There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

On robust estimation of the location parameter

In the world, wind power is rapidly becoming a generation technology of significance. Unpredictability and variability of wind power generation is one of the fundamental difficulties faced by power system operators. Good forecasting tools are urgent needed under the relevant issues associated with the integration of wind energy into the power system. This paper gives a bibliographical survey on the general background of research and developments in the fields of wind speed and wind power forecasting. Based on the assessment of wind power forecasting models, further direction for additional research and application is proposed.

A review on the forecasting of wind speed and generated power

http://pierrepinson.com/31761/Literature/foley2012.pdf

Current methods and advances in forecasting of wind power generation

In this paper we present a new approach to detect, localize, and investigate the feasibility of classifying various types of power quality disturbances. The approach is based on wavelet transform analysis, particularly the dyadic-orthonormal wavelet transform. The key idea underlying the approach is to decompose a given disturbance signal into other signals which represent a smoothed version and a detailed version of the original signal. The decomposition is performed using multiresolution signal decomposition techniques. We demonstrate and test our proposed technique to detect and localize disturbances with actual power line disturbances. In order to enhance the detection outcomes, we utilize the squared wavelet transform coefficients of the analyzed power line signal. Based on the results of the detection and localization, we carry out an initial investigation of the ability to uniquely characterize various types of power quality disturbances. This investigation is based on characterizing the uniqueness of the squared wavelet transform coefficients for each power quality disturbance.

Power quality assessment via wavelet transform analysis

An autonomous expert system for turning raw power quality measurements into answers, called the AnswerModule is presented in this paper. The AnswerModule is developed to provide quick and accurate answers to specific questions. The AnswerModule is implemented in a substation monitoring system. In this paper the underlying technology to develop the AnswerModule is presented. An example of a capacitor switching AnswerModule is also presented. This AnswerModule is designed to answer two specific questions when an event is captured by the monitoring instrument. The first question is whether the captured event is caused by energizing a capacitor bank, and if that is the case, where the capacitor bank is located, i.e., upstream or downstream from the monitoring location. Experimental results are presented in this paper to validate the accuracy of the answers.

AnswerModule: autonomous expert systems for turning raw PQ measurements into answers

We analyze scheduling a hybrid wind-conventional generator system to make it dispatchable, with the aim of profit maximization. Our models ensure that with high probability we satisfy the day-ahead power promised by the model, using combined output of the conventional and wind generators. We consider two scenarios, which differ in whether the conventional generator must commit to its schedule prior to observing the wind-power realizations or has the flexibility to adapt in near real-time to these realizations. We investigate the synergy between the conventional generator and wind farm in these two scenarios. Computationally, the non-adaptive model is relatively tractable, benefiting from a strong extended-variable formulation as an integer program. The adaptive model is a two-stage stochastic integer program with joint chance constraints. Such models have seen limited attention in the literature because of the computational challenges they pose. However, we develop an iterative regularization scheme in which we solve a sequence of sample average approximations under a growing sample size. This reduces computational effort dramatically, and our empirical results suggest that it heuristically achieves high-quality solutions. Using data from a wind farm in Texas, we demonstrate that the adaptive model significantly outperforms the non-adaptive model in terms of synergy between the conventional generator and the wind farm, with expected profit more than doubled.

An adaptive model with joint chance constraints for a hybrid wind-conventional generator system

Changes in solar irradiance cause variations in photovoltaic (PV) power generation and thus affect customer voltage. Load tap changers in substations are used to mitigate voltage variations, but they are relatively slow and cannot regulate the voltage adequately. Furthermore, abrupt voltage changes induced by PVs could greatly cause mechanical wear and reduce their lifetime. This letter develops a novel voltage smoothing control algorithm for distributed energy storage systems to reduce the impact of PV generation on voltage quality. Different from other works, the proposed control can improve the performance by having both active and reactive power control and monitoring voltage directly. The technique's performance is verified through simulation and modeling of the IEEE 4-bus test system. The proposed technique can effectively smoothen the voltage and reduce the number of tap operations by approximately 50%.

A Voltage Smoothing Algorithm Using Energy Storage PQ Control in PV-Integrated Power Grid

Transmission lines are a vital part of power systems and are prone to a variety of short-circuit faults. It is imperative to identify the fault location to restore the system as quickly as possible for maintaining the system integrity. Impedance-based fault location algorithms are most commonly used but they are prone to several sources of error such as fault resistance and mutual coupling between the lines and may not provide accurate results in the presence of complex network configurations such as three-terminal lines. Though information about mutual coupling or knowledge of complex network configuration is known, they cannot be directly used in impedance-based fault location algorithms. This study proposes a novel automated generic framework for model-based fault location approach which uses the power system model to overcome the shortcomings of impedance-based fault location methods. A combination of power system simulation software and a control and processing software provide the flexibility to be able to incorporate all the available information about the system to accurately estimate the fault location. Furthermore, this study provides key insights to implement the proposed framework in an effective and efficient manner by using reduced equivalent circuits.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-gtd.2018.5483

Universal model-based fault location for improved system integrity

This paper presents an analysis of the voltage regulation for four wind turbine technologies and compares the reactive power control methods (constant power factor control, active power factor control, and active voltage control). The test system used in this study is a radial distribution circuit with a wind turbine connected at the end of the feeder. The distribution circuit model and the wind turbine model are developed in Open Distribution System Simulator™ (OpenDSS). Simulation results show that the constant power factor control and the active power factor control regulate the power factor of the wind turbine to the desired value. In addition, the active voltage control regulates the voltage at the point of interconnection to the desired value.

Surya Santoso

Papers

AnswerModule: autonomous expert systems for turning raw PQ measurements into answers

An adaptive model with joint chance constraints for a hybrid wind-conventional generator system

A Voltage Smoothing Algorithm Using Energy Storage PQ Control in PV-Integrated Power Grid

Universal model-based fault location for improved system integrity

Voltage regulation in distribution circuits with wind power