Synchrophasors\u27 Application in SVC for Industrial Networks

It is widely understood that as fuel and energy prices continue to increase, new and innovative ways of becoming more energy efficient will be required. This couldn\u27t be more apparent than in industry, where every decision is constrained by economics. Power factor correction is a cost effective way for industry to have economically sound improvements with maximum efficiency benefits. It is proposed that in large industrial systems, where an SVC (Static Var Control) system could be used, synchrophasor measurements could also be used to control the SVC and provide enhanced historical analysis. Currently, many protective relays used in industry provided by SEL (Schweitzer Engineering Laboratories) already have this capability built-in. While synchrophasor measurement technology is still relatively unknown, they are a powerful tool that could greatly increase power system control, efficiency and historical data analysi

Coordinated active power reduction strategy for voltage rise mitigation in LV distribution network

Integration of renewable energy systems by the utility, customers, and the third party into the electric power system, most especially in the MV and LV distribution networks grew over the last decade due to the liberalization of the electricity market, rising energy demand, and increasing environmental concern. The distributed rooftop PV system contributes to relieve the overall load, reduce losses, avoid conventional generation upgrade, and better matching of demand on the LV distribution network. Originally, the LV distribution network is designed for unidirectional current flow, that is from the substation to customers. However, a high penetration of rooftop solar PVs (with power levels typically ranging from 1 – 10 kW) may lead to the current flowing in the reverse direction and this could result in a sudden voltage rise. These negative impacts on the network have discouraged the distribution network operators (DNOs) to allow increased PV penetration in the LV distribution network because some customers load, and equipment are sensitive to voltage perturbation. Presently, the most applied voltage rise mitigation strategy for high rooftop solar PV penetration is the total disconnect from the LV distribution network when the voltage at the point of common coupling (PCC) goes above statutory voltage limits. However, the sudden disconnection of the PV system from the grid can cause network perturbation and affect the security of the network. This action may also cause voltage instability in the network and can reduce the lifetime of grid equipment such as voltage regulators, air conditioner etc. Due to this negative impact, different voltage rise mitigation strategies such as the active transformer with on load tap changers (OLTC), distributed battery energy storage system and reactive power support (D-STATCOM, etc.) have been used to curtail voltage rise in the distribution network. However, the implementation of D-STATCOM device on a radial LV distribution network results in high line current and losses. This may be detrimental to the distribution network. Therefore, in this thesis, a coordinated active power reduction (CAPR) strategy is proposed using a modified PWM PI current control strategy to ramp down the output power and voltage of a grid-tied voltage source inverter (VSI). In the proposed strategy, a reactive reference is generated based on the measured voltage level at the PCC using a threshold voltage algorithm to regulate the amplitude of the modulating signal to increase the off time of the high frequency signal which shut down the PV array momentary in an extremely short time and allow the VSI to absorb some reactive power through the freewheeling diode and reduce voltage. The proposed CAPR strategy was designed and simulated on a scaled down simple radial LV distribution network in MATLAB®/Simulink® software environment. The results show that the CAPR can ramp down the PV output power, reduce reverse power flow and reduce the sudden voltage rise at the point of common coupling (PCC) within ±5% of the standard voltage limit. The study also compares the performance of the proposed CAPR strategy to that of the distributed static compensator (D-STATCOM) and battery energy storage system (BESS) with respect to response time to curtail sudden voltage rise, losses and reverse power flow. The investigation shows that the D-STATCOM has the faster response time to curtail voltage rise. However, the voltage rise reduction is accompanied by high current, losses and reverse active power flow. The introduction of the BESS demonstrates better performance than the D- STATCOM device in terms of reverse power flow and losses. The CAPR strategy performs better than both D-STATCOM and BESS in terms of line losses and reverse power flow reduction

Multi-objective power quality optimization of smart grid based on improved differential evolution

In the modern generation, Electric Power has become one of the fundamental needs for humans to survive. This is due to the dependence of continuous availability of power. However, for electric power to be available to the society, it has to pass through a number of complex stages. Through each stage power quality problems are experienced on the grid. Under-voltages and over-voltages are the most common electric problems experienced on the grid, causing industries and business firms losses of Billions of dollars each year. Researchers from different regions are attracted by an idea that will overcome all the electrical issues experienced in the traditional grid using Artificial Intelligence (AI). The idea is said to provide electric power that is sustainable, economical, reliable and efficient to the society based on Evolutionary Algorithms (EAs). The idea is Smart Grid. The research focused on Power Quality Optimization in Smart Grid based on improved Differential Evolution (DE), with the objective functions to minimize voltage swells, counterbalance voltage sags and eliminate voltage surges or spikes, while maximizing the power quality. During Differential Evolution improvement research, elimination of stagnation, better and fast convergence speed were achieved based on modification of DE’s mutation schemes and parameter control selection. DE/Modi/2 and DE/Modi/3 modified mutation schemes proved to be the excellent improvement for DE algorithm by achieving excellent optimization results with regards to convergence speed and elimination of stagnation during simulations. The improved DE was used to optimize Power Quality in smart grid in combination with the reconfigured and modified Dynamic Voltage Restorer (DVR). Excellent convergence results of voltage swells and voltage sags minimization were achieved based on application of multi-objective parallel operation strategy during simulations. MATLAB was used to model the proposed solution and experimental simulations.Electrical and Mining EngineeringM. Tech. (Electrical Engineering

Utility Applications of Smart Online Energy Systems: A case for Investing in Online Power Electronics

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