S. Y. Zhu et al.
calculate the new power generation plan according to the ratios of the present power output. The formula is:
min( )
/
.. ,
/
iN
Pi Pset
PiPi Ki
sti jN
PjPj Kj
∈
∆ −∆
∆= ∈
∆
∑
(3)
4.1.2. Section Power Control
In order to reduce the power load of specified section, users are allowed by wind power control system not only
by specifying the wind power plan of the selected wind farms one by one, but also by setting total amount of
adjustment value of specified sections. New wind power generation plan of the related wind farms or wind farm
sections can be calculated by the wind control system automatically.
The object of peak wind power control is all wind farms in the power grid, while the object of section wind
power control is the associated wind farms which had been pre specified. By configuration, users can divide the
wind farms into several wind power control subsets (section), and control the power of corresponding sections
by the method of adjusting the power generation plan of each subset.
Section wind power control has the same calculation methods as peak wind power control, because wind
farms involved in Section power control are the subset of those involved in peak power control.
4.1.3. Flow Chart of Wind Power Limit Mode
The flow chart of wind power limit mode is shown in Figure 2.
4.2. Wind Power Remove Limit Mode
4.2.1. Principle of Removing Limit Control Operation
In order to balance the load growth or increase wind power electricity of specified sections, it is supported by
wind power control system to allow users to cancel the power limit plan for wind farms by selecting wind farms
manually. It is also supported by the system to cancel the power limit plan by setting the total control amount,
and then selecting wind farms automatically according to that amount, so as to allow wind farms to increase the
power output as far as possible.
When remove the wind power restrictions, users should consider comprehensively about the wind farm
evaluation index result and the beginning time of wind farm restrictions. After that, wind farms should be se-
lected and the power limit should be canceled one by one. Then, waiting for a period of time, calculate the
power change before and after the control. If the power change is greater than the total adjustment amount, the
control operation can be terminated, otherwise operation continues by selecting more wind farms.
4.2.2. Flow Chart of Wind Power Remove Limit Mode
The flow chart of wind power remove limit mode is shown in Figure 3.
5. Close Loop Mode Control
In order to track the change of electrical power grid, wind power peak control system should also have the func-
tion of calculating and sending the power plan of wind farms automatically. This is called the close loop control
mode.
Close loop control mode, namely the power schedule automatic calculation mode. Here is the workflow of
this mode: Under user’s permission, wind power peak control system runs all calculation periodically, tracks the
power grid operation state automatically, without considering various prediction results, gives out the real-time
calculation result of current power plan to meet the current power load, and then directly send control com-
mands to the relevant wind farms.
The calculation principle of close loop wind power control model is: first, calculate power system standby
load ηs, when ηs is less than the lower bound value ε1, calculate the required adjustment value of improving the
system load, then calculate the wind farms which are needed to remove the output limit. At the same time, ad-
justability, priority and other factors should be considered, so as to maintain the output power of hydropower
and thermal reducing evenly.