Frequency Response Analysis of a Single-Area Power System with a Modified LFC Model Considering Demand Response and Virtual Inertia

Abstract

The modern electric power system is foreseen to have increased penetration of controllable loads under demand response programs and renewable energy resources coupled with energy storage systems which can provide virtual inertia. In this paper, the conventional model of an electric power system is appended by considering, individually and collaboratively, the role of demand response and virtual inertia for the purpose of frequency analysis and control. Most existing literature on this topic either considers one of these two roles or lacks in providing a general model of power system with demand response and virtual inertia. The proposed model is presented in general form and can include/exclude demand response and/or virtual inertia. Further, power system operator can opt the power shares from conventional, demand response, and virtual inertia loops for frequency regulation and can also evaluate the impact of other parameters such as time delays and frequency deadbands on system frequency response. The mathematical formulation of steady-state values of frequency deviation and power contribution from all resources is provided and validated by simulation results under various scenarios including a case of wind intermittency.

Modeling the Impact of Modified Inertia Coefficient (H) due to ESS in Power System Frequency Response Analysis

“…This study presents a VISMA control method for the full converter wind turbine and assumes minute-level energy storage in the dc link as the energy buffer. A recent study [17] models the role of VI and demand response programs for the FR process of a power system. The results of this study show that the VISMA can play a vital role in stabilizing the frequency response of a power system.…”

“…The major part of existing literature that addresses the FR process in the presence of ESS considers a conventional load frequency control (LFC) model [8,15,18,21]. Some other studies, such as [17,22], adopt modified LFC models to attain the objective of FR while considering the connection or disconnection of a large load or generation. In these studies, however, there is no to very little contemplation over the intrinsic changes to the power system due to the addition of energy storage devices.…”

Impacts of Responsive Loads and Energy Storage System on Frequency Response of a Multi-Machine Power System

“…Considering an escalated and simultaneous integration of responsive loads and ESS in smart grids, further research is needed to discuss their combined role. The authors of this work presented a modified LFC model considering responsive loads and ESS and discussed their individual and combined role in improving the frequency response [21]. In Reference [22], a droop controlled distributed generation framework integrated with DR is developed for frequency regulation with the objectives of emission reduction and cost minimization.…”

“…In contrast to previously mentioned literature which either discuss DR [6][7][8][9][10][11] or ESS [16][17][18][19][20], this work considers their combined operation in a smart grid environment. Moreover, prevalent multi-machine power system is considered for mathematical modelling and simulation results instead of a single-machine power system [21][22][23][24][25].…”

“…The communication delay in DR control mainly depends on the communication infrastructure and size of the power system. With the modern fast-paced communication network in smart grids, a quicker restoration of frequency profile with the help of responsive loads is achievable [9][10][11]21]. Figure 2 shows the model of a multi-machine power system augmented with battery energy storage system (BESS) and responsive loads connected through DR programs.…”