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An innovative nonlinear (IN) H∞ control for static synchronous compensator (STATCOM) to improve voltage stability of power system is proposed. Taking the parameter deviations, external disturbances and unmodelled dynamics into account, the nonlinear dynamic model of STATCOM can be transformed into a standard Hamiltonian structure with the help of coordinate transformation. Using the Hamiltonian structure of STATCOM, an IN H∞ control is designed for STATCOM. A two‐area four‐machine power system is used to testify the robustness and effectiveness of the proposed IN H∞ control in comparison with the feedback linearisation (FL) control. The numerical simulation results indicate that the IN H∞ control has better performance than the FL control. [ABSTRACT FROM AUTHOR]

By adopting the concept of virtual quadrature source (VQS), a novel method for power transmission control-ac-ac converter with controllable phase and amplitude (ACCPA) was proposed, which has two control variables and is able to continuously regulate the phase and the amplitude of its output voltage independently. The operation principle was studied in detail, and the relationship with the optimization of control parameters of ACCPA's two duty ratios was analyzed for regulating the phase and amplitude of its output voltage. The phase is regulated in the front part, and the amplitude is regulated in the back part. For phase regulation, two methods were proposed to select optimal control parameters dynamically. The curves followed by two methods are crossed at the reference phase angle and have the same initial control parameters. It is necessary to adjust two independent control parameters for method 1 and one parameter for method 2. So method 2 is simple, easy to implement and has high control stability in comparison with method 1. The control strategy of ACCPA was presented and a prototype of single-phase ACCPA was manufactured. The experimental results verified the correctness of the theory and the feasibility of the control strategy. [ABSTRACT FROM AUTHOR]

A three-phase nonlinear load emulator using a power electronic converter is presented in this study. The proposed nonlinear load emulator is intended to be used in an ultrawide-area grid transmission network emulator, also called hardware testbed (HTB). The emulator converter is controlled in rectifier mode to act as the real nonlinear three-phase diode rectifier load. This paper presents an accurate controller for the nonlinear load emulator based on a three-phase diode rectifier system to be used in the HTB. This study also demonstrates simulation and experimental results for verification of the proposed controller. [ABSTRACT FROM AUTHOR]

This study presents an analytical approach for finding the possible impacts of flexible AC transmission system (FACTS) devices such as unified power flow controller (UPFC) and off‐shore wind penetration on distance relay characteristics. Generating relay tripping characteristics is one of the challenging issues for transmission line distance relays as the present day transmission systems is subjected to a more stressed environment with respect to power system operation. Moreover, inclusion of FACTS devices such as UPFC in the transmission system seriously impacts the performance of the distance relays as the apparent impedance changes. Furthermore, the reach setting of the relay is significantly affected as the relay end voltage fluctuates continuously when off‐shore wind‐farms are connected to power transmission systems. Thus, generating tripping characteristics for appropriate operating conditions is a demanding concern and the same has been addressed in the proposed research work. Extensive testing is carried out in generating relay tripping characteristics with possible variations under the operating conditions of UPFC and wind‐farm and it is observed that the characteristics are significantly affected for different operating conditions. Furthermore, the performance of the derived relay characteristics is validated on possible transmission line fault events and is found to work effectively. [ABSTRACT FROM AUTHOR]

Unified power flow controller (UPFC) is one of the multipurpose flexible AC transmission system devices which controls the transmission line parameters independently and simultaneously. This study presents a novel power flow controlling method based on terminal sliding mode control (TSMC) method using UPFC. The proposed controller has the advantages of finite‐time convergence and chattering‐free properties. A chattering‐free state variable controller is designed and employed to address the problems of reference tracking, robustness against uncertainties and disturbances performance of the proposed controller is compared with an existing sliding mode controller (SMC) and a PI controller. Chattering phenomena and discontinuity of the sliding mode controller are also eliminated. Another objective of the proposed control scheme is to use only locally‐measurable states, and to avoid remote long distance measurements. An adaptive observer is used to estimate the receiving end bus voltage, to avoid the data transfer problems over long distances, and to fulfil advantages such as fault detection and isolation. The presented observer could also be used to estimate the measurable states of the system. Simulation results demonstrate the efficiency of the proposed controllers. It is shown that the convergence time of the proposed TSMC is lower than those of the SMC and PID controllers'. Stability of the proposed controllers is mathematically proved. The performance of the presented adaptive observer, in the noisy environment, is also evaluated by simulation. Finally, simulation results of the suggested controllers under transient states and faulty conditions are presented. [ABSTRACT FROM AUTHOR]

