# Modeling Wind Farms for Power System Stability Studies

Wind energy conversion systems comprise of wind energy, and the mechanical and electrical equipment to convert this into electrical energy. The controls are an important part of being able to deliver the power to the network. Modeling wind systems for power system stability simulation studies requires careful analysis of the equipment and controls to determine the key factors that affect stability in the timeframe and bandwidth of such studies.

There are a number of public and proprietary models of wind turbine units and wind farms available for use with commercial power flow and stability simulation packages. Manufacturers of wind turbines also provide specialized models. Consultants, such as Pterra, labs and research organizations may also develop special user models. Hence, there is a variety of models to choose from. However, there are four basic types of wind farms. In selecting generic models, it may be sufficient to apply the best fit with one of the four basic types. This is particularly appropriate in planning studies.

# C01: Power Flow Analysis and Applications

The power flow is a basic tool of power system analysis that is required knowledge for anyone who wants to work in this field. In this introductory course, review the basic principles of power flows with emphasis on applications to practical steady-state analysis. Learn how to model various types of power system equipment, and how the modeling of such equipment influence power flow solution performance and results. Learn about various methods for solving the power flow, the intrinsic characteristics and when to apply them, especially in ill-conditioned cases. Then, apply the power flow to typical power system problems, including contingency analysis, voltage control and reactive power analysis, and transfer analysis. Fill in your knowledge base of practical power flow analysis techniques and applications in a short course that is suited to today’s needs.

# CO2: Dynamic Simulation Analysis and Applications

Power system stability is an essential aspect of modern power systems. The assessment of stability, both transient and voltage, requires a detailed representation of control response from power system equipment in the millisec to minutes timeframe. The time-domain dynamic simulation is the basic tool for stability assessment. We will introduce the basic concepts of stability and dynamic simulation and illustrate them through hands-on case studies. We will use commercial software for instruction and provide coaching for the software you actually use at work. Come away with a stronger understanding of stability and the use and application of dynamic simulators.

# CO3: Developing User Models for Dynamic Simulation

From time to time it is necessary to develop user models for equipment which do not have representation in commercial software packages for stability assessments. Emerging technologies and new equipment are typical bases for user models. This course introduces the basis for dynamic models, the range of responses they are intended to simulate, and then goes right into the mechanics of developing your own dynamic model.

Learn about power system controls and how these can be translated into special user models that work with today’s commercial simulation software. Be able to write your own models, debug other’s models and modify an existing model to suite your analytical needs. This is an advanced applications course. It is recommended that participants have prior experience with dynamic simulations and software programming to gain the most benefit from attending this course.

# CO4: HVDC Transmission Analysis and Applications

High Voltage Direct Current (HVDC) Transmission is seeing a resurgence in applications and studies for electric power grids. In this introductory course, review the basic principles of HVDC conversion technology, transmission design and characteristics with emphasis on applications to practical analysis. Learn how to model HVDC from existing and conceptual designs for use in steady-state and dynamic simulations of interconnected networks. Apply HVDC models to practical power system applications and evaluate their impact on key aspects such as contingency analysis, dynamic stability and voltage control.

# CO5: Applications in Voltage Stability

The industry, by experience and research, now understands more about voltage stability than it did just a few short years ago. Phenomena such as slow and fast collapse, the voltage ledge, self-restoring loads and composite load-voltage relationships have become a part of the practical operating experience rather than abstruse theoretical concepts. The course brings you to the actual indicators, analytical methods and operating bases for voltage instability, still based on sound theory, but focused on models, measurements and controls that are rooted in the practical power system. Speak and apply voltage stability with a new confidence with knowledge you bring to work from this course.

# CO6: Applications in Wind Power Interconnection

Wind power is an emerging resource in electric power systems. However, harnessing this energy and interconnecting into existing transmission grids entails major challenges. This course provides an introductory coverage of the basics of steady-state, short circuit and stability assessment of wind farm interconnection, individually and in conjunction with other wind farms. The discussions cover the various technology for converting wind energy to electric power, the electrical characteristics of each and the impacts on existing grids. Hands-on exercise allow participants to conduct detailed assessments of power flow and stability simulations for a sample wind farm and grid. For any planner, operator, designer or market participant, wind farms represent an important new technology and challenge. This course will help you get a step ahead in understanding the interconnection requirements for and potential impacts of wind farms.

# CO7: Distributed Generation Analysis and Applications Course

Distributed generation has become a viable option and is gaining wider acceptance to utilities, customers, and independent power producers. While DG offers many advantages, the utility typically requires system impact study for interconnecting DG to the existing electric grid to ensure it would not adversely impact the operation, reliability and safety of the grid. This course covers the technical aspects of DG integration from the viewpoint of both independent power producer and utility. Specific topics include: islanding, steady state power flow, voltage regulation, short-circuit, protective relaying, power quality (flicker and harmonic), power factor, system stability, grounding, and ground fault overvoltage.

# Transient, Temporary and Ground Fault Overvoltages at Wind Farm Installations

Wind farms by the nature of their design and operating characteristics are susceptible to a variety of overvoltages.  Hence it is always important to conduct studies and tests of the various levels of overvoltages and how the equipment at the wind farm are able to withstand with or without mitigation measures.  In this Blog, we will provide an overview of the issues, the analytical approach and potential mitigation.  Then, we demonstrate how these are applied to a sample wind farm.

# Flicker Trouble Ahead for Solar PV Inverters?

(Updated March 7, 2013 with additional text shown in red.)

The seemingly innocuous flickering of lamps could be a new technical battleground for the further growth and spread of photovoltaic (“PV”) electric power. On one side of the impending conflict is the flicker standard, a venerable reference that could very well trace its roots back to the advent of the electric age. On the other side are the new darlings of the power industry — environment-friendly, renewable solar power. The one thing about solar power is that in bulk amounts, its units need to be connected to existing electrical systems, and a side effect of this integration is the production of flicker. The more PV devices connected to the same electrical circuit, the more flicker is produced and the closer the level of flicker is to the allowable limit defined by the flicker standard.