A thorough and exhaustive presentation of theoretical analysis and practical techniques for the small-signal analysis and control of large modern electric power systems as well as an assessment of ...their stability and damping performance. Such systems may contain many hundreds of synchronous generators and high voltage power electronics equipment known as FACTS Devices. The book describes new techniques not only for the tuning and analysis of stabilizers for systems with many generators and FACTS Devices but also for their coordination. Of practical interest, these techniques are illustrated with relevant examples based on a multi-machine power system containing FACTS Devices for operating conditions ranging from light to peak load. By introducing new analytical concepts, using examples, and by employing production-grade software, practical insights are provided into the significance and application of various analytical techniques.
On August 14, 2003, a cascading outage of transmission and generation facilities in the North American Eastern Interconnection resulted in a blackout of most of New York state as well as parts of ...Pennsylvania, Ohio, Michigan, and Ontario, Canada. On September 23, 2003, nearly four million customers lost power in eastern Denmark and southern Sweden following a cascading outage that struck Scandinavia. Days later, a cascading outage between Italy and the rest of central Europe left most of Italy in darkness on September 28. These major blackouts are among the worst power system failures in the last few decades. The Power System Stability and Power System Stability Controls Subcommittees of the IEEE PES Power System Dynamic Performance Committee sponsored an all day panel session with experts from around the world. The experts described their recent work on the investigation of grid blackouts. The session offered a unique forum for discussion of possible root causes and necessary steps to reduce the risk of blackouts. This white paper presents the major conclusions drawn from the presentations and ensuing discussions during the all day session, focusing on the root causes of grid blackouts. This paper presents general conclusions drawn by this Committee together with recommendations based on lessons learned.
Microindentation creep and dynamic mechanical thermo-analysis measurements were carried out on compacted specimens of cement paste prepared at water/cement ratios of 1.00, 0.50 and 0.40 and hydrated ...for 45 years. Similar data was obtained for pastes prepared at
w
/
c
= 0.40 and hydrated only 2 months. Creep modulus–mass-loss curves were plotted for all the systems studied. These curves were used to emphasize salient differences between all the paste systems. The influence of degree of hydration, volume concentration of C–S–H, capillary porosity, C–S–H chain-length and the restraining effect of the unhydrated cement particles on creep are parameters that are used to provide a possible explanation for the observation that the creep of the old pastes is higher than creep of the young pastes. The structural role of water in the creep process at various stages of equilibrium drying from the 11 % RH condition is discussed.
This paper presents a detailed account of model development for a heavy-duty gas-turbine generator, based on field testing. Some salient points are discussed. These include a more elegant way of ...modeling the ambient temperature and frequency dependence of the turbine power output, the deadband in the governor response and the importance of modeling the excitation system limiters for system studies.
A dynamic mechanical analysis (DMTA) technique was used to assess the mechanical performance of 1.4 nm tobermorite (T), jennite (J) and mixtures of tobermorite and jennite and tobermorite and calcium ...hydroxide (CH). A comparison of E′ (storage modulus) and tan∂ (internal friction) versus temperature curves for compacted solid bodies of these mineral systems with corresponding curves for cement paste hydrated for 2 month and 3 years (both referred to as ‘young’) and 45-year-old paste (referred to as ‘old’) was made. Original data was provided to assess the practical validity of the Richardson–Groves composition-based models for the C-S-H in cement paste. Differences in mechanical performance between the ‘young’ paste and the ‘old’ paste could be accounted for by application of a T/J dominant model (‘young’ paste) and a J–T/CH structural model with a minor amount of T (‘old paste’).
The effect of prolonged hydration of Portland cement paste on engineering behavior was investigated using dynamic mechanical thermo-analysis (DMTA) methods. Specimens ranged in age from 3 days to ...45 years. Compacts of hydrated cement powders and normally hydrated paste specimens were tested. Age dependent nanostructural characteristics of C–S–H were shown to influence the mechanical response of cement paste. Evidence was provided to support the use of compacts as structural models for hydrated cement paste. Details of ageing effects on the DMTA parameters (storage modulus and internal friction) as a function of temperature and porosity are reported.
This paper presents a description of modeling and application studies related to a modern static VAr system (SVS) installation in a utility grid. The SVS incorporates a fully integrated static VAr ...compensator (SVC) and coordinated, automatically switched capacitor banks using a sophisticated control system. The capacitor banks are switched by individual circuit breakers. Descriptions are provided for the SVC control strategy and various levels of modeling details for the application and design studies performed for this device. The stability model described in the paper expands on a previously published work to incorporate the slow susceptance regulator, coordinated/automatic capacitor switching, as well as pertinent protection functions. New insight is presented on the effect of SVC controls on the torsional damping of nearby generators and how such interaction can be easily avoided through proper voltage regulator tuning.
Dynamic mechanical thermoanalysis (DMTA) was conducted on compacted specimens of calcium silicate hydrates (C-S-H), 1.4 nm tobermorite, jennite, and compacted hydrated Portland cement paste powders, ...as well as hardened cement paste. The synthetic silicates are key elements for compositional models of the hydrated calcium silicates present in cement paste. The study focuses on the nanostructural effects due to the removal of water from the 11 % RH condition. The DMTA results (
E
′ and tan∂ versus temperature curves) in the 25–110 °C range mimicked those of DMA (
E
′ and tan∂ versus mass loss curves) conducted at room temperature for C-S-H and cement paste. In addition, the DMTA curves for 1.4 nm tobermorite and jennite in the temperature range 110–300 °C were sensitive to phase changes including the transition of 1.4 nm tobermorite to 1.1 nm tobermorite and other forms, as well as the transition of jennite to metajennite. The DMTA curves of a 50/50 mixture of 1.4 nm tobermorite and jennite exhibit similarities and differences to that of hydrated cement paste that are influenced by porosity and the amorphous nature of C-S-H in the cement paste. The study provides useful data for evaluating Taylor’s concept of a possible tobermorite-jennite model for the C-S-H present in hydrated cement paste.
By using the concept of induced torque coefficients, a method is developed for the simultaneous coordination of power system stabilizers (PSSs) and FACTS device stabilizers (FDSs) in order to enhance ...the damping of the rotor modes of oscillation in a multimachine system. The proposed coordination scheme employs linear programming. However, because eigenanalysis using the QR algorithm is required, it is limited to systems with less than 600-700 states. A case study is given which illustrates the coordination of PSSs and FDSs in a three-area system with 29 stations, 3 SVCs and 400 states.
Dynamic mechanical analysis measurements were made on the following calcium-silicate- hydrate systems: 1.4 nm tobermorite (T), jennite (J), synthetic C–S–H (C/S = 0.80, 1.20 and 1.50) and cement ...paste. The age of the cement paste varied from 3 days to 45 years. Plots of storage modulus versus porosity were constructed for all these materials. The non-uniqueness of the curves is discussed with reference to Taylor’s analysis of strength-porosity curves and the influence of particle type, density and crystallinity. Additional insights regarding the practical application of T–J and T–CH nanostructural models for the C–S–H nanostructure in hydrated cements is provided.
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