Both world’s population and energy consumption per capita are projected to double in 2050 by recent studies. In the meantime, the power grids are aging according to recent reports. This represents a strong impetus, necessity and opportunity for grid modernization. Grid modernization represents a win-win-win situation for consumers, grid operators/utilities, and the environment. Six basic characteristics of a modern power grid are discussed, which are electronic, fractal, structured, fault-tolerant, resilient and asynchronous. This paper presents a unique realistic vision for the modern grid architecture that is physically realizable with today’s state-of-the-art technologies. It is shown that we can meet the world’s challenge in energy demand by optimally managing capacities in generation, transmission and distribution, and behind the meter using power electronics and systems (PEAS) technology.

Developing high penetration of wind and solar photovoltaic (PV) power generation is an inevitable choice to maintain ecological civilization and realize sustainable development of the society. On one hand, wind and solar PV power generation can be developed in areas near the load centers and consumed locally with extensive distributed wind and solar PV power generation systems, i.e., the so-called “local development and consumption” mode. On the other hand, wind and solar PV power generation can also be developed in areas far away from the load centers with wind and solar PV bases and then the electricity generated there will be transmitted to the load centers by long distance transmission lines (e.g. by UHVDC lines), i.e., the so-called “large-scale and long-distance transmission” mode. Nevertheless, how wind and solar PV power is developed and consumed will make a big difference to the smooth realization of high penetration renewable energy scene. The following conclusions have already been achieved in a study based on mathematical optimization approach that under the current situation that coal-fired thermal power units play the main role in peak load regulation, the only way to achieve high penetration of wind and solar PV power generation is with local development and consumption mode. To help readers understand the above conclusion better, firstly, in this paper, the basic features of interconnected power systems are introduced and compared with the basic features of the internet. Then, from the philosophy of interconnected power systems, a qualitative analysis and brief illustration are carried out to the two modes above in the following three perspectives: renewable energy electricity ratio, system operation and available regulation capacity. Finally, through a specific simulation case, the effective measures needed to help power system integrating high penetration of wind and solar PV power are displayed under the condition of taking the local development and consumption mode.

Microgrids are self-controllable localized power systems which represent a building block of smart grid. Microgrid master controller considers communication, control, and management functionalities, which play a significant role in economic and secure operations of microgrids. This paper applies the principles introduced in the design and the operation of the master controller at IIT microgrid to discuss the merits of smart grid. After presenting the hierarchy in the IIT microgrid control architecture, this paper discusses the implementation details and the laboratory setup for testing the IIT microgrid master controller. This paper also points out potential burdens assumed by microgrid master controllers to reflect the emergence of software-defined networking technologies as well as the development of networked microgrids and energy hubs.

Toward the vision of building power systems with high proportion of renewable energy, the development of distributed electro-thermic energy systems promoting the participation of “demand side” into power grid operation is one of the key technologies, in addition to increasing renewable generation utilization ratio and building a multi-energy grid. The value, function and challenges of distributed electro-thermic energy systems are introduced for developing power systems with high proportion of renewable energy, case studies on the new commercial applications of high performance, distributed electro-thermic energy systems in Denmark and Germany are presented, its characteristics as well as engineering and economic conditions are briefly discussed. At last, application prospect and development thinking of advanced distributed electro-thermic energy system in China are provided; with a realistic example of Shenzhen Grid, its value of application are analyzed, and the suggestions are provided for its promotion in China.

Along with technical trends in recent years, modern power distribution systems are rapidly evolving into complex cyber-physical systems integrated with a large number of dispersed energy resources, multi-disciplinary communication technology and computing & control technology, referred as “active distribution network (AND)”. This paper discusses the vision of constructing the data-centric energy ecosystem in AND. The definition and key characteristics of energy ecosystem are discussed. Particularly, a distributed, data-centric cyber-physical infrastructure is proposed to support constructing the energy ecosystem in future ADNs. We also discuss the multi-dimensional service model and interaction environment which the infrastructure can deliver to AND. Finally, we propose some innovative data-centric applications that can be built on the cyber-physical infrastructure, which can also be considered as a roadmap for future open research and development.

