Automatic Generation Control Service Research Articles

Ancillary services from wind and solar energy in modern power grids: A comprehensive review and simulation study

Renewable energy sources like wind and solar have increased demand for surplus power capacity. The demand is primarily fueled by the growing impact of forecasting errors associated with these intermittent energy sources. Implementing advanced control methods for automatic generation control (AGC) is essential to integrate wind and solar power with conventional generation sources to balance the power system and reduce reliance on traditional reserves. Therefore, this paper comprehensively overviews solar and wind energy integration in the AGC framework to provide optimal grid ancillary services. Initially, the paper presents an overview of the basic equations used to integrate reserve power from the photovoltaic (PV) system by employing the de-loading strategy. Subsequently, a comprehensive review is conducted on integrating the PV system in AGC strategies to provide grid ancillary services. The study also analyzes the contribution of wind power in AGC services using relevant equations and past practices. The paper presents a real-time dynamic control strategy to optimize the dispatch of the AGC unit by integrating the operating reserves from wind energy systems in conjunction with thermal power systems. The study simulates an 8-bus, 5-machine model using the Dig-SILENT Power Factory. The findings reveal that utilizing operating reserves from wind power can significantly reduce large-scale forecasting errors in massively renewable energy resources (RES) integrated power systems, thereby ensuring the necessary system operational security and reducing the reliance on traditional generating units.

Distributed Cooperative AGC Method for New Power System With Heterogeneous Frequency Regulation Resources

The inverter-interfaced renewable energy is increasing in future new power systems, both the system rotary inertia and frequency regulation capacity of traditional units are decreasing and becoming increasingly insufficient. It is urgent to explore various types of frequency regulation resources, especially for inverter-interfaced units that show fast response speed. The heterogeneous frequency regulation resources generally have different system models, capacities, and response speeds, which challenges the automatic generation control (AGC). In this paper, to make the heterogeneous frequency regulation resources provide improved frequency regulation performance, a novel distributed cooperative AGC method is proposed. Firstly, a distributed consensus-based area control error (ACE) discovery algorithm is proposed. Then, each frequency regulation unit can participate in the frequency regulation with an individual PI controller based on the discovered ACE information. Finally, by controlling the low-speed AGC units to generate more power, it can release the power capacity of the high-speed AGC units to prepare for the following round of AGC services. Furthermore, the communication delays are also considered for the proposed distributed AGC algorithm design. The improved performance of the proposed AGC method is verified based on the simulation study of a two-area power system with five different kinds of frequency regulation units.

Hour-Ahead Optimization Strategy for Shared Energy Storage of Renewable Energy Power Stations to Provide Frequency Regulation Service

With the rapid growth of intermittent renewable energy sources, it is critical to ensure that renewable power generators have the capability to perform primary frequency response (PFR). This paper proposes a framework for using a shared battery energy storage system (BESS) to undertake the PFR obligations for multiple wind and photovoltaic (PV) power plants and provide commercial automatic generation control (AGC) service in the ancillary service market at the same time. Furthermore, an optimal bidding strategy in the hour-ahead energy and ancillary service markets is proposed to maximize the BESS' benefits, considering frequency regulation performance, battery degradation cost, and the state of charge (SoC) limits. The optimization model is first built as a chance-constrained optimization problem and then transformed into mixed-integer quadratically constrained programming using Wasserstein metric-based distributionally robust optimization technique. Simulation results show that the proposed optimal bidding strategy and solution method can effectively take advantage of a BESS to perform PFR and provide AGC services simultaneously and improve its economic benefits.

Cooperative Relaying Strategies for Smart Grid Communications: Bargaining Models and Solutions

In smart grid, the frequency regulation can be provided by both the automatic generation control (AGC) and the demand-side regulation, and the regulation errors increase the electricity costs to the utility company. The demand-side regulation adopts a hierarchical communication architecture, and the data aggregator unit (DAU) may suffer from congestions which consequently increase the costs to the utility company for more AGC service except for the demand-side regulation. In this paper, we employed the base stations as relays and formulated the electricity costs-based upon the regulation errors and the packets loss model. Specifically, the utility company decides the relaying bandwidth to minimize its electricity costs, and the relay selects the base price to maximize its profits. The novelty of this paper is twofold. First, we formulate the interactions between the utility company and the relay as a bargaining problem. Second, we utilize the Nash bargaining solution (NBS) and Raiffa–Kalai–Smorodinsky (RBS) bargaining solution to achieve the Pareto-optimal outcome. Furthermore, we extended the results to the case with multiple DAUs and multiple relays. The numerical results demonstrate the cost reduction of the utility company and the profit increase of the relay under the NBS or RBS strategy. In addition, the NBS strategy can bring about more profits for the relay than the RBS strategy, while the RBS strategy can provide a fairer payoff allocation and lower costs to the utility company than the NBS strategy.

