Systems and methods for using electric vehicles as mobile energy storage
View Patent ↗Systems and methods are disclosed for energy management by receiving parameters from commercial building energy system components; optimizing models of system components; optimizing for selected objective functions; generating an optimal operation schedule for the system components; analyzing economic and environmental impacts and optimizing operations of electric vehicles (EVs) for mobile energy storage in commercial buildings.
1. A method for energy management, comprising:
receiving parameters from management system components;
with a processor, optimizing for one or more selected objective functions optimizing economic and environmental impacts using EVs as mobile energy storage systems for a microgrid powering home or office;
generating an optimal operation schedule for the micro-grid management system components;
optimizing operations of one or more electric vehicles (EVs) for mobile energy storage (MES); and
analyzing economic and environmental impacts;
formulating Maximization of Daily Profit Objective function; and
modeling daily profit of the microgrid as:
min
p
dc
C
g
dc
+
∑
t
=
1
T
τ
[
-
p
sp
,
t
C
g
,
t
sp
+
p
g
,
t
C
g
,
t
s
+
∑
i
=
1
N
l
c
i
,
t
+
∑
m
=
1
N
m
c
m
,
t
+
∑
f
=
1
N
f
c
f
,
t
+
c
pv
om
+
c
ses
,
t
+
c
mes
,
t
]
where τ is time interval, p is charging power, and where C g,t sp , C g,t s , and C g dc denote spinning reserve price, energy charges, and demand charges of the grid, respectively.
2. The method of claim 1 , comprising modeling of the EVs for optimal planning, operation, and control purposes.
3. The method of claim 1 , comprising determining energy balance of the MES as:
ⅇ
mes
,
t
=
(
1
-
Φ
mes
)
e
mes
,
t
-
1
+
τ
(
p
mes
,
t
chg
η
mes
chg
-
p
mes
,
t
dch
η
mes
dch
)
+
E
mes
,
t
conn
-
E
mes
,
t
disc
where E mes,t conn and E mes,t disc represent energy level of EVs connected to and disconnected from the building at time t, respectively.
4. The method of claim 1 , comprising determining energy storage level of MES is limited by minimum and maximum available capacities of the MES at each time interval, E mes,t and Ē mes,t respectively, as follows:
SOC mes Ē mes,t ≦e mes,t ≦ SOC mes Ē mes,t
where Ē mes,t takes into account physically available connected capacity of EVs to the building and the EV owners' preferences on available energy at the disconnection time of the EV.
5. The method of claim 4 , wherein if EV owners do not provide any specific disconnection time energy level of their vehicles, determining Ē mes,t of the MES is built based on the rated capacity connected and disconnected EVs' batteries using the following equation:
Ē mes,t =( Ē mes,t-1 +Ē mes,t conn −Ē mes,t disc )
E mes,t =( Ē mes,t-1 +Ē mes,t conn −Ē mes,t disc )
where Ē mes,t conn and Ē mes,t disc represent connected and disconnected EV capacities at time t.
6. The method of claim 1 , comprising considering charge/discharge constraints of EVs.
7. The method of claim 6 , comprising applying constraints to ensure that p mes,t chg and p mes,t dch are less than maximum charging and discharging power of the MES at each time interval:
0 ≦p mes,t chg ≦u mes,t chg P mes,t
0 ≦p mes,t dch ≦u mes,t dch P mes,t
where P mes,t and P mes,t are calculated as follows:
P mes,t =( P mes,t-1 + P mes,t conn − P mes,t disc ).
8. The method of claim 6 , comprising determining operational and maintenance costs of the MES with degradation costs and charging and discharging cycles capacity loss of the MES.
