Effect Of Series Compensation Research Articles

Analytical methods for series compensation of a transmission line

The paper proposes an analytical approach to evaluate the effects of series compensation of an overhead transmission line (OHL) concerning the increase of (1) loadability and (2) practical loading of the line. The first part of the paper focuses only on the line characteristics, and proposes an analytical approach to determine the loadability curves of the line as a function of the compensating capacitive reactance. In the second part of the paper, the perspective shifts to examine the power loading of the selected OHL in a meshed electrical network. The target is to evaluate the compensation degree required to achieve a desired power flow increase in the line. To this purpose a fast analytical method, based on the compensation theorem, is presented. Preserving the linearity of the network model, the proposed method allows computation of the needed compensation degree by means of a closed form equation. Numerical applications performed on two simple test networks allow to compare the method with an ad hoc implemented classical optimal power flow. The results validate the method and highlight its effectiveness as a simple and useful tool to support power system planners and designers.

Modeling series compensation effect on the bus impedance matrix for online applications

This paper derives new expressions for updating Bus Impedance Matrix (Zbus) elements to account for the modification of the series impedance of a line connected between two existing buses. Such kind of modification is not accounted for in Brown's method and requires building Zbus all over again which is time-consuming, and redundant. Afterwards, we show that a modified form of Sherman–Morisson identity is the generalization of our work. We test our modeling approach with seven systems of different sizes. Results show very minor errors between the predictions of our techniques and Brown's method. Further, speed comparison shows that our method substantially improves calculation speed from a few minutes with Brown and Bus Admittance Matrix (Ybus) inversion methods to seconds (1.35s and 2.9s for 2383 and 3120 bus systems, respectively) making it more suitable for online applications.

Prony method implementation in distance relays to mitigate the effect of series-compensated transmission lines

This paper characterizes the error in distance relay operation due to the existence of asynchronous frequency components when a fault in a line with series compensation occurs. The distance relay model and the impact of non-filtered frequency components using the conventional digital filters is presented, an error will appear in voltage and current fundamental frequency phasors estimation and, by consequence an error, in apparent impedance estimation. Then, the proposed distance relay algorithm using the Prony method as a filter and its application considerations are described. Next, the line series compensation effects in distance relay estimation are presented, showing the importance of the estimation of the fundamental frequency phasor. Afterward, the effect of series compensation in distance relay performance is characterized by evaluating a simulated fault event. Finally, the proposed algorithm is evaluated in reach and operation time of the simulated and real fault events using a 3D operation characteristic of the relay.

A Research on Fixed Series Compensation

Series compensation can improve the line efficiency significantly, reduce line loss and raise line voltage obviously. The paper introduces the basic principles of series compensation, and studies the influence of series compensation’s installation position on compensation effect, the loss reduction effect of series compensation as well as the influence of series compensation on power flow control.

Subsynchronous resonance in a series‐compensated Great Britain transmission network

In Great Britain (GB), increased levels of wind penetration require substantial reinforcements for transmitting power from Scotland to England. In the National Grid 2020 Vision, offshore and onshore infrastructure reinforcements have been proposed, the inland reinforcement including series compensation (fixed capacitors). A possible detrimental effect of onshore series compensation is the appearance of subsynchronous resonance (SSR). SSR caused by the interaction between turbogenerators and a series-compensated electrical network is studied. A three-machine system representing the onshore-reinforced mainland GB system is examined. The effect of series compensation equipment on SSR is assessed. The effects of quadrature boosters in the network are also investigated. Time-domain simulations are carried out in power systems computed aided design (PSCAD) whereas system modelling and eigenvalue analyses are conducted in MATLAB.

A New Digital Distance Relaying Scheme for Series-Compensated Double-Circuit Line During Open Conductor and Ground Fault

This paper presents a new digital distance relaying scheme which takes care of a simultaneous open conductor and ground fault occurring coincidently on the same phase at the same point on a series-compensated double-circuit line. The effect of series compensation, mutual zero-sequence coupling, remote infeed/outfeed, and fault resistance on the relay reach has been considered by the proposed scheme. The conventional digital distance relay having facility of series compensation fails to provide adequate protection in the presence of such conditions. The proposed scheme is based on the derivation of the compensated values of impedance using symmetrical component theory. To validate the proposed scheme, numerous computer simulations have been carried out using MATLAB/SIMULINK software on an existing 400-kV, 300-km-long series-compensated double-circuit transmission line. At the end, a comparative evaluation between the proposed scheme and the conventional scheme having a facility of series compensation is carried out. Simulation results demonstrate the effectiveness of the proposed scheme since the percentage error is within ±4.19%.

