Distributed Static Series Compensator Research Articles

Improving the resilience of large-scale power systems using distributed static series compensators

Natural disasters such as hurricanes can cause severe damages at the transmission level, resulting in widespread power outages and renewable energy curtailment. To reduce such power outages and renewable curtailment, this study takes advantage of the power flow control capability of distributed static series compensators (DSSC) and proposes a model to optimally deploy DSSC in face of natural disasters. The model is based on stochastic optimization and can determine the optimal locations and quantities of the DSSC modules in power systems considering transmission contingencies. With a high computational efficiency, the model can meet the time frame requirement for DSSC redeployment after natural disasters to improve the resilience of large-scale, real-world power systems. The model was implemented on a modified Texas 2000-bus test system under different conditions, and results show that the proposed model can optimally allocate DSSC to mitigate transmission congestions in both normal operations and emergent situations after natural disasters. By optimally redeploying DSSC using the proposed model after natural disasters, load shedding and renewable energy curtailment can be reduced up to 100% and 90%, respectively, improving the resilience of the power system.

Coordinated investment in wind‐rich regions using dynamic line rating, energy storage and distributed static series compensation to facilitate congestion management

Wind farms installed at wind-rich regions often located in remote areas increase overloads in the weak adjacent transmission network. As a result of this congestion, extra transmission capacity is required to avoid wind energy or load curtailment that can be achieved by applying some modifications. New line construction and line uprating have been recognised as conventional solutions for the transmission capacity increase. Meanwhile, in the last decade, these solutions have brought several serious issues for the network operators, forcing them to evaluate and install different types of assets based on state-of-the-art technology in order to harvest the existing lines at the maximum possible level. An investment model is developed to relieve the congestion, including dynamic line rating (DLR), distributed static series compensation and energy storage systems (ESS), with a simplified unit commitment implementation. The resulting mixed-integer linear model is then solved with the classic Benders decomposition. Installations of DLR and distributed static series compensator (DSSC) on the same line are formulated, with techno-economic analysis performed for different asset combinations on the IEEE RTS 24 bus system, for high wind energy share scenarios. Wind curtailment levels are studied for different DLR/DSSC approaches, including the impact of practical implementation requirements. Based upon additional interlinking constraints, the robustness of investment decisions for independent DLR and DSSC investments is compared against approaches where DLR and DSSC investments are permitted on the same line. The investment based on sequential incorporation of the unit commitment in the study is also investigated to reflect the importance of the integration of the unit scheduling in the model for high renewable systems.

Optimal Coordinated Operation of Distributed Static Series Compensators for Wide-area Network Congestion Relief

Relieving network congestions is a critical goal for the safe and flexible operation of modern power systems, especially in the presence of intermittent renewables or distributed generation. This paper deals with the real-time coordinated operation of distributed static series compensators (DSSCs) to remove network congestions by suitable modifications of the branch reactance. Several objective functions are considered and discussed to minimize the number of the devices involved in the control actions, the total losses or the total reactive power exchanged, leading to a non-convex mixed-integer non-linear programming problem. Then, a heuristic methodology combining the solution of a regular NLP with k-means clustering algorithm is proposed to get rid of the binary variables, in an attempt to reduce the computational cost. The proposed coordinated operation strategy of the DSSCs is tested on several benchmark systems, providing feasible and sufficiently optimal solutions in a reasonable time frame for practical systems.

Transient stability enhancement in the presence of optimally placed D-FACTS

<span lang="EN-US">The power flow in power system can be controlled in an effective method by using FACTS devices through transmission lines. Distributed FACTS represent a new way to overcome these drawbacks. They are cost-effective, light weighted, higher performance and minimization of environmental impact. They are placed in a distribution method and in selected lines in the network according to line flow stability indices based on load flow calculations. In this paper, distributed static series compensator (DSSC) is used in order to attain the required power flow control by modifying the line reactance. They are installed directly on the present H.V transmission lines and as a result does not require H.V insulation. The load flow analysis has been carried using mat lab and the simulation for the purpose of stability by using Power World Simulator software. The results show an enhancement in stability performances of the system over the conventional controllers. </span>

Power Quality Improvement of Grid Connected Inverter using DSSC

In most of the distribution systems, major issue named as Power quality is concern. Maximum power quality problems including harmonic compensation, voltage sags and voltage flickers are mitigating using Distributed Flexible Alternating Current Transmission System (D-FACTS) Devices. Distribution Static Series Compensator (DSSC) is one of the DFACT devices. The Simulation and modeling of DSSC for grid connected inverter with power quality improvement is presented here. Also, complexity and cost can be reduced by using Distributed Static Series Compensator (DSSC). More capabilities are posses by the same. MATLAB SIMULINK model is presented in this paper with results and discussion. Here, Total Harmonics Distortion is calculated with & without DSSC.

