HEMSs and enabled demand response in electricity market: An overview
Introduction
Traditional Electrical Grid has generation, transmission, distribution and control capabilities, but there is a lack of information and communication technology (ICT) element, particularly at the consumer side. The existing grid is radial, built for centralized generation and generally depends upon manual restoration [1]. Most power plants use fossil fuels to generate electricity as a bulk in central power stations but are less efficient, cause CO2 emissions and other harmful effects. Integration of ICTs into the grid makes it possible to take fast and accurate decisions [2] and consequently, forms an efficient electrical network of all connected components to deliver reliable, sustainable, and secure electricity to the consumer. CO2 emission can be reduced significantly by using renewable energy resources for electricity generation. These resources are distributed throughout the grid, and have the ability to generate electricity in the range of kilowatts (for residential buildings) up to some megawatts (for commercial buildings and factories) [3]. Efficient control and management of the renewable resources is an important element of smart grid. Many techniques like, active and reactive load improvements, reducing line losses and distribution optimization etc were used in the past in order to improve energy efficiency. Due to the recent advancements in ICT technologies, energy efficiency has improved significantly by efficient load management [4]. Power quality is another important aspect of power system that determines fitness of the supplied electricity for the consumer devices. Ideally the electric supply should have a constant amplitude and frequency. However, this is seldom the case in practice due to nonlinear effects of power electronics, impedance mismatch etc. This leads to reduced efficiency and life time as well as increased running cost of the appliances. Solutions to power quality related problems involve advanced control methodologies. A lot of effort has been made by researchers in order to overcome power quality issues; see for instance [5] and [6]. Advanced control and ICTs give us an opportunity to achieve reliable and efficient power system, as well as efficient power consumption and reduced energy cost by employing demand-side energy management.
The term, demand-side energy management, demand-side load management or load management, in short, refers to the adjustment of demand to match supply. It is the planning, monitoring and implementation of those utility actions, designed to influence customer electricity usage by introducing dynamic load management programs. A lot of work is being done to match the supply and demand by various load management schemes so that we could have reliable, sustainable, economical and secure power system. It is stated in [7] that worldwide residential energy consumption is about 27%. Hence it is imperative to improve energy efficiency on consumer part. A Key concept used for this purpose is demand side management (DSM) [8]. Most of the DSM programs are utility driven in which consumers are not active, but current research work in this area has highlighted need of DSM programs involving active consumers. In this context DSM programs have following four elements, depending upon the applied measures and timings as a consumer process: Energy efficiency, time of use (ToU), demand response (DR), and spinning reserve [9]. Spinning reserve is back-up energy production capacity which can be made available for a transmission system within 10 min and can operate continuously for at least 2 h, once it is brought online.
According to US Federal Energy Regulatory Commission (FERC), Demand Response (DR) is defined as incentives offered to electricity users on reducing their electricity consumption in response to a utility’s need for electricity due to a high, system-wide demand for electricity or emergencies that could affect the transmission grid [1], [10].
Typically, DR events may occur in the range of 1 to 4 h depending on duration of peak load in a given area and includes dimming or turning off of lighting, shutting down a portion of a manufacturing process or adjusting controllable heating, ventilation and air conditioning (HVAC) levels. Alternatively, onsite generation can be used to shift load drawn from the power grid. Improving energy efficiency and system reliability are the main objectives of DR. Customers can participate in the DR program competition offered by the energy market to change the consumption pattern in response to the price variations [11], [12]. DR is becoming the essential task of grid operators and utilities in order to manage peak demand for industrial/commercial and residential sectors. It is estimated that about eleven million households are subscribed to DR programs all over the globe. This rate will be extended up to 32.5 million by 2018 [13]. DR programs are developed to provide incentives to the residential customers and work under the umbrella of HEMSs. A HEMS usually consists of smart appliances, smart meters, advanced control systems and in-home displays. HEMS focuses on power management; home appliances are monitored and controlled to optimize difference in electric supply and demand [14].
Remaining paper is structured as follows. Section 2 describes the basic functions and evolution of HEMS. HEMSs based on various technologies and standards, particularly residential applications, are presented in Section 3. Research work and analysis on residential energy consumption management at peak hours (DR strategies) through a home energy management system (HEMS) at the distribution level, as well as DR architectures and models have been described in Section 4. Section 5 consists of numerical analysis based on the data of a local grid station in Pakistan (Abbottabad 132KV feeder). Section 6 concludes the paper.
Section snippets
Basic functions and evolution of HEMS
A home energy management system encompasses any product or service that monitors, controls, and analyzes electrical energy at home. This definition includes residential utility demand response programs, home automation services, personal energy management, data analysis and visualization, auditing, and related security services [15]. The end goal of HEMS is to reduce energy cost, conserve energy and improve consumers’ comfort level. HEMSs are in operation for decades and their key function is
HEMS scenarios
There are many implementations of HEMSs in which different ICTs have been used. Some deployments of HEMS use power line communications (PLC) as an information transfer medium. This section also describes standards and technologies in designing a suitable HEMS required for a particular scenario (Fig. 1).
Power Line Communication (PLC) carries out high speed data transmission through power lines, but the drawback of using PLC is narrowband noise which increases with increase in frequency of the
An overview
Demand response (DR) is a class of demand-side management programs in which utilities offer incentives to customers in order to reduce their consumption during peak hours. Interest in DR has increased with the introduction of new technologies during the past decade. Many utilities and independent system operators (ISOs) in deregulated electricity markets have recognized benefits of DR. Utilities offer DR programs to the consumers, in order to reduce peak load in specified timings which in turn
Numerical analysis and simulation
Home energy management system in conjunction with DR programs has affected the consumers and the electrical utilities and has forced the policy makers to take initiatives for the future developments. As consumer participation is essential for the success of any DR program, consumer’s satisfaction and needs must be prioritized and analyzed before the launch of any such program.
End users are facilitated by offering DR programs that are either incentive based or price based [80]. During peak
Conclusions
A home energy management system (HEMS) provides a platform to monitor and control energy consumption at home. It involves various ICTs working with each other in a compatible manner. DR programs are employed in order to provide users with incentives so that the load is shifted from peak to off-peak hours. DR programs work under the platform of HEMS that provides means to retrieve energy consumption information in real time. For the smooth conduct of all these programs there are many challenges
References (88)
- et al.
The effect of utility time-varying pricing and load control strategies on residential summer peak electricity use: a review
Energy Policy
(2010) - et al.
An economic welfare analysis of demand response in the PJM electricity market
Energy Policy
(2008) - et al.
Demand response in US electricity markets: empirical evidence.
Energy
(2010) - et al.
Industrial applications of production planning with optimal electricity demand.
Appl Energy
(1993) - et al.
A summary of demand response in electricity markets
Electr Power Syst Res
(2008) - et al.
Smart grid communication: its challenges and opportunities
IEEE Trans Smart Grid
(2013) - et al.
A survey on smart grid communications: from an architecture overview to standardization activities. In: Handbook of green information and communication systems
(2012) - et al.
Energy management and operational planning of a microgrid with a PV-based active generator for smart grid applications
IEEE Trans Ind Electron
(2011) - Molderink, Albert, Vincent Bakker, Maurice GC Bosman, Johann L. Hurink, Gerard JM Smit. Domestic energy management...
- et al.
An inductively active filtering method for power quality improvement of distribution networks with nonlinear loads
IEEE Trans Power Delivery
(2013)