Series Capacitor Banks Research Articles

Local current-based method for fault identification and location on series capacitor-compensated transmission line with different configurations

This paper proposes a new efficient method for fault detection, faulty phase selection, and fault point identification on series capacitor-compensated transmission line. The method is based on sensing only the three phase current at the relay site. A reverse synchronous reference frame (RSRF) approach is proposed for fast fault detection and classification. Then, an analytical algorithm based on symmetrical components theory is presented for accurate estimation of fault location. Three possible arrangements of the series capacitor bank (SCB) on the line are analyzed. The SCB and the associated protective metal oxide surge arrestor (MOV) are modeled thoroughly to characterize its behavior during fault. In addition to its simplicity and practicality, the proposed scheme is equipped with decaying DC offset removal technique that allows fast extraction of the current phasors within one fundamental cycle. The proposed method works well for all ground and non-ground faults; it does not need pre-fault information; does not require any communication facilities; avoids high voltage measurement; and works smoothly for a wide range of fault resistance values. The efficacy of the proposed method is proved by a large number of simulated cases under a variety of operating conditions.

A linearized MOV model-based method for fault location on off-terminal series capacitor bank-compensated transmission line using one-end current

This paper proposes a method for fault location on single and double-circuits series capacitor bank-compensated transmission line (SCTL). A common situation for installing the series capacitor bank (SCB) is to place it some point away from the terminal substations. One-end measurement-based fault locators are favorable for many utilities due to simplicity and less cost especially if they are accurate enough. For impedance-based one-end fault locators on SCTL, the current passing in the SCB is unknown for about 50% of faults. This prevents the prediction of the challenging metal oxide varistor (MOV) behavior that is inevitable for a one-end method. Herein, the nonlinear characteristics of the MOV protecting the SCB are simplified by a linearized simple yet precise model. This makes it possible to express the SCB-MOV characteristics as a linearized function of the far-end current for faults upstream the SCB keeping the nonlinear characteristics of the MOV. This eventually enables to estimate the fault current contribution of the far-end. Hence, an analytical fault distance estimation algorithm is derived for both single and parallel transmission lines using the sequence-networks modeling of the system. Beside simplicity and robustness, the proposed method is found to be accurate enough in locating a big number of faults under a variety of conditions.

Transient and Protection Performance of a Fixed Series Compensated 500 kV Transmission Line During Various Types of Faulty Conditions

This paper presents a comparison of results between inserted and non-inserted series compensation technology in the network during healthy and faulty conditions. The numerous types of fault have been examined in compensated and uncompensated conditions. It was found in the literature that the transfer of power without series compensation led to increase the transient current and voltage. Therefore, a fixed series compensation scheme is adopted in normal and faulty conditions of the transmission line to solve the problem mentioned above using MATLAB/SIMULINK. Also, this paper introduces the addition of two compensated units associated with a suitable protection system in a transmission line. This technique can improve the performance of 500 kV extra high voltage transmission line and mitigate the fault current magnitude during various type of faults such as phase to ground (Ph-G), double phase to ground (2Ph-G), three phase to ground (3Ph-G). In addition, concerning the overvoltage problems across a series capacitor bank during the disturbance, the system is boosted by a protection technique associated with a suitable control system. The design is inserted into the system to protect the series capacitor bank, which in turn overcomes the severity of overvoltage on several types of faulty conditions. It also simulated and evaluated with the help of MATLAB/SIMULINK.

Simulation of power lines with longitudinal compensation device

With series compensation of the line reactance, the problem of its protection against overcurrents arises regarding relay protection. The greater the degree of compensation, the greater the problem. When compensating for more than 50% of the reactance of the line, the protection of power transmission lines becomes practically impossible due to the failure or false operation of all existing kinds and types of protection [1, 2]. Therefore, as for now, the compensation of the line reactance usually is no more than 50% [3, 4], which does not allow to reveal the full potential of the line in terms of its transmission capacity. The goal of this research was to study the processes occurring in emergency modes on power lines equipped with a series capacitor bank, the understanding of which would help to produce algorithms that can protect power lines with SCB with a degree of the longitudinal resistance compensation of the line of more than 50%.

