Regulation Reserve Research Articles

Coordinated bidding of wind and thermal energy in joint energy and reserve markets of Spain by considering the uncertainties

There are several reasons why participants, namely conventional participants, and moreover, wind power producers, have been facing an inevitable uncertainty problem in the current short-term electricity market; one reason is the stochastic nature of market prices, and the other is the wind output power uncertainty. To relive the undesirable effects of these uncertainties on wind energy trading, this research proposes a coordinated bidding of wind and thermal units in day-ahead market, adjustment market and regulation reserve market based on the Iberian Peninsula short-term electricity market rules. In the proposed method, a blended integer stochastic linear programming design maximises the expected profits while controlling the risks. One of the main properties of the developed method is modelling the uncertainty of market expenses and wind output energy. Another feature is considering the conditional value at risk criterion to handle the trading risks. The case study is divided into four specific cases in which different kinds of participation are evaluated. These differences attribute to the bidding in various market types. Simulation results indicate that coordinated bidding in the regulation reserve market has more advantages over coordinated bidding in the adjustment market. Furthermore, participation in both adjustment market and regulation reserve market leads to a dramatic decrease in likely deviations in the regulation reserve market, and as a result, coordination advantages become less effective.

Swing Contracts With Dynamic Reserves for Flexible Service Management

The increasing penetration of variable energy resources in modern electric power systems requires additional flexibility in reserve provision to maintain reliable and efficient grid operations. However, full recognition and appropriate compensation of this flexibility is difficult to ensure within current power market designs due to rigidity in reserve definitions and requirements. This paper proposes a new mixed-integer linear programming formulation for the optimal clearing of a day-ahead market based on swing contracts with dynamically updated regulation reserve zones. Five-bus and 30-bus test cases are used to illustrate the effectiveness of the proposed new market design.

Investigation of vagal afferent functioning using the Heartbeat Event Related Potential

Although there has been much support for HRV Biofeedback as an effective intervention for various disorders, there is a lack of comprehension of the underlying mechanisms. The predominant theories of increased vagal efferents and baroreflex gain are insufficient in explaining the frequent observations that HRV Biofeedback impacts changes in constructs beyond ANS mediation, such as emotion regulation, attentional control, and self-regulatory reserve. It has been suspected that vagal afferent functioning may be the underlying mechanism, but little research has explored this. Previously, researchers measured cortical evoked potentials contingent to the heart, or an indication of vagal afferent functioning (Schandry et al., 1986). Twenty-five participants were randomly stratified to HRV Biofeedback or EMG Biofeedback for four sessions. Repeated measures ANOVAs revealed that the HRV group exhibited statistically significantly increased baseline Heartbeat Event-Related Potentials (updated term for ‘evoked potential’) while the relaxation control group did not. The results of this study provide initial support to the premise that HRV Biofeedback stimulates changes in the vagal afferent pathway that are longer lasting than simply the short term effects of breathing.

Deriving Optimal End of Day Storage for Pumped-Storage Power Plants in the Joint Energy and Reserve Day-Ahead Scheduling

This paper presents a new methodology to maximise the income and derive the optimal end of day storage of closed-loop and daily-cycle pumped-storage hydropower plants. The plants participate in the day-ahead energy market as a price-taker and in the secondary regulation reserve market as a price-maker, in the context of the Iberian electricity system. The real-time use of the committed reserves is considered in the model formulation. The operation of the plants with the proposed methodology is compared to the ones that use an end of day storage of an empty reservoir or half of the storage capacity. Results show that the proposed methodology increases the maximum theoretical income in all the plants analysed both if they only participate in the day-ahead energy market and if they also participate in the secondary regulation service. It is also shown that the increase in the maximum theoretical income strongly depends on the size of the plant. In addition, it is proven that the end of day storages change notably in the new reserve-driven strategies of pumped-storage hydropower plants and that the proposed methodology is even more recommended if the secondary regulation service is considered.

