Study on the performance indicators for smart grids: a comprehensive review

This paper presents a detailed review on performance indicators for smart grid (SG) such as voltage stability enhancement, reliability evaluation, vulnerability assessment, Supervisory Control and Data Acquisition (SCADA) and communication systems. Smart grids reliability assessment can be performed by analytically or by simulation. Analytical method utilizes the load point assessment techniques, whereas the simulation technique uses the Monte Carlo simulation (MCS) technique. The reliability index evaluations will consider the presence or absence of energy storage elements using the simulation technologies such as MCS, and the analytical methods such as systems average interruption frequency index (SAIFI), and other load point indices. This paper also presents the difference between SCADA and substation automation, and the fact that substation automation, though it uses the basic concepts of SCADA, is far more advanced in nature

Technical performance and stability analysis of eskom power network using 600kv, 800kv, and 1000kv hvdc.

Master of Medical Science in Electrical Engineering. University of KwaZulu-Natal, Durban 2016.In designing electric power networks or implementing major expansions to existing networks, a number of the key issues regarding the technical performance of the network at both transmission and distribution level must be ascertained, namely: voltage regulation, voltage fluctuations, electrical losses, transmission/distribution plant loading and utilization, fault level, generation stability, harmonics, phase balancing, supply availability and system security. System studies and analysis conducted from time to time to ascertain the operating state of a network, taking into account, load growth projections for the future. Undue stresses on the system or anticipated problems are determined from power flow analysis or during operation and maintenance. Using a modified Eskom network (KwaZulu-Natal sub-grid) as a case study, the technical and stability analysis for different high voltage direct current (HVDC) transmission voltages: 600kV, 800kV and 1000kV were carried out using DIgSILENT PowerFactory engineering software tool, as an alternative for bulk power transfer using high voltage alternating current (HVAC) link along the major corridors. Static analysis using PV and QV curves; dynamic analysis using RMS time domain and electromagnetic EMT analysis were carried out. Dynamic analyses were performed to determine the system fault levels and critical fault clearing time. Results obtained from this investigation show that 600kV and 800kV HVDC transmission systems have greater power capacity than equivalent HVAC line. HVDC delivery systems were observed to have lower electrical losses, better voltage profile, increase fault clearing time, enabling robust protection schemes to be installed. Voltage distortion due to harmonic content and imperfect current waveform in Cahosa-Bassa LCC-HVDC link were also investigated, and re-engineering with the use of VSC-HVDC technology has been proposed. This option provides reduced harmonic content, excellent sinusoidal waveform and minimal vulnerability to commutation failure. A financial and economic analysis of a 500kV HVAC double circuit and ±600kV HVDC transmission network were compared. HVDC system was proposed the most suitable scheme for bulk transmission of electric power over long distances due to high efficiency and better economics

H2 Control for Improved Stability of Multi-area Electric Power System with High Levels of Inverter-Based Generation

Increased generation capacity from non-dispatchable energy resources such as wind and solar has created challenges to ensuring the reliable delivery of electric power. This research develops a systematic three-step method of assessing the reliability of electric power systems under a variety of different possible fault conditions to ensure that overall system stability is preserved in a manner the meets regulatory requirements. The first step is a risk-based reliability method (RBRM) that accounts for the probability of a line outage versus the severity of impact. This allows system planners to judiciously allocate expenses for reliability improvements based on the greatest economic benefit. The second approach is the synchrophasor validation method (SVM) which allows system planners and analysis to develop accurate models of electric power system behavior. This improves the decision making capability for implementing new system designs and equipment choices. The third new area is the development of norm-based wide-area control methods that optimize system stability and reliability based on the statistical characteristics found in the first two steps. This norm-based approach includes calculating optimal values for parameters of flexible ac transmission system (FACTS) devices and high voltage direct current (HVDC) links in order to have results within the regulatory requirements of the North American Electric Reliability Corporation (NERC). Power flow and frequency criteria are used to verify conformance with the regulations. These criteria are evaluated under N-1-1 conditions in two reduced order models to demonstrate the ability of the norm-based wide-area controller to maintain performance of these systems within acceptable ranges. The obtained simulation results confirm the benefits of the proposed technique in meeting regulatory requirements under conditions of N-1-1 contingencies in electric power systems with large amounts of renewable energy resources

Efficacy of Smart PV Inverter as a Strategic Mitigator of Network Harmonic Resonance and a Suppressor of Temporary Overvoltage Phenomenon in Distribution Systems

The research work explores the design of Smart PV inverters in terms of modelling and investigates the efficacy of a Smart PV inverter as a strategic mitigator of network harmonic resonance phenomenon and a suppressor of Temporary Overvoltage (TOV) in distribution systems. The new application and the control strategy of Smart PV inverters can also be extended to SmartPark-Plug in Electric Vehicles as the grid becomes smarter. As the grid is becoming smarter, more challenges are encountered with the integration of PV plants in distribution systems. Smart PV inverters nowadays are equipped with specialized controllers for exchanging reactive power with the grid based on the available capacity of the inverter, after the real power generation. Although present investigators are researching on several applications of Smart PV inverters, none of the research-work in real time and in documentation have addressed the benefits of employing Smart PV inverters to mitigate network resonances. U.S based standard IEEE 519 for power quality describes the network resonance as a major contributor that has an impact on the harmonic levels. This dissertation proposes a new application for the first time in utilizing a Smart PV inverter to act as a virtual detuner in mitigating network resonance. As a part of the Smart PV inverter design, the LCL filter plays a vital role on network harmonic resonance and further has a direct impact on the stability of the controller and rest of the distribution system. Temporary Overvoltage (TOV) phenomenon is more pronounced especially during unbalanced faults like single line to ground faults (SLGF) in the presence of PV. Such an abnormal incident can damage the customer loads. IEEE 142-“Effective grounding” technique is employed to design the grounding scheme for synchronous based generators. The utilities have been trying to make a PV system comply with IEEE 142 standard as well. Several utilities are still employing the same grounding schemes even now. The attempt has resulted in diminishing the efficacy of protection schemes. Further, millions of dollars and power has been wasted by the utilities. As a result, the concept of effective grounding for PV system has become a challenge when utilities try to mitigate TOV. With an intention of economical aspects in distribution systems planning, this dissertation also proposes a new application and a novel control scheme for utilizing Smart PV/Smart Park inverters to mitigate TOV in distribution systems for the first time. In other words, this novel application can serve as an effective and supporting schema towards ineffective grounding systems. PSCAD/EMTDC has been used throughout the course of research. The idea of Smart inverters serving as a virtual detuner in mitigating network harmonic resonance and as a TOV suppressor in distribution systems has been devised based on the basic principle of VAR injection and absorption with a new control strategy respectively. This research would further serve as a pioneering approach for researchers and planning engineers working in distribution systems

Demand-Side Flexibility for Energy Transitions: Ensuring the Competitive Development of Demand Response Options

This report provides an overview of the current debates about demand response development, focusing primarily on Europe, with some comparisons to the United States. ‘Demand response’ includes strategies that involve end-use customers adapting or altering their electricity demand in response to grid conditions or market prices. It is viewed as a multi-purpose power-system resource that enhances the energy system’s capacity to cope with increasing demand, rising costs of conventional transmission and distribution grids, and increasing share of intermittent renewable energy. The report reviews risks, opportunities, potential, consumer engagement market design, and policy and regulation