Diesel-storage independent microgrid and virtual dynamic synchronous control method and system therefor
A diesel-storage independent microgrid and a virtual dynamic synchronous control method and system are described. An adaptive dynamic synchronous torque and pre-synchronous compensation phase angles are introduced into a energy storage converter control system to realize output voltage and power synchronization before and after parallel connection of the system. By compensating the pre-synchronous phase angles, the phase angles of a diesel generator and an energy storage converter are kept consistent before parallel connection, which reduces current impact during the parallel process. By introducing the adaptive dynamic synchronous torque, after the parallel connection of the system, the virtual torque of the energy storage converter can be adaptively and dynamically adjusted according to the current accelerations of the diesel generator and the energy storage converter under the condition that the inertial parameter of a diesel engine is black-boxed.
1. A method for calculating a dynamic synchronous torque damping coefficient of a diesel-storage independent microgrid, wherein the diesel-storage independent microgrid comprises a diesel generator and an energy storage battery; the diesel generator is connected to a power supply bus; the energy storage battery is connected to the power supply bus through an energy storage converter; the power supply bus is connected to a conventional load and a pulsed load; the dynamic synchronous torque damping coefficient H damp is calculated by the following formula:
H
damp
=
{
H
damp
0
(
❘
"\[LeftBracketingBar]"
a
g
2
-
a
g
1
❘
"\[RightBracketingBar]"
≤
C
)
H
damp
0
+
k
❘
"\[LeftBracketingBar]"
ω
2
-
ω
1
❘
"\[RightBracketingBar]"
ω
2
-
ω
1
(
a
g
2
-
a
g
1
)
(
❘
"\[LeftBracketingBar]"
a
g
2
-
a
g
1
❘
"\[RightBracketingBar]"
>
C
)
;
wherein H damp0 represents a steady-state value of the dynamic synchronous torque damping coefficient, k is an adaptive adjustment factor, and C is a threshold value of the difference between the angular acceleration a g1 of the diesel generator and the angular acceleration a g2 of the energy storage converter; ω 1 and ω 2 are respectively the voltage angular frequency of the diesel generator and the voltage angular frequency of the energy storage converter.
2. The method for calculating a dynamic synchronous torque damping coefficient of a diesel-storage independent microgrid according to claim 1 , wherein the calculation formula of the threshold value C of the difference between the angular acceleration a g1 of the diesel generator and the angular acceleration a g2 of the energy storage converter is:
C
=
❘
"\[LeftBracketingBar]"
a
g
1_
0
-
a
g
2_
0
❘
"\[RightBracketingBar]"
=
5
%
P
load
_
n
ω
n
(
D
P
1
+
D
p
2
)
(
D
P
1
J
1
-
D
P
2
J
2
)
=<
D
P
2
2
J
·
5
%
P
load
_
n
ω
n
(
D
P
1
+
D
p
2
)
;
wherein P load_n is a rated load power of the diesel-storage independent microgrid, a g1_0 is an initial value of the angular acceleration of the diesel generator, a g2_0 is an initial value of the angular acceleration of the energy storage converter, J 1 is an inertia coefficient of the diesel generator, J 2 is a virtual inertia coefficient of the energy storage converter, D p1 is a damping coefficient of the diesel generator, D p2 is a damping coefficient of the energy storage converter, and ω n is a rated output angular frequency of the energy storage converter.
3. A virtual dynamic synchronous control method for a diesel-storage independent microgrid, wherein the diesel-storage independent microgrid comprises a diesel generator and an energy storage battery; the diesel generator is connected to a power supply bus; the energy storage battery is connected to the power supply bus through an energy storage converter; the power supply bus is connected to a conventional load and a pulsed load; the method comprises the following steps:
S1, calculating a control angular frequency instruction value ω 2 of the energy storage converter:
P
N
ω
n
-
P
e
2
ω
n
=
J
2
d
ω
2
dt
+
D
p
2
(
ω
n
-
ω
2
)
+
T
H
2
;
T
H
2
=
∫
H
damp
(
a
v
2
-
a
g
1
)
;
wherein P N is a rated output power of the energy storage converter, ω n is a rated output angular frequency of the energy storage converter, J 2 is a virtual inertia coefficient of the energy storage converter, D p2 is a damping coefficient of the energy storage converter, T H2 is a virtual dynamic synchronous torque of the energy storage converter, a g1 is an angular acceleration of the diesel generator, a v2 is an angular acceleration of the energy storage converter, P e2 is an active power output by the energy storage converter, and the dynamic synchronous torque damping coefficient H damp is obtained according to the method for calculation of claim 2 ;
S2, using the following formula to calculate an a phase voltage control signal output by the energy storage converter: U va *:U va *=U p2 sin θ 2 *; θ 2 *=θ 2 +Δφ 2 ; θ 2 =∫ω 2 dt; wherein θ 2 is an output voltage control phase angle instruction value of the energy storage converter, U p2 is an output voltage instruction peak value of the energy storage converter, Δφ 2 is a pre-synchronous control phase angle compensation value of the energy storage converter, and b and c phase voltage control signals of the energy storage converter lag 120° and 240° respectively; and
S3, performing pulse width modulation (PWM) on an iphase voltage control signal U vi * of the energy storage converter to obtain a drive signal for a switch tube in the energy storage converter, where i=a, b, c.