Value of perfect information of spot prices in the joint energy and reserve hourly scheduling of pumped storage plants

The value of perfect information of the day-ahead energy prices is studied in the context of the operation of a closed-loop and daily-cycle pumped-storage hydropower plant, participating in the spot market as a price-taker and in the secondary regulation reserve market as a price-maker. The impact of the real-time use of the regulation reserves is also taken into account. Results show that the value of perfect information of the spot prices in the Iberian electricity market decreases if the plant also participates in the secondary regulation service. Several novel indicators to better explain the value of perfect information are presented and evaluated. Finally, several regression models to roughly estimate the value of perfect information of any price forecasting model are obtained. These might help to evaluate the investment in pumped-storage hydropower plants.

Economic Viability of Pumped-Storage Power Plants Equipped with Ternary Units and Considering Hydraulic Short-Circuit Operation

This paper analyses the economic viability of pumped-storage hydropower plants equipped with ternary units and considering hydraulic short-circuit operation. The analysed plant is assumed to participate in the day-ahead energy market and in the secondary regulation service of the Spanish power system. A deterministic day-ahead energy and reserve scheduling model is used to estimate the maximum theoretical income of the plant assuming perfect information of the next day prices and the residual demand curves of the secondary regulation reserve market. Results show that the pay-back periods with and without the hydraulic short-circuit operation are significantly lower than their expected lifetime and that the pay-back periods can be reduced with the inclusion of the hydraulic short-circuit operation.

Coordinated multi-area energy and regulation joint dispatch under wind power uncertainty

Proliferated integration of variable renewable resources, especially wind power, in multi-area power systems brings about critical needs to coordinate balancing resources over the whole interconnected system. This paper proposes a coordination methodology in the real-time electricity market between regional interconnected power systems. The new method optimally dispatches generating units, determines interregional energy trading, and allocates regulation reserve throughout the entire system. The balancing resources in participating areas are shared and more effectively used to tackle the wind power uncertainty by means of a combined automatic generation control system. In order to comply with the existing operating philosophy of regional electricity markets, the augmented Lagrangian relaxation along with alternative direction method of multipliers are applied to provide a fully decentralized procedure with limited data interchanges between neighboring regions. Performance of the proposed method is examined on a two-area 6-bus and the modified three-area IEEE 118-bus test systems. The results confirm the applicability and effectiveness of the proposed model in providing flexible energy trading, regulation sharing, improved economic efficiency, and increased ability to integrate variable renewable energy into the power systems.

Day-ahead scheduling of virtual power plant in joint energy and regulation reserve markets under uncertainties

This paper presents a day-ahead scheduling framework for virtual power plant (VPP) in a joint energy and regulation reserve (RR) markets. The proposed VPP clusters a mix of generation units in term of synchronous distributed generation (SDG) and wind power plant (WPP) as well as storage facilities such as electrical vehicles (EVs) and small pumped storage plant (PSP). It is assumed that VPP provides required RR through its SDG and small PSP based on the delivery request probability of day-ahead market. In order to aggregate EVs, the VPP establishes bilateral incentive contracts with vehicle owners. Moreover, impact of carbon dioxide (CO2) emission of SDG is included by means of penalty cost function. Different uncertain parameters with regard to wind generation, EV owner behaviors, energy and RR market prices and regulation up and down probabilities are considered using a point estimate method (PEM). The case studies are applied to demonstrate the effectiveness of the scheduling model.

Possibilities of increasing the effectiveness of medical and psychological rehabilitation taking into account the prevailing part of the autonomic nervous system in specialists of EMERCOM of Russia

