Requirements for Power Hardware-in-the-Loop Emulation of Distribution Grid Challenges

The ongoing transition of low voltage (LV) power grids towards active systems requires novel evaluation and testing concepts, in particular for realistic testing of devices. Power Hardware-in-the-Loop (PHIL) evaluations are a promising approach for this purpose. This paper presents preliminary investigations addressing the systematic design of PHIL applications and their applicable stability mechanisms and gives a detailed review of the related work. A requirement analysis for emulation of grid situations demanding system services is given and the realization of a PHIL setup is demonstrated in a residential scenario, comprising a hybrid electrical energy storage system (HESS)

Advanced Testing Chain Supporting the Validation of Smart Grid Systems and Technologies

New testing and development procedures and methods are needed to address topics like power system stability, operation and control in the context of grid integration of rapidly developing smart grid technologies. In this context, individual testing of units and components has to be reconsidered and appropriate testing procedures and methods need to be described and implemented. This paper addresses these needs by proposing a holistic and enhanced testing methodology that integrates simulation/software- and hardware-based testing infrastructure. This approach presents the advantage of a testing environment, which is very close to f i eld testing, includes the grid dynamic behavior feedback and is risks-free for the power system, for the equipment under test and for the personnel executing the tests. Furthermore, this paper gives an overview of successful implementation of the proposed testing approach within different testing infrastructure available at the premises of different research institutes in Europe.Comment: 2018 IEEE Workshop on Complexity in Engineering (COMPENG

DALILA - Design architectures in a Living Lab

Real-time testing of a Multi-Microgrid system emulated in Matlab Simulink. The experimental tests were undercarried on real hardware components through a analog/digital converter (Power Harware in The Loop).This thesis provides an overview of Microgrids and Multi-Microgrids control architectures and validates control functionalities through the combined efforts of numerical simulation and practical tests in a real laboratory by using Power Hardware In the Loop (PHIL) technology. The thesis is divided in five major topics. The first topic is related with Microgrids, Multi-Microgrids and Smartgrids. It starts by describing the context of such concepts and their implications on power systems: the operational challenges they brought along are laid out in order to make sense out of the proposed solutions. Afterwards it details what characterizes these concepts and the essential components behind them. The devices that enable main functionalities such as autonomous operation, active demand response, voltage/var control, blackstart, etc. This involves explaining the models of microgeneration units, storage devices, electric vehicles and system coordinators. Lastly, there is mentioning to some international reference projects.The second topic is related with Living Labs. In order to conduct experiments regarding Microgrids/Smartgrids, it is necessary to identify key laboratory infrastructures and their main experimental objectives. Therefore, a brief outlook of the most notorious international laboratories and their topics of research is presented.The third topic revolves around the simulation mechanics and the software utilized to study power systems behaviour, which in this case was \textit{Matlab Simulink}. A base case of a Multi-Microgrid system scenario was built based on an existing rural grid and is presented. The MicroSource modelling and the control strategy implemented are described and test results are driven and analysed. The fourth topic details the theory associated with the PHIL converter and describes the series of steps to be followed that allow interaction with \textit{Simulink} and proper operation. Finally, the last topic describes the experimental tests that were under carried in the laboratory and their respective results. These results will serve to validate the ones obtained in the simulation environment. This serves the purpose of demonstrating microgrid operation and testing

Design and Implementation of a True Decentralized Autonomous Control Architecture for Microgrids

Microgrids can serve as an integral part of the future power distribution systems. Most microgrids are currently managed by centralized controllers. There are two major concerns associated with the centralized controllers. One is that the single controller can become performance and reliability bottleneck for the entire system and its failure can bring the entire system down. The second concern is the communication delays that can degrade the system performance. As a solution, a true decentralized control architecture for microgrids is developed and presented. Distributing the control functions to local agents decreases the possibility of network congestion, and leads to the mitigation of long distance transmission of critical commands. Decentralization will also enhance the reliability of the system since the single point of failure is eliminated. In the proposed architecture, primary and secondary microgrid controls layers are combined into one physical layer. Tertiary control is performed by the controller located at the grid point of connection. Each decentralized controller is responsible of multicasting its status and local measurements, creating a general awareness of the microgrid status among all decentralized controllers. The proof-of concept implementation provides a practical evidence of the successful mitigation of the drawback of control command transmission over the network. A Failure Management Unit comprises failure detection mechanisms and a recovery algorithm is proposed and applied to a microgrid case study. Coordination between controllers during the recovery period requires low-bandwidth communications, which has no significant overhead on the communication infrastructure. The proof-of-concept of the true decentralization of microgrid control architecture is implemented using Hardware-in-the-Loop platform. The test results show a robust detection and recovery outcome during a system failure. System test results show the robustness of the proposed architecture for microgrid energy management and control scenarios