Flexible AC transmission system devices provide the opportunity to improve the usage of the current transmission facilities by controlling network flows and nodal voltages. The optimal steady‐state settings of these devices can be determined using optimal power flow calculations. However, this requires knowledge of the system parameters, generation settings and loads. A two‐stage regression‐based control scheme is proposed to determine the optimal settings of thyristor‐controlled series compensators (TCSCs) with the objective to optimally utilise the current transmission system in the presence of renewable energy resources. A regression function describing the relationship between a set of key measurements and the optimal device settings is determined in the offline simulation. This function is then used to calculate the optimal device settings by only receiving the information from a limited number of key measurements without solving the OPF problem in the online operation. Studies are carried out with TCSCs in three‐test systems, the IEEE 14‐bus system, a 28‐bus system and the IEEE 118‐bus system. The simulation results with one, two and four TCSCs are presented, illustrating the performance of the proposed regression‐based control scheme. [ABSTRACT FROM AUTHOR]

This paper presents the design and compares the performance of linear, decoupled and direct power controllers (DPC) for three-phase matrix converters operating as unified power flow controllers (UPFC). A simplified steady-state model of the matrix converter-based UPFC fitted with a modified Venturini high-frequency pulse width modulator is first used to design the linear controllers for the transmission line active (P) and reactive (Q) powers. In order to minimize the resulting cross coupling between P and Q power controllers, decoupled linear controllers (DLC) are synthesized using inverse dynamics linearization. DPC are then developed using sliding-mode control techniques, in order to guarantee both robustness and decoupled control. The designed P and Q power controllers are compared using simulations and experimental results. Linear controllers show acceptable steady-state behavior but still exhibit coupling between P and Q powers in transient operation. DLC are free from cross coupling but are parameter sensitive. Results obtained by DPC show decoupled power control with zero error tracking and faster responses with no overshoot and no steady-state error. All the designed controllers were implemented using the same digital signal processing hardware. [ABSTRACT FROM AUTHOR]

Voltage-sourced converter (VSC)-based static synchronous compensators (STATCOMs) are used for voltage regulation in transmission and distribution systems. Unlike PWM-controlled STATCOMs, angle-controlled STATCOMs are switched at line frequency to limit the system losses. In recent years, angle-controlled STATCOMs have been deployed by utilities for the purpose of transmission system voltage regulation, voltage stability improvement, and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and faults in the utility. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and faults. The main improvement is a substantial decrease in the negative sequence current and dc-link voltage oscillations under power system faults by the proposed control. This eliminates the need to redesign the STACOM power components to operate under fault current and dc-link voltage oscillations. The proposed control structure is designed based on adding appropriate oscillations to the conventional angle-controller output that is the control angle by which the VSC voltage vector leads/lags the line voltage vector. Since this control structure uses two angles for controlling the VSC output voltage, it is called dual angle control (DAC). PSCAD/EMTDC and experimental results verify the validity of the proposed control structure under unbalanced system conditions and faults. The experiments were conducted on a transient network analyzer, a unique hardware-based flexible ac transmission system simulator which was designed to study system faults and transients for a 2 × 100 MVA STATCOM field installation. [ABSTRACT FROM AUTHOR]

Self‐healing is one of the characteristics of the smart grid. A self‐healing power grid can identify and react to disturbance and restore power systems with little or even no human intervention. A wide area measurement (WAM) and wide area information (WAI)‐based control strategy is proposed to fast react to overloads and restore the power grid in the self‐healing power grid. The basic principle is to redistribute the power flow of a contingency transmission line to other lines with unified power flow controller (UPFC). To implement the control strategy, the reverse current network and nodal analysis method, instead of the iteration algorithm and optimisation method, is applied to redistribute the power flow. The proposed WAM/WAI‐based nodal analysis can relieve overloads quickly and effectively while realising the control objective accurately. Moreover, a grid simplification method is applied to further reduce computation cost. IEEE 39‐bus test system‐based simulation is applied to verify the proposed control strategy. The results show that the control strategy can relieve overloads effectively in about tens of milliseconds. Thus, it could be an online controller for a self‐healing power grid to deal with harmful contingencies. [ABSTRACT FROM AUTHOR]