Relevance. Specialists of EMERCOM of Russia are engaged in hazardous activities and, therefore, are at risk of mental and physical health disorders. Further measures are required to recover their borderline functional states, preserve and restore mental and physical health, thus increasing the body’s resistance to adverse occupational factors. Intention. To analyze possible effects of the prevailing part of autonomous (vegetative) nervous system on the effectiveness of rehabilitation measures, the choice of the course duration and content of the proposed programs. Methods. The object of research is a long-term medical and psychological rehabilitation, the subject – functional indices reflecting the state of somatic and mental health. The techniques of detailed psychophysiological research are described. Results and Discussion. The results obtained indicate the need to consider the predominant activity of the autonomic nervous system in specialists of EMERCOM of Russia (sympatheticotonia, normotonia, parasympatheticotonia) when implementing rehabilitation programs. Recommendations were made for adapting the basic standard health-promoting long-term program to the current vegetative status of the Russia EMERCOM specialists in order to normalize neurohumoral regulation and increase adaptive reserves. The results indicate the feasibility of correction techniques in parasympatheticotonia (activating regimen to enhance sympathetic and reduce parasympathetic tone) as well as increased number and intensity of rehabilitation measures. In sympatheticotonia, a light regimen was indicated (to reduce sympathetic activity and increase parasympathetic tone); the number and intensity of rehabilitation measures were also decreased. Conclusion. Knowledge of prevailing activity of the autonomic nervous system in Russia EMERCOM specialists helps to predict the risk of psychosomatic diseases and to develop and implement personalized measures for mastering self-control and coping skills.

Optimal Energy and Reserve Scheduling of Pumped-Storage Power Plants Considering Hydraulic Short-Circuit Operation

This paper presents a mixed-integer model for the hourly energy and reserve scheduling of a price-taker and closed-loop pumped-storage hydropower plant operating in hydraulic short-circuit mode. The plant participates in the spot market and in the secondary regulation reserve market, taking into account the regulation energy due to the real-time use of the regulation-up and -down reserves. The proposed model is used to compare the maximum theoretical income of the plant with and without considering hydraulic short-circuit operation. Numerical results demonstrate that the operation in hydraulic short-circuit mode could help significantly to enlarge the income of the power plant and that the secondary regulation reserve market might be the main source of revenue in a realistic setting characterized by a high level of renewable energy sources in the generation mix.

The effect of PV siting on power system flexibility needs

Locations of photovoltaic (PV) systems affect the variability and uncertainty of their power generation, and as a result the amount of flexible resources needed to balance supply and demand. However, studies on the integration of renewable electricity into power systems focus on the total amount of renewable generation, and not their locations. This paper uses a hidden state, spatial-statistical model to simulate how locational arrangements and balancing policies affect the need for reserves—load following and regulation—in California’s power system when including 12GW of photovoltaic generators and 9.5GW of wind.Our results show that locations of utility-scale PV systems significantly affect on the amount of reserves needed for balancing their variability and uncertainty. When PV is geographically dispersed the additional load following and regulation reserve needs are small; on average <1.2% and <0.05% of installed PV capacity respectively. These rise to 5.6% and 0.2% in centralized scenarios. Most the benefits of this dispersion can be achieved with relatively few, 25, systems. These are sized at roughly 500MW each, which is about the size of the largest systems in California today. Almost all of the load following reserve need is driven by errors in the hourly forecasts of solar generation. These can be mitigated either by better forecasts, or dispersing plants.Siting policies for PV must weigh system flexibility against other locational concerns, such as the energy and capacity value of the solar resource in an area. We find a small trade off between energy and reserves; where dispersed systems require less reserves but also have lower capacity factors than more centralized systems. However, we find a much greater trade-off between energy and capacity value in California; where the regions that produce the most energy on average—in the Mojave desert—tend to be cloudy during current peak demand hours, which occur during Summer afternoons.

