yupu Lu, Junbo Sun, Chenghong Gu, and Jilai Yu. 2016. "Optimal Operation of Network-Connected Combined Heat and Powers for Customer Profit Maximization" Energies 9, no. 6: 442. https://doi.org/10.3390/en9060442
APA StyleXie, D., Lu, Y., Sun, J., Gu, C., & Yu, J. (2016). Optimal Operation of Network-Connected Combined Heat and Powers for Customer Profit Maximization. Energies, 9(6), 442. https://doi.org/10.3390/en9060442