Optimal management of the automatic generation control service in smart user grids including electric vehicles and distributed resources

This paper presents an analysis and systemization of automatic generation control (AGC) in distribution networks (DNs) with high penetration of distributed resources, including electric vehicles (EVs). A methodology is developed that allows designing the AGC service at the distribution level, and an optimization model is proposed to assess the potential of AGC provision from EVs according to an objective of optimal economic management. A realistic case study is considered to analyze the proposed approach, and to illustrate both the potential of the methodology and the effectiveness of the optimization model. Results show that the proposed methodology represents a flexible tool that any system operator could use for the operational planning and the management of ancillary services such as AGC with EVs.

Automatic generation control scheme for frequency linked price signal followed in India

Indian electricity market has adopted a concept of frequency linked commercial tariff system, commonly referred to as availability-based tariff (ABT), where variation in system frequency is used as market signal to encourage utilities to change generation in real time operation. As frequency varies with real power imbalance, proper incentive is rewarded for automatic generation control (AGC) service provided by the generating utility for making up the real power mismatch. In ABT, the rate of unscheduled interchange (RUI) for AGC service is fixed depending upon the frequency condition prevailing at that time. The conventional AGC system though tries to bring the frequency error to zero but it would be an ineffective solution for participating generating utilities under ABT since incentive/penalty varies with frequency. This paper investigates the rules and advocacy of ABT more strategically and develops a model for AGC based on conventional if-then logics for load-frequency regulation scheme that will respond to the frequency-based price signal in a profitable manner. The proposed model is tested on IEEE 14 bus system and part of northern region grid of India.

Discussion on the Pattern of Competitive Trade in the AGC Ancillary Service Market

Electric ancillary service is an important method that ensures the power system to operate safely and stably. This paper discusses the optimum selection of Automatic Generation Control (AGC) units in the Electric AGC Ancillary Service Market. In this paper a mathematical model is proposed to select the generating unit to perform AGC function in light of minimizing the AGC services purchase fee. Several forms that are used to pay the AGC service business are also discussed in the paper. The application to a realistic system shows that the idea and the method presented in this paper are correct and feasible.

New Design for the Spanish AGC Scheme Using an Adaptive Gain Controller

This paper investigates the application of adaptive control to the Spanish load-frequency regulation scheme, Automatic Generation Control (AGC). The Spanish AGC system regulates the frequency and the power exchange between France and Spain. The system is hierarchically structured with one master regulator that coordinates four control areas. Each control area is composed of several generating units providing AGC service. Coordinating signals are sent to the control areas so that the global system response achieves the objective established by the System Operator. The participation of each control area in the service is set according to the rated share that it has obtained in the secondary-reserve market and its relative response speed compared to that of the rest of the control areas. Some problems, such as the lack of sensitivity to the quality of the reserve provided by the control areas, have been detected in the operation of the current AGC scheme. A new design, which is presented in this paper, has been developed in order to overcome these problems. This paper attempts to outline how this new design improves the global AGC system response and the distribution of the regulation effort among the control areas. The proposed strategy is compared with the present design by means of simulation.

Determination of AGC capacity requirement and dispatch considering performance penalties

A continuous and near instantaneous balance between generation supply and load demand must be maintained in power system operation. As a kind of regulation reserve, automatic generation control (AGC) is widely employed for maintaining system security and reliability, especially for controlling frequency deviation and supporting commercial transactions. In a competitive electricity market, AGC services are either contracted via negotiations between the market operator and generation companies concerned, or procured via a certain form of auction. A new framework to determine AGC capacity requirement and to deal with regulation dispatch under uncertain demand in a competitive electricity market is presented in this paper. First, the stochastic characteristics of AGC capacity requirement and services are analyzed. A stochastic optimization decision-making model for determining optimal AGC capacity requirement is then developed, followed by a pricing analysis which reveals that a trade-off between economic efficiency and system security must be made by the market operator. Finally, an optimal AGC dispatch algorithm is suggested. A numerical study is given to further demonstrate the essential features of the proposed model and method.