Photovoltaic Frequency–Watt Curve Design for Frequency Regulation and Fast Contingency Reserves

When renewable energy resources are installed in electricity grids, they typically increase generation variability and displace thermal generator control action and inertia. Grid operators combat these emerging challenges with advanced distributed energy resource (DER) functions to support frequency and provide voltage regulation and protection mechanisms. This paper focuses on providing frequency reserves using autonomous IEC TR 61850-90-7 pointwise frequency–watt (FW) functions that adjust DER active power as a function of measured grid frequency. The importance of incorporating FW functions into a fleet of photovoltaic (PV) systems is demonstrated in simulation. Effects of FW curve design, including curtailment, deadband, and droop, were analyzed against performance metrics using Latin hypercube sampling for 20%, 70%, and 120% PV penetration scenarios on the Hawaiian island of Lanai. Finally, to understand the financial implications of FW functions to utilities, a performance function was defined based on monetary costs attributable to curtailed PV production, load shedding, and generator wear. An optimization wrapper was then created to find the best FW function curve for each penetration level. It was found that in all cases, the utility would save money by implementing appropriate FW functions.

Optimal Participation of an Electric Vehicle Aggregator in Day-Ahead Energy and Reserve Markets

An aggregator acts as a mediator between the system operator and residential customers, enabling mutually beneficial coordination for electric vehicle (EV) owners and the power system. The aggregator aims to maximize its profits from trading energy and regulation reserve in wholesale markets. Since the aggregator does not own EV batteries, the EV owners must be reimbursed for the degradation of their batteries due to the additional cycling beyond transportation needs. This paper proposes a bidding strategy for the aggregator to maximize its profits from participating in competitive energy and different regulating reserves markets, while compensating EV owners for degradation. The results show that depending on the battery cost, the aggregator splits its resources between the energy and reserves markets. The results also show the system operator attains cost savings, if an aggregator uses EVs to provide services.

Providing frequency regulation reserve services using demand response scheduling

During power grid contingencies, frequency regulation is a primary concern. Historically, frequency regulation during contingency events has been the sole responsibility of the power utility. We present a practical method of using distributed demand response scheduling to provide frequency regulation during contingency events. This paper discusses the implementation of a control system model for the use of distributed energy storage systems such as battery banks and electric water heaters as a source of ancillary services. We present an algorithm which handles the optimization of demand response scheduling for normal operation and during contingency events. We use dynamic programming as an optimization tool. A price signal is developed using optimal power flow calculations to determine the locational marginal price of electricity, while sensor data for water usage is also collected. Using these inputs to dynamic programming, the optimal control signals are given as output. We assume a market model in which distributed demand response resources are sold as a commodity on the open market and profits from demand response aggregators as brokers of distributed demand response resources can be calculated. In considering control decisions for regulation of transient changes in frequency, we focus on IEEE standard 1547 in order to prevent the safety shut-off of inverter-based generation and further exacerbation of frequency droop. This method is applied to IEEE case 118 as a demonstration of the method in practice.

Optimal planning and operation of energy storage systems in radial networks for wind power integration with reserve support

Though energy storage system (ESS) is a promising approach to alleviate the variability of non-dispatchable wind power and other forms of renewable energy sources, its high investment cost has impeded its wide deployment. Aiming at exploiting the arbitrage benefit of ESS in reserve market and raising revenue of shareholders, this study explores the optimal planning and operation of ESS in radial networks. Besides load balancing, ESS is used to provide three kinds of operating reserve services in presence of high wind power penetration, including spinning reserve, upward and downward regulation reserves. In light of the capacity limitation of ESS, the time duration of reserve provision has been taken into account. In the proposed model, unit commitment and AC optimal power flow (AC-OPF) are combined together over sequential time series to find the optimal location and size of ESSs. In order to reduce the computational complexity, the extended DistFlow model of AC-OPF is adopted to convert the problem into a mixed-integer second-order cone programming. Numerical studies on the IEEE 34-bus distribution test feeder are used to investigate the effects of ESS with respect to various penetration levels of wind power and load scales.

An Integrated Dynamic Market Mechanism for Real-Time Markets and Frequency Regulation

The intermittent and uncertain nature of renewables represents a major challenge for large scale adoption of sustainable energy resources. Of particular concern is the need to maintain both quality of grid frequency and low costs of regulation reserves in the face of increasing fluctuations in renewables. To this end, we propose an integrated dynamic market mechanism (DMM), which combines real-time market and frequency regulation allowing market players, including renewable generators and flexible consumers, to iteratively negotiate electricity prices at the wholesale level while using the most recent information on the available wind power and the quality of grid frequency. Main features of the integrated DMM are as follows: 1) a Newton-Raphson-based method, which leads to fast convergence to the optimal dispatch; and 2) use of an aggregated frequency error as a feedback signal for the negotiation process, which leads to reduced regulation capacity requirements. The benefits of this DMM are illustrated via simulations on the IEEE 118 bus system.