4. The virtual dynamic synchronous control method for a diesel-storage independent microgrid according to claim 3 , wherein the calculation formula of the pre-synchronous control phase angle compensation value Δ φ2 of the energy storage converter is:
Δφ
2
=
SW
·
k
c
s
(
φ
2
-
φ
1
)
;
wherein k c is an integral control parameter, φ 1 and φ 2 represent a voltage phase angle of the diesel generator and a voltage phase angle of the energy storage converter respectively, SW is a switch, the value of SW is 1 before the diesel generator and the energy storage converter are connected in parallel, and the value of SW is 0 after the diesel generator and the energy storage converter are connected in parallel.
5. The virtual dynamic synchronous control method for a diesel-storage independent microgrid according to claim 4 , wherein the calculation formulas of the angular acceleration a g1 of the diesel generator and the angular acceleration a g2 of the energy storage converter are respectively:
{
a
g
1
=
ω
1
(
n
+
1
)
-
ω
1
(
n
)
T
s
a
g
2
=
T
n
2
-
T
D
2
-
T
e
2
-
T
H
2
J
2
=
T
2
J
2
;
wherein ω 1 (n+1) and ω 1 (n) are respectively (n+1)-th and n-th angular velocity sampling values of the diesel generator set, T s is an angular velocity sampling period of the diesel generator set, T n2 is a rated torque of the energy storage converter, T D2 is a damping torque of the energy storage converter, T e2 is an electromagnetic torque of the energy storage converter, T 2 is a resultant torque of the energy storage converter, and J 2 is the virtual inertia coefficient of the energy storage converter.
6. A power supply control method for a diesel-storage independent microgrid, wherein the diesel-storage independent microgrid comprises a diesel generator and an energy storage battery; the diesel generator is connected to a power supply bus; the energy storage battery is connected to the power supply bus through an energy storage converter; the power supply bus is connected to a conventional load and a pulsed load; the method comprises:
before a diesel generator and an energy storage converter are connected in parallel, compensating pre-synchronous phase angles to keep the phase angles of the diesel generator and the energy storage converter consistent, wherein a compensation value for the pre-synchronous phase angles is:
Δφ
2
=
SW
·
k
C
s
(
φ
2
-
φ
1
)
;
where k e is an integral control parameter, SW is a switch, the value of SW is 1 before the diesel generator and the energy storage converter are connected in parallel, the value of SW is 0 after the diesel generator and the energy storage converter are connected in parallel, and φ 1 and φ 2 represent a voltage phase angle of the diesel generator and a voltage phase angle of the energy storage converter respectively; and after the diesel generator and the energy storage converter are connected in parallel, controlling the energy storage converter by using the virtual dynamic synchronous control method according to claim 5 .
7. A virtual dynamic synchronous control system for a diesel-storage independent microgrid, comprising computer equipment, wherein the computer equipment is configured or programmed to execute the steps of the method according to claim 6 .
8. A diesel-storage independent microgrid, comprising the virtual dynamic synchronous control system according to claim 7 .