When a high voltage direct current (HVDC) link connects two distinct power systems, the latter are usually modelled by two infinite buses. However, in some context of use, the HVDC links are no longer separating two systems but they are embedded into meshed AC systems in parallel with other AC lines and interact with other elements of the power system. This led us to enhance the control objectives by considering stability requirements. In this context, the previous modeling assumption presents serious limitations. Instead, a more efficient control model is used. It is developed such that the concerned dynamics of the system are taken into account during the synthesis. It is shown how the controllers of the HVDC converters can be synthesised using the control model mentioned above such that global grid performances are ensured, in addition to the local objectives like power and DC voltage control. In order to avoid remote measures, an output feedback control which uses only local measures is developed. The new controller is tested in comparison with the standard vector control and a non‐linear feedback linearisation control via simulation tests. The tests showed that the controller synthesised using the new control model contributes to a better coordination of the control actions and thus improve grid performances. In particular, the transient stability of the neighbour zone is a priori taken into account at the synthesis level. [ABSTRACT FROM AUTHOR]

This study investigates the subsynchronous resonance (SSR) characteristics in the systems with doubly‐fed induction generators and series compensated ac lines, by using the transfer‐function analysis approach. A new SSR mitigation method by a proper control of a series capacitor (SC) is also presented with the effectiveness evaluated. SSR mitigation by a proper control of the SC is attractive since it does not incur any additional cost. This shows that there are no technical obstacles to use a series compensation as a means to improve the power transmission capability in the systems with a high wind energy penetration. [ABSTRACT FROM AUTHOR]

Hybrid multilevel converters (HMCs) are more attractive than the traditional multilevel converters, such as modular converters, because they offer all the features needed in a modern voltage source converter‐based dc transmission system with reduced size and weight, at a competitive level of semiconductor losses. Therefore this study investigates the viability of a HMC that uses dc side H‐bridge chain links, for high‐voltage dc and flexible ac transmission systems. In addition, its operating principle, modulation and capacitor voltage balancing, and control are investigated. This study focuses on response of this HMC to ac and dc network faults, with special attention paid to device issues that may arise under extreme network faults. Therefore the HMC with dc side chain links is simulated as one station of point‐to‐point dc transmission system that operates in an inversion mode, with all the necessary control systems incorporated. The major results and findings of subjecting this version of the hybrid converter to ac and dc networks faults are presented and discussed. [ABSTRACT FROM AUTHOR]

Hydro‐Québec's electrical transmission system is an extensive, international grid located in Québec, Canada with extensions into the northeastern United States of America. For large power systems such as this, one of the major issues is to maintain the steady‐state performance of the network. From this point of view, flexible AC transmission system (FACTS) devices could be effective tools to improve power system security by reducing the power flow on overloaded lines, which in turn would result in an increased loadability of the power system, reduced transmission line losses, improved stability and security and, ultimately, a more energy‐efficient transmission system. Therefore in this study, the authors will present the effects of different types of FACTS devices on the performance of Hydro‐Québec's power system. The optimal locations and rating of these FACTS controllers will be determined with a view to improving network security using an optimisation algorithm based on a genetic algorithm. The effects of six different FACTS devices including static VAR compensator (SVC), thyristor‐controlled series capacitor (TCSC), thyristor‐controlled voltage regulator (TCVR), thyristor‐controlled phase‐shifting transformer (TCPST), unified power flow controller (UPFC) and static synchronous compensator (STATCOM) with energy storage are compared. Using the presented results, the effects of different types of FACTS devices on the Hydro‐Québec network will be analysed and compared with those of a STATCOM equipped with energy storage from the viewpoints of static loadability and losses. [ABSTRACT FROM AUTHOR]