Optimization model and economic assessment of collaborative charging using Vehicle-to-Building

Electric vehicles and plug-in hybrids are gaining popularity on the personal transportation market. These vehicles store energy that is unused when parked. This distributed energy source can therefore be used to provide ancillary services such as grid regulation or spinning reserves, but also for demand-side management. In this paper, we are proposing the concept of collaborative charging in the context of Vehicle-to-Building, where the vehicle and building operators engage themselves into a synergistic relation, with vehicles freely charged in exchange for shaving power peaks of buildings. For that purpose, simulations of vehicle fleets are conducted, with the charging schedule optimized by a linear programming model that is applied to manage the electric demand of a suburban university campus. These simulations, made in the context of a regulated electric market, demonstrate that collaborative charging can be financially viable for both the institution hosting the system and the participants.

Effect of the Coordinative Optimization of Interruptible Loads in Primary Frequency Regulation on Frequency Recovery

When faults and disturbances occur in power systems, backup power resources respond to maintain the system’s frequency, and the frequency recovery effect is related to the primary frequency regulation of the reserve capacity provided by and the response speeds of the system’s generating units and interruptible loads. The relationships between a system’s frequency and the frequency regulation capacity of the generating units and the interruptible loads are different. In this paper, an index for the frequency recovery effect is proposed based on the static frequency adjustment coefficient of the interruptible load and the adjustment coefficients of the generating units, and an optimization model of an interruptible load participating in primary frequency regulation is built with the objective of minimizing the cost of the primary frequency regulation reserve that uses the system’s frequency recovery effect as a constraint. The simulation results verify the validity of the model.

Frequency aware robust economic dispatch

This paper proposes a novel frequency aware robust economic dispatch (FARED) approach to exploit the synergistic capability of accommodating uncertain loads and renewable generation by accounting for both the frequency regulation effect and optimal participation mechanism of secondary regulation reserves for conventional units in response to uncertainties in the robust optimization counterpart of security constrained economic dispatch. The FARED is formulated as a robust optimization problem. In this formulation the allowable frequency deviation and the possible load or renewable generation curtailments are expressed in terms of variable uncertainty sets. The variables in the formulation are described as interval variables and treated in affine form. In order to improve the computational tractability, the dominant constraints which can be the candidates of tight transmission constraints are determined by complementarity constraints. Then the robust optimization problem is simplified to a bilinear programming problem based on duality theory. Finally, the effectiveness and efficiency of the proposed method are illustrated based on several study cases.

V2G 전기자동차의 부하관리 자원 활용을 위한 적정 지원금 산정에 관한 연구

Recently, various energy efficiency optimization activities are ongoing globally by integrating conventional grids with ICT (Information and Communication Technology). In this sense, various smart grid projects, which power suppliers and consumers exchange useful informations bilaterally in real time, have been being carried out. The electric vehicle diffusion program is one of the projects and it has been spotlighted because it could resolve green gas problem, fuel economy and tightening environmental regulations. In this paper, the economics of V2G system which consists of electric vehicles and the charging infrastructure is evaluated comparing electric vehicles for V2G with common electric vehicles. Additional benefits of V2G are analyzed in the viewpoint of load leveling, frequency regulation and operation reserve. To find this benefit, electricity sales is modeled mathematically considering depth of discharge, maximum capacity reduction, etc. Benefit and cost analysis methods with the modeling are proposed to decide whether the introduction of V2G systems. Additionally, the methods will contribute to derive the future production and the unit cost of electric vehicle and battery and to get the technical and economic analysis.