9. The method of claim 8 , wherein the capacity loss is proportional to the number of charging and discharging cycles as follows:
v
ses
,
t
chg
≥
u
ses
,
t
chg
-
u
ses
,
t
-
1
chg
v
ses
,
t
dch
≥
u
ses
,
t
dch
-
u
ses
,
t
-
1
dch
C
mes
,
t
=
C
mes
dg
1
2
(
v
mes
,
t
chg
+
v
mes
,
t
dch
)
+
C
mes
c
E
_
mes
,
t
+
p
mes
,
t
dch
η
mes
dch
C
mes
,
t
s
-
p
mes
,
t
chg
η
mes
chg
C
mes
,
t
d
where C mes dg represents costs of the MES degradation per cycle to be paid by the μG operator to EV owners to reimburse their battery degradation due to charge and discharge by the EMS, C mes c denotes capacity costs to be paid by the μG operator to EV owners for the hours connecting their vehicles to the building EMS. C mes,t s and C mes,t d represent the selling and buying energy price of the EV, respectively.
10. The method of claim 1 , comprising modeling degradation costs of EV batteries.
11. The method of claim 10 , comprising determining
C
mes
,
t
=
C
mes
dg
1
2
(
v
mes
,
t
chg
+
v
mes
,
t
dch
)
+
C
mes
c
E
_
mes
,
t
+
p
mes
,
t
dch
η
mes
dch
C
mes
,
t
s
-
p
mes
,
t
chg
η
mes
chg
C
mes
,
t
d
where C mes dg represents costs of the MES degradation per cycle to be paid by the μG operator to EV owners to reimburse their battery degradation due to charge and discharge by the EMS, C mes c denotes capacity costs to be paid by the μG operator to EV owners for the hours connecting their vehicles to the building EMS.
12. The method of claim 1 , comprising modeling contribution of EVs in Spinning Reserve requirements.
13. The method of claim 12 , comprising determining:
p ses,t sp and p mes,t sp represent the spinning reserve provided by the SES and MES at time t, respectively, and calculated as follows:
p
ses
,
t
sp
=
min
{
(
e
ses
,
t
-
SOC
_
ses
E
_
ses
)
τ
,
P
_
ses
-
p
ses
,
t
dch
}
p
mes
,
t
sp
=
min
{
(
e
mes
,
t
-
SOC
_
mes
E
_
mes
,
t
)
τ
,
P
_
mes
,
t
-
p
mes
,
t
dch
}
;
and
reformulating constraints as follows:
p
ses
,
t
sp
≤
(
e
ses
,
t
-
SOC
_
ses
E
_
ses
)
τ
p
ses
,
t
sp
≤
P
_
ses
-
p
ses
,
t
dch
p
mes
,
t
sp
≤
(
e
mes
,
t
-
SOC
_
mes
E
_
mes
,
t
)
τ
p
mes
,
t
sp
≤
P
_
mes
,
t
-
p
mes
,
t
dch
.
14. The method of claim 1 , comprising performing modeling of a grid connection by a microgrid and the grid, wherein a connection between the microgrid and the grid has a maximum power transfer capability limit as follows:
− P g >p g,t ≦ P g .
15. The method of claim 1 , comprising considering peak demand charges for grid connection.
16. The method of claim 1 , wherein a grid-connected mode, a microgrid participates in ancillary service markets of the grid market using:
p sp,t =Σ i=1 N i ( P i u i,t −p i,t )+Σ m=1 N m ( P m u m,t −p m,t )+Σ f=1 N f ( P f u f,t −p f,t )+ p mes,t sp +p ses,t sp −0.1 P D,t
where p sp,t is the amount of spinning reserve power that the μG can offer in the ancillary service market.
17. The method of claim 1 , comprising minimizing GHG Emissions Objective function.
18. The method of claim 17 , wherein minimization of GHG emissions of the microgrid in a grid-connected mode comprises:
min
∑
t
=
1
T
τ
[
∑
i
=
1
N
i
ɛ
i
GHG
p
i
,
t
η
i
+
ɛ
m
GHG
p
m
,
t
η
m
+
ɛ
f
GHG
p
f
,
t
η
f
+
ɛ
g
,
t
GHG
p
g
,
t
]
+
(
e
mes
,
T
-
e
mes
,
0
)
ɛ
mes
GHG
where ε g,t GHG denotes marginal GHG emission of the grid at time t.