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Renewable electricity generations are promising to address the global energy issue while they also place great pressure on the reliability of power grids due to their intermittent nature. In recent years, existing heating, ventilation and air-conditioning (HVAC) systems in buildings have attracted increasing attention to implement continuous demand response in providing frequency regulation service, which can enhance instantaneous power balance and reliability of power grids without extra huge investment. When providing frequency regulation service, the power use of HVAC systems would follow the regulation signals. On the other hand, these signals, acting as continuous disturbances, affect naturally the building indoor environment control at the demand side. In this paper, a novel control strategy is proposed, which can prevent the sacrifice of the building indoor environment when providing the service. The core element of this control strategy is a frequency disturbance compensation scheme, which is developed based on the concept of "disturbance-observer-based control". Experimental results show that the use of the proposed strategy can achieve significant improvement in the building indoor environment control without sacrificing the quality of frequency regulation service. In addition, the wear level of the valve was not affected significantly when adopting the frequency disturbance compensation scheme. • A control strategy of HVAC systems is proposed for power grid frequency regulation. • Experimental tests are conducted to validate this proposed novel control strategy. • It works effectively in preventing the impacts on indoor environment control. • It can also ensure the high quality of frequency regulation service to power grids. • The valve wear level is not affected significantly when adopting the novel strategy. [ABSTRACT FROM AUTHOR]

• Grid-building interaction is developed considering multiple requests of both sides. • An enhanced interaction is developed to address demand prediction uncertainty. • Dynamic pricing and daily building demand are optimized via Stackelberg game. • The win-win situation for grid and buildings are validated by on-site data. • Multiple benefits for grid and buildings are achieved in the proposed interactions. Bidirectional interaction between power grid and buildings is a key characteristic of smart grids. Achieving a win-win situation for a grid and buildings with such interactions remains a challenge. Game theory is a powerful tool for using strategic analysis to identify the best interactions between multiple players. Stackelberg game can effectively reflect the core status of grid and the auxiliary position of buildings in this interaction (particularly in demand response programs), but no study used this game to establish such interactions while simultaneously considering the multiple requirements of grid and buildings, particularly for the commercial sector. In this study, therefore, basic and enhanced interaction strategies between a grid and buildings are developed using the Stackelberg game based on their identified Nash equilibria. The grid optimizes the price to maximize its net profit and reduce demand fluctuation, and individual building optimizes the hourly power demand to minimize electricity bill and effects of demand alternation from the baseline. In addition, the effects of building demand baseline uncertainty on the interaction are investigated and the enhanced robust interaction is proposed to deal with such uncertainty. Real site data of buildings on a campus in Hong Kong are used to validate the proposed interaction strategies. The results show that the proposed basic interaction increased net profit by 8% and reduced demand fluctuation by about 40% for the grid, with savings in electricity bills of 2.5–8.3% for the buildings. Moreover, the proposed robust interaction effectively relieved the negative effects caused by prediction uncertainty. [ABSTRACT FROM AUTHOR]

• A new concept and feature of grid-responsive building and the needs are presented. • Opportunities/challenges for buildings to provide ancillary services are presented. • Applications/methods for HVAC systems to provide ancillary services are investigated. • Potential capacities of HVAC systems to provide ancillary services are quantified. Renewable electricity generations have been growing rapidly in recent years worldwide as a result of efforts to address the global energy issue. However, it has also imposed increasing challenges on the balance of power grids due to their intermittent nature. Building sector, as the largest consumer, is expected increasingly to play an important role in providing ancillary services (AS) to relieve stress and reduce the needs of investment for power balance of the smart grids. Grid-responsive building therefore becomes a worthwhile and essential feature of buildings today and in the future. This paper provides an overview of the classification, benefits, applications as well as methods/technologies for HVAC systems in non-residential buildings to provide ancillary services, as fast responses (i.e., in the magnitude of seconds or minutes) to the needs of smart grids. In addition, the challenges of applications and potential solutions are investigated and summarized. The potential capacities of HVAC systems in the entire non-residential building sector in Hong Kong for providing frequency regulation (FR) and spinning reserve are also quantified. [ABSTRACT FROM AUTHOR]