Inductive power transfer (IPT) is an emerging technology that may create new possibilities for wireless power charging and transfer applications. However, the rather complex control method and low efficiency remain the key obstructing factors for general deployment. In a regularly compensated IPT circuit, high efficiency and controllability of the voltage transfer function are always conflicting requirements under varying load conditions. In this paper, the relationships among compensation parameters, circuit efficiency, voltage transfer function, and conduction angle of the input current relative to the input voltage are studied. A design and optimization method is proposed to achieve a better overall efficiency as well as good output voltage controllability. An IPT system design procedure is illustrated with design curves to achieve a desirable voltage transfer ratio, optimizing between efficiency enhancement and current rating of the switches. The analysis is supported with experimental results. [ABSTRACT FROM AUTHOR]

Corrective transmission switching schemes are an essential part of grid operations and are used to improve the reliability of the grid as well as the operational efficiency. Today, the transmission switching schemes are established based on the operator's past knowledge of the system as well as other ad-hoc methods. In this paper, three topology control (corrective transmission switching) methodologies are presented along with the detailed formulation of robust corrective switching. By incorporating robust optimization into the corrective switching framework, the switching solution is guaranteed to be feasible for a range of system operating states. The robust model can be solved offline to suggest switching actions that can be used in a dynamic security assessment tool in real-time. The proposed robust topology control algorithm can also generate multiple corrective switching actions for a particular contingency. The robust topology control formulation is tested on an IEEE 118-bus test case with different uncertainty sets. [ABSTRACT FROM PUBLISHER]

Unified power flow controller (UPFC) is one of the most versatile and complex flexible AC transmission system (FACTS) devices. It is emerged with a proven capability of instantaneous control of transmission line parameters. This study presents an approach based on the direct Lyapunov stability theory with finite‐time convergence and chattering‐free characteristics to improve damping of power oscillations using UPFC. A state‐variable control strategy is derived and implemented to tackle the problem of finite‐time convergence of system states. In the suggested method, the chattering phenomena and discontinuity of the controller, that is common in finite‐time controllers, are removed to obtain a continuous and smooth controller. The suggested controller is simple and clear than the conventional famous finite‐time controllers for double‐integrator systems. Simulation results are given to illustrate the effectiveness and robustness against parameter uncertainty and external disturbances of the proposed algorithm. It is shown that the settling time of the system, enhanced with the proposed controller is significantly less than the conventional non‐linear controllers. The proposed controller is investigated on UPFC connected to a two‐bus power system. [ABSTRACT FROM AUTHOR]

The article presents application of evolutionary algorithm for cost-optimal dispatch of ancillary services in power transmission system of the Czech Republic. The problem is formulated as a nonlinear optimization problem taking into account both continuous and discrete control variables. The optimal setting of control variables such as schedule for activation of regulation reserves, which minimizes the regulation energy costs while maintaining required control performance, are determined via evolution algorithm. The proposed control scheme is tested on historical data from the transmission system operator. [ABSTRACT FROM PUBLISHER]

There is currently a national push to create a smarter grid. Currently, the full control of transmission assets is not built in network optimization models. With more sophisticated modeling of transmission assets, it is possible to better utilize the current infrastructure to improve the social welfare. Co-optimizing the generation with the network topology has been shown to reduce the total dispatch cost. In this paper, we propose the concept of just-in-time transmission. This concept is predicated on the fact that transmission that is a detriment to network efficiency can be kept offline when not needed and, with the proper smart grid/advanced technology, can be switched back into service once there is a disturbance. We determine which lines to have offline based on the optimal transmission switching model previously proposed. A secondary topic of this paper focuses on flowgate bidding. Approved by the Federal Energy Regulatory Commission and implemented within the SPP and NYISO networks, flowgate bidding is defined as allowing a line's flow to exceed its rated capacity for a short period of time for a set penalty, i.e., price. We demonstrate the effectiveness of these models by testing them on large-scale ISO network models. [ABSTRACT FROM AUTHOR]