Industrial Use of Distributed Generation in Real-Time Energy and Ancillary Service Markets

Industrial consumers of energy now have the opportunity to participate directly in electricity generation. This report seeks to give the reader (1) insights into the various types of generation services that distributed generation (DG) units could provide, (2) a mechanism to evaluate the economics of using DG, (3) an overview of the status of DG deployment in selected states, and (4) a summary of the communication technologies involved with DG and what testing activities are needed to encourage industrial application of DG. Section 1 provides details on electricity markets and the types of services that can be offered. Subsequent sections in the report address the technical requirements for participating in such markets, the economic decision process that an industrial energy user should go through in evaluating distributed generation, the status of current deployment efforts, and the requirements for test-bed or field demonstration projects

Analysis of Smart Transformer features for electric distribution

The distribution grid is undergoing deep changes created by the integration of new generation resources, such as renewables, and new loads, like electric vehicles. These new actors impact on the distribution grid management, introducing 1) higher variability of the grid power demand and subsequent power unbalance, 2) reverse power flow with increased overvoltage conditions in case of high power production and low power consumption, cables and transformer overload in case of low power production and high power consumption, and 3) decreased system inertia, due to the power electronics-connection of the resources. The Smart Transformer (ST) enables the management of the distribution grid, absolving three main tasks: 1) adapting the voltage level from medium to low voltage grids; 2) managing the distribution grid during the aforementioned issues; and 3) offering higher controllability of distribution and transmission grid. This work describes in details the ST controllers and their tuning, taking into account the services to be provided. The ST enables the direct control of the voltage waveform in the ST-fed grid, varying the voltage amplitude and frequency. This allows to interact with the voltage-sensitive loads power consumption and droop controlled-generators in order to shape the power consumption of the ST-fed grid. Applying this control the ST can offer services to the grid, like limiting the reverse power flow in the medium voltage grid, or managing its overload conditions. The accuracy of these services can be increased if the identification of the grid power sensitivity to voltage and frequency is carried out. The ST, applying a controlled voltage amplitude and frequency variation, performs the on-line load sensitivity identification and evaluates in real time the grid sensitivity. This identification enables the offer of new ancillary services to the distribution and transmission grids

Initialization and synchronization of power hardware-in-the-loop simulations : a Great Britain network case study

The hardware under test (HUT) in a power hardware in the loop (PHIL) implementation can have a significant effect on overall system stability. In some cases, the system under investigation will actually be unstable unless the HUT is already connected and operating. Accordingly, initialization of the real-time simulation can be difficult, and may lead to abnormal parameters of frequency and voltage. Therefore, a method for initializing the simulation appropriately without the HUT is proposed in this contribution. Once the initialization is accomplished a synchronization process is also proposed. The synchronization process depends on the selected method for initialization and therefore both methods need to be compatible. In this contribution, a recommended practice for the initialization of PHIL simulations for synchronous power systems is presented. Experimental validation of the proposed method of establishing a PHIL simulation for a Great Britain network case study demonstrates the effectiveness of the approach in achieving stable operation

Advancements in Real-Time Simulation of Power and Energy Systems

Modern power and energy systems are characterized by the wide integration of distributed generation, storage and electric vehicles, adoption of ICT solutions, and interconnection of different energy carriers and consumer engagement, posing new challenges and creating new opportunities. Advanced testing and validation methods are needed to efficiently validate power equipment and controls in the contemporary complex environment and support the transition to a cleaner and sustainable energy system. Real-time hardware-in-the-loop (HIL) simulation has proven to be an effective method for validating and de-risking power system equipment in highly realistic, flexible, and repeatable conditions. Controller hardware-in-the-loop (CHIL) and power hardware-in-the-loop (PHIL) are the two main HIL simulation methods used in industry and academia that contribute to system-level testing enhancement by exploiting the flexibility of digital simulations in testing actual controllers and power equipment. This book addresses recent advances in real-time HIL simulation in several domains (also in new and promising areas), including technique improvements to promote its wider use. It is composed of 14 papers dealing with advances in HIL testing of power electronic converters, power system protection, modeling for real-time digital simulation, co-simulation, geographically distributed HIL, and multiphysics HIL, among other topics