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| 2010-01 | Integrating Wind Power Efficiently into Electricity Markets Poses New Regulatory Challenges
Slides for PSERC Tele-Seminar on January 19, 2010
The inherent variability of generation from renewable sources, such as wind and solar power, may 1) increase the operating costs associated with additional ramping requirements, and 2) increase the amount of installed conventional generating capacity needed to maintain the operating reliability of a network. The additional system costs for both of these factors can be mitigated by providing additional services from, for example, controllable loads and storage capacity. This presentation uses a case study to demonstrate that these services are not adequately compensated by typical regulatory practices. As a result, current regulation will not provide the correct economic incentives to ensure that reliability standards are maintained on networks with high penetrations of generation from renewable sources. The proposed solution to this problem is to develop a hierarchical structure for operating and managing networks that will make it easier to control the increased uses of distributed energy resources that are likely to provide many of the new services needed to maintain system reliability in the future. This hierarchical structure will also make it more practical to set the correct economic incentives for providing these services efficiently.
This tele-seminar is based on on-going projects with PSERC and the Consortium for Electric Reliability Technology Solutions.
| Tim Mount, Cornell Univ. | 2/15/2010 | 610.9k | PDF |
| 2010-02 | Impact of Increased DFIG Wind Penetration on Power Systems and Markets: Small Signal and Transient Stability
Slides for PSERC Tele-Seminar on February 2, 2010
Among the several wind generation technologies, variable speed wind turbines utilizing doubly fed induction generators (DFIGs) are gaining prominence in the power industry. As the performance is largely determined by the converter and the associated controls, a DFIG is an asynchronous generator. Since DFIGs are asynchronous machines, they primarily have four mechanisms by which they can affect the damping of electromechanical modes (since they themselves do not participate in the modes): displacing synchronous machines thereby affecting the modes; impacting major path flows thereby affecting the synchronizing forces; displacing synchronous machines that have power system stabilizers; DFIG controls interacting with the damping torque on nearby large synchronous generators. Following a large disturbance, the restoring mechanisms that bring the affected generators back to synchronism are related to the interaction between the synchronizing forces and the inertia of the generators in the system. In the case of a DFIG, however, the inertia of the turbine is effectively decoupled from the system. The power electronic converter at the heart of the DFIG controls the performance and acts as an interface between the machine and the grid. With conventional control, rotor currents are always controlled to extract maximum energy from the wind. Hence, with the increased penetration of DFIG based wind farms, the effective inertia of the system will be reduced and system reliability following large disturbances could be significantly affected. This webinar gives results of analyses of these issues.
This is the first of four DFIG tele-seminars. | Vijay Vittal, Arizona State Univ. | 2/16/2010 | 269.7k | PDF |
| 2010-03 | Impact of Increased DFIG Wind Penetration on Power Systems and Markets: Frequency Response and Stability
Slides for PSERC Tele-Seminar on February 9, 2010
Wind energy, being non-dispatchable, has different operational characteristics than conventional energy sources. Additionally high levels of wind penetration create issues of power system control and interconnection issues. In this work we focus on MW-frequency control issues, system attributes, the grid problems introduced due to those attributes, and possible solutions to address them. The ultimate objective is to provide an approach for identifying the right combination of solutions for a given power system with a given projection regarding wind penetration levels. To do so, we need to establish the performance impact of each solution on each problem and we need to estimate cost per unit for each solution. The overall problem is an optimization problem of a combinatorial nature. The challenge is to ensure, at a particular wind penetration level, minimum cost and, at the same time, maximum impact sets of solution. Although this is the ultimate goal of our work, the objective in this project was to understand the impact of high wind penetration on transient frequency dip and on regulation/reserve requirements.
