Dynamic Harmonic Domain Modeling of Flexible Alternating Current Transmission System Controllers

Flexible alternating current transmission system (FACTS) and multi-line FACTS controllers play an important role in electrical power transmission systems by improving power quality and increasing power transmission capacity. These controllers are nonlinear and highly complex when compared to mechanical switches. Consequently, during transient conditions, it is very difficult to use conventional time and frequency domain techniques alone to determine the precise dynamic behavior of the harmonics introduced into the system by these controllers. In particular, the time-varying nature of the harmonic components is not captured by these techniques. The contribution of this work to the state of power systems analysis is the development of new models for seven important and widely-used FACTS controllers (static synchronous series compensator (SSSC), unified power flow controller (UPFC), fixed capacitor-thyristor controlled reactor (FC-TCR), thyristor controlled switched capacitor (TCSC), generalized unified power flow controller (GUPFC), interline power flow controller (IPFC), and generalized interline power flow controller (GIPFC)) using a technique called the dynamic harmonic domain method. These models are more accurate than existing models and aid the power systems engineer in designing improved control systems. The models were simulated in the presence of disturbances to show the evolution in time of the harmonic coefficients and power quality indices. The results of these simulations show the dynamic harmonic response of these FACTS controllers under transient conditions in much more detail than can be obtained from time-domain simulations, and they can also be used to analyze system performance under steady-state conditions. Some of the FACTS controllers\u27 models discussed in this work have a common DC link, but for proper operation, the DC side voltage must be held constant. The dynamic harmonic domain method was applied to the FACTS devices to design feedback controllers, which help in maintaining constant DC

Dynamic Harmonic Domain Modeling of Flexible Alternating Current Transmission System Controllers

Flexible alternating current transmission system (FACTS) and multi-line FACTS controllers play an important role in electrical power transmission systems by improving power quality and increasing power transmission capacity. These controllers are nonlinear and highly complex when compared to mechanical switches. Consequently, during transient conditions, it is very difficult to use conventional time and frequency domain techniques alone to determine the precise dynamic behavior of the harmonics introduced into the system by these controllers. In particular, the time-varying nature of the harmonic components is not captured by these techniques. The contribution of this work to the state of power systems analysis is the development of new models for seven important and widely-used FACTS controllers (static synchronous series compensator (SSSC), unified power flow controller (UPFC), fixed capacitor-thyristor controlled reactor (FC-TCR), thyristor controlled switched capacitor (TCSC), generalized unified power flow controller (GUPFC), interline power flow controller (IPFC), and generalized interline power flow controller (GIPFC)) using a technique called the dynamic harmonic domain method. These models are more accurate than existing models and aid the power systems engineer in designing improved control systems. The models were simulated in the presence of disturbances to show the evolution in time of the harmonic coefficients and power quality indices. The results of these simulations show the dynamic harmonic response of these FACTS controllers under transient conditions in much more detail than can be obtained from time-domain simulations, and they can also be used to analyze system performance under steady-state conditions. Some of the FACTS controllers\u27 models discussed in this work have a common DC link, but for proper operation, the DC side voltage must be held constant. The dynamic harmonic domain method was applied to the FACTS devices to design feedback controllers, which help in maintaining constant DC

Dynamic Modeling and Analysis of Generalized Power Flow Controller

This paper presents a unified solution to compute power quality indices in the generalized unified power flow controller (GUPFC) during steady and transient conditions using a dynamic harmonic domain technique. This technique allows the user to analyze harmonics generated in the GUPFC more precisely than using time domain techniques. The derivation of a model is presented and then simulated in the presence of voltage disturbances to demonstrate its use in power quality assessment. The results of the proposed model are validated against time domain simulations

Evaluation of Representative Smart Grid Investment Grant Project Technologies: Distributed Generation

This document is one of a series of reports estimating the benefits of deploying technologies similar to those implemented on the Smart Grid Investment Grant (SGIG) projects. Four technical reports cover the various types of technologies deployed in the SGIG projects, distribution automation, demand response, energy storage, and renewables integration. A fifth report in the series examines the benefits of deploying these technologies on a national level. This technical report examines the impacts of addition of renewable resources- solar and wind in the distribution system as deployed in the SGIG projects

Maternal serum ischemia modified albumin as a marker for hypertensive disorders of pregnancy: a pilot study

Background: Hypoxia driven oxidative stress of the placenta contributes to the pathogenesis of preeclampsia. Serum Ischemia Modified Albumin (IMA) has recently emerged as an oxidative stress marker, used in diagnosis of cardiac ischemia. Aim: To determine the efficiency of serum IMA in differentiating hypertensive disorders of pregnancy (pregnancy induced hypertension, preeclampsia) from normal pregnancy.Methods: It was a case control study. Pregnant women ≥32 weeks of gestation. Study population were included 3 groups, 19 Normotensive Pregnant (NP) women as controls, 18 pregnant women with Pregnancy Induced Hypertension (PIH) and 19 with preeclampsia (PE). Serum IMA was estimated by Enzyme Linked Immune Sorbent Assay (ELISA). Results were analyzed by student ‘t’test. Critical values for serum IMA were obtained by Receiver Operation Characteristics (ROC) curves.Results: Serum IMA levels were significantly elevated in PE (56.84 ± 21.57 ng/ml) when compared with PIH (36.24 ± 14.51 ng/ml) and NP (35.47 ± 11.58 ng/ml) (P value <0.001). With a cutoff of 38.33 ng/ml, sensitivity and specificity for preeclampsia was 88.9% and 73.7% respectively.Conclusions: Our study demonstrated that serum IMA, an oxidative stress marker is elevated in PE & PIH. Hence serum IMA can undergo further evaluation as a marker of PE.

Dynamic Companion Harmonic Circuit Models for Analysis of Power Systems with Embedded Power Electronics Devices

In this paper a methodology that extends the dynamic harmonic domain (DHD) analysis of large networks is presented. The method combines DHD analysis and discrete companion circuit modeling resulting in a powerful analytic technique called dynamic companion harmonic circuit modeling. It provides for a complete dynamic harmonic analysis of the system while preserving the advantages of discrete companion circuit models. The methodology is illustrated by its application to a three-node power system, where reactive power compensation is achieved using a fixed-capacitor, thyristor-controlled reactor (FC-TCR) and its control system

Evaluation of Representative Smart Grid Investment Grant Project Technologies: Distributed Generation

This document is one of a series of reports estimating the benefits of deploying technologies similar to those implemented on the Smart Grid Investment Grant (SGIG) projects. Four technical reports cover the various types of technologies deployed in the SGIG projects, distribution automation, demand response, energy storage, and renewables integration. A fifth report in the series examines the benefits of deploying these technologies on a national level. This technical report examines the impacts of addition of renewable resources- solar and wind in the distribution system as deployed in the SGIG projects

New Boron Analogues of Pyrophosphates and Deoxynucleoside Boranophosphates

Tetraethyldicyanoborane pyrophosphate (2) and 3'-(diethylphosphite-cyanoborano)-5'-dimethoxytrityl.N4-benzoyl-deoxycytidine (3) have been synthesized in 70% and 76% yields, respectively. The compatibility of the substituted boranophosphates with common protecting groups is hereby demonstrated