Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hierarchical Frequency Control of Hybrid Power Plants Using Frequency
  Response Observer   Frequency control (FC) enables utility-scale grid-connected hybrid power
plants (HPPs) to operate in compliance with grid code requirements while to
capture value streams from provision of frequency control services (FCSs). In
this paper, a novel hierarchical FC approach is proposed to allow HPPs to
provide three types of FCSs, namely fast frequency response (FFR), frequency
containment response (FCR) and frequency restoration response (FRR). To
accommodate state-of-the-art fast FC, controllers for fast FCSs, such as FFR
and FCR, are implemented at asset controllers, while controllers for slow FCSs
like FRR are implemented at plant controllers or the HPP controller (HPPC).
Control counteraction issue, which arises across control hierarchy, is then
discussed. To solve this issue, an innovative frequency response observer
(FROB) is proposed. Inspired by the concept of disturbance observer (DOB), FROB
at plant controllers and the HPPC accurately estimates frequency response
initiated at asset controllers, and the obtained estimation is used for control
compensation at plant controllers and the HPPC to avoid control counteraction.
This scheme achieves robust performance even when there are system
uncertainties existing in HPPs, such as parameter uncertainty, unknown control
malfunction, and time-varying communication delays. The proposed approach is
implemented in a power system dynamic model in MATLAB/Simulink to highlight its
effectiveness and robustness.

37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph