An Assessment of PIER Electric Grid Research 2003-2014 White Paper

This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of California’s California Institute for Energy and the Environment, from 2003-2014

Strategic distribution network planning with smart grid technologies

This paper presents a multiyear distribution network planning optimization model for managing the operation and capacity of distribution systems with significant penetration of distributed generation (DG). The model considers investment in both traditional network and smart grid technologies, including dynamic line rating, quadrature-booster, and active network management, while optimizing the settings of network control devices and, if necessary, the curtailment of DG output taking into account its network access arrangement (firm or non-firm). A set of studies on a 33 kV real distribution network in the U.K. has been carried out to test the model. The main objective of the studies is to evaluate and compare the performance of different investment approaches, i.e., incremental and strategic investment. The studies also demonstrate the ability of the model to determine the optimal DG connection points to reduce the overall system cost. The results of the studies are discussed in this paper

Probabilistic Reliability Analysis of Electric Power Systems with Smart Grid Technologies and Water Distribution Networks: Modeling, Assessment, and Comparison

With the rapid growth of population, the modern human society is becoming more and more dependent on the proper operation of critical infrastructures - the interconnected electrical power system, the drinking water distribution and supply system, the natural gas transmission and distribution system, and so forth. It has become an important issue to maintain reliable functions of these critical systems. As a result, comprehensive reliability evaluation is highly needed to quantify their reliability in an objective manner. Conventionally, deterministic criteria were used in reliability evaluations. However, it lacked the ability to model and quantify the stochastic nature of system behaviors such as component failures. In light of these facts, this thesis deploys probabilistic methodologies for conducting quantitative reliability modeling and assessment for nation’s critical infrastructures including electrical power networks incorporating smart grid technologies and water distribution networks. Power system operators are faced with the increasingly complicated operating conditions in bulk power systems. Yet due to the huge investment needed to build new power delivery facilities, cost-effective solutions such as new operational strategies are becoming more attractive and viable in recent years. Optimal transmission switching (OTS) and dynamic thermal rating (DTR) are two such technologies which offer a potential solution to improving the power system reliability by more fully utilizing the existing power delivery assets. In this thesis, these two technologies are first discussed, which are then incorporated into the power system reliability evaluation procedure. Case studies are conducted on modified RTS-79 and RTS-96 systems using MATLAB and IBM CPLEX. The obtained simulation results have shown that with the enforcement of either OTS or DTR technology, the overall system reliability can be improved, and system reliability can be further improved if both technologies are enforced. The growing urban population has brought great stress to the aging drinking water distribution systems. It is becoming more challenging to maintain a reliable drinking water distribution system so as to meet the growing water demand. Thus, a comprehensive reliability evaluation of the aging water delivery infrastructure is of critical importance to enable informed decision-making in asset management of the potable water sector. This thesis also proposes a probabilistic reliability evaluation methodology for water distribution systems based on Monte Carlo simulation (MCS) that takes into account both mechanical failures and hydraulic failures. Additionally, a C++ based software tool is developed to implement the proposed method. Case studies based on two representative water distribution systems are performed to demonstrate the effectiveness of the proposed method. A comparison is made between the reliability analysis of electrical power systems and that of water distribution systems. As interconnected capacitated networks, both systems share similarities in certain aspects such as component modeling and adequacy constraints. However, the specific features of the target systems should also be taken into consideration in the reliability modeling and evaluation in order to obtain a more comprehensive and accurate estimation of the actual system reliability

European White Book on Real-Time Power Hardware in the Loop Testing : DERlab Report No. R- 005.0

The European White Book on Real-Time-Powerhardware-in-the-Loop testing is intended to serve as a reference document on the future of testing of electrical power equipment, with specifi c focus on the emerging hardware-in-the-loop activities and application thereof within testing facilities and procedures. It will provide an outlook of how this powerful tool can be utilised to support the development, testing and validation of specifi cally DER equipment. It aims to report on international experience gained thus far and provides case studies on developments and specifi c technical issues, such as the hardware/software interface. This white book compliments the already existing series of DERlab European white books, covering topics such as grid-inverters and grid-connected storag

Power system planning methods and experiences in the energy transition framework

In recent years, the unbundling of the electricity market together with the profound “energy landscape” transformation have made the transmission network development planning a very complex multi-objective problem. The climate and energy objectives defined at the European level aim for a deepening integration of the European power markets and the electricity sector is recognized as one of the main contributors to the energy transition from a thermal-based power system to a renewable-based one. In the deregulated framework, network planners have to satisfy multiple different objectives, including: facilitating competition between market participants, providing non-discriminatory access to all generation resources for all customers, including green resources, mitigating transmission congestions, efficiently allocating the network development actions, minimizing risks associated with investments, enhancing power system security and reliability and minimizing the transmission infrastructure environmental impact. Further complexities are related to the significant uncertainty about future energy scenarios and policy rules. In particular, the increasing distributed renewable energy source integration dictated by the European energy targets, raises several issues in terms of future power flow patterns, power system flexibility and inertia requirements, and cost-effective development strategies identification. The thesis aims to investigate various aspects concerning the transmission network planning, with particular reference to the Italian power system and the experience gained working in the “Grid Planning and Interconnections Department” of Terna, the Italian Transmission System Operator. One of the main topics of this work is the use of the series compensation to exploit operating limits of underused portions of the HV – EHV transmission network in parallel to critically loaded ones, in order to control and provide alternative paths for power flows. The purpose is to extend the allowable transmission capacity across internal market sections. To this aim, a specific application of series compensation (together with reconductoring) to exploit the transfer capacity of a 250 km long, 230 kV-50 Hz transmission backbone spanning the critical section Centre South – Centre North is illustrated. The results are validated by means of static assessment and similar applications could be hypothesized for grid portions in the South of Italy where the primary network is mainly unloaded whereas the sub-transmission network reaches high levels of loading because of the huge renewable generation capacity situated there. A further characteristic of modern power systems is the need to integrate high levels of renewable energies while fulfilling reliability and security requirements. The offshore wind farms perspectives in the Italian transmission system are evaluated, considering policies, environmental and technical aspects. Furthermore, the adoption of the HVDC technology in parallel to the AC traditional system topic is addressed: planning static and dynamic studies involving a real HVDC Italian project are proposed. In particular, the impact of the planned HVDC link on the loadability and the dynamic performance of the system is investigated in medium and in long-term future planning scenarios. The evaluation of the thermal performance of a specific grid portion in the South of Italy affected by significant increase of power generation by variable energy sources is proposed both in the current situation and in the future scenarios in order to highlight the benefits related to the presence of the planned network reinforcements. Finally, some issues of the prospective reduced inertia systems are illustrated and a possible methodology to evaluate the economic impact of inertia constraints in long-term market studies is proposed. In the light of the emerging concept of power system flexibility, traditional planning evolved to assess the ability of the system to employ its resources when dealing with the changes in load demand and variable generation. Flexibility analyses of the Italian power system, carried out in terms of some market studies-based metrics and grid infrastructure-based indexes, are provided. The flexibility requirements assessment in planning scenarios are of interest to evaluate the impact of network development actions and have been included in the yearly National Development Plan. The last research topic involves the cost-effective target capacity assessment methodology developed by Terna in compliance with the Regulator directives presented together with the results yielded by its application to each significant market section of the Italian power system. The methodology has been positively evaluated from academic independent expert reviewers, and its outputs are relevant for the policy makers, regulatory authority and market participant to assess and co-design the energy transition plan of a future European interconnected power system