Automatic Generation Control Response Research Articles

Health-aware coordinate long-term and short-term operation for BESS in energy and frequency regulation markets

The penetration of renewable energy in modern power systems is still increasing. Battery energy storage can rapidly respond to a dispatch order and is expected to provide multiple auxiliary services. However, deep charging cycles have negative impacts on battery health. This paper presents a health-aware long-term operation strategy for lithium-ion battery energy storage participating in the energy and frequency regulation markets. The strategy determines the capacity bounds that can be bid in the energy and frequency regulation markets and updates these bounds every three months, aiming to preserve battery health and increase market revenue. A long-term operational modeling framework is proposed to address the multi-timescale nature, integrating frequency control, energy arbitrage, and the evolution of battery degradation in a holistic model. A nonlinear degradation model is developed to approximate the health impact of main stress factors, which captures the nonlinearity of three-stage capacity degradation process caused by the formation of solid electrolyte interphase film and lithium plating. For intraday operation, a two-scale stochastic programming model is proposed, in which the market bidding and automatic generation control response are simulated in the timescales of one hour and two seconds, respectively. This simulation based method is closer to industrial practice, as it accounts for various factors in BESS operation. For the seasonal update of the capacity allocation strategy, a dynamic programming problem is established and solved based on the nonlinear degradation model and the daily revenue obtained from simulation of intraday operation; the capacity allocation strategy is determined from the renowned Principle of Optimality by Bellman. This two timescale modeling framework captures the interaction between short-term operation strategy and long-term degradation process. Numerical simulations validate that the proposed method can slow down battery degradation and increase lifetime revenue.

An innovative LFC scheme for multi-area microgrid incorporating with hydrogen-based demand response mechanism

Due to the unpredictability of renewable energy sources (RESs) in Microgrids (MG), the Load Frequency Control (LFC) mechanism is crucial for frequency management of these systems. Frequency control in MGs can be made more cost-effective with the help of demand-side management by temporarily boosting or decreasing power usage, in addition to Automatic Generation Control (AGC) techniques. Hydrogen can provide considerable benefits to MGs since it can be used in two ways: as a fuel cell for electricity generation or as an electrolyzer for power consumption, satisfying the needs of AGC and demand response (DR) simultaneously utilizing Hydrogen Energy Storage (HES) system. This research proposes an MG structure that integrates appropriate energy storage technologies, is able to provide both energy and waste management, and enables use of a variety of RES (including solar, wind, wastewater, agricultural, and residential wastes). With the newly announced Improved-Salp Swarm Algorithm (ISSA), this research aims to design a novel double-input interval type-2 fuzzy fractional order proportional-integral-derivative PI + TID (DIT2-FOPI + TID) cascade controller for LFC of multi-area MGs considering DR with a broad range of Distributed energy resources (DER). In all case studies, the proposed controller demonstrates outstanding effectiveness within the setting of LFC of MGs and, especially by employing DRM approaches, boosts frequency response performance by up to 65%. The results indicate that the dynamic frequency response of the MG is significantly enhanced by the addition of DRM capability with the HES system.

Dynamic availability of energy storage in district heating networks for automatic generation control of a CHP plant

To increase power generation flexibility, combined heat and power (CHP) plant needs to improve automatic generation control (AGC) performance. A new approach to use energy storage (ES) in district heating networks (DHN) for AGC is proposed. First, the capacity of ES is analyzed quantitatively. By mechanism analysis of energy flow and conversion between DHN and CHP plant, the capacity and dynamic characteristics of ES in DHN is calculated quantitatively. The calculation result includes the maximum ES capacity and available time, the ES already used by CHP unit, and the remaining available ES and time. Second, basing on the quantitative analysis of ES, a control scheme is designed to make reasonable use of ES. The control scheme uses heat extraction valves as ES control variable and is designed basing on relative gain array method. Finally, a case study of a 330 MW CHP plant is given. The calculation results show that the maximum available time of ES in DHN is 2.85 h. And the simulation results show that the power generation increases by consuming ES in DHN and the AGC response is improved.

HESS Sizing Methodology for an Existing Thermal Generator for the Promotion of AGC Response Ability

Due to the increasing penetration of renewables, power systems with lower inertia may result in larger frequency excursion. The emergency of new inertia and fast-frequency response characteristics made energy storage systems (ESSs) much more attractive in recent years. ESS can largely improve the frequency regulation capability of a traditional thermal generating unit with relatively slow ramp rate. In this paper, a novel method for sizing a hybrid energy storage system (HESS) to improve automatic generation control (AGC) response of an existing thermal generator is presented, which strikes a right balance between the extra benefit from faster AGC response and the increased HESS cost. First, a novel control scheme for HESS is proposed to improve both the AGC response speed and the precision of a HESS-generator system. And then, based on the benefit analysis of AGC response, a novel cost-benefit-based optimization model is presented for HESS configuration with the aim of maximizing the AGC response benefit of HESS-generator system. Finally, using actual historical data, the simulation is conducted to demonstrate the effectiveness of the presented sizing methodology.

Dynamic Gain-Tuning Control (DGTC) Approach for AGC With Effects of Wind Power

Variable wind power output introduces new challenges to power system frequency regulation and control, such as automatic generation control (AGC) which is very important to regulate power system frequency. The existing methods to design control gains for proportional-integral (PI) controllers in AGC are either time consuming or easily affected by the designer's experience. Further, the control gains are usually designed with fixed values for specific scenarios in the studied power system. The desired response may not be achieved when variable wind power is integrated into power systems. To address these challenges, a dynamic gain tuning control (DGTC) method for AGC is proposed in this paper. By the proposed control method, PI control gains can be dynamically adjusted to reach the desired performance. The proposed method is tested in a modified IEEE 39 bus system with actual wind data, and compared with conventional control approach with well-tuned fixed gains in the simulation. The simulation results show that the proposed control method provides better AGC response with less deviation of system frequency and tie-line flow under variable wind power.

The Joint Adequacy of AGC and Primary Frequency Response in Single Balancing Authority Systems

This paper generalizes previous work on automatic generation control (AGC) gain in a single balancing authority system. In previous work, a control performance standard 1 (CPS1)-compliant AGC gain for a single balancing authority interconnection was proposed, assuming that frequency response can be decoupled from AGC dynamics by widening governor dead bands. However, current practices suggest that widening dead bands may not be a wise course to take as it may deteriorate primary frequency response. This paper formulates sufficient conditions for the adequacy of the joint operation of AGC control and primary frequency response to be consistent with frequency response adequacy. Historical data and a simulation of ERCOT are presented to show numerical results.

Automatic Generation Control of Multigeneration Power System

Load frequency Control (LFC) is used for many years as part of Automatic Generation Control (AGC) in power system around the world. In a mixed power system, it is usual to find an area regulated by hydro generation interconnected to another area regulated by thermal generation or in combination of both. In the following study, performance of AGC for Thermal, Hydro and Thermal turbine based power system is examined, including how frequency bias setting influences AGC response and inadvertent interchange. Control performance analysis of three area interconnected systems is simulated and studied through Matlab Simulink software. Integral square error and Integral time absolute error has been used as performance criterion. It is shown that integral time absolute error (ITAE) as performance index leads to faster optimization of controller gain.