Endogenous Approach of a Frequency-Constrained Unit Commitment in Islanded Microgrid Systems

Power reserves are usually scheduled in day-ahead unit commitment (UC) to minimize operating costs while maintaining system security. In applying basic UC (bUC) after a contingency, the system frequency may fall upon the activation of the load-shedding global control (under-frequency load-shedding or UFLS) limits. Small isolated microgrids are more sensitive to this issue due to their lack of inertia. Including dynamic considerations into the bUC problem can minimize UFLS activation and also avoid the need for the operator to later check the short-term feasibility of a bUC solution. These proposals are known as Frequency-Constrained UC (FCUC), although the implementation are very time-consuming. FCUC implementation will increase the system’s operational costs, which should be calculated to estimate remuneration to the safety service based on the additional reserve provision. The electrical system of Gran Canaria island has suffered several episodes of greater blackouts in recent years. Shortly, there will be 242 MW of wind generation installed (26% of the thermal power installed on Gran Canaria). The main objective of this work is to improve the island system reliability by means of an FCUC formulation applied by the system operator in practice, including renewable sources. The results show that the frequency values remained within the admissible boundaries, but the system’s operational costs increased by around 13%.

Download Full-text

Risk-Based Active Power Redispatch Optimization

Energies ◽

10.3390/en13030716 ◽

2020 ◽

Vol 13 (3) ◽

pp. 716

Author(s):

Karol Wawrzyniak ◽

Endika Urresti Padrón ◽

Wojciech Jaworski ◽

Roman Korab

Keyword(s):

Power System ◽

Transmission Lines ◽

Unit Commitment ◽

Load Shedding ◽

Security Assessment ◽

Reference Case ◽

Dynamic Security Assessment ◽

System Operator ◽

Remedial Actions ◽

The Cost

Risk-based redispatch optimization is proposed as a methodology to support the Transmission System Operator (TSO) with preventive remedial actions obtained by extending the security-constrained unit commitment/economic dispatch with constraints resulting from the risk assessed for the power system. Although being heuristic, the methodology is based on comprehensive dynamic security assessment as time-domain simulations are used, allowing to express the degree of all types of instabilities, e.g., caused by contingencies, in monetary terms. Therefore, the risk is assessed as the expected value of the cost incurred by the TSO. Such an approach forms a new pathway to including risk in planning procedures already used by TSOs. Results obtained for the IEEE39 dynamic power system, with costs assigned to load shedding and generator tripping due to single transmission lines short-circuits, are shown as a reference case.

Download Full-text

Power System Operator in Mexico Reveals Millions in Savings by Updating Its Short-Term Thermal Unit Commitment Model

INFORMS Journal on Applied Analytics ◽

10.1287/inte.2016.0863 ◽

2016 ◽

Vol 46 (6) ◽

pp. 493-502 ◽

Cited By ~ 2

Author(s):

José L. Ceciliano-Meza ◽

Juan Álvarez López ◽

Armando De la Torre Sánchez ◽

Rolando Nieva Gómez ◽

Isaías Guillén Moya ◽

...

Keyword(s):

Power System ◽

Unit Commitment ◽

Thermal Unit ◽

Short Term ◽

System Operator

Download Full-text

Risk-based Active Power Redispatch Optimization

10.20944/preprints201911.0059.v1 ◽

2019 ◽

Author(s):

Karol Wawrzyniak ◽

Endika Urresti Padrón ◽

Wojciech Jaworski ◽

Roman Korab

Keyword(s):

Power System ◽

Transmission Lines ◽

Unit Commitment ◽

Load Shedding ◽

Security Assessment ◽

Reference Case ◽

Dynamic Security Assessment ◽

System Operator ◽

Remedial Actions ◽

The Cost

Risk-based redispatch optimization is proposed as a methodology to support the Transmission System Operator (TSO) with preventive remedial actions obtained by extending the security constrained unit commitment/economic dispatch with constraints resulting from the risk assessed for the power system. Although being heuristic, the methodology is based on comprehensive dynamic security assessment as time-domain simulations are used, allowing to express the degree of all types of instabilities, e.g., caused by contingencies, in monetary terms. Therefore, the risk is assessed as the expected value of the cost incurred by the TSO. Such approach forms a new pathway to including risk in planning procedures already used by TSOs. Results obtained for the IEEE39 dynamic power system, with costs assigned to load shedding and generator tripping due to single transmission lines short-circuits, are shown as a reference case.