Currently, there is a national push for a smarter electric grid, one that is more controllable and flexible. The full control of transmission assets are not currently built into electric network optimization models. Optimal transmission switching is a straightforward way to leverage grid controllability: to make better use of the existing system and meet growing demand with existing infrastructure. Previous papers have shown that optimizing the network topology improves the dispatch of electrical networks. Such optimal topology dispatch can be categorized as a smart grid application where there is a co-optimization of both generators and transmission topology. In this paper we present a co-optimization formulation of the generation unit commitment and transmission switching problem while ensuring N-1 reliability. We show that the optimal topology of the network can vary from hour to hour. We also show that optimizing the topology can change the optimal unit commitment schedule. This problem is large and computationally complex even for medium sized systems. We present decomposition and computational approaches to solving this problem. Results are presented for the IEEE RTS 96 test case. [ABSTRACT FROM AUTHOR]

Currently, there is a national push for a smarter electric grid, one that is more controllable and flexible. Only limited control and flexibility of electric assets is currently built into electric network optimization models. Optimal transmission switching is a low cost way to leverage grid controllability: to make better use of the existing system and meet growing demand with existing infrastructure. Such control and flexibility can be categorized as a “smart grid application” where there is a co-optimization of both generators or loads and transmission topology. In this paper we form the dual problem and examine the multi-period N-1 reliable unit commitment and transmission switching problem with integer variables fixed to their optimal values. Results including LMPs and marginal cost distributions are presented for the IEEE RTS 96 test problem. The applications of this analysis in improving the efficiency of ISO and RTO markets are discussed. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the N-i reliable dc optimal dispatch with transmission switching. The model is a mixed integer program (MIP) with binary variables representing the state of the transmission element (line or transformer) and the model can be used for planning and/or operations. We then attempt to find solutions to this problem using the IEEE 118-bus and the RTS 96 system test cases. The IEEE 118-bus test case is analyzed at varying load levels. Using simple heuristics, we demonstrate that these networks can be operated to satisfy N-1 standards while cutting costs by incorporating transmission switching into the dispatch. In some cases, the percent savings from transmission switching was higher with an N-1 DCOPF formulation than with a DCOPF formulation. [ABSTRACT FROM AUTHOR]

Developing active series compensation in transmission systems is challenging due to the large currents and voltage capabilities required. The main purpose of this paper is to show that the magnetic energy recovery switch (MERS) can be an attractive new series compensator by applying appropriate control. The MERS is similar to a single-phase full bridge, meaning that compared to the gate-commutated series capacitor, it has twice the number of active switches. However, advantages, such as the double voltage-current operating range, eliminating the need for reverse blocking switches, zero current turn-on, and a lower current conduction period of each switch can make the MERS an attractive alternative. The basic characteristics of the MERS have been found to be similar to a series connection of a voltage source and a capacitor in steady state. With this dual characteristic, a control method has been developed where the minimization of the harmonics in the series-injected voltage and stable operation during large setpoint changes have been achieved. The resulting subharmonic characteristic also indicates a low risk of subsynchronous resonance. Experimental results verify the proposed configuration and control. [ABSTRACT FROM AUTHOR]

In this paper, we continue to analyze optimal dispatch of generation and transmission topology to meet load as a mixed integer program (MIP) with binary variables representing the state of the transmission element (line or transformer). Previous research showed a 25% savings by dispatching the IEEE 118-bus test case. This paper is an extension of that work. It presents how changing the topology affects nodal prices, load payment, generation revenues, cost, and rents, congestion rents, and flowgate prices. Results indicate that changing the topology to cut costs typically results in lower load payments and higher generation rents for this network. Computational issues are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, we formulate the problem of finding an optimal generation dispatch and transmission topology to meet a specific inflexible load as a mixed integer program. Our model is a mixed-integer linear program because it employs binary variables to represent the state of the equipment and linear relationships to describe the physical system. We find that on the standard 118-bus IEEE test case a savings of 25% in system dispatch cost can be achieved. [ABSTRACT FROM AUTHOR]

