Primary Frequency Control with Flywheel Energy Storage Technologies

Over the last decade, concerns about greenhouse gas emissions have increased. Different strategies have been developed to minimize those effects, leading to the development of renewable energy sources worldwide. In recent years, the deployment of solar photovoltaic and wind energy-based renewable generation technologies have been growing at a fast pace. The penetration of these technologies into the power system network introduces new challenges for frequency and voltage stability because of the intermittency of these energy sources, and the increasing risk of significant voltage/frequency variations. The significant penetration of renewable sources requires fast regulation of the frequency deviations; hence, the implementation of primary frequency controls is necessary. There exists different techniques and strategies for primary frequency control, where governor regulation and under frequency load shedding are two of the best known, but these have several limitations regarding fast response. Thus, new control techniques based on energy storage systems, which are able to provide fast frequency control, are being studied. In this context, a flywheel energy storage (FES) system is studied and modeled in this thesis for frequency control in power systems, using the well-known software Dynamic Simulation Assessment Tool (DSATools)®, to allow researchers and practitioners to readily model FES in power system studies, particularly the Independent Electric System Operator (IESO) of Ontario. The proposed FES DSATools® model is tested and compared using a previously proposed test system with a large wind energy system (WES), which creates significant frequency and voltage fluctuations due to its characteristics. The FES stores and delivers energy to the power system, as required by the network, through a back-to-back power electronic converter system. A frequency/speed limiter controller is used, considering the network frequency deviation and the FES rotational speed in the active control of the flywheel-side converter for active power control of the flywheel. A static var compensator (SVC) for voltage control is also studied. The presented studies consider disturbances from sudden changes in the wind speed, which affect the WES output active power, creating considerable problems for the test system's stability. The simulation results suggest that the proposed FES model implemented on the system studied, provides effective primary frequency control, and it also improves the network voltage. Thus, the FES is shown to maintain system stability, increasing the operational efficiency of conventional and renewable generators

Controller to enable the enhanced frequency response services from a multi-electrical energy storage system

The increased adoption of renewable energy generation is reducing the inertial response of the Great Britain (GB) power system, which translates into larger frequency variations in both transient and pseudo-steady-state operation. To help mitigate this, National Grid (NG), the transmission system operator in GB, has designed a control scheme called Enhanced Frequency Response (EFR) specifically aimed at energy storage systems (ESSs). This paper proposes a control system that enables the provision of EFR services from a multi-electrical energy storage system (M-EESS) and at the same time allows the management of the state of charge (SOC) of each ESS. The proposed control system uses a Fuzzy Logic Controller (FLC) to maintain the SOC as near as possible to the desired SOC of each ESS while providing EFR. The performance of the proposed controller is validated in transient and steady-state domains. Simulation results highlight the benefits of managing the SOC of the energy storage assets with the proposed controller. These benefits include a reduced rate of change of frequency (ROCOF) and frequency nadir following a loss of generation as well as an increase in the service performance measure (SPM) which renders into increased economic benefits for the service provider

Performance and Economic Evaluation of Storage Technologies

In the last decade there has been a drastic increase in the penetration of variable generation (VG) such as wind and solar. VG increases the MW variability that must be met in the regulation and reserve markets. If VG penetration levels are allowed to increase without providing additional flexibility in the form of fast response regulation, reserves, and capacity, then the required capabilities will be provided by the existing conventional generation fleet. This do-nothing approach will lead to increased cycling of the existing plants and thus weaken the health of the current grid. The increase VG capacity penetration will also necessitate increased transmission capability in the grid in order to facilitate increased VG energy penetration. All these boils down to endowing the grid with the capability to be flexible by investigating the various options such as transmission expansion, demand control, fast responding generation, VG MW output control, expanding the balancing areas and/or investing in storage technology. In this dissertation, the primary focus is on storage technologies, which is one of the attractive means to meet VG variability due to their fast response. With sufficient energy storage capability, they also promise many other valuable grid services such as peak shaving, load leveling, relieving congestion, increasing VG energy penetration, and deferring generation and transmission expansion plans. The objective and contribution of the dissertation is hinged on developing tools and assessment methodologies to perform economic assessment of storage. The work develops a high-fidelity technology adaptive storage dispatch model for production costing study within a co-optimized energy and ancillary market. This tool is used to investigate the grid benefits and economic viability of different class of storage under various wind penetration scenarios, compare them with other competing solutions, and devise appropriate monetizing schemes for their services. This work also proposes an integrated approach involving production costing and automatic generation control simulation tools to assess short-term storages. Based on the application in IEEE 24 bus system, many conclusions and indicators on storage venture\u27s profitability and risks are drawn

Energy storage for black start services : a review

With the increasing deployment of renewable energy-based power generation plants, the power system is becoming increasingly vulnerable due to the intermittent nature of renewable energy, and a blackout can be the worst scenario. The current auxiliary generators must be upgraded to energy sources with substantially high power and storage capacity, a short response time, good profitability, and minimal environmental concern. Difficulties in the power restoration of renewable energy generators should also be addressed. The different energy storage methods can store and release electrical/thermal/mechanical energy and provide flexibility and stability to the power system. Herein, a review of the use of energy storage methods for black start services is provided, for which little has been discussed in the literature. First, the challenges that impede a stable, environmentally friendly, and cost-effective energy storage-based black start are identified. The energy storage-based black start service may lack supply resilience. Second, the typical energy storage-based black start service, including explanations on its steps and configurations, is introduced. Black start services with different energy storage technologies, including electrochemical, thermal, and electromechanical resources, are compared. Results suggest that hybridization of energy storage technologies should be developed, which mitigates the disadvantages of individual energy storage methods, considering the deployment of energy storage-based black start services

Integrated Flywheel Technology, 1983

Topics of discussion included: technology assessment of the integrated flywheel systems, potential of system concepts, identification of critical areas needing development and, to scope and define an appropriate program for coordinated activity