Download Full-text

Impact of demand response programs in unit-commitment problems in energy optimization

10.33774/miir-2021-bh7q2 ◽

2021 ◽

Author(s):

Caio Costa de Barros Pimentel Luke ◽

Danielle de Freitas ◽

Felipe Atenas Maldonado ◽

Luigi Viola ◽

Tiago Lino Bello ◽

...

Keyword(s):

Demand Response ◽

Power Plants ◽

Unit Commitment ◽

Thermal Power ◽

Unit Commitment Problem ◽

Commitment Problem ◽

System Operator ◽

Pros And Cons ◽

Demand Response Programs ◽

Commitment Problems

Demand response is currently being tested by the Brazilian independent system operator, ONS, and by the trading chamber, CCEE. The program considers the reduction of consumption of some registered clients, as an alternative to dispatching thermal power plants according to merit order. The DESSEM computational tool, developed by CEPEL, is currently run by the ONS to define the next-day dispatch for the whole country. The results obtained using an academic version of DESSEM are used to benchmark and compare DESSEM's performance to relocate the load of demand offered by the operator to different clients under different configurations of the power system. Pros and cons are analyzed for different mathematical formulations, particularly regarding their impact on prices, operating costs, and computational times. Special attention is paid to determining the robustness of the considered models for a variety of optimality requirements for solving the unit-commitment problem.

Download Full-text

An Under Voltage Load Shedding Scheme Based on a Short Term Voltage Instability Detection Method

Mediterranean Conference on Power Generation, Transmission, Distribution and Energy Conversion (MEDPOWER 2018) ◽

10.1049/cp.2018.1881 ◽

2018 ◽

Author(s):

A. Joseph ◽

M. Cvetkovic ◽

P. Palensky

Keyword(s):

Detection Method ◽

Load Shedding ◽

Short Term ◽

Voltage Instability

Download Full-text

Short-Term Operational Scheduling of Unit Commitment Using Binary Alternative Moth-Flame Optimization

IEEE Access ◽

10.1109/access.2021.3051175 ◽

2021 ◽

Vol 9 ◽

pp. 12267-12281

Author(s):

Soraphon Kigsirisin ◽

Hajime Miyauchi

Keyword(s):

Unit Commitment ◽

Short Term

Download Full-text

Profit-Based Unit Commitment for a GENCO Equipped with Compressed Air Energy Storage and Concentrating Solar Power Units

Energies ◽

10.3390/en14030576 ◽

2021 ◽

Vol 14 (3) ◽

pp. 576

Author(s):

Mostafa Nasouri Gilvaei ◽

Mahmood Hosseini Imani ◽

Mojtaba Jabbari Ghadi ◽

Li Li ◽

Anahita Golrang

Keyword(s):

Energy Storage ◽

Solar Power ◽

Unit Commitment ◽

Thermal Power ◽

System Structure ◽

Compressed Air ◽

Mixed Integer ◽

Compressed Air Energy Storage ◽

Concentrating Solar Power ◽

Unit Commitment Problem

With the advent of restructuring in the power industry, the conventional unit commitment problem in power systems, involving the minimization of operation costs in a traditional vertically integrated system structure, has been transformed to the profit-based unit commitment (PBUC) approach, whereby generation companies (GENCOs) perform scheduling of the available production units with the aim of profit maximization. Generally, a GENCO solves the PBUC problem for participation in the day-ahead market (DAM) through determining the commitment and scheduling of fossil-fuel-based units to maximize their own profit according to a set of forecasted price and load data. This study presents a methodology to achieve optimal offering curves for a price-taker GENCO owning compressed air energy storage (CAES) and concentrating solar power (CSP) units, in addition to conventional thermal power plants. Various technical and physical constraints regarding the generation units are considered in the provided model. The proposed framework is mathematically described as a mixed-integer linear programming (MILP) problem, which is solved by using commercial software packages. Meanwhile, several cases are analyzed to evaluate the impacts of CAES and CSP units on the optimal solution of the PBUC problem. The achieved results demonstrate that incorporating the CAES and CSP units into the self-scheduling problem faced by the GENCO would increase its profitability in the DAM to a great extent.

Download Full-text