Abstract Power demand management, particularly demand response controls, is the effort from the demand side to help the supply side management for helping maintain grid balance and also bring the economic benefits for building owners. Most of building demand management and demand response control strategies for commercial buildings only focus on a single building. However, as for the cluster-level buildings, which are sometimes involved in an account for electricity charge and also the main concern of smart grids, such conventional individual-level control strategies will not be effective. A game theory-based decentralized control strategy is therefore developed for cluster-level building demand management by simultaneously optimizing the indoor air temperature set-point and the operation of active thermal storage. Without gathering all the required information of buildings to a central optimization system, the cluster-level building demand management can be realized in a decentralized way. Case studies are conducted and results show that the proposed decentralized control strategy can increase the peak demand reduction, over two times than that when the demand management of buildings is conducted in an uncoordinated mode. Meanwhile, the performance of the proposed decentralized control strategy is closely approached to the results that are optimized in a centralized mode. [ABSTRACT FROM AUTHOR]

Abstract The proportion of electric generation from renewable resource has been growing rapidly in recent years, especially in Microgrids in remote areas. However, the intermitted nature of the renewable energy resource has posed a great pressure on the reliability of power grids and asked a great amount of ancillary services, especially for frequency regulation (FR). Heating, ventilation, and air-conditioning (HVAC) systems are promising resources to solve this challenge because they can take full use of thermal storage capacity of buildings. In this paper, a pump in HVAC system in a hotel is employed to provide the frequency regulation by adjusting its frequency to follow the automatic generation control (AGC) signals, RegA and RegD signals from Pennsylvania–New Jersey–Maryland (PJM). Performance scores are adopted to assess the control performance. In addition, the thermal capacity of the cooling coil is considered to evaluate its side-effect when providing this service. The results indicate that the pump can provide nearly 30kW total capacity with a relatively high average performance score. Moreover, the impact to indoor air temperature is almost neglectable with the thermal capacity of the cooling coil and indoor air hedging against the fluctuation of pump frequency. [ABSTRACT FROM AUTHOR]

Abstract Demand response (DR) is a set of demand-side activities to reduce or shift electricity use to improve the electric grid efficiency and reliability. Shutting down part of operating chillers directly in central air-conditioning systems of buildings to meet the urgent demand reduction needs of power grids has received increasing attention recently. A model predictive control strategy is developed for optimizing the operation of a central air-conditioning system integrated with an active cold storage during such fast demand response events. The primary objective of the proposed control strategy is to maximize the power reduction with a profile pattern preferred by power grids as well as to maintain the indoor air temperature within an acceptable level during fast DR period. The MPC controller determines the control outputs of chiller power demand and active storage discharge rate based on the discrete-time state space building thermal response model. Test results show that expected profile pattern (i.e., maximum and stable) of power reduction was achieved by the proposed MPC strategy during fast DR events. Meanwhile, the indoor air temperature was maintained within the acceptable range. [ABSTRACT FROM AUTHOR]

Abstract Shutting down part of operating chillers directly in central air-conditioning systems of buildings to meet the urgent demand reduction needs of power grids has received increasing attention recently. However, due to limited cooling supply during above demand response (DR) events, the indoor air temperature and particularly relative humidity would often increase to unacceptable levels, resulting in the failures of DR controls. Considering the restriction on power use during DR events, rational use of limited cooling supply turns out to be the inevitable choice. The feedback control strategies commonly-used today cannot properly deal with the environment and system control issues under limited cooling supply during DR events. However, no study on this problem can be found in the research literature. As the first effort, two control strategies (i.e., optimal and near-optimal) are developed to address the environment control issues (concerning both indoor temperature and humidity controls) under a pre-determined power limiting threshold during DR events. The optimal control strategy optimizes the air flow set-points of individual AHUs (air handling units) using model-based prediction and genetic algorithm to achieve the best possible indoor environment control. The near-optimal control strategy approaches such best environment control using a simple empirical method. Case studies are conducted and the results show that the air flow settings have significant impacts on the indoor environment controlled under limited cooling supply. Both control strategies can achieve significant improvements in the indoor temperature and humidity controls as well as significant fan power saving. Highlights • The big challenge of poor indoor environment control in fast DR is addressed. • Two strategies optimize indoor temperature and RH controls via AHU airflow settings. • Best possible indoor environment can be achieved by optimal strategy in fast DR events. • A near-optimal strategy using empirical settings offers an alternative for applications. • Indoor environment control is improved significantly with significant fan power reduction. [ABSTRACT FROM AUTHOR]