This paper considers the formal design for the grid frequency control in an offshore wind farm connected with line-commutated converter high voltage dc (HVDC) link. The control paradigm is based on using the grid frequency control to regulate the HVDC rectifier firing angle or dc-link current and hence control the power flow in the system. The dynamic behaviors of the system are verified by comparing the response from derived transfer functions and PSCAD simulations; hence the grid frequency controllers are designed. The control system performance has been validated by simulations of normal operation and fault regimes. The work provides a good basis for wider research investigation into wind farm operation. [ABSTRACT FROM AUTHOR]

An overview of the open architecture for the control center modernization and consolidation project at British Columbia Transmission Corporation (BCTC) is discussed. The design is based on the technology strategy of creating a long-term, cost-effective, sound, and sustainable solution. The integration solution provided allows modular introduction of new applications and upgrading of individual applications without impacting the rest of the system. The approach consists of a pragmatic, real-world decision-making framework that addresses multiple conflicting requirements and constraints. The architecture creates an open and flexible framework for evolving the consolidated control centers into a scalable infrastructure for evolution and implementation of a long-term roadmap. [ABSTRACT FROM PUBLISHER]

The implementation of synchronized phasor measurements for system monitoring and control is receiving unparalleled attention in the power industry.In this article, we describe recent work to incorporate phasor measurements from several locations in the transmission system into a control center state estimator, the prime application for assisting the operators to understand the operating state of the power system and for making informed decisions with respect to scheduling transmission capacity and responding to contingencies. [ABSTRACT FROM PUBLISHER]

Flexible AC transmission systems (FACTS) devices can control power flow in the transmission system to improve asset utilization, relieve congestion, and limit loop flows. High costs and reliability concerns have restricted their use in these applications. The concept of distributed FACTS (D-FACTS) is introduced as a way to remove these barriers. A new device, the distributed static series compensator (DSSC), attaches directly to existing HV or EHV conductors and so does not require HV insulation. It can be manufactured at low cost from conventional industrial-grade components. The DSSC modules are distributed, a few per conductor mile, to achieve the desired power flow control functionality by effectively changing the line reactance. Experimental results from a prototype module are presented, along with examples of the benefits deriving from a system of DSSC devices. [ABSTRACT FROM AUTHOR]

Tertiary control is the highest level in hierarchical control of microgrids to perform power exchange between the microgrid and external networks. In this Letter, a tertiary control strategy based on predictive function control (PFC) is proposed to manage power flow in DC microgrid (DCMG) clusters. Unlike linear PI control suitable for single-input and single-output systems, the PFC strategy is a nonlinear control method and capable of multiple input and multiple output control tasks with multiple objectives optimisation on-line. By solving the cost function in the finite receding horizon, voltage set points are computed in real-time to create bus voltage difference for power transfer between interconnected DCMGs. The PFC-based tertiary control for the DCMG cluster is verified through simulations. [ABSTRACT FROM AUTHOR]

This paper documents electromagnetic transient simulation models for conventional flexible AC transmission systems (FACTS) that do not employ voltage-sourced converter (VSC) technology. The FACTS controllers included in this document are classified into four categories: (1) shunt controllers (2) series controllers (3) combined shunt and series controllers (4) auxiliary controllers. Modeling techniques of these controllers are reviewed and the key aspects of each model are summarized. A comprehensive list of references is also included in this paper to provide further detailed information to the readers. [ABSTRACT FROM PUBLISHER]

A novel approach based on genetic search is presented for the design of a supplementary subsynchronous damping controller (SSDC) that is capable of damping out subsynchronous oscillation (SSO) in a parallel AC/DC transmission system. The problem of selecting the parameters of the SSDC is converted to a minimax optimization problem, which is solved by genetic algorithms with an eigenvalue-based objective function. The aim of the proposed control strategy is to choose the best controller parameters in such a way that the dominant eigenvalues of the closed-loop system are shifted to the left-hand side of s-plane as far as possible. Both the eigenvalue analysis and the detailed simulation results demonstrate the effectiveness of the proposed SSDC. [ABSTRACT FROM PUBLISHER]