Controlled Switching of Series Compensated Transmission Lines: Challenges and Solutions

A new controlled switching method for purely series compensated transmission lines is proposed here. The main idea is based on the estimation of trapped charges using a recursive digital filter for correction of the secondary voltage of the capacitive voltage transformer. Several operating conditions of series capacitor banks are taken into account to define the controlled switching strategy for transmission line reclosing. It is also shown that one can take advantage of the existing techniques for uncompensated and shunt compensated lines. The challenges and potentialities of the proposed method are highlighted through alternative transient program (ATP) of a 500-kV power system where switching transient overvoltages are limited to 1.85 p.u.

A Compound Current Limiter and Circuit Breaker

The protection of sensitive loads against voltage drop is a concern for the power system. A fast fault current limiter and circuit breaker can be a solution for rapid voltage recovery of sensitive loads. This paper proposes a compound type of current limiter and circuit breaker (CLCB) which can limit fault current and fast break to adjust voltage sags at the protected buses. In addition, it can act as a circuit breaker to open the faulty line. The proposed CLCB is based on a series L-C resonance, which contains a resonant transformer and a series capacitor bank. Moreover, the CLCB includes two anti-parallel power electronic switches (a diode and an IGBT) connected in series with bus couplers. In order to perform an analysis of CLCB performance, the proposed structure was simulated using MATLAB. In addition, an experimental prototype was built, tested, and the experimental results were reported. Comparisons show that experimental results were in fair agreement with the simulation results and confirm CLCB’s ability to act as a fault current limiter and a circuit breaker.

Damping Subsynchronous Resonance Using a Static Synchronous Series Compensator Based Supplementary Damping Controller

This paper investigates the effectiveness of a supplementary damping controller around a Static Synchronous Series Compensator (SSSC) in mitigating the torsional oscillations due to interaction of series compensated transmission line with the nearby turbine-generator shafts. The main objective of the controller is to suppress the unstable torsional oscillations with frequencies coinciding with the turbine-generator shaft torsional modes, through modulation of the reactance provided by the SSSC. Detailed simulation studies are done in Power System Computer Aided Design (PSCAD) using a single machine infinite bus (SMIB) power system adopted from the IEEE first benchmark model (FBM) for subsynchronous resonance analysis. The results show that this supplementary damping controller can provide positive damping to the unstable torsional oscillations due to presence of conventional series capacitors in the line or an SSSC or a combination of both the SSSC and conventional series capacitor banks.

Improvement of Traction Power Supply System Efficiency by Using Series Capacitor Banks

The article deals with improvement of traction power supply system efficiency by means of series capacitor banks. The train schedule on electrified railways using alternating current power supply is provided by specified voltage value in its traction power supply system. Arm currents feeding traction loads lower voltage value in traction power supply system. Series capacitor banks are widely applied for voltage level boost. It is proved in the article that rational installation of series capacitor banks in traction substation feeders adds to the solution of the problem. New formulas for calculating resistance and power of series capacitor banks are recommended.

Reliability, availability and maintainability study for failure analysis in series capacitor bank

In this research, the objective is introducing the fundamentals of reliability analysis, it has been applied to the planning and design of Series Capacitor (SC) Bank, applied for power lines. It considers the cost of power outages, the decision process for new and existing power equipment in several systems, as well as the ability to make quantitative analysis “Cost – Vs. - Reliability” trade-off studies. The lack of credible data concerning equipment reliability and the cost of power outages has hindered engineers in making such studies. The study case considers a Reliability, Availability, and Maintainability (RAM) calculations, it has been performed for the series capacitor banks to be located at Cotaruse 220 kV, 4500 m over sea level (mosl) in a substation, located in Peru. The calculations are divided into forced and scheduled outages. A crew delay (for example: travel time) of 2 h, as well as 1 h for switching, have been included in calculations. The results are divided into forced and scheduled outages with a reliability calculation and spare parts are listed in this research.

