Fault Induced Delayed Voltage Recovery (FIDVR) Phenomenon: Modeling and Guidelines

Feb 19, 2019 | Blog

Fault Induced Delayed Voltage Recovery (FIDVR) Phenomenon:
Modeling and Guidelines

By: Sarina Adhikari, Senior Consultant
sadhikari@enernex.com
865-218-4600 x6177

Access the Published Article via IEEE Xplore

Broadly speaking, voltage sensitive loads are classified into two different categories: static or steady state, and dynamic loads. Accurate modeling of loads in the simulation environment that can closely mimic the behavior of the real-world load dynamics is a big modeling challenge. Bonneville Power Administration (BPA) and Western Electricity Coordinating Council (WECC) developed the Composite Load Model structure comprising of different types of static loads, electronic loads, three phase and single-phase compressor motor loads. The main drivers of the phenomenon termed as Fault Induced Delayed Voltage Recovery (FIDVR) are single phase low inertia compressor motors.

The phenomenon in which the system voltage remains at excessively low levels for the duration of several seconds, even after the clearing of a transmission, sub transmission, or distribution fault are classified as FIDVR events. In a system with large percentage of single-phase induction motor loads with constant torque characteristics, the motor stalls when the system voltage dips to some low values during the fault conditions. These type of low inertia motors draw huge amount of reactive power from the grid during the depressed voltage conditions. These motors draw 5-6 times their steady state current in this stalled or locked-rotor condition. As a result, the system voltage remains at the depressed state for a long time until the thermal protection kicks in and trips the single-phase motor loads. Once the motors are taken out of the system, the system voltage gradually recovers. It can take as long as 30 seconds for the system voltage to get back to normal during the FIDVR phenomenon. The aftermath of FIDVR event could be voltage collapse and several cascading events on the electrical power system. These type events typically occur in the peak hot summer days when there are large number of single-phase air conditioning (A/C) compressor motors in operation.

The illustration of a typical FIDVR event showing successive sequence of events is provided in Figure 1. It shows a typical delayed voltage recovery profile on a 230 KV circuit located in Southern California following a fault. The voltage decreased to around 79 percent of the nominal voltage (as pointed by 1) following the fault. This reduction in voltage caused the A/C units to stall. These stalled A/C units depressed the system voltage from the nominal voltage level (as pointed by 2). As the thermal overload protection switches of the A/C units were operated by tripping the units off the connected system, the voltage recovered to the value higher than the nominal by around 6 percent in this case (as pointed by 3).

Figure 1: Typical delayed voltage recovery event that was recorded following a 230kV transmission fault in Southern California[1]

As some of the motor loads tripped out of the system while the capacitor banks were still online, voltage response overshoot was observed. The overvoltage condition, in turn, resulted in the tripping of some capacitor banks and made the load side transformer taps to operate as shown in point 4. This helped in decreasing the initial voltage overshoot to some extent. After some interval, the loads, including the A/C loads, began to reconnect back to the system. As some of the capacitor banks had already tripped, the system voltage went below the nominal voltage as shown by the points 5 and 6 in the figure. These types of conditions make the system vulnerable to voltage collapse followed by other cascading events. The light inertia induction motors, such as air conditioner motors, lose their speed rapidly following the voltage dip conditions. According to the test results, such motors will stall for all faults with the duration more than five cycles and the voltage dip magnitude less than 60% of the nominal voltage.

EnerNex developed a computer simulation model in GE PSLF by utilizing the composite load model that replicated the FIDVR event in the Valley substation of Southern California Edison (SCE) that occurred in 2004. Figure 2 shows the voltage profile at 115 kV Valley bus measured by the Phasor Measurement Unit (PMU) as compared to the one obtained from the developed PSLF Valley aggregated system model with WECC parameterized composite load model. It shows that with the proper choice of model parameters, it is possible to replicate the real world FIDVR event in the computer simulation environment. It was also proved that loss of voltage sensitive loads in the system is a key factor in replicating these types of FIDVR events.

Figure 2: Measured Vs Simulated voltage profile at Valley 115kV bus during the FIDVR event at Valley station of Southern California Edison (SCE).