Imbalance Reduction of Three-phase Line Current Using Reactive Power Injection of the Distributed Static Series Compensator

This paper proposes the imbalance reduction algorithm for a three-phase line current in the power transmission system using distributed static series compensators (DSSCs). The DSSC compensates reactive power by injecting a reactive voltage into the transmission line, which can control the magnitude of the line current. In the proposed algorithm, the three-phase line current becomes equally balanced by adjusting the magnitude of the injected reactive voltage. By doing so, the power transmission capability of the transmission line is improved. To verify the performance of the algorithm, the simulations are done by PSIM software, and the experiments are conducted using the scaled down transmission system with the DSSC prototype modules. Both the simulations and the experiments show that the proposed algorithm can effectively compensate significant imbalance conditions.

DSSC: A Distributed Power Flow Controller

Distributed Static Series Compensator (DSSC) is a distributed power flow controller connected in series providing active power flow control through transmission line in cost effective way. DSSC is a low power compensator that can be directly attached on the existing transmission line. This paper presents modeling and control of Distributed Static Series Compensator in MATLAB software. Mathematical model of DSSC device is developed and it is implemented on two bus system to demonstrate power flow control through line. For significant power flow control number of DSSC devices need to be connected on the line. A particle swarm optimization technique is used to find optimum number of DSSC devices on the existing line with the objective that no line would be overloaded. Optimum number of DSSC devices is implemented on IEEE-14 bus test system and demonstrated power flow control.

Impact Analysis of DSSC on Distance Relay Performance under Fault Conditions

This paper demonstrates the impact analysis of the Distributed Static Series Compensator (DSSC), on the performance of distance relay protection of high voltage transmission lines. The concept of DSSC model with its control circuit and distance relay are described. A five bus test system with DSSC and distance relay is designed with the help of MATLAB/SIMULINK software. The impact of DSSC on distance protection relay for different fault conditions and various fault locations is analyzed. The results of simulation show that the connection of DSSC in the transmission system changes the transmission line impedance greatly as estimated by the distance relay to be less or greater than the actual impedance in fault conditions. Hence, the distance relay performance changes, either over reaches or under reaches.

Contingency Analysis of Ethiopia’s 230 kV Transmission Network

Transmission line congestion is any one of the failure that leads the overall transmission network to be either in over loaded or under loaded condition. Loading effects of the entire network may lead the system to cascaded outage or total blackout. The study concentrated on the contingency analysis of Ethiopia’s 230KV transmission network a case of Sebeta to Kaliti transmission line. The outage of this line cause overloading on Gefersa to Kaliti transmission line and makes the system not to be secure and reliable; further cascaded outage will lead the system to the total blackout. The analysis of such problems has been investigated by considering four scenarios like normal state, single line outage, cascaded line outage and inserting Distributed Static Series Compensator (DSSC) in to the over- loaded line. As a result, the system became reliable and secure by inserting the device in the most sensitive line of the network.

Optimal distributed static series compensator placement for enhancing power system loadability and reliability

Distributed static series compensator (DSSC) is a member of the family of distributed flexible AC transmission system devices that can be attached directly to conductors of transmission lines. DSSCs are able to compensate for and adjust the line reactance; thus, they could be widely used in stability-limited transmission systems. Owing to economic matters, the optimal placement of DSSCs is of a great interest from practical viewpoints. This study presents an approach to find the optimal locations of DSSCs to enhance the system loadability and reliability using the DC load flow model. The optimisation problem is solved using the mixed-integer linear programming. A compromise between improving the system loadability and reliability is fulfilled and a wide range of non-dominated optimal solutions is calculated. The final solution is then selected using the fuzzy satisfying method. Numerical studies are conducted on the IEEE reliability test system (IEE-RTS).

