Robust Power System Security Research Articles

Day-ahead Generation Scheduling with Information Gap Decision Models

Recently, because of global warming countermeasures, interest in renewable energy has increased, particularly photovoltaic power generation (PV). On the other hand, when PV, whose output varies greatly depending on weather conditions, is introduced into the power systems in a large amount, several issues and problems are raised. It becomes difficult to adjust the voltage of the distribution systems and secure adjustment power to absorb PV output fluctuations, which affects the system frequency. In contrast, the authors have proposed the concept of robust power system security, which can apply the conventional N-1 reliability to uncertain environments. Furthermore, we formulated and developed a robust dynamic feasible (RDF) region and proposed a computation method for the evaluation index that indicates the size of the RDF region. However, executing this index calculation in a large-scale system can take a huge amount of time. Moreover, the calculation is expected to become complicated depending on the future development of a robust power system security index. In this paper, we formulate a novel method for assessing uncertainty using the Information Gap Decision Theory (IGDT). Based on the concept of the robust confidence region developed in our previous research, the authors have proposed an uncertainty model and are studying the application of IGDT theory for robust confidence evaluation using the proposed model. The simulation results confirm and validate the effectiveness of this proposed model.

Addressing the Security risk of a Massive Deployment of Photovoltaic Power for Electric Power Systems

Future electric power systems will incorporate a high percentage of Photovoltaic (PV) power generation as a means of mitigating environmental issues including global warming and energy depletion. The author observes that if the increase in uncertainties brought about by the PV penetration cannot be prevented, then it will be difficult to carry out the N-1 security level. To ensure the N-1 security requirement is met despite the uncertainties, paper has suggested a new notion of "robust power system security" along with many conditions to be met. In this research, and offer a model of uncertainties caused by PV generation, and use robust power system security to guide our choice of parameters. Next, simulate the system to learn more about, how PV and load disconnections affect stability, and how Fault Ride Through (FRT) and Dynamic Voltage Support (DVS) influence stability. Finally, it is demonstrated that the massive penetration of PV would significantly raise the complexity of burden jobs in future power system operation planning and real-time operation.

Robust Power System Security Assessment Under Uncertainties Using Bi-Level Optimization

Due to rapid expansions of renewable energy (RE) generations, it becomes more important to assess the feasibility of power system operation under limited controllable resources. Especially, exact evaluation of the system reserve for preserving system security is required under erroneous RE output predictions. This paper proposes a method to evaluate the size of the feasible region of power system operation in control space for the examination of the effective system reserve margin under uncertainties. Predicted RE and demands with their confidence intervals (CIs) are specified to formulate a problem for the evaluation of the size of the worst-case feasible region, where positive size implies feasibility, while negative, infeasibility. The method computes the degree of system security, which is referred to as “Robust Power System Security” in this paper. The problem is formulated as bi-level optimization, which is linearized and transformed into the mixed integer linear programming (MILP) problem. This is a new approach in the treatment of uncertainties. We use DC power flow and linear constrained dynamic economic dispatch problem to demonstrate the effectiveness of the proposed method. The proposed approach is useful in power system planning in analyzing the feasibility of dynamic real-time operation in future circumstance.

A Simple and Reliable Photovoltaic Forecast for Reliable Power System Operation Control

Abstract Recently various forecasting methods for photovoltaic (PV) generation have been proposed in the literature. However, these standard methods cannot be successfully and widely used in general due to the fact that they require access to specialized data that are not always and everywhere readily available in practice. Furthermore, prediction accuracy of such methods tends to deteriorate specially due to data scarcity. This paper proposes a simple and reliable PV forecasting method using machine learning and neural networks. Confidence interval (CI) results are specifically provided for the local supply-demand control as well as for the robust power system security. The proposed method uses only weather forecasting data that are provided by the Japan Meteorological Agency (JMA) and which is available to the public. The proposed method maintains a high level of accuracy by using real-time correlation data between the specific target and the neighboring areas. Multiple neural networks are constructed based on a weather clustering technique. It has been confirmed through extensive simulation results that the proposed method demonstrates robustness in prediction accuracy and CI effectiveness.

