Adaptive inertia control method of IIDG based on VSG
The invention provides an adaptive inertial control method based on IIDG (Inverter Interfaced Distributed Generator) of a virtual synchronous motor. By building an adaptive virtual inertia and IIDG output frequency model, the adaptive control sensitive factor is selected from a model according to the virtual synchronous motor dynamic response features; the adaptive inertial upper and lower limits are selected from a model according to the energy storage configuration constraint; the IIDG optimization control strategy is obtained. The control on the grid-connected inverter distributive power supply can be realized, so that the IIDG output is more stable; the interference on the system can be well handled; meanwhile, the characteristics of small overshoot and fast response are realized; the ultra-high dynamic features are realized.
1. A method for controlling an adaptive inertia of IIDG (Inverter-Inter-faced Distributed Generator) based on VSG (Virtual Synchronous Generator), comprising establishing a model of adaptive virtual inertia and IIDG output frequency, and selecting a sensitivity factor from a model based on dynamic response characteristics of the VSG, then, selecting upper and lower limits of an adaptive inertia from a model based on energy storage configuration constraints, and obtaining an optimal control strategy of IIDG;
said model of adaptive virtual inertia and IIDG output frequency is specifically described as follows:
H
=
H
h
k
a
2
(
ω
-
ω
ref
)
2
+
H
0
k
a
2
(
ω
-
ω
ref
)
2
+
1
,
wherein, k a is the sensitivity factor, H 0 is IIDG's rated virtual inertia; when ω=ω ref , the virtual inertia H=H 0 ; when |ω−ω ref |→∞, the virtual inertia H is H=H h .
2. The method according to claim 1 , wherein for the sensitivity factor: increasing response speed when a larger k a is adopted that ensures to reset control parameters and to avoid delay; keeping the control parameters at a constant state if a smaller k a is adopted which avoids disturbances.
3. The method according to claim 1 , wherein one tenth of allowable value Δf p of the sensitivity factor is set as a boundary of a response sensitivity range, and the sensitivity factor is
k
a
=
1
2
π
×
0.1
Δ
f
p
.
4. The method according to claim 1 , wherein for the upper and lower limits of the adaptive inertia: the virtual inertia H is a parameter that is adjusted in real time along with ω, and there is an regulation range in the change process, wherein H h is an upper limit of value range of H, H 0 is a lower limit of the value range of the virtual inertia H; the upper limit H h and the lower limit H 0 of H is created according to capacitive energy storage of IIDG or battery energy storage configuration constraint.
5. A system for implementing the method as described in claim 1 , comprising a VSG active-frequency (P-f) adaptive inertia control unit used for active and frequency regulation and a pulse width modulation control unit used for generating on-off signals for electronic power switch of an inverter, wherein, the active-frequency adaptive inertia control unit simulates swing equation of a synchronous generator and gives three-phase voltage phase δ of IIDG by introducing inertia characteristics and based on reference value P ref of active power with the adaptive inertia control method; the pulse width modulation control unit gives a three-phase modulation ratio m according to reference value E of three-phase voltage range and three-phase voltage phase δ combing real-time sampled voltage and current output by IIDG.
6. The system according to claim 5 , wherein the three-phase voltage phase δ is calculated by receiving P ref and ω ref output by the energy management layer and measuring P, ω and ω grid of an actual active power output; δ
2
H
d
ω
dt
=
P
ref
-
P
-
k
(
ω
-
ω
grid
)
+
1
D
(
ω
ref
-
ω
grid
)
,
wherein, H is the virtual inertia, P is the active power output by an inverter port under VSG control, k is a damping factor, ω is output radian frequency of IIDG, ω grid is common bus radian frequency and D is an active droop coefficient.