Decentralized Demand Side Management with Rooftop PV in Residential Distribution Network

In the past extensive researches have been conducted on demand side management (DSM) program which aims at reducing peak loads and saving electricity cost. In this paper, we propose a framework to study decentralized household demand side management in a residential distribution network which consists of multiple smart homes with schedulable electrical appliances and some rooftop photovoltaic generation units. Each smart home makes individual appliance scheduling to optimize the electric energy cost according to the day-ahead forecast of electricity prices and its willingness for convenience sacrifice. Using the developed simulation model, we examine the performance of decentralized household DSM and study their impacts on the distribution network operation and renewable integration, in terms of utilization efficiency of rooftop PV generation, overall voltage deviation, real power loss, and possible reverse power flows.Comment: 5 pages, 7 figures, ISGT 2018 conferenc

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

MODELING AND ASSESSING THE SUSTAINABILITY OF DISTRIBUTED SOLAR PHOTOVOLTAICS ADOPTION

Participation of distributed solar photovoltaic (PV) generation in the organized electricity wholesale market is expected to increase under the Federal Energy Regulatory Commission Order 2222 announced in 2020. Our understanding about the technical, economic, and environmental tradeoffs and co-benefits of solar PV adoption on both building and regional scales remains limited, especially considering the complexity of varied distributed solar PV-battery system designs and operation strategies as well as the dynamic interactions of these distributed generations with the centralized grid. This dissertation therefore aims to investigate the grid load reduction, life cycle cost, and life cycle environmental (e.g., carbon, water, and energy footprints) performances of typical distributed PV systems considering their dynamic interactions with the centralized grid. This dissertation intends to examine the possible scenarios in which future adoption of PV systems can facilitate economic saving, reduce environmental footprints, relieve centralized grid stress, and supplement differential electricity demands of residential energy users on both building and city scales. To this end, a modeling framework was developed consisting of a stochastic residential electricity demand model, a system dynamics model of solar energy generation, energy balance, storage, and selling, and life cycle economic and environmental assessment model. The stochastic residential electricity demand simulation considered five typical types of household occupants and eight types of households. The generated solar energy, grid supply, and residential demand were balanced for each residential building using energy balance model. This model was further scaled up to a city level using Boston, MA as a testbed. On the building level, we found a clear tradeoff between the life cycle cost and environmental savings when sizing the PV systems differently. Moreover, installing a solar PV-battery system but without an effective control strategy can result in sub-optimized peak-load reduction, economic, and environmental outcomes. Installing solar PV-battery systems with proper controls can achieve the highest on-peak load reductions and economic benefits under the time-of-use utility rate design. However, they do not necessarily provide the highest environmental benefits, indicating a potential technical, environmental, and economic tradeoff. Our regional analysis found a large penetration of solar PV systems may result in a steeper ramp-up of the grid load during winter days, but it may provide load-shedding benefits during summer days. Large buildings may perform the best technically and environmentally when adopting solar PV systems, but they may have higher life cycle costs

MODELING AND ASSESSING THE SUSTAINABILITY OF DISTRIBUTED SOLAR PHOTOVOLTAICS ADOPTION

Participation of distributed solar photovoltaic (PV) generation in the organized electricity wholesale market is expected to increase under the Federal Energy Regulatory Commission Order 2222 announced in 2020. Our understanding about the technical, economic, and environmental tradeoffs and co-benefits of solar PV adoption on both building and regional scales remains limited, especially considering the complexity of varied distributed solar PV-battery system designs and operation strategies as well as the dynamic interactions of these distributed generations with the centralized grid. This dissertation therefore aims to investigate the grid load reduction, life cycle cost, and life cycle environmental (e.g., carbon, water, and energy footprints) performances of typical distributed PV systems considering their dynamic interactions with the centralized grid. This dissertation intends to examine the possible scenarios in which future adoption of PV systems can facilitate economic saving, reduce environmental footprints, relieve centralized grid stress, and supplement differential electricity demands of residential energy users on both building and city scales. To this end, a modeling framework was developed consisting of a stochastic residential electricity demand model, a system dynamics model of solar energy generation, energy balance, storage, and selling, and life cycle economic and environmental assessment model. The stochastic residential electricity demand simulation considered five typical types of household occupants and eight types of households. The generated solar energy, grid supply, and residential demand were balanced for each residential building using energy balance model. This model was further scaled up to a city level using Boston, MA as a testbed. On the building level, we found a clear tradeoff between the life cycle cost and environmental savings when sizing the PV systems differently. Moreover, installing a solar PV-battery system but without an effective control strategy can result in sub-optimized peak-load reduction, economic, and environmental outcomes. Installing solar PV-battery systems with proper controls can achieve the highest on-peak load reductions and economic benefits under the time-of-use utility rate design. However, they do not necessarily provide the highest environmental benefits, indicating a potential technical, environmental, and economic tradeoff. Our regional analysis found a large penetration of solar PV systems may result in a steeper ramp-up of the grid load during winter days, but it may provide load-shedding benefits during summer days. Large buildings may perform the best technically and environmentally when adopting solar PV systems, but they may have higher life cycle costs