A solution is proposed to mitigating voltage fluctuations caused by stochastic changes in wind and marine current speeds and also electrical faults in an integrated off-shore wind farm and marine current farm (OWF-MCF) system connected to a complex power grid. Two sets of PI controllers are proposed for a thyristor-controlled reactor (TCR)-based static var compensator (SVC) and also for a static synchronous compensator (STATCOM) to alleviate the voltage oscillations and improve the stability. Performances of the proposed scheme are compared and analyzed. The OWF makes use of the popular type III wind energy conversion system while the MCF utilizes a generic induction generator marine turbine, the integrated OWF-MCF energy system with two kinds of proposed controllers is also capable of extracting the maximum kinetic energy from the ambient environment.

Loading margin sensitivity analyses are often performed for voltage stability assessment (VSA) and control due to the complexity of such applications. Traditional power system algebraic model based loading margin sensitivity analyses require full detailed system models and non-trivial amount of computation, therefore they are not good candidate for online applications. Based on the coupled single-port circuit concept, this paper proposes a new method of measurement-based wide-area loading margin sensitivity (WALMS) for VSA and control that is suitable for online applications. Enabled by wide-area measurement systems and their measurements, the proposed model derives the analytical expression of the sensitivity of loading margin (LM) versus active power injection, reactive power injection and generator terminal voltage. Consequently, the WALMS is computational more efficiently than its model-based counterparts. Based on the WALMS, a multi-step control strategy is developed to improve voltage stability. Simulation results on the IEEE 39-bus system verify the WALMS and validate the multi-step control strategy benchmarked with traditional continuation power flow when system is close to voltage collapsing point. Further tests on the IEEE 14, 57 and 300-bus systems are performed to demonstrate the applicability of the WALMS. Evidently, the multiple simulations results show that the measurement-based WALMS has great potential to be integrated to online VSA and control applications.

Utilizing more active resources on the demand side is one promising strategy to address the problem of operating future grids with large renewable energies. In the integration of increasing load-side resources at all system levels, load-side control and blending of transmission and distribution systems are two major trends that may be utilized in future grid control paradigms. The modeling and control of distributed controllable resources and renewable sources is a significant challenge, as it requires new mathematical models and coordination methods. It is necessary to determine a new network structures and a control paradigm that is cost effective and robust to future changes. This paper will provide an overview of our ideas to address these challenges. The goal of this work aimed to determine the control architectures for bidirectional delivery systems, which can overcome new challenges with greater demand-side and storage participation. A layer-based control paradigm is proposed, every piece of equipment will be accounted and represented by a node or branch in a granulated graph. These allow model layers where nodes represent lower voltage networks to capture ‘drill-down’ modeling from transmission to sub-transmission to distribution in a signal coordinated model. Specific research projects are described related to granular control, frequency control, and voltage control.

With the advantages of high efficiency, low cost, and wide range of application, the energy trading mechanism designed by game theory is an effective measure to cope with the intermittency and uncertainty of the renewable energy. Meanwhile, it also makes the power gird possess more flexible demand response abilities. Under this mechanism, customers turn traditional "passive" patterns into "active" patterns while energy suppliers possess a more flexible power dispatch and distribution planning strategy. First of all, a multi-microgrid based energy trading framework is introduced where the main structure and the key elements, including load classification, processing methods of renewable energy, are briefly described. And then, the market pricing mechanism is presented by different game theoretical models in the multi-microgrid based energy trading framework. Meanwhile, the competitive relationship among the game players of the energy trading is explained. Next, by an investigation of typical real-world case studies, the energy trading mechanism of the smart grid is illusatrated. Finally, relevant multi-microgrid based energy trading problems are discussed which shows the future direction of this research.

Operation planning of power systems is mostly carried out in hourly intervals using unit commitment (UC). Nowadays, increasing penetrations of renewable energy sources at consumer side have caused large load variations on power system. Therefore, intra-hour optimal power flow (OPF) calculations considering most likely scenarios are mandatory to maintain the economy and the security requirements of power system operations to ensure the reliability of the electricity supply. On the other hand, traditional meta-heuristic methods which are more suitable as per the structure of OPF problems, may not be practical due to longer execution times. To address these issues, this paper presents an evolutionary multitasking framework for parallel execution of multiple OPF problems at different load demands. Simulation results show that multitasking substantially improves the utilization of evolutionary algorithms in OPF problems showing the potential for computations in fast timescale in comparison to canonical evolutionary algorithms (EA).