STATCOM is a FACTS controller that is used in power systems to regulate the line voltage, enhance the power transmission capacity and extend the transient stability margin. STATCOM is conventionally realized by a voltage-source converter; however, being a current injection device, its performance can be improved when realized by a current-source converter (CSC) that can generate a controllable current directly at its output terminals. In this paper, a STATCOM based on the current-source converter topology is proposed. The nonlinear model of the current-source converter, which is the source of the difficulties in the controller design, has been modified to a linear model through a novel modeling technique. The proposed modeling technique is not based on the linearization of a set of nonlinear equations around an operating point. Instead, the power balance equation and a nonlinear input transformation are used to derive a linear model independent of the operating point. This model acts as the basis for the design of a decoupled state-feedback controller. The proposed STATCOM has been simulated using the PSCAD/EMTDC package. The simulation results show that a CSC-based STATCOM can result in excellent current and voltage waveforms as well as very short response time while operating at a low switching frequency. This makes the proposed scheme suitable for high power applications. [ABSTRACT FROM PUBLISHER]

This article focuses on how the Midwest Independent Transmission Operator and American Transmission Company managed a disaster recovery event of significant proportions and duration following outages caused by a flood in the upper Peninsula of Michigan in May 2003. It is an example of how transmission system operators avoid system collapse and isolation and prevent cascading outages over a wider proportion of the electric transmission delivery system in a region. [ABSTRACT FROM PUBLISHER]

A new line current profile based dynamic line rating system has been implemented at Idaho Power Company by real-time exchange of data with Energy Management System and real-time weather data from the Internet. Increased utilization of transmission critical path is made possible by wide-area real-time dynamic rating using Internet based weather data. Economic analysis shows significant benefit of operating transmission lines at higher ratings by taking advantage of favorable weather conditions during overload conditions. A case study of an internal transmission interface including the Brownlee East path in Idaho Power using the new dynamic line rating system and an associated overload mitigation system is presented. It is shown there is minimum risk of overloading a circuit by increased transmission path utilization under N-1 contingency conditions. [ABSTRACT FROM AUTHOR]

The unified power flow controller (UPFC) combines the advantageous features of both shunt and series compensations; therefore, it is an effective device that can adjust power system parameters in order to increase power transfer capability, stabilize the system and improve the economics of a power system. This paper presents the exact pi-model of the UPFC-inserted transmission lines from which the injection-model using two-port networks is derived. The equations derived in this paper are applied to a small test system, where the impact of UPFC on OPF results is shown. [ABSTRACT FROM PUBLISHER]

A methodology is presented to coordinate multiple controllers based on minimizing a criterion, and in order to enhance the damping of power oscillations. A procedure is carried out using the linearized version for the system under a nominal case, though the proposed methodology indirectly takes into account different operating points to obtain robust controllers. Simulation results show that the controllers can improve the transient stability of the power system under three-phase faults, considering different load levels. [ABSTRACT FROM PUBLISHER]

Of grave concern is the decline in the reliability of our bulk electric power systems brought on by restructuring. Conditions on our transmission systems have affected the installed capacity needed and how it should be operated. Some of the existing software packages that are being used to make reliability evaluations and to plan and operate systems are inadequate and should be used with careful restraint while new tools are being developed and coordinated with evolving institutional arrangements. To solve our reliability problems, additional technology is needed. Those developing needed software and computer methods should be made aware of the problems that are occurring on our transmission system and what it will take to solve them. This article provides some specific examples of these areas of concern [ABSTRACT FROM PUBLISHER]

This letter presents a hybrid genetic algorithm (GA) method to solve optimal power flow (OPF) in power systems incorporating flexible AC transmission systems (FACTS). In the solution process, GA is integrated with conventional OPF to select the best control parameters to minimize the total generation fuel cost and keep the power flows within the security limits. A case study using an IEEE test system is presented to demonstrate its applicability [ABSTRACT FROM PUBLISHER]

This article discusses the implementation of an operational monitoring and fault diagnosis system (OMFDS) for a ±20 MVAr voltage-sourced STATCOM based on gate-turn-off thyristor (GTO). It well fulfills the purpose of real-time supervision, intelligent alarm handling, post-fault system analysis and gratifying man-machine interaction. The proposed system, with minor modification if needed, can also be applicable to other FACTS controllers or other power electronic devices [ABSTRACT FROM PUBLISHER]