When receiving an urgent request from a smart grid, shutting down part of operating chillers directly in the air-conditioning system in a building can achieve immediate power reduction. However, no study has addressed how to determine the number of chillers/pumps to be shut down and how to regulate the load of retained equipment systematically during DR events. This paper presents a new approach to address these issues based on three schemes. A power demand optimization scheme predicts the building cooling demand and the power limiting threshold in response to a received DR request. A system sequence control resetting scheme determines the number of operating chillers/pumps to be retained. An online control/regulation scheme ensures the system power following the expected profile by regulating the total chilled water flow delivered to the building and therefore the chiller load. It also employs a cooling distributor to distribute chilled water to individual zones concerning different sensitivities/sacrifices to temperature increases. Case studies are conducted on a simulated dynamic building air-conditioning system. Results show that, during DR events, the proposed strategy can achieve the expected power reduction (i.e., about 23%) and also maintain acceptable zone temperature even though uncertainties exist in the prediction process. [ABSTRACT FROM AUTHOR]

Power demand response (DR) of buildings is considered as one of most promising solutions to power imbalance and reliability issues in smart grids while demand response control of air-conditioning systems is a most effective means. A fast demand response control strategy, direct load control by shutting down part of operating chillers, has received great attention in recent DR researches and applications. This method, however, would lead to uneven indoor air temperature rises among individual air-conditioned spaces due to the failure of proper distribution of limited cooling supply by the conventional demand-based feedback control strategy commonly used today. A novel supply-based feedback control strategy is therefore proposed to effectively solve the problems caused by the fast demand response and power limiting control strategy. This proposed strategy employs global and local cooling distributors based on adaptive utility function to reset the set-points of chilled water flow and air flow for each zone and space online. Simplified offline and online identification methods, for the two parameters respectively, ensure the convenience and robustness of the adaptive utility function in applications. Case studies are conducted on a simulated air-conditioning system to test and validate the proposed control strategy. Results show that the proposed control strategy is capable not only to maintain even indoor air temperature rises, but also to avoid the operation problems during DR events. Moreover, rather high indoor relative humidity is obviously decreased. The power rebound phenomenon is also relieved and the original comfort control of spaces can be resumed much quickly. [ABSTRACT FROM AUTHOR]

Shutting down part of operating chillers in HVAC (heating ventilating and air-conditioning) is a direct and effective mean allowing immediate responses of buildings to the power reduction requests of a smart grid.This paper presents a summary on the demand response control strategies and the problems when using the current conventional demand-based air-conditioning control strategies for fast demand response as well as the reasons of rebound problems after a DR event. The proposed cooling supply-based strategy aims at properly controlling air-conditioning systems when the cooling supply is not sufficient to fulfil the cooling demand of a building. This strategy can effectively solve problems of immediate power demand limiting control in response to the urgent requests of a smart grid as well as the rebound problems after the demand response event. [ABSTRACT FROM AUTHOR]