This is the second of four DFIG tele-seminars. | Jim McCalley, Iowa State Univ. | 2/16/2010 | 1.0M | PDF |
| 2010-04 | Impact of Increased DFIG Wind Penetration on Power Systems and Markets: Voltage Response and Stability
Slides for PSERC Tele-Seminar on Feb. 16, 2010
This tele-seminar gives the results from a PSERC projectthat examined the impact of increased penetration of doubly-fed induction generator (DFIG) wind generation on power system dynamic performance and hence reliability. DFIG wind turbines use controls that effectively isolate the inertia from the grid. In addition, large wind farms are typically connected to the grid at lower voltage levels resulting in higher fault currents. As a result, the increase in penetration of wind generation may affect a power system's transient stability, overall frequency response, regulation, voltage response, fault ride-through capability, and load-following capability. The impact of increased wind penetration was analyzed under two scenarios: a) Increased wind penetration with concomitant displacement of aged conventional generation, and b) Increased wind penetration without any decrease in existing conventional generation. Analyses identified the conditions under which increased wind penetration could result in violation of reliability criteria. Other selected critical system impact issues were studied, such as on low-voltage ride through and dynamic reactive compensation as per the requirements of FERC standards, and on the effects of increased wind penetration on frequency stability. Solutions of identified problems were explored.
This is the third of four DFIG tele-seminars.
| V. Ajjarapu, Iowa State Univ. | 2/15/2010 | 765.2k | PDF |
| 2010-05 | Impact of Increased DFIG Wind Generator Penetration on Power Systems and Markets: Market Mechanisms
Slides for the PSERC Tele-Seminar on Feb. 23, 2010.
Increased penetration of wind-based resources into the generation mix is expected to have a distinct impact on the functioning of power markets. As electricity markets gravitate towards a regime where renewables, such as wind power, are an integral part of a firm’s generation mix, multiple questions persist in terms of how market mechanisms should evolve to contend with the challenges arising from uncertainty and intermittency. In this research, we developed a flexible methodology for modeling strategic behavior in markets where firms may have wind-based generation. Importantly, we introduce a risk-based mechanism that charges firms when their bids have a large exposure to risk. Our research effort concentrated on the developing a modeling framework that can accommodate a host of complexities, ranging from capturing uncertainty and risk preferences in the setting of a two-settlement forward-spot market.
We derive some insights using a 53-node model of the Belgian network. Here, we allow a set of generators, some with a significant proportion of wind assets, to compete in the forward and spot-market in the face of uncertainty. Our models provide several insights for market design. For instance, we observe that higher levels of risk-aversion lead to lower participation in the forward markets while higher level of wind penetration. This tele-seminar provides an overview of the research on market mechanisms for wind power integration.
This is the last of four DFIG tele-seminars. | Uday V. Shanbhag, Univ. of Illinois at Urbana/Champaign | 2/23/2010 | 3.1M | PDF |
| 2010-06 | Singular Values and Principal Component Analysis in PMU Data Interpretation
Slides for the PSERC Tele-seminar on March 2, 2010
Applications requiring interpretation of very large data sets have long relied on a range of techniques generally titled “Principal Component Analysis” (PCA), and PCA’s analytic underpinning, the Singular Value Decomposition (SVD). Problems as varied as gene sequencing, geological sensing for oil/gas exploration, and even NetFlix’s film recommendation system make use of these standard analytic tools. However, despite the enormous volume of Phasor Measurement Unit (PMU) data being collected in North America and around the world, to date the power systems community appears to have overlooked these powerful methods as a means to process and interpret PMU data. In this seminar, we will argue that PMU data is particularly well suited to the application of SVD methods. A relatively low cost computation of largest singular value and vector, applied to a matrix of windowed PMU measurements, offers an effective view of system operating point sensitivity to changes in system inputs and network parameters, adaptively capturing system sensitivity to both power injection changes and network topology changes. Using simple power flow analysis, synthetically generated computational examples, and real-world PMU data, this work seeks to demonstrate that this SVD computation on a set of windowed PMU samples yields a measurement-based, “model free” indicator of proximity to system voltage stability limits and related operating problems. | Chris DeMarco, Univ. of Wisconsin-Madison | 3/1/2010 | 722.7k | PDF |
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