Electric Reliability Council Of Texas System Research Articles

Replicating Real-World Wind Farm SSR Events

In 2017, three sub-synchronous resonance (SSR) events were reported in the transmission system of Electric Reliability Council of Texas (ERCOT). These three events with different consequences are due to the same cause, i.e., Type-3 wind farms radially connected to a series compensated transmission line. The objectives of this paper are: 1) to build a testbed to replicate these real-world events and investigate what causes the different consequences; 2) to find out the impact of wind penetration level and wind speed on SSR; and 3) to investigate how to mitigate SSR. The replication testbed is built in MATLAB/Simpowersystems with each wind farm represented by a single aggregated wind turbine with full dynamics. The challenge of replication is the limited information about those three events, the ERCOT system, and the wind farms. Nevertheless, relying on simplification and assumptions, we are able to replicate the three events. Our contributions include the configured testbed for Type-3 wind farm SSR studies, diagnosis of impacting factors on SSR, and the confirmation of an SSR mitigation strategy through grid-side converter ac voltage command signal modulation.

Design of a New Primary Frequency Control Market for Hosting Frequency Response Reserve Offers From Both Generators and Loads

This paper presents the design of a new primary frequency control (PFC) market for hosting frequency response reserve (FRR) offers from both generators and loads. Traditionally, FRR is provided by synchronous generators. Advanced control and monitoring technologies have enabled loads to provide fast and discrete PFC, which is complementary to the slow and continuous governor response provided by synchronous generators. In this paper, the performance of the PFC provided by the load is benchmarked by the equivalent amount of PFC provided by the synchronous generators at each typical system inertia condition using the actual dynamic network models and operation data of the Electric Reliability Council of Texas (ERCOT) system. Then, a new real-time PFC market mechanism is proposed to accept and value the PFC offers from both generators and loads. A few case studies are presented to illustrate the new market mechanism and demonstrate its effectiveness for mitigating price spikes. The results of this paper are applicable to other low-inertia power grids similar to the ERCOT system for procuring ancillary services that are essential to host high penetration of renewable resources.

Dynamics of Market Power in ERCOT System: A Fundamental CSFE With Network Constraints

Previous studies of market power within a regional system have considered multiple competing generation operators and the role of transmission constraints. However, these studies typically assume simplified structures in which each operator is restricted to a unique node in a transmission constrained network. Real systems typically have operators making decisions for units in several zones at once. Past studies also implicitly treated market power as a static concept for a given set of market rules and network configuration. We demonstrate that market power is dynamic, and can vary significantly with fuel prices and even with large-scale weather patterns. We also demonstrate the impact on region-wide market power of operators that manage units in multiple zones. We use the Electric Reliability Council of Texas (ERCOT) as an illustrative case study, and apply a conjectured supply function equilibrium (CSFE) approach that accounts for transmission constraints. We show that the companies with greater influence on the market price will depend on the relative prices of coal and natural gas. We also show that a weather event, such as a period without any wind, can have a substantial impact on market power.

Integration of Wind Generation Into the ERCOT Market

This paper examines the market rules implemented within the Electric Reliability Council of Texas (ERCOT) zonal and nodal market designs related to the integration of wind generation. Currently, there is almost 10 000 MW of wind generation installed and operating in the ERCOT market. Total ERCOT summer peak load is in excess of 65 000 MW and wind generation penetration has exceeded 25% on several instances. This paper discusses the various rules and market mechanisms put in place to effectively deal with a high penetration of variable wind generation while maintaining adequate system reliability and creating proper market price signals for wind generation. Specifically, the paper includes treatment of wind generation in both the zonal and nodal markets, including day-ahead markets and real-time operations and describes the actual market outcomes which have been realized through several years of increasing penetration of wind generation on the ERCOT system.

Regulation Adequacy Analysis Under High Wind Penetration Scenarios in ERCOT Nodal

The significant expansion of wind power capacity in the Electric Reliability Council of Texas (ERCOT) will increase the amount of ancillary services (AS) necessary to maintain ERCOT system frequency targets. This paper analyzes ERCOT regulation adequacy from a simplified dynamical model of ERCOT validated by empirical data. The model includes a representation of system frequency response characteristics; a stochastic, empirical-based model of wind power expansion; and a model of net load forecast error based on current performances. The simulation uses current ERCOT methodology for determining regulation, and NERC Balancing Authority Standards to examine frequency control performance.

A comparison of distributed optimal power flow algorithms

We present an approach to parallelizing optimal power flow (OPF) that is suitable for coarse-grained distributed implementation and is applicable to very large interconnected power systems. The proposed distributed scheme can be used to coordinate a heterogeneous collection of utilities. Three mathematical decomposition coordination methods are introduced to implement the proposed distributed scheme: the auxiliary problem principle (APP), the predictor-corrector proximal multiplier method (PCPM), and the alternating direction method (ADM). We demonstrate the approach on several medium size systems, including IEEE Test Systems and parts of the ERCOT (Electric Reliability Council of Texas) system.