• The time-shiftable and comfort-based loads are modeled as flexibility resources. • Users' dissatisfaction costs are quantified based on comfort indicators. • A Stackelberg game relation is developed between aggregator and users. • Transactional services prices and flexibility capacities are optimized based on Nash Equilibrium. The building sector has great potential to provide multiple flexibility services contributing to a more efficient and reliable electricity network. However, such demand-side flexibility is still obstructed by limited market access and a sheer lack of business models. Lack of studies investigates building users' trade-off between the profits from flexibility contribution and the satisfaction of load and indoor comfort. How to determine the attractive diversifying revenue streams for users' contribution to multiple flexibility services remains relatively uninvestigated. Therefore, this paper develops a game-theoretic optimization scheme based on the intermediary aggregator to unlock the considerable flexibility potential of buildings. A bi-level optimization problem is formulated to determine the optimal transactional prices of multiple flexibility services offered by the agent and the flexibility capacities provided by buildings based on the Nash Equilibrium of the Stackelberg game. The game relation can effectively capture the interaction between building users and the aggregator agent and depict the trade-off between electricity bills and users' satisfaction. The optimization results of the case study show that a win-win situation can be yielded under the proposed interactive scheme. The aggregator agent and building users can increase the profit by 37.4% and 5.6%-5.9%, respectively, and the total peak demand can be reduced by 6.3%. Meanwhile, setting proper discomfort cost coefficients and transactional price thresholds can effectively improve the negotiation of profit distribution between different stakeholders. [ABSTRACT FROM AUTHOR]

District cooling system (DCS) has been widely used because of its low cost and high energy efficiency. Excessive studies have been done on DCSs, based on either actual projects or hypothesis. This paper presents a comprehensive review on the research and applications of DCSs. The characteristics and problems of DCS are introduced. The performance and progress of DCS integrated with sustainable energy technologies are summarized, including systems integrated with renewable energy systems, combined cooling, heating and power systems, and thermal storage systems. Efforts on the optimization of DCS are reviewed and categorized, including the efforts on district planning, DCS design, operation and control. An introduction on the existing typical DCS projects in China is presented. Challenges and opportunities for future application of DCS are discussed including the uncertainty issues at design stage, the control optimization and integration with smart gird. [ABSTRACT FROM AUTHOR]

Smart grid is considered as a promising solution in improving the power reliability and sustainability where demand response is one important ingredient. Demand response (DR) is a set of demand-side activities to reduce or shift electricity use to improve the electric grid efficiency and reliability. This paper presents the investigations on the power demand alternation potential for buildings involving both active and passive cold storages to support the demand response of buildings connected to smart grids. A control strategy is developed to provide immediate and stepped power demand reduction through shutting chiller(s) down when requested. The primary control objective of the developed control strategy is to restrain the building indoor temperature rise as to maintain indoor thermal comfort within certain level during the DR event. The chiller power reduction is also controlled under certain power reduction set-point. The results show that stepped and significant power reduction can be achieved through shutting chiller(s) down when requested. The power demand reduction and indoor temperature during the DR event can be also predicted accurately. The power demand reduction is stable which is predictable for the system operators. [ABSTRACT FROM AUTHOR]

With the increasing integration of renewable energies into electrical grids, power imbalance has become one of the most critical issues in grid operations. The end-users at power demand side can actually make use of their demand reduction potentials to contribute to the grid power balance. Conventional demand responses of end-users can provide considerable power demand reductions, but the demand responses are usually subject to significant delay and cannot fulfill the needs of grid real time operation. In this paper, a fast chiller power demand response control strategy for commercial buildings is therefore proposed which facilitates buildings to act as grid “operating reserves” by providing rapid demand responses to grid request within minutes. However, simply shutting down some essential operating chillers would result in disordered chilled water flow distribution and uneven indoor thermal comfort degradation. This strategy has therefore taken essential measures to solve such problems effectively. Simulation case studies are conducted to investigate the operation dynamics and energy performance of HVAC systems in the demand response events controlled by the strategy. Results show that fast and significant power demand reductions can be achieved without sacrificing the thermal comfort too much. [ABSTRACT FROM AUTHOR]

This paper presents a novel air-conditioning system with proactive demand response to smart grid. The system consists of a chilled water storage system (CWS) and a temperature and humidity independent control (THIC) air-conditioning system. Using this system, building power demand can be flexibly controlled as desired by implementing two demand response strategies: demand side bidding (DSB) strategy and demand as frequency controlled reserve (DFR) strategy, in respond to the day-ahead and hour-ahead power balance requirements of the grid, respectively. Considerable benefits can be achieved for both power companies and end-users under incentive pricing mechanisms. A case study concerning on the demand response performance of the proposed system is also conducted in an office building. [ABSTRACT FROM AUTHOR]

