Use of Adaptive Thermal Storage System as Smart Load for Voltage Control and Demand Response

Abstract

 Abstract--This paper describes how a large-scale ice-thermal storage can be turned into a smart load for fast voltage control and demand-side management in power systems with intermittent renewable power whilst maintaining its existing function of load shaving. The possibility of modifying a conventional thermal load has been practically demonstrated in a refrigerator using power electronics technology. With the help of an electric spring, the modified thermal load can reduce power imbalance in buildings whilst providing active and reactive power compensation for the power grid. Based on practical data, a building energy model incorporating a largescale ice-thermal storage system has been successfully used to demonstrate the advantageous demand-response features using computer simulation of both grid connected and isolated power systems. The results indicate the potential of using ice-thermal storage in tall buildings in reducing voltage and frequency fluctuations in weak power grids. Almost all urban population growth in the next 30 years will occur in cities of developing countries. According to [2], there are over 411 cities with population over 1 million. In Europe, buildings consume about 40% of total electricity [3]. In many large Asian cities, such as Singapore, Hong Kong and Taipei, plans have been made to install offshore wind farms. Such off wind farms will be linked to the local power grids that supply electricity to many tall buildings. In a recent real case study on the impact of offshore wind farm connection in Taiwan [4], four issues have been highlighted. They are: load flow, fault current, voltage variation and transient stability. In large Asian cities, residential, commercial and industrial buildings consume over 90% of the total electricity generated for the city. Commercial buildings alone consume 66% of total electricity and are therefore the major factor in power consumption [5] (Fig.1) consumption of tall buildings can in principle be "smartly controlled" with modern Power Electronics Technology so that it can be "adaptive" to the availability of traditional and renewable power generation. If this can be achieved, new doors could be opened to utilize the smart building energy concept to interact with future power grid fed with a mixture of traditional and renewable power generation. Smart building energy usage can be a highly effective demand-response solution to meeting the objectives of enhancing power system stability and reducing energy wastage, energy storage requirements and operating costs.Energy storage is an effective means to handle power supply and demand imbalance. However, large-scale battery storage is usually not practically viable because of cost, limited capacities and environmental issues. In tall buildings, thermal load is a considerable portion of the total electric load. It is shown in [6] that thermal loads contribute to about 45% of the total electric power consumption in buildings (Fig.1). The use of thermal energy storage in commercial buildings has been consid...

Thermal Energy Storage for Grid Applications: Current Status and Emerging Trends

“…The contribution of ETS systems including heat losses for the microgrid energy management has been modelled in [60], together with other DER, taking into account the network constraints and the control of the reactive power support. In [80] an ice-thermal storage system is used in building energy models to assist voltage control and reduce the frequency fluctuations in weak electrical networks.…”

Demand Side Management Strategy for Distribution Networks Volt/Var Control: A FCS-Model Predictive Control Approach

“…This methodology was tested via a simulation of the IEEE 37node test feeder, running a nonlinear AC power flow and the control was able to maintain the voltage within the allowable boundaries. In Luo et al (2017), an electrical coil was used to turn an ice-thermal storage unit in a smart building to provide VVC with a DR technique. The authors first developed a building energy model based on real measurements that incorporates the aforementioned three-phase electric spring.…”

A Review and Analysis of Trends Related to Demand Response

“…In the revision, there was a notable trend headed towards the use of batteries and electric accumulators in general [145,163]. However, some articles used thermal storage [155,164] and even water storage [165,166]. The common use of storage systems is tied to the offer of the resource for the hours of higher consumption rates for the flattening of the demand curve.…”