Frequency regulation in wind integrated power system

This Thesis has broader implications in terms of improvement in wind generation modeling which is a current requirement for prospective operational planning tools for future grid. This thesis mainly deals with various modelling issues encountered in wind integrated power system for frequency regulation. Thesis provides development of grid code compatible, frequency responsive type 4 wind turbine generator system and analysis of the wind energy systems frequency regulation capability and their integration impact on interconnected power system.<br /

Improving Grid Hosting Capacity and Inertia Response with High Penetration of Renewable Generation

To achieve a more sustainable supply of electricity, utilizing renewable energy resources is a promising solution. However, the inclusion of intermittent renewable energy resources in electric power systems, if not appropriately managed and controlled, will raise a new set of technical challenges in both voltage and frequency control and jeopardizes the reliability and stability of the power system, as one of the most critical infrastructures in the today’s world. This dissertation aims to answer how to achieve high penetration of renewable generations in the entire power system without jeopardizing its security and reliability. First, we tackle the data insufficiency in testing new methods and concepts in renewable generation integration and develop a toolkit to generate any number of synthetic power grids feathering the same properties of real power grids. Next, we focus on small-scale PV systems as the most growing renewable generation in distribution networks and develop a detailed impact assessment framework to examine its impacts on the system and provide installation scheme recommendations to improve the hosting capacity of PV systems in the distribution networks. Following, we examine smart homes with rooftop PV systems and propose a new demand side management algorithm to make the best use of distributed renewable energy. Finally, the findings in the aforementioned three parts have been incorporated to solve the challenge of inertia response and hosting capacity of renewables in transmission network

Extraction of Inertial and Droop Response from Utility Scale Battery Pack at the State of Charging.

M.S. Thesis. University of Hawaiʻi at Mānoa 2018

Virtual Power Plant Concepts for Ancillary Market - Demonstration, Development, and Validation

The increased penetration of distributed energy resources and renewables open up issues in power systems as a whole. Chapter 1 discusses these issues, and highlights the literature solutions. The concept of VPP is highlighted, different options are explored, and the use of VPP is motivated. The chapter further discusses different ancillary services, with both technical and market perspectives. It makes a clear demarcation amongst transmission and distribution level VPPs, and their economic and technical aspects. Different components within VPP are also highlighted in this chapter. The models of VPP, based on SGAM, are presented in Chapter 2, with detailed test cases. The models characterize VPP as an aggregator at TSO, VPP as DER-Aggregator/DERMS at DSO-DMS, and VPP as business case for flexibility to DSO-DMS. It includes the VPP actors, their characteristics, and a compact architecture based on SGAM. It further splits VPP participants in different software: MATLAB/Simulink, DIgSILENT, and LabVIEW for defined test cases. These are further elaborated in detail in the next chapters, and all are discussed w.r.t regulatory, technical, and economic aspects. Chapter 3 co-simulates VPP-DERMS (Distributed Energy Resource Management System as a Virtual Power Plant) based customers' DR through LabVIEW. It develops interface to customers' meters for reactive power visibility, and then develops a HMI and recording tool at VPP controller. The performance of the tool is analyzed in the chapter, which is in fact the modeling of Modbus based customers' interaction for reactive power. Chapter 4 co-simulates effects of DER on a distribution grid in DIgSILENT. A distribution grid is modelled in DIgSILENT, and then DERs are added to the network. Node voltages and line loading are analyzed in the absence and presence of unplanned DERs. Then the network is seen from two perspectives \u2013 flexibility that can be provided to TSO with STATCOM at transmission node, and flexibility that can be provided to DSO with planned DGs at distribution node. Chapter 5 co-simulates storage model in MATLAB/Simulink. It starts with the techno-economic analysis of potential storage systems, and then to realize the storage model for simulation. The model of selected storage system is implemented in MATLAB/Simulink, and then a explicit service test case is developed within VPP-aggregator to analyze the flexibility margin by storage. Next step is the integration of these co-simulators within different service platform levels. The objective of Chapter 6 is to develop an interface amongst co-simulators to simulate the VPP chain. At first step, the co-simulators are realized within tags: wind farm tags are created in DIgSILENT, customers' based tags are built in LabVIEW, and storage tags are located inside MATLAB/Simulink. Then communication amongst the co-interfaces is done by the development of Matrikon OPC server and explorer platform. The master platform is implemented in LabVIEW-RT tool. Then test cases are defined for the validation of platform, which is performed in Chapter 7. Chapter 7 is dedicated to the validation of the formulated VPPs \u2013 DERMS, business VPP, and aggregator. DERMS based model is validated within DIgSILENT, by using a portion of the Italian distribution grid. Aggregator based model is validated within DIgSILENT, by using the IEEE 9 bus transmission test model. Business VPP model is validated using IEC 61850 compliant feature of DIgSILENT for the same distribution grid in a translational manner. The validated VPP is used as an application for power system reliability, which is presented in Chapter 8. It describes the conventional schemes for power system protection, and the issues with DER penetration. It then models a VPP, and verifies its functionality for power system protection. Chapter 9 concludes the thesis

Fuzzy logic based virtual inertia control of DFIG based wind generator for stability improvement of hybrid power system

Large integration of renewable energy sources (RESs), such as wind power and solar photovoltaic (PV) plants, into the power systems, impacts the system frequency stability. Normally, a wind farm (WF) and PV system do not provide frequency support because of the uncontrollability of the input energy. Moreover, overall system inertia will be reduced due to massive integration of RES because conventional generation units that provide reserve power need to be decreased. To overcome the problems of frequency stability as well as power system transient stability resulting from the insufficient inertia response, this paper proposes a new method to enhance the transient stability of the power system with RESs introduced, in which variable speed wind turbine with doubly fed induction generator (VSWT-DFIG) supplies its kinetic energy (KE) during generation outage to stabilize conventional synchronous generators (SGs). A suitable fuzzy logic based virtual inertia controller (VIC) is proposed to release the stored KE efficiently during transient period. This fuzzy logic controller (FLC) can continuously adjust the VIC gain depending upon the incoming wind speed. To verify the effectiveness of the proposed VIC, simulation analyses are performed on a multi-machine hybrid power system model composed of PV plant, VSWT-DFIG, fixed speed wind turbine with squirrel cage induction generator (FSWT-SCIG), and conventional SGs