9. A virtual dynamic synchronous control method for a diesel-storage independent microgrid, wherein the diesel-storage independent microgrid comprises a diesel generator and an energy storage battery; the diesel generator is connected to a power supply bus; the energy storage battery is connected to the power supply bus through an energy storage converter; the power supply bus is connected to a conventional load and a pulsed load; the method comprises the following steps:
S1, calculating a control angular frequency instruction value ω 2 of the energy storage converter:
P
N
ω
n
-
P
e
2
ω
n
=
J
2
d
ω
2
dt
+
D
p
2
(
ω
n
-
ω
2
)
+
T
H
2
;
T
H
2
=
∫
H
damp
(
a
v
2
-
a
g
1
)
;
wherein P N is a rated output power of the energy storage converter, ω n is a rated output angular frequency of the energy storage converter, J 2 is a virtual inertia coefficient of the energy storage converter, D p2 is a damping coefficient of the energy storage converter, T H2 is a virtual dynamic synchronous torque of the energy storage converter, a g1 is an angular acceleration of the diesel generator, a v2 is an angular acceleration of the energy storage converter, P e2 is an active power output by the energy storage converter, and the dynamic synchronous torque damping coefficient H damp is obtained according to the method of calculation of claim 1 :
S2, using the following formula to calculate an a phase voltage control signal output by the energy storage converter: U va *:U va *=U p2 sin θ 2 *; θ 2 *=θ 2 +Δφ 2 ; θ 2 =∫ω 2 dt; wherein θ 2 is an output voltage control phase angle instruction value of the energy storage converter, U p2 is an output voltage instruction peak value of the energy storage converter, Uφ 2 is a pre-synchronous control phase angle compensation value of the energy storage converter, and b and c phase voltage control signals of the energy storage converter lag 120° and 240° respectively; and
S3, performing pulse width modulation (PWM) on an iphase voltage control signal U vi * of the energy storage converter to obtain a drive signal for a switch tube in the energy storage converter, where i=a, b, c.
10. The virtual dynamic synchronous control method for a diesel-storage independent microgrid according to claim 9 , wherein the calculation formula of the pre-synchronous control phase angle compensation value Δ φ2 of the energy storage converter is:
Δφ
2
=
SW
·
k
c
s
(
φ
2
-
φ
1
)
,
wherein k e is an integral control parameter, φ 1 and φ 2 represent a voltage phase angle of the diesel generator and a voltage phase angle of the energy storage converter respectively, SW is a switch, the value of SW is 1 before the diesel generator and the energy storage converter are connected in parallel, and the value of SW is 0 after the diesel generator and the energy storage converter are connected in parallel.
11. The virtual dynamic synchronous control method for a diesel-storage independent microgrid according to claim 9 , wherein the calculation formulas of the angular acceleration a g1 of the diesel generator and the angular acceleration a g2 of the energy storage converter are respectively:
{
a
g
1
=
ω
1
(
n
+
1
)
-
ω
1
(
n
)
T
s
a
g
2
=
T
n
2
-
T
D
2
-
T
e
2
-
T
H
2
J
2
=
T
2
J
2
;
wherein ω 1 (n+1) and ω 1 (n) are respectively (n+1)-th and n-th angular velocity sampling values of the diesel generator set, T s is an angular velocity sampling period of the diesel generator set, T n2 is a rated torque of the energy storage converter, T D2 is a damping torque of the energy storage converter, T e2 is an electromagnetic torque of the energy storage converter, T 2 is a resultant torque of the energy storage converter, and J 2 is the virtual inertia coefficient of the energy storage converter.
12. A power supply control method for a diesel-storage independent microgrid, wherein the diesel-storage independent microgrid comprises a diesel generator and an energy storage battery; the diesel generator is connected to a power supply bus; the energy storage battery is connected to the power supply bus through an energy storage converter; the power supply bus is connected to a conventional load and a pulsed load; the method comprises:
before a diesel generator and an energy storage converter are connected in parallel, compensating pre-synchronous phase angles to keep the phase angles of the diesel generator and the energy storage converter consistent, wherein a compensation value for the pre-synchronous phase angles is: Δφ 2 =SW·k c /s(φ 2 −φ 1 ), where k c is an integral control parameter, SW is a switch, the value of SW is 1 before the diesel generator and the energy storage converter are connected in parallel, the value of SW is 0 after the diesel generator and the energy storage converter are connected in parallel, and φ 1 and φ 2 represent a voltage phase angle of the diesel generator and a voltage phase angle of the energy storage converter respectively; and
after the diesel generator and the energy storage converter are connected in parallel, controlling the energy storage converter by using the virtual dynamic synchronous control method according to claim 9 .
13. A virtual dynamic synchronous control system for a diesel-storage independent microgrid, comprising computer equipment, wherein the computer equipment is configured or programmed to execute the steps of the method according to claim 9 .
14. A diesel-storage independent microgrid, comprising the virtual dynamic synchronous control system according to claim 13 .