A Study on the Power System Security under Future Uncertainties

SUMMARYIn this paper, we propose three applications to quantitatively evaluate N‐1 security with increased uncertainties. By using a robust dynamic security region (RDS), which is based on the concept of robust power system security (RS), the key region for judging the security and a new evaluation index for quantitative analysis, we can evaluate power system security as follows. (1) The calculation of the RDS at the time of yearly peak load demand can be recognized as the benchmark for the N‐1 security at present, and this method can be applied to the future power system with increased renewable energy resources (RES) such as PV. (2) We show the yearly declining trend for N‐1 security resulting from increased PV deployment year by year. (3) We calculate the necessary amount of additional power supply capacity, including conventional electric power generators or storage batteries, needed for maintaining the N‐1 security at the present level. The effectiveness of the proposed method is demonstrated through simulations using a model system with three machines.

A new method of evaluating robust power system security against uncertainties

The rapid expansion of renewable energy (RE) generation is leading to severe problems related to the reliability of network operation. Power system security is threatened by increased uncertainties of RE outputs and reduced controllable resources. Therefore, it is important to evaluate the robustness of the system controllability in order to preserve system security against uncertainties of RE outputs. We refer to the robustness of the system in this context as ‘robust power system security’. This paper proposes a new formulation for evaluating the robust security region in controllable parameter space where the conventional N‐1 security criterion suffices in the presence of uncertainties. We specify the confidence interval (CI) of uncertain parameters and obtain the worst case feasible region defined by a set of security constraints, which is a very new approach in the treatment of uncertainties. We use the minimum set of static constraints in the load dispatching problem with CI of RE prediction to evaluate the security region, which is referred to as the robust static security region (RSS) in this paper. The proposed method is useful to assess the degree of difficulty of system planning and operation from the viewpoint of the balance between controllable generator capacity and RE uncertainties. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Security issues for mega penetration of photovoltaic power generation in future electric power systems. A case study of stability for power swing oscillation using the IEEJ WEST 10‐machine model

AbstractMega penetration of photovoltaic power generation (PV) will be introduced in future electric power systems, dealing with environmental problems such as global warming and energy exhaustion. The authors have pointed out that difficulties will arise in meeting the N‐1 security standard if increases in uncertainties cannot be avoided due to PV penetration. Thus, we have proposed a new concept of “robust power system security” together with several conditions to be satisfied in order to guarantee the N‐1 security standard under uncertainties. In this paper, (1) a model of uncertainties due to PV generation is proposed based on robust power system security; a method for proper parameter selection is also provided. Then, (2) the influence on the stability of the PV and load disconnection from the power system is studied through simulation using the model system; (3) the effect of PV fault ride‐through (FRT) on stability is investigated along with dynamic voltage support (DVS). Finally, it is shown that (4) complicated and burdensome tasks will be considerably increased in power system operation planning and real‐time operation under future circumstances by the mega penetration of PV. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 1–13, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22391

An Application of Robust Power System Security to Future Electric Power System and its Evaluation under Uncertainties

In this paper, we explain how the N-1 security will be difficult to keep up and propose the countermeasure under high-penetration of PV in the future. It is a fact that no effective methodologies exist to analyze the N-1 security quantitatively in relation to PV penetration. In order to overcome the present situation, we propose a solution for the subject by using the concept of Robust Power System Security as a new evaluation index for quantitative analysis. The followings are shown that (1) the relation between PV penetration and the N-1 security is clearly trade-off, (2) installation of storage batteries is effective to enhance the N-1 security and (3) power system operators will be able to monitor the N-1 security condition directly by visualizing this concept. The effectiveness of the proposed method is demonstrated through simulations using a three machines model system.

Issues for power system operation for future renewable energy penetration: Robust power system security

AbstractA large amount of PV penetration may introduce uncertainties in future power system planning and operations. This paper proposes the concept of “Robust Security (RS)” and the “RS region” in order to investigate power system security in the presence of a large amount of uncertainties. The RS region is defined as the region of power system operation where the system is secure under uncertainties. It is shown that the region tends to shrink and disappear for a high degree of PV penetration. Emerging problems concerned with security in future power systems are investigated. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(1): 30–38, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22289