Distributed Series Static Compensator Deployment Using a Linearized Transmission System Model

Distributed static series compensators (DSSCs) are power-electronics devices that can inject positive or negative reactive impedance into a transmission line by connecting to it in series through a transformer suspended from the line. This paper presents a method for linearizing a transmission network, allowing the relationships between the network operating points and the injected reactances to be easily derived and thereby illuminating how best to deploy DSSCs. The model, which is general and applies to arbitrarily complex systems, is simplified into a form that provides additional insights without knowledge of the system topology or operating state. Using standard IEEE test systems, examples are given where DSSCs are used to raise load bus voltage, reduce line current, or reduce generator reactive power.

Enhancement and Design Considerations Distributed FACTS for Mitigation of Power Quality problem

This paper introduces the concept of a distributed static series compensator (DSSC) for 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. Index Terms: Distributed FACTS, Flexible AC Transmission Systems (FACTS), interconnected power systems, MATLAB Simulink and programming, Power flow control.

DISTRIBUTED STATIC SERIES COMPENSATOR (DSSC) APPLICATION TO POWER SYSTEM- A REVIEW

This paper is showcasing review of distributed static series compensator ( DSSC) & explains the effect of insertion of DSSC in transmission line power flow control. FACTS ( Flexible AC Transmission System) technology the aspect of Power Electronics offers High speed & reliability of switching & thus the value of electric energy is enhance. Along with merits there are certain problems offered by FACTS technology which leads to complexity in operation & overall cost investment becomes large. The solution to this is DFACTS technology i.e Distributed FACTS devices can be used in distributed position and DSSC belongs to DFACTS family.

Interaction analysis of multifunction FACTS and D-FACTS controllers by MRGA

With the growing application of flexible AC transmission systems (FACTS) and distributed FACTS (D-FACTS), the coordinating problem of FACTS and D-FACTS controllers in joint operation must be considered in modern power systems. The main purpose of this paper is to investigate the possible interaction that may occur between the distributed static series compensator (DSSC) and the static synchronous compensator (STATCOM) when they operate concurrently in the power system. The modified relative gain array (MRGA) is implemented to analyze the interactions. The application of MRGA for the effective design of multiobjective controllers of the STATCOM and DSSC is demonstrated by 2 cases of study: the first case includes the contradiction among the AC voltage control, DC link capacitor voltage control, and power oscillation damping controller of the STATCOM, and the second case is dedicated to the interaction between the different controllers of the DSSC and the STATCOM. The simulation results are carried out in PSCAD/EMTDC in order to verify the results obtained from MRGA analysis in both cases of study.

Fault Current Limitation (FCL) and Voltage Dip Improvement Thanks to Distributed Static Series Compensator (DSSC)

This paper presents the comprehensive implementation of Distributed Static Series Compensator (DSSC) to limit the fault currents in power systems. This is the first time that the limitation of fault currents with D-FACTS devices is addressed. DSSC is one of the D-FACTS families whichoperate in a similar manner as Static Synchronous Series Compensator (SSSC) but in smaller size, lower price and more capability. The effectiveness of the DSSC in fault current limitation is investigated through the series voltage effect upon the line. The short circuit current limitation strategy presented here exhibited that besides of the power flow control which is carried out by DSSC; it can also perform this additional function. In the following the potency of the DSSC in reduction of instantaneous voltage dip range during fault current limiting mode is clarified. Furthermore, it is disclosed that with performing more DSSC in the power system, the entire system voltage dip will be improved. In order to validate the claims, computer simulations using PSCAD/EMTDC are exploited.