Power System Distortions Mitigation Using Switched Filter Compensator

This paper proposes a novel low-cost switched power filter compensator (SFC). This proposed SFC is considered as a new topology of distribution FACTS. The proposed SFC scheme is based on a switching on/off process for connecting /disconnecting double tuned arm filters intermittently with two parallel capacitor-banks. The parallel capacitor-banks are connected at the two sides of series capacitor bank. When the switch is on, the SFC works as a double tuned filter while when the switch is off, the SFC works as series/shunt compensator. The switching process is controlled by a pulsing signal generated from PWM circuit. The modulation control signal of PWM is generated from a multi-loop traditional control. The Matlab Simulink environment is used to validate the ability of SFC to mitigate power quality problems, stabilize the system voltage and enhance the system power factor. The results show that the effectiveness of SFC to solve the system quality problems. This novel topology might be extended to be used with renewable energy resources interconnection and microgrids performance applications.

Engineering model of the electric drives of separation device for simulation of automatic control systems of reactive power compensation by means of serially connected capacitors

It is developed a mathematical model for an electric drive of high-speed separation device in terms of the modeling dynamic systems Simulink, MATLAB. The model is focused on the study of the automatic control systems of the power factor (Cosφ) of an actuator by compensating the reactive component of the total power by switching a capacitor bank in series with the actuator. The model is based on the methodology of the structural modeling of dynamic processes.

Attaining Higher Reliability in Power Systems by Using Facts

Overload in transmission systems and higher demand of electric energy have necessitated higher production of electric energy. However, it is very difficult to obtain new limits for transmission lines. Therefore, power generation and transmission companies try to make use of maximum capacity of their transmission lines. As a novel technology, FACTS have enabled companies to generate higher energy along with attaining high level system reliability. FACTS is composed of several components, e.g. TCSC, UPFC, and SVC. TCSC is a capacitor reactance compensator including a capacitor bank in series which is paralleled with a thyristor-controlled reator to provide a series capacitor reactance with uniform variations. UPFC is able to control transmission line voltage, impedance, and angle simultaneously or optionally and it can control real and reactive power flow in line. Also, it can compensate reactive power in parallel with independent control capability. SVC is a static generator of reactive power in which output are changed in a way that specific parameters in electric power systems are preserved or controlled. The present paper considered these three components of FACTS technology which are able to increase control and efficiency of transmission lines to achieve higher level of power systems reliability. DOI: 10.5901/mjss.2015.v6n6s2p728

A robust FACTS PV-smart grid interface scheme for efficient energy utilisation

In the last two decades, wind and PV system have been increased remarkably. A novel FACTS-based PV-DC-AC interface scheme using VSI-6 pulse scheme with a switched filter compensator (SFC) scheme developed by the first author is validated for efficient energy utilisation and decoupled DC-AC interface with robust stand under normal and faults (open and short circuit) conditions. The proposed FACTS scheme enhances power quality and ensures efficient energy utilisation and stabilised interface to the smart grid. The FACTS scheme is based on a hybrid power filter-capacitive compensation scheme with SPWM-dual switching strategy using a dual series and shunt capacitor banks. The hybrid control scheme uses a modified fast acting dynamic error driven time-descaled/decoupled multi-regulation loops with an additional inter-coupled weighted controller. The proposed FACTS-scheme is tested using the MATLAB-Simulink Simulation Environment. The unified AC study system was tested under different operating/fault conditions including normal loading and open/short circuit fault conditions.

Considerations for the application of series capacitors to radial power distribution circuits

This paper summarizes many of the considerations in the application of series capacitors on radial distribution circuits. The effects of series capacitors on receiving end voltages are illustrated via phasor diagrams and power-voltage characteristics. The unique voltage profile of the compensated distribution circuit is presented. Discussed are the various types of distribution circuit problems that series capacitors typically used to solve. Application guidelines are presented to help minimize oscillatory interactions with transformers and motors. The various protection schemes used in practical series capacitor banks are discussed. The information required to specify distribution series capacitor banks is outlined.