Highlights: [•] Interactive building power demand management strategy for integrating commercial buildings into smart grid. [•] Quantify demand and demand alteration characteristics of commercial buildings to facilitate the smart grid optimization. [•] Building thermal storage model is developed for predicting power demand alteration potential. [•] Commercial buildings can contribute significantly and effectively in grid power demand management. [ABSTRACT FROM AUTHOR]

Ensuring the power balance and reliability of power grids is an increasing challenge due to the increasing involvement of intermittent renewable power generations. The use of existing heating, ventilation and air-conditioning (HVAC) systems in buildings has attracted increasing attention to implement continuous demand response in providing frequency regulation service, which can enhance instantaneous power balance and reliability of power grids without extra huge investment. However, the energy flexibility of buildings is not consistent, and the capacity available for frequency regulation service changes over time due to the changes of working conditions. In this study, a hierarchical optimal control strategy, consisting of a regulation bidding controller and a power use following controller, is proposed. It optimizes the power use baseline and regulation capacity, and controls HVAC systems to provide qualified frequency regulation service, considering the tradeoff between financial reward (regulation capacity) and thermal comfort while satisfying the operating constraints of HVAC systems. The proposed control strategy is validated on a simulation test platform. Results show that the strategy can maximize the use of regulation capacity provided by HVAC systems while ensuring the indoor environment control quality under a given guarantee rate. • A control strategy is proposed to use HVAC systems for frequency regulation service. • The distribution of hourly maximum accumulated offset (MAO) of AGC signal is stable. • The hourly MAO of the AGC signal corresponds to room's maximum temperature offset. • The proposed control strategy considers both financial rewards and thermal comfort. [ABSTRACT FROM AUTHOR]

The demand side is increasingly expected to provide energy flexibility for power grid economy and reliability. Buildings have various flexibility sources that can be effectively utilized for such purposes. According to different requirements of demand responses to power grid on response duration, response direction and response speed (within seconds, minutes, or even longer timescales), building energy flexibility is categorized as fast regulation, moderate regulation, load shedding, load shifting and load covering. In this paper, a comprehensive method is proposed to quantify building energy flexibility based on these categories. Two sets of flexibility indexes (flexibility capacities and flexibility ratios) for the above five energy flexibilities are proposed. An implementation case study is conducted to illustrate the use of these indexes and to validate the effectiveness of using them in flexibility performance assessment of buildings in particular. The impacts of different system design and control parameters on flexibility performance are also investigated quantitatively. The potential economic benefits of utilizing those energy flexibilities are analyzed in a real electricity market with an optimized use of different flexibility sources. Results show that electricity costs can be reduced by up to 21% if the market is available for such grid-responsive buildings. • A quantification methodology for five energy flexibilities of building is proposed. • Case study is conducted to verify the effectiveness of proposed flexibility index. • Impacts of major parameters on the building energy flexibility are analyzed. • Economic potential of utilizing flexibilities in electricity markets is investigated. • 21% of electricity cost reduction can be achieved by ultilizing energy flexibilities. [ABSTRACT FROM AUTHOR]

The rapid development of remote telemetry, control and communication technologies in smart grids enables the demand side to provide energy flexibility for power grid economy and reliability. The building sector, as a consumer of large amounts of electricity, has various flexible loads that can be effectively utilized for such purposes if buildings and their energy systems are under proper design and control. In this paper, a systematic methodology is proposed for categorizing the building energy flexibility according to different power grid requirements. Considering the requirements of response duration, response direction and response speed (within seconds, minutes, or even longer timescale), the flexibility can be categorized as fast regulation, moderate regulation, load shedding, load shifting and load covering. A comprehensive review is presented to summarize and compare various flexibility sources, their characteristics and capabilities in buildings for providing those five different types of energy flexibility. The analysis of available information technologies and business development indicate great capability and potential of buildings to participate in energy flexibility markets as a practical demand side management instrument. Three major limitations in existing research and energy markets are identified as the major challenges for the future development of energy flexible buildings. • Requirements on demand side flexibility are summarized based on electricity markets. • Five building energy flexibilities are categorized based on grid requirements. • The characteristics of various building response technologies are investigated. • Contributions of buildings to flexibilities of different timescales are investigated. • Major challenges are identified for future development of energy flexible buildings. [ABSTRACT FROM AUTHOR]

