Increasing demand for electricity has placed heavy stress on power system security. Therefore, this paper focuses on the problem of how to maximize power system static security in terms of branch loading and voltage level under normal operation and even the most critical single line contingency conditions. This paper proposes a hybrid approach to find out the optimal locations and settings of two classical types of flexible AC transmission system (FACTS) devices, namely thyristor-controlled series compensators (TCSCs) and static var compensators (SVCs) for solving this problem. Our proposed approach requires a two-step strategy. Firstly, the min cut algorithm (MCA) and tangent vector technique (TVT) are applied to determine the proper candidate locations of TCSC and SVC respectively so as to reduce the search scope for a solution to the problem, and then the cuckoo search algorithm (CSA) is employed to solve this problem by simultaneously optimizing the locations and settings for TCSC and SVC installation. The proposed hybrid approach has been verified on the IEEE 6-bus and modified IEEE 14-bus test systems. The results indicate that CSA outperforms particle swarm optimization (PSO), proving its effectiveness and potential, and they also show that our proposed hybrid approach can find the best locations and settings for TCSC and SVC devices as an effective way for enhancing power system static security by removing or alleviating the overloads and voltage violations under normal operation and even the most critical single line contingency conditions. Using this hybrid approach, the search space for solution to the problem becomes limited hence the computational burden will be decreased.

https://www.mdpi.com/1996-1073/10/9/1305/pdf

A Hybrid Approach for Power System Security Enhancement via Optimal Installation of Flexible AC Transmission System (FACTS) Devices

Today's Power system is more complex and consequently it would lead to less security. To meet the demand and better security levels with existing transmission lines, the Flexible AC Transmission System (FACTS) devices are one of the alternates. In this paper a Newton Raphson(NR) algorithm was developed to find out the best operating point of a Static Var Compensator(SVC) for the enhancement of system security. The proposed algorithm minimizes the security index iteratively. Security index indicates the overload level of transmission lines. The proposed algorithm is verified by IEEE 5 bus system. Line power flows and bus voltages and bus angles are obtained by the Newton Raphson algorithm and the security index is calculated for both the cases with and without SVC. The results show that the voltage profile can be enhanced and the security margin increased by applying the proposed algorithm.

Modeling and simulation of static var compensator to enhance the power system security

The backbone of any power grid, the transmission and sub-transmission networks, should be flexible, robust, resilient and self-healing to cope with wide types of network adverse conditions and operations. Power electronic applications are making a major impact on the present and future state of power systems generation, transmission and distribution. These applications include FACTS (Flexible Alternating Current Transmission), HVDC (High Voltage Direct Current) in transmission and Custom Power devices in distribution. FACTS devices are some of the advanced assets that network planners can use to make the transmission grid become more flexible and robust. Many established research ideas to advance operations of these devices have been published in the open literature over the last ten years. The most recent publications in this field are reviewed in this thesis. A critical analysis of literature and existing conditions reveals a range of potentials that are ideal for development in Qatar’s increasingly strained electricity network. As a result of demand surge in Qatar in recent years and the forecast to grow in the same rate, the need for improvement in Qatar Power Transmission System (QPTS) is great and significant. Conventional planning and operational solutions such as conductor up-rating, and fixed series capacitors (FSC) are considered. However there are growing challenges on getting new rights of ways for new overhead lines and even corridors for new cables. Advanced FACTS devices are considered for dynamic control of power flows and voltages, such as TCSC (Thyristor Controlled Series Capacitor) and GUPFC (Generalized, Unified Power Flow Controller). The research in this thesis examines the potential for QPTS to improve and develop, with emphasis on increased output through integrated online energy systems, online FACTS and HVDC controllers based on synchrophasor measurements. The devices are modelled in Siemens PTI’s PSS®E software, through steady-state mode case study to investigate power flow control and voltage support. Comparison between similar FACTS technologies, such as SVC and STATCOM, is also presented. The improvement in power flow imbalance between transmission lines with different ratings and lengths is studied. The FACTS devices are tested for voltage support to enhance the network voltage profile and hence increase security and reliability to important industrial customers. Optimization techniques of the FACTS devices allocation and rating are generally discussed considering the voltage improvement and optimal power flow control. The results achieved showing the network improvement with using the FACTS are presented in the case studies. In a separate case study, applying medium voltage custom power devices to convert DC battery storage and photovoltaic energy into AC energy using a power conversion system is discussed. The dynamic mode of the STATCOM is modelled in QPTS in the succeeding case study using the same software and compared with the capacitor banks. This is followed by another case of HVDC analysis modelled with and without STATCOM present. The thesis discussed the real time operation and control of power system physical parameters in QPTS using capacitors, FACTS and HVDC. The key contribution of this thesis is the application and resting of all sorts of FACTS and HVDC in QPTS. The system wide area, coordinated control of FACTS (Online Power Electronics-OPE) is a new concept. Another major contribution is being able to look at a system wide approach for a transmission smart grid application. The results of thesis are presented in international conferences in USA, Hong Kong, France, Portugal, and locally in the Arabian Gulf (Dubai, Oman and Qatar). The thesis’s papers are listed in the ‘References’ section and in Appendix-F.

Utility applications of smart online energy systems : a case for investing in online power electronics

The problem of transmission network congestion or overloading poses a serious challenge to most power utilities around the world. One solution to this problem is the use of FACTS devices. This paper presents an empirical comparison of different optimal placement models of FACTS devices in a power system network with the objective to maximize the system loadability (SL). The three configuration are considered in this comparison. In the first case only TCPST is considered, while in the second case only TCSC is considered and in the third one a combination of several devices is considered. The results show that the first and the third configuration performs better economically and in terms of system losses.

Comparison of Different Optimal Placement Models of FACTS Devices in Power System Networks on a Limited Budget

System security enhancement using hybrid HUA‐GPC approach under transmission line(s) and/or generator(s) outage conditions

The role of the FACTS device in power system security enhancement is very important. But type and location of this device must be defining. This paper presents a novel algorithm for allocation of multi-type FACTS devices based on Genetic Algorithm (GA) using a multi-objective optimization function. Proposed algorithm is tested on IEEE 5&6test system and WSCC 9-bus power system and enhancement security index to more of the double and decrease the loss of system about 25%. With shown the comparison of this paper results and result in a recent paper, indicate the ability of proposed method to enhancement of power system security.

Power system security improvement with optimal placement of FACTS devices using genetic algorithms

In this paper, a scalable hybrid video codec has been developed for HDTV video signals. The intra frame pictures are coded based on wavelet transform and inter frame pictures are coded with a standard MPEG-2 codec. By scalable coding of HDTV, channels transmit with various speeds and capacities; In addition, receivers can work at different resolutions. Base layer and enhancement layer of the frame picture are coded with same codec. This paper compares scalable hybrid coding with scalable MPEG-2 codec and scalable DWT2 method for HDTV video signals. It is showed that the quality of intra frame improves by using the proposed codec in comparison with two other methods. By this improvement, the quality of sequence increases.

Jalal Teymouri

Papers

Power system security improvement with optimal placement of FACTS devices using genetic algorithms

Hybrid spatial scalable video codec for HDTV video images