A novel fuseless capacitor bank design using conventional single-bushing capacitors

A novel fuseless capacitor bank design using conventional single-bushing capacitors is presented. The design can be used for shunt and series capacitor bank installations. Technical and economic comparisons of the new design with the present industry standard design for fuseless capacitor banks are presented.

Summary of the IEEE Special Publication on "Series capacitor bank protection" TP-126-0

Summary of the IEEE Special Publication on "Series capacitor bank protection" TP-126-0

GPS travelling wave fault locator systems: investigation into the anomalous measurements related to lightning strikes

A new fault location system based on the travelling wave principle and capable of locating faults on power lines to within /spl plusmn/one tower span (300 m) has been successfully developed and applied to BC Hydro's extensive 500 kV network. Unlike earlier schemes which are based on impedance measurements, its accuracy is not affected by load conditions, high grounding resistance and most notably series capacitor banks. This system measures the time of arrival of a fault-generated travelling wave at the line terminals using the precise timing signals from the Global Positioning System (GPS). Operating experience with the fault locator on lightning related faults indicated highly accurate results were obtained for the majority of the cases. In a few of the lightning-caused disturbances, the system gave anomalous measurements. This paper describes the operation of the system, summarizes the operating experience and explains the observed anomalous measurements.

Overvoltage protection scheme for series capacitor banks on high voltage distribution systems

An analysis of the overvoltage protection requirements for a series capacitor bank on a high-voltage distribution system (16/27.6 kV) is presented. The problems encountered in providing the required degree of protection are illustrated with an actual case study of an installation implemented by Ontario Hydro. The overvoltage protection scheme, an essential component of the series capacitor bank installation, was reliable and effective in two years of service that saw no capacitor failures. The scheme is based on readily available, off-the-shelf equipment and can be easily adapted to any installation with similar operating requirements. The ring gap, which is the only custom-made component of the system, is simple and could be fabricated by most utilities' machine shops.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

EHV series capacitor banks: a new approach to platform to grounds signalling, relay protection and supervision

A method for platform-to-ground signaling, relay protection, and supervision of EHV (extremely high voltage) series capacitor banks is presented. The system comprises optical current transducers, optical fiber system, interface unit, and microprocessor-based protection supervision and control equipment located in the control room. The optical current transducer, located at high potential, does not need its own power supply, since it is powered with light from ground level via the optical fiber system. The microprocessor-based protection and supervision system comprises all the protection functions required for the series capacitor bank. In addition, it includes a number of supervision and logging functions. Typical applications of the new system, besides EHV series capacitor banks, are for current measurements in substations and other EHV installations. Operating experience from an unattended 400 kV pilot installation was excellent.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

EHV Series Capacitor Banks. A New Approach to Platform to Ground Signalling, Relay Protection and Supervision

Series capacitor banks for transmission systems above 145 kV, are normally erected for technical and economical reasons on fully insulated platforms per phase. Several methods have been used to realize the relay protection for series capacitor banks erected on platforms. One of the first designs used in the 1950's utilized protection relays and auxiliary power equipment on the insulated platforms. Signal communication was carried out by mechanical contact devices, which transmitted on/off signals from platform level to ground. In the late 1960's, the mechanical contact devices were replaced by fibre optics. The protection relays, together with electronic equipment and auxiliary power equipment, were still located on the insulated platforms. However, to give the relay protection of series capacitors the same simplicity as for ordinary substations, a new concept was introduced in the early 1970's. A number of signals were transmitted between EHV potential and ground via a modified current transformer. The relay protection and control equipment was located in the control room. The new Protection and Supervision system includes the advantages and excludes the disadvantages of the foregoing systems. The new system comprises optical current transformers, and a microprocessor-based protection, supervision and control system, located in the control room. Optical fibres connect the current transducers on the platform with the equipment in the control room. Auxiliary power to the current transducers is transmitted by light from ground level.