Heating, ventilation and air-conditioning systems (HVAC), at demand side, have been regarded increasingly as promising candidates to provide frequency regulation service to smart power grids. To assess the performance of the frequency regulation service provided by the demand side, dedicated frequency regulation test signals have been proposed that are relatively demanding and critical to power grids considering the quality of the service provided by the demand side. However, other practical signals might be demanding and critical to buildings at the demand side considering the impact of the service on indoor environment control. In this study, a set of criteria is proposed to assess the demanding level of frequency regulation signals to power grids and buildings at demand side, respectively. The impacts of providing frequency regulation service (to power grids) on indoor environment control are quantified when HVAC systems are following practical signals with different demanding levels to buildings. The results show that indoor air temperature can have a relatively large offset when HVAC systems are following frequency regulation signals demanding to buildings. In addition, the indoor air temperature offset will increase when regulation capacity provided increases. Two dedicated test signals for buildings are therefore recommended to verify the environment control performance of buildings when providing frequency regulation service to power grids. • Impact of frequency regulation (FR) service on indoor environment control is studied. • Criteria are proposed to assess demanding levels of FR signals to grids & buildings. • Indoor temperature has a large offset when following FR signals critical to buildings. • Indoor temperature offset will increase when regulation capacity provided increases. • Two dedicated test signals are proposed for indoor environment control assessment. [ABSTRACT FROM AUTHOR]

The increased generation of renewable power is challenging in terms of the power balance and reliability of power grids due to the intermittent nature of renewable sources. Heating, ventilation, and air-conditioning (HVAC) systems in buildings, at demand side, are promising candidates for providing frequency regulation. In this study, we systematically assessed the use of variable-speed pumps in HVAC systems for frequency regulation. The dynamic characteristics of the pump were investigated. The results show that the power of the pump can response to the frequency change rapidly (returning stable within 1s), while the response of flow rate is slightly slower. A frequency regulation control strategy is proposed and implemented on a test rig. From the viewpoint of power grids, the experimental results show that the pump can provide high-quality frequency regulation (performance scores of 0.989 and 0.968). From the viewpoint of buildings, the experimental results indicate that the fluctuation magnitude of the air-handling unit outlet air temperature increases (from 3.3 K to 7.1 K) with increasing automatic generation control (AGC) signal frequency, whereas the fluctuation magnitude of the indoor air temperature increases to some extent and then decreases when the frequency of the AGC signal is above a certain level. • Experiments are conducted on using pumps in buildings for grid frequency regulation. • Dynamic characteristic of variable-speed pumps under frequency regulation is tested. • Pumps can provide frequency regulation with high performance scores (0.989/0.968). • Impacts of frequency regulation on HVAC control & indoor environment are studied. • Impacts of communication delay on performance scores are investigated. [ABSTRACT FROM AUTHOR]

Power demand response is considered as one of the most promising solutions in relieving the power imbalance of an electrical grid that results a series of critical problems to the gird and end-users. In order to effectively make use of the demand response potentials of buildings, this paper presents a novel air-conditioning system with proactive demand control for daily load shifting and real time power balance in the developing smart grid. This system consists of a chilled water storage system (CWS) and a temperature and humidity independent control (THIC) air-conditioning system, which can significantly reduce the storage volume of the chilled water tank and effectively enable a building with more flexibility in changing its electricity usage patterns. The power demand of the proposed air-conditioning system can be flexibly controlled as desired by implementing two types of demand response strategies: demand side bidding (DSB) strategy and demand as frequency controlled reserve (DFR) strategy, in respond to the day-ahead and hour-ahead power change requirements of the grid, respectively. Considerable benefits (e.g., energy and cost savings) can be achieved for both the electricity utilities and building owners under incentive pricing or tariffs. A case study is conducted in a simulation platform to demonstrate the application of the proposed system in an office building. [ABSTRACT FROM AUTHOR]