A detailed sensitivity analysis of different parameters of the composite load model on the system voltage profile was performed as well. In summary, the most sensitive parameters that affect voltage response of a system with large percentage of single-phase A/C compressor motors fall into the following categories:

Thermal contactor trip characteristics
Thermal time constants
Undervoltage protection characteristics
Single-phase machine stall characteristics (Vstall, Tstall)

Based on the results of sensitivity analysis of various parameters of three-phase and single-phase compressor A/C motor loads, we produced a guideline showing some typical values of different parameters to replicate the real world FIDVR events. We have also presented a broad guideline for steady state cascading simulations.

Significant Contributions:

The major outcomes of this work are summarized below:

A validated computer simulation model with the WECC composite load model developed in GE PSLF platform.
Detailed sensitivity analysis of the effects of different composite load model parameters on system voltage response.
A general guideline about the most sensitive composite load model parameters and typical values of those parameters that are required to replicate the real world FIDVR type events in computer simulations.
A detailed guideline on simulations of steady state cascading events.
A proof of concept that actual practical system events cannot be replicated without modeling the loss of voltage-sensitive load in the system.

[1] Source: R. Bravo, R. Yinger, D. Chassin, H. Huang, N. Lu, I. Hiskens, and G. Venkataramanan, “ Final Project Report – Load Modeling Transmission Research”, Lawrence Berkeley National Laboratory (LBNL), March 2010, [Online] Available: https://web.eecs.umich.edu/~hiskens/publications/LM_Final_Report.pdf (Last Accessed: Nov 05, 2018)

Smart Metering (SM) and Advanced Metering Infrastructure (AMI)

Smart Metering and AMI is a transformational process addressing multiple business and technical needs of the utility enterprise. This is more than just smart meters and communications networks; it includes all of the back end applications that can leverage the meter assets, such as outage notification, demand response, call center optimization, disputed billing process handling, pre-payment opportunities, and service connection management methods and procedures, to name a few.

Implementing SM and AMI faces the same business, engineering, and operational challenges as any other across-the-utility information technology endeavors – most notably risk associated with embracing proprietary technology, missing functionality and early obsolescence. Effective SM and AMI development, implementation, and operation relies on a marriage of electric power engineering with information technology expertise: a key component of EnerNex’s expertise and experience.

EnerNex provides an array of engineering and consulting services geared towards intelligent and effective implementation of SM and AMI. This covers all phases of project development, starting with capturing system requirements where our experts leverage a “Use Case” centric view of activities needed to be accomplished and their interaction with systems and other users. Subsequent project steps typically examine other critical areas, such as: modeling of business cases, building inter-department consensus, assembling and assessing system functional requirements and non-functional requirements, developing a system design, hardware and software specifications and standards, complete procurement services including RFI and RFQ process support, supplier rating system, response evaluation methodology, deployment management, and training of office and field personnel.

Demand Response (DR)

Demand response can be as simple as load interruption directed by the energy supplier in response to severe demand requirements, to complex customer defined load management in response to price signals. DR is one of the components of a “Non-Wires Alternative” that many utilities are effectively using to avoid expensive distribution fortification or upgrade.

Often the success and/or failure of demand response programs can be linked to program implementation challenges such as rate/tariff design rate structures communication (e.g. price signals) or ineffective incentives used by utilities to encourage customers to accept operational change. The issues of program design, rate structure and customer impact have a tremendous influence on the success or failure of load management initiatives. Demand response has traditionally been used as a tool of the energy industry to ensure system stability. However, the introduction of microelectronics, communications, home automation and the Internet of Things (IoT) has led to the development of cost effective solutions that have the capability to allow the consumer to take control of managing their energy load and ultimately, the price they pay for energy.

EnerNex has the experience and skills to turn your DR program into a successful operational asset and customer engagement process that can deliver value to all parties.

Energy Assurance Planning

Natural and man-made disasters cause an estimated $57B in average annual costs for all parties; large single events have resulted in losses of $100B or more. Events, such as the World Trade Center disaster, Hurricane Katrina, and most recently Hurricane Helene, have demonstrated an acute need to revisit, revise and implement an effective energy assurance plan. Energy assurance plans assess the functionality and interdependencies of buildings and infrastructure systems and the role they play in sustaining service and rapidly restoring critical services to a community following a hazard event.

