G. JIN ET AL. 453
Table 2. The recommendations of parameter value settings of two power plants in power system.
Power Plant Types Parameter Setting Adjustable Differential Coefficient Frequency Modulation Limiter
scope 4%-5%
Upper limiter:35%,no lower limiter
A Plant Mechanic hydraulicProposed value 4% 35%
Scope 4%-5%
Upper limiter:35%,no lower limiter
B Plant DEH Proposed value 4% ±35%
Power Plant Types Parameter Setting Frequency Modulation Dead Band OPC Value
scope / /
A Plant Mechanic hydraulicProposed value / /
Scope ≤ ±0.034Hz 103%-108%
B Plant DEH Proposed value ±0.017Hz 106%
6. Conclusions
This paper analyses the power grid and unit influence
factors on the isolated system operation. And the system
frequency response model is applied to analyze the spe-
cific influences. By simulating and analyzing the stabil-
ity of regional power system under different load distur-
bances, regulating system parameters and control logics,
parameter settings and control strategies are proposed to
improve the ability of isolated system operation. In the
view of the frequency characteristic difference between
the isolated system operation and networking operation,
we have proposed the optimizing scheme of under fre-
quency load shedding which has considered the fre-
quency characteristic differences. This scheme can meet
the frequency stability requirement both of networking
operation and isolated system operation. Taking the
practical power system as an example, we have con-
ducted the real isolated system operation test. This test
shows the correctness and effectiveness of the proposed
method. The coordinated control strategies improve the
ability of power grid and unit to deal with the accident.
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