A fast power demand response (DR) strategy involving both active and passive cold storages is presented. This control strategy provides an immediate and stepped power demand reduction through shutting chiller(s) down when requested. The results show that the power demand reduction and building indoor temperature during the DR event can be predicted accurately. The power demand reduction is stable which is more predictable for the grid management. The building indoor temperature rise is restrained and indoor thermal comfort is improved through use of a small scale active storage system during the DR event. The incentive bought by an existing DR program is used to calculate the economic benefit of the demand reduction controlled by the developed fast DR strategy. In addition, an electricity price structure in South China is introduced to calculate the cost saving potentials of the active storages, when a storage-priority control is used to shift peak demand in normal days. The results show that small scale active storages can also offer significant life-cycle cost saving for building demand management. [ABSTRACT FROM AUTHOR]

This paper presents a systematic review to align current and future research in smart grids (SG) and smart urban energy systems (SUES) and unify the diverse but fragmented research in urban energy management. First, the common research themes repeatedly appearing in the SG and SUES literature are categorized into logical physical, cyber, and social energy processes. Critical findings are summarized for each part, i.e., the advances and trends in physical energy generation, transmission, consumption, and storage processes of cities for energy interventions, the cyber process chain of energy sensing, modeling, forecasting, scheduling, coordinating, and adapting for enhancing the "smartness" of power and urban energy systems, and the social energy processes of understanding, protecting, engaging, and governing human to be a new smartness dimension. Second, the process-based framework provides insights on the design and implementation of SG and SUES for engineers, planners, and policymakers, such as optimizing the system performance by upgrading individual processes and exploring new links among identified physical, cyber, and social energy processes. The upscaling barriers and strategies of sustainable energy technologies in the development and deployment stages are also summarized to scale up sustainable energy processes to a higher level. Finally, future research directions are envisioned, including developing data markets, privacy-preserving data sharing and analytics for urban-scale energy modeling, refining policy and standards for safety, privacy, cybersecurity, and interoperability issues, assessing technology maturity and energy system success factors, and removing regulatory and structural barriers. [Display omitted] • A systematic review intersecting smart grid and smart urban energy systems is done. • A holistic multi-scale multi-process cyber-physical-social framework is developed. • Advances and trends in physical/cyber/social energy processes are reviewed. • Sustainable upgradation, integration, and scale-up of energy processes are suggested. • Guidelines and future directions are given for smart grid and urban energy systems. [ABSTRACT FROM AUTHOR]

• A simplified room thermal model in state-space representation is developed. • Performance maps of inverter ACs are developed for online applications. • A frequency-based model predictive control method is developed for inverter ACs. • The model predictive controller makes ACs price-responsive and grid-interactive. In the context of smart grids, residential air conditioners, as the major contributors to home electricity bills and loads on electrical grids, need to be not only energy-efficient, but also grid-responsive to relieve power supply-demand imbalance. Existing demand response control strategies for residential air conditioners focus on single-speed type and mainly adopt temperature set point reset to respond to hourly day-ahead electricity prices. This study represents the first attempt to directly control the operating frequency of inverter air conditioners in response to high-granularity electricity price signals, i.e., 5-minute real-time electricity prices, using model predictive control method. A simplified room thermal model in the stochastic state-space representation and performance maps of an inverter air conditioner are developed and integrated for predicting the coupled thermal response of an air-conditioned room. A demand response-enabled model predictive controller is designed based on the coupled model to optimally control the operating frequency of the inverter air conditioner while taking account of all the influential variables including weather conditions, occupancy, and 5-min real-time electricity prices. A Kalman filter is adopted to estimate the unmeasurable variables and remove the noises in measurements. A TRNSYS-MATLAB co-simulation testbed is developed to test the thermal and energy performances of the model predictive controller. Results show that compared to the PID controller, the demand response-enabled model predictive controller can implement automatic and optimal precooling to improve occupant's thermal comfort at the beginning of occupancy. Moreover, it can also reduce average power consumption during peak demand periods by 17.31% to 38.86% compared with the PID controller and reduce all-day electricity costs by 0.42% to 22.16%. The frequency-based model predictive control method enables residential inverter air conditioners to be more grid-friendly and cost-efficient. [ABSTRACT FROM AUTHOR]