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

Developing wind power simulations and laboratory experiments for renewable energy systems courses

This paper studies a novel mixed-integer linear programming (MILP) formulation on the application of mobile energy storage (MES) to assist with black-start restoration following the full blackout of an electrical network. By synthesizing techniques in the literature to model generator black start and MES activity, the formulation is the first to integrate the two concepts. Furthermore, it recognizes that the manner in which MES facilitates black-start (BS) restoration may differ depending on what component damages occurred during the event that induced the blackout. Within the IEEE 14-Bus System, testing of the formulation has not only confirmed its efficacy but also underscored circumstances where BS restoration could especially benefit from MES intervention in practice. With an MES sized at 2.59% of total MW generation capacity, in certain damage configuration categories the median load energy unserved is reduced by as much as 45.52 MWh (8.26%), and the median final load supplied is raised by as much as 22.98 MW (10.39%).

Optimal Black-Start Restoration Assisted by Mobile Energy Storage

Low-frequency high-voltage ac transmission scheme has recently been proposed as an alternative approach for bulk power transmission. This paper proposes a multi-period optimal power flow (OPF) for a multi-frequency HVac transmission system that interconnects both conventional 50/60-Hz and low-frequency grids using back-to-back converters with a centralized control scheme. The OPF objective is to minimize system losses by determining the optimal dispatch for generators, shunt capacitors, and converters. The OPF constraints include the operational constraints of all HVac grid and converter stations. The resulting mixed-integer nonlinear programing problem is solved using a proposed framework based on the predictor-corrector primal-dual interior-point method. The proposed OPF formulation and solution approach are verified using a multi-frequency HVac transmission system that is modified from the IEEE 57-bus system. The results with the optimal dispatch from the proposed method during a simulated day show a significant loss reduction and an improved voltage regulation compared to those when an arbitrary dispatch is chosen.

Loss Minimization With Optimal Power Dispatch in Multi-Frequency HVac Power Systems

Phasor measurement units are widely used for enhancing awareness of the operation of transmission and distribution networks. Their synchronized measurements enable the development of multiple near-real-time applications that are unattainable with SCADA data only. However, the accuracy of PMU measurements is highly dependent on the chosen algorithms. This paper illustrates that a certain PMU model is unable to accurately estimate system frequency as it drifts away from its nominal value (the estimated frequency profile is contaminated with pseudo-oscillations). Moreover, three devices connected at the same location produce divergent estimates during off-nominal frequency operation. Then, a technique is proposed for directly estimating frequency from phase angle measurements through numerical derivatives. It is shown to accurately estimate the system frequency regardless of nominal or off-nominal frequency operation, and it eliminates the two issues presented previously.

Frequency Retrieval from PMU Data Corrupted with Pseudo-Oscillations during Off-Nominal Operation

As the share of wind power generation increases, the power system stability may be adversely affected. Wind interconnection studies are conducted to evaluate and anticipate the interactions between the wind project and the power system. Various metrics have been developed to evaluate the system strength at the point of interconnection: short-circuit ratio, voltage stability limit, and system inertia. These metrics, unfortunately, rely on network data which may not be readily available. In this paper, a voltage phase angle based index is proposed for evaluating a transmission bus strength. The proposed metric describes the sensitivity of the change of voltage phase angle to the change of active power flow. The proposed metric requires no network information but solely rely on PMU measurements. The validity of the proposed metric is demonstrated by applying it to analyzing the system strength of the Panhandle region of the ERCOT transmission network. Through field data, it is shown that the proposed metric correctly identifies buses as strong or weak. Moreover, the metric can determine the system strength caused by varying wind power production. It is shown that the system strength decreases during high wind power generation, and vice versa.

Surya Santoso

Papers

Developing wind power simulations and laboratory experiments for renewable energy systems courses

Optimal Black-Start Restoration Assisted by Mobile Energy Storage

Loss Minimization With Optimal Power Dispatch in Multi-Frequency HVac Power Systems

Frequency Retrieval from PMU Data Corrupted with Pseudo-Oscillations during Off-Nominal Operation

PMU-Based Evaluation of Transmission Bus Strength through Angle Sensitivity Metrics