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Summary form only given.This paper presents results from an analysis of voltage stability following severe contingencies in the PJM system. The analyses involved the use of steady-state (OPF) and short and long-term simulation tools. The results highlight the importance of adequate load modeling in assessing the performance of and solutions to voltage instability. UVLS is shown to be beneficial in...
This paper presents a modified particle swarm optimization (MPSO) method to realize optimal reactive power dispatch (ORPD) considering voltage stability improvement. The ORPD problem is formulated as a nonlinear constrained multi- objective optimization problem, the sub-objective is to minimal the real power losses, minimal control number and maximal voltage stability margin. The mutation is incorporated...
A computationally simple algorithm is developed for studying the load shedding problem in emergencies where an ac power flow solution cannot be found for the stressed system. The proposed algorithm is divided into two sub-problems: restoring solvability sub-problem and improving voltage stability margin (VSM) sub-problem. Linear optimization (LP)-based optimal power flow (OPF) is applied to solve...
In this paper a nonlinear multi-objective optimization problem is formulated to maximize social welfare and the maximum distance to collapse point in an open power market using reactive support like static VAr compensator (SVC). The production and consumption costs of reactive power are included in the multi-objective OPF which are intended to provide proper market signals to the electricity market...
Recent power system events have shown that voltage collapse can be a root cause of some widespread outages. The thrust of this paper is to discuss some means of mitigating system voltage depressions that are available through the scheme which utilizes both reactive current droop compensation and line drop compensation. The point that the voltage regulator controls can be acquired by a new method which...
This paper focuses on the important aspect of estimating and quantifying the voltage stability risk with and without VAR support It is motivated by the perception that VAR support guarantees additional security and is economically justifiable. A decision tree based model is designed for estimating the risk, which accounts for both future system uncertainties and consequences associated with violation...
As certain electric power facilities have been used for a long time, some of these facilities have to be replaced due to age. Meanwhile, as the deregulation of the electric power industry has been prevailing, cost reduction and effective use of existing facilities are required in addition to ensuring stability. In this paper, we propose a new technique for optimal shunt capacitor (SC) reallocation...
A new design of load shedding against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring a transmission voltage and controlling a group of loads. Each controller acts in closed-loop, shedding amounts that vary in magnitude and time according to the evolution of its monitored voltage. The whole system operates without information exchange between controllers,...
Based upon the experience gained from the 2004 blackout and the on-line voltage security assessment operation that is in service since 2005, the Hellenic transmission system operator (HTSO) decided to automate the process of load shedding in the Hellenic Interconnected System, in order to reduce the risk of voltage collapse in the event of critical contingencies. Analytical description of the design...
This paper discusses the results of preliminary studies conducted to evaluate the potential for application of static VAR compensators (SVCs) and thryristor controlled series capacitors (TCSCs) on the Mexican interconnected system. The work synthesizes the progress in a research effort to study means to remove power transfer limitations in the 400/230 kV transmission system. The study compares the...
The use of interline power flow controller (IPFC) for maximizing voltage-stability limited power transfer and damping power swings is investigated. An IPFC consist of two voltage-sourced converters inserted in series in transmission lines, whose DC capacitors are coupled. This paper discusses the regulation modes of an IPFC and its control strategies at rated capacity. The rated-capacity operation...
With the wide application of synchronized phase measurement unit (PMU) in power system, the wide-area measurement system (WAMS) has enabled the use of a combination of measured information from remote location for global control purpose. However, the impact of time delays introduced by remote information's transmission in WAMS has to be considered, and the closed-loop power systems need be modeled...
This paper presents a description of a comprehensive study to evaluate various reactive power compensation strategies for dealing with potential voltage stability issues in the Tucson electric power company (TEP) 138 kV electrical network, if the network is operated with minimal local generation on-line. The study also looked at the impact of added reactive compensation in lieu of running existing...
This panel paper addresses applications of intelligent techniques on flexible AC transmission system (FACTS) devices in terms of steady state and transient improvement of power systems. Taking advantages of the FACTS devices depends greatly on how these devices are placed in the power system, namely on their location and size. In a practical power system, allocation of the devices depends on a comprehensive...
Increasing wind power penetration into power grids is desirable because of its environmental and other benefits. Unfortunately, wind farms could cause serious voltage stability problems due to their output variability and intermittency. It is important to minimize impacts on voltage stability. We propose to use energy storage systems (ESS) to control the intermittency of wind power. The proposed solution,...
This paper presents a unified preventive control approach considering voltage instability and thermal overload. Firstly, a new concept of generalized loading margin (GLM) is proposed. By using GLM, contingency and load increase scenario are represented using a unified parameter, and the unsolvable contingencies are treated the same as the solvable contingencies. Then, we discuss the use of a general...
This paper provides an overview of emergency voltage stability controls in power systems. First, a brief review is made of voltage instability mechanisms, countermeasures, and system protection schemes. Next, the paper discusses various aspects of emergency controls, including generator voltage control, load tap changer modified control and load shedding, pointing out some important features and addressing...
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