A New Fault Current Limiter and its Application in Micro-Grid

In this paper, a new type fault current limiter (FCL) topology is put forward for Micro-Grid (MG) system fault, which mainly consists of limiting inductance, bypass inductance and series compensation capacitors. The switching circuit is used to change circuit structure through the power diode bridge and FGCT, in the event of a fault the current limiting inductance is switched to limit short-circuit current. The topology has the advantages of switch quickly, simple control, and series compensation effect. Establishes a equivalent model of MG system with FCL, discusses the impact of FCL installation location to system short-circuit protection, and proposes the installation location program. Matlab is used for system modeling and simulation results show that the effect of the current limiter, which is installed on the outlet of the MG system power for three-phase short-circuit protection, is obvious, and has the function of inhibiting voltage sag.

05/02542 Effects of series compensation on spot price power markets

05/02542 Effects of series compensation on spot price power markets

Effects of series compensation on spot price power markets

The operation of a deregulated power market becomes more complex as the generation scheduling is dependent on suppliers' and consumers' bids. With large number of transactions in the power market changing in time, it is more likely for some transmission lines to face congestion. Series compensation, such as TCSC, with its ability to directly control the power flow can be very helpful to improve the operation of transmission networks. The effects of TCSC on the operation of a spot price power market are studied in this paper using the modified IEEE 14-bus system. Optimal Power Flow incorporating TCSC is used to implement the spot price market. Linear bids are used to model suppliers' and consumers' bids. Issues of location and cost of TCSC are discussed. The effects of levels of TCSC compensation on wide range of system quantities are studied. The effects on the total social benefit, the spot prices, transmission congestion, total generation and consumption, benefit to individual supplier and consumer etc. are discussed. It is demonstrated that though use of TCSC makes the system more efficient and augments competition in the market, it is not easy to establish general relationships between the levels of compensation and various market quantities. Simulation studies like these can be used to assess the effects of TCSC in specific systems.

A new accurate fault locating algorithm for series compensated lines

Summary form only given as follows. This paper presents a new, accurate and robust fault locating algorithm for series compensated lines. The algorithm is developed as a one-end fundamental frequency based technique and offsets both the series compensation effect and the reactance effect resulting from the remote end in-feed. The method uses phase coordinates (abc) instead of symmetrical components [012]. The basic algorithm is presented for a line compensated by one three-phase bank of series capacitors. The presented fault locating method has been extensively tested using the EMTP model of a 400 kV 300 km transmission line. The enclosed results demonstrate very high accuracy and robustness of the algorithm.

Investigation of the Effect of Series Compensation on Fault Location for EHV Transmission Lines

Abstract This paper describes an accurate fault location algorithms based on two end measurements of voltage and current phasors for EHV transmission lines. The algorithm is implemented for plain, shunt and series compensated, transposed and untransposed transmission lines. The algorithm is free of source impedance variations and includes the effect of shunt capacitance. The effect on the accuracy of the algorithm due to point on wave of fault initiation, fault location on the line, fault type, variations of the fault resistance and errors due to signal processing, is investigated. The algorithm is found to be very accurate for plain and shunt compensated lines but needs further improvements to cater for series compensated lines.

Effect of series compensation on the voltage instability of EHV long lines

In this paper, the effects of the operating conditions and dynamic performance on the voltage instability phenomena of EHV lines with series compensation is discussed. Exponential modelling of loads and exact long-line equations are used in the analysis. Graphs showing the variations of the receiving-end voltage and the transformer tap ratio with time for an assumed load variation are given. It is shown that when series compensation is provided, the chances of voltage instability occurring are less. The effect of switched series compensation on the voltage instability is also investigated. The error in using short-line equations for the analysis of voltage instability phenomena is highlighted. The random loading conditions of the system and the random load parameter variations are also considered for the first time in analysing the voltage instability phenomenon.