EnerNex assists our clients in developing comprehensive energy assurance plans that mitigate and minimize the impact of energy disruptions. Our experts assess critical infrastructure risks and evaluate appropriate mitigation strategies and can help in developing an effective business continuity/disaster recovery (BC/DR) plan for utilities and your customers.

Microgrid Development

As the electric grid becomes more distributed and interactive, microgrids are playing an increasingly important role in our energy future. Decision makers at military bases, corporate and institutional campuses, residential communities and critical facilities across the world are exploring and implementing microgrids to meet economic, resiliency and environmental goals. Utility-grade microgrids are being deployed to meet transmission constraints, reliability requirements and safe-havens in the event of a significant storm event.

Microgrid_development Graphic steps to support grid modernization

Bringing together a portfolio of distributed energy resources into a controllable, islandable microgrid comes with its own set of challenges. The key to solving these challenges is in architecting a system to support information exchanges between components across well-defined points of interoperability (interfaces) in a technology independent manner. This interoperability ensures that the system is resilient to technology change. Modern systems engineering techniques must be employed to ensure that individual sub‐systems are clearly identified, their functions enumerated, their data requirements known, and the points of interoperability clearly specified, along with the commensurate monitoring, command and control that is needed to ensure grid stability. With such architecture, we can apply best of breed technology available today to support those information exchanges at interface boundaries but be free to upgrade / change the implementation technology later without causing a ripple effect throughout the system.

Enterprise Architecture

Enterprise Architecture focuses on aligning an organization’s business strategies with its anticipated, desired and planned technology enhancements. Enterprise Architecture provides a framework to cost-effectively transition from a current “as-is” technology to future enterprise-wide technological solutions. An effective Enterprise Architecture program aligns business investments with long-term business strategies while minimizing risk and providing superior technological solutions. EnerNex’s key asset is its highly skilled and experienced staff who are closely connected to both the smart grid and EA standards and practices. We provide clients with the insight necessary to operate a fully functioning smart grid, which is flexible, scalable, and vendor independent.

Grid Modernization Roadmap

Utility companies across the globe are continually modernizing their grid. Each company often has different rationales, objectives and priorities. Frequently, smart grid plans are developed for individual, incremental initiatives, rather than as a part of a whole, intelligent and interoperable infrastructure. Planning may be developed around technology choices rather than business and technical requirements. The result of incremental and flawed planning leads to increased cost and risk, lost opportunities, disconnected expectations and dead ends.

EnerNex’s approach to grid modernization roadmap development follows a proven, industry-standard approach to grid modernization planning by collaboratively working with the utility to develop a set of prioritized and time-phased grid modernization initiatives unique to its business strategy and objectives. The roadmap developed is holistic, requirements-based, business value driven and actionable. It often builds on and leverages existing applications and infrastructure, and incorporates industry standards to ensure interoperability, flexibility and reduced cost and risk.

Utility Communications

Utility communication and control systems are increasingly interconnected to each other and to public networks and as a result, they are becoming increasingly more susceptible to disruptions and cyber attacks. EnerNex has experience with the various issues relating to development, implementation and optimization including feasibility analysis, design, software development and customization, project management and acceptance. Our expertise extends from being involved in the development of the fundamental standards that support utility communication and automation, through deployment and securing of those resources. EnerNex personnel were heavily involved in development of such standards and protocols as IEC 61850, IEC 60870-5 and DNp3. Our staff played a key role in the EPRI Utility Communication Architecture (UCA) project and the IntelliGrid Architecture effort.

Grid Modernization & Grid Architecture

by EnerNex | Jun 20, 2025 | Grid Modernization

Helping our clients implement and integrate grid modernization technologies and processes that are aligned with tomorrow’s utility. A Grid Modernization program frequently includes many complex utility engineering and operational topics, many times the scope of these...

Enabling Grid Integration of Electric Vehicles: NEMA EVSE 40011 Standard

by EnerNex | Apr 22, 2025 | Article

We’re excited to share our involvement in an important industry milestone: the development of the NEMA EVSE 40011 standard, which supports the integration of electric vehicles into the grid. This effort represents a crucial step toward ensuring safe, effective, and...

Grid Modernization with Artificial Intelligence

by EnerNex | Jan 29, 2025 | Article

_______________________________________________________________________________________________________________________ Introduction The electric power industry is undergoing a transformative era, driven by digitalization, renewable energy integration, and increasing...