Sub-Synchronous Resonance damping using Distributed Static Series Compensator (DSSC) enhanced with fuzzy logic controller

When a steam Turbine-Generator is connected to a series compensated long transmission line, an adverse phenomenon namely Sub-Synchronous Resonance (SSR) may occur. The main purpose of this work is to verify the capability of the Distributed Static Series Compensator (DSSC) as a member of D-FACTS family in mitigating the SSR. Two novel controllers as: the Particle Swarm Optimization (PSO)-based Conventional Damping Controller (CDC) and the Fuzzy Logic Based Damping Controller (FLBDC) are designed and implemented in traditional controller of the DSSC in order to provide the effective damping. The system stability is studied through time domain simulations, Fast Fourier Transform (FFT) analysis, and a Performance Index (PI) which is defined based on the dynamics of the power system. Simulation results are carried out with MATLAB/Simulink on the IEEE Second Benchmark Model (SBM) aggregated with the DSSC modules. Three various cases of study are considered in order to compare the operation of the proposed FLBDC with the PSO based CDC in different transient states.

Transient Stability Enhancement in Power System Using DSSC and DSSC with FLC

Long distance AC transmission system is often subjected to stability problems which limit the transmission capability. Large power systems often suffer from weakly damped swings between synchronous generators. This paper aims to enhance the transient stability of the power system with the use of distributed static series compensator (DSSC) and DSSC with fuzzy logic controller (FLBDSSC). First of all, a detailed simulation model of the DSSC has been presented. DSSC has a function like static synchronous series compensator (SSSC) but is in smaller size and lower price along with more other capabilities. Likewise, DSSC lies in transmission lines in a distributed fashion. In this work, we designed a fuzzy logic controller to use the DSSC for enhancing transient stability in in a two-machine, two-area power system. The parameters of the fuzzy logic controller are varied widely by a suitable choice of membership function and parameters in the rule base. Simulation results demonstrate the effectiveness of the fuzzy controller for transient stability enhancement by DSSC.

Probabilistic Worth Assessment of Distributed Static Series Compensators

The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a number of DSSCs. To illustrate the worth of DSSC utilization, the increment in the expected interruption cost is computed by using a composite reliability assessment. In the contingency analysis procedure, incorporating the active control of power flow provided by DSSCs makes the optimal load curtailment subproblem nonlinear. In order to linearize the subproblem, a novel set of inequalities is extracted. Numerical analysis on the IEEE Reliability Test System (RTS) is conducted to examine the effect of DSSC on composite reliability indices. The results reveal the effectiveness of proposed models and illustrate that DSSCs enhance the system reliability.

Distributed static series compensator (DSSC) for subsynchronous resonance alleviation and power oscillation damping

SUMMARYSubsynchronous resonance (SSR) is a frequent adverse phenomenon in series‐compensated lines threatening either or both mechanical facilities and power system stability. It is widely accepted that flexible ac transmission system (FACTS) can provide an effective solution to relieve the SSR. On the other hand, the advent of distributed FACTS (D‐FACTS) technology has led to the more economical deployment of the flexible devices in the power system control. This paper aims to verify the capability of distributed static series compensator (DSSC) in SSR mitigation. As a member of D‐FACTS family, the DSSC functions in the same way as a static synchronous series compensator (SSSC), but is in smaller size, lower in price, and possesses more capabilities. DSSC lies in transmission lines in a distributed manner. In this work, as the first step a detailed simulation model for the DSSC is extracted. In the following, simulations are carried out using EMTDC/PSCAD on the IEEE first SSR benchmark model aggregated with DSSC modules. Simulation results demonstrate that the DSSC modules which already installed in the power system with the primary objective of power flow control can also damp SSR with the use of an auxiliary SSR damping (SSRD) controller. Extensive time domain simulations are utilized to validate the effective performance of DSSC in mitigating SSR. Copyright © 2011 John Wiley & Sons, Ltd.

Transient Stability Enhancement by DSSC with Fuzzy Supplementary Controller

The distributed flexible alternative current transmission system (D-FACTS) is a recently developed FACTS technology. Distributed Static Series Compensator (DSSC) is one example of DFACTS devices. DSSC functions in the same way as a Static Synchronous Series Compensator (SSSC), but is smaller in size, lower in price, and possesses more capabilities. Likewise, DSSC lies in transmission lines in a distributed manner. In this work, we designed a fuzzy logic controller to use the DSSC for enhancing transient stability in a two-machine, two-area power system. The parameters of the fuzzy logic controller are varied widely by a suitable choice of membership function and parameters in the rule base. Simulation results demonstrate the effectiveness of the fuzzy controller for transient stability enhancement by DSSC.