Load Scheduling with Maximum Demand and Time of Use pricing for Microgrids

Several demand side management (DSM) techniques and algorithms have been used in the literature. These algorithms show that by adopting DSM and Time-of-Use (TOU) price tariffs; electricity cost significantly decreases, and optimal load scheduling is achieved. However, the purpose of the DSM is to not only lower the electricity cost, but also to avoid the peak load even if the electricity prices low. To address this concern, this dissertation starts with a brief literature review on the existing DSM algorithms and schemes. These algorithms can be suitable for Direct Load Control (DLC) schemes, Demand Response (DR), and load scheduling strategies. \end{abstract} Secondly, the dissertations compares two of DSM algorithms to show the performance based on cost minimization, voltage fluctuation, and system power loss [see in Chapter 5]. The results show the importance of balance between objectives such as electricity cost minimization, peak load occurrence, and voltage fluctuation evolution while simultaneously optimizing the cost

An assessment of high distributed PV generation on eThekwini electricity distribution network.

Masters Degree. University of KwaZulu-Natal, Durban.Small-scale Distributed Photovoltaic Generation (DPVG) continues to grow with increasing operational challenges for electricity utilities and Distribution Network (DN) operators. In Low Voltage (LV) DNs, there are well researched potential issues that arise with high Photovoltaic (PV) penetration. These include: feeder voltage rise, voltage fluctuations and reverse power flow. Among these, the most important issue is voltage rise at the LV distribution feeder. In a broader perspective, to this point in time, there has not been more detailed research on small-scale DPVG interconnections in the LV networks in South Africa (SA) and in the KwaZulu-Natal (KZN) region. There is a great need for research in this field for ensuring network efficiency, reliability and future regulatory standards. Other network systems have been studied around the world were conditions, environment, network characteristics and electricity customer loads will be different; e.g in the North-West of England, Germany, and Queensland, Australia. Hence, the main objective of this research study is to analyze the mentioned problems, identify and test the appropriate mitigation solutions, in the event of high DPVG. This study was carried out on a typical SAn LV DN model, which represents an existing housing development estate at eThekwini Municipality. Consequently the aim is to identify solutions suitable for networks in SAn or of similar architect and characteristics. As a result, a specific application is undertaken at the KZN region, which is also representative of network characteristics of SAn networks. A voltage rise, voltage fluctuation and network power loss issues were analyzed at different PV penetration levels and varying customer loads. An innovative approach of utilization of a standard central On-Load-Tap-Change (Off-LTC) transformer for voltage regulation with high DPVG was tested. Usage of this technique has not been reported in the literature to date. National standards in SA were used as a basic guide in this study and stated the possibility of grid voltage control of distributed PV inverters. Assessment of the typical LV network showed that there is indeed voltage rise and hence possible voltage fluctuation, when PV system output power varies. The Off-LTC transformer was able to maintain network voltages within the allowed operational range and reduced the magnitude of voltage rise. This implies that there is a possibility of avoiding expensive upgrades of the existing and widespread Off-LTC transformers technology

Protection Considerations of Future Distribution Networks with Large Penetration of Single Phase Residential Rooftop Photovoltaic Systems

Solar Photovoltaics now constitute a significant part of electrical power generation for many utilities around the world. This penetration of PVs introduces many technical challenges. This thesis has investigated the impact of high penetration level of single phase rooftop PVs on protection of low voltage and medium voltage and distribution networks and proposed necessary recommendation to improve the performance of protection systems of these networks