Demand response programs offer efficient solutions for many power system problems, such as high generation cost, high demand’s peak to average ratio, high emissions, reliability issues and congestion in generation, transmission and distribution systems. Their main function is to assist power systems during peak demand hours and also during contingencies. They are a subcategory of the family of demand side management (DSM) strategies. DR programs are classified into two broad categories; price-based DR programs and incentive-based DR programs. In order to exploit their full potential, DR programs must be implemented optimally. Such a problem, which here is referred to as “DR optimisation problem”, is a hot research topic and has been frequently researched in the literature. This paper aims to review different research works on DR optimisation problems. Based on the conducted review, some directions for future research are proposed.

Optimisation of demand response in electric power systems, a review

In this paper, a novel iterative $Q$ -learning method called “dual iterative $Q$ -learning algorithm” is developed to solve the optimal battery management and control problem in smart residential environments. In the developed algorithm, two iterations are introduced, which are internal and external iterations, where internal iteration minimizes the total cost of power loads in each period, and the external iteration makes the iterative $Q$ -function converge to the optimum. Based on the dual iterative $Q$ -learning algorithm, the convergence property of the iterative $Q$ -learning method for the optimal battery management and control problem is proven for the first time, which guarantees that both the iterative $Q$ -function and the iterative control law reach the optimum. Implementing the algorithm by neural networks, numerical results and comparisons are given to illustrate the performance of the developed algorithm.

A Novel Dual Iterative $Q$ -Learning Method for Optimal Battery Management in Smart Residential Environments

This paper proposes a new robust load frequency control (LFC) scheme for multiarea power systems based on the second-order sliding mode control and an extended disturbance observer. First, a reduced-order model of the power system LFC is derived. In this model, the load variations and net exchange tie-line power deviations are combined as a lumped disturbance which can be estimated by the extended disturbance observer. Second, a novel sliding surface is designed with the new transformed state variables obtained from the estimated disturbance. The system dynamics can be indicated by sliding surface design using the eigenvalue assignment or the optimal sliding manifold technique. The sliding variable is driven to the sliding surface with a second-order sliding mode algorithm named supertwisting algorithm. The stability of the proposed LFC scheme and the extended disturbance observer is proved using Lyapunov method. The merits of the scheme include faster response speed, stronger robustness against disturbances arising from power system parameter errors, and unmodeled dynamics, and the full consideration of tie-line power flow scheduling variations. Finally, numerical simulations verify the effectiveness of the LFC scheme and reveal its advantages over the state of the arts.

A Robust Load Frequency Control Scheme for Power Systems Based on Second-Order Sliding Mode and Extended Disturbance Observer

An optimized communication and control infrastructure, based on the microgrid building block concept, for active distribution systems is essential to facilitate powerful control framework under the smart grid paradigm. In this paper, a novel methodology for designing a communication and control infrastructure is presented. The new design takes into account both communication system and distribution system-related aspects. The proposed design facilitates systematic and optimized clustering of the distribution system into a set of virtual microgrids with optimized communication requirements while considering the power quality aspects, characteristics of distributed generation units, distributed energy storage units, and distributed reactive sources. The new design facilitates robust infrastructure for smart distribution systems operation and control, e.g., self-healing control and optimized system-level operation, by using virtual microgrids as building blocks in future distribution systems. The motivations, conceptual design, problem formulation and solution algorithms are presented in this paper. The well-known PG&E 69-bus distribution system is selected as a test case and through several sensitivity studies, the effect of optimization coefficients on the design, and the robustness of the algorithm are investigated. Finally, the algorithm is tested on the IEEE 123-bus distribution system.

Optimized Multiple Microgrid-Based Clustering of Active Distribution Systems Considering Communication and Control Requirements

With the deregulation of the electric power energy market, providing quality power has become an important concern of both power suppliers and customers. Efforts have been made to improve the power quality using passive filters, active power filters, hybrid filters and the new concept of custom power. This paper presents a comprehensive review of compensating custom power devices mainly DSTATCOM (distribution static compensator), DVR (dynamic voltage restorer) and UPQC (unified power quality compensator). It is aimed at providing a broad perspective on the status of compensating devices in electric power distribution system to researchers and application engineers dealing with power quality problems. Classified references presented in this paper would serve quick and useful applications.

A Review of Compensating Type Custom Power Devices for Power Quality Improvement

The basic idea of decentralized demand response systems is not new, however, material presented in the subject matter literature is usually limited to general ideas and possible system services. In this paper, the original stochastic decentralized active demand response (DADR) system is presented in the form of an application-ready control algorithm. The results of simulation investigations have confirmed that the proposed stochastic DADR solution, because of its high dynamic response in dealing with disturbance phenomena, might be used as part of both the primary and the secondary load frequency control in electrical power systems. The applicability of the proposed algorithm for control of refrigerators has been numerically tested for various system parameters. Fulfillment of all assumed DADR system requirements concerning high dynamic, “soft” operation, fair share in service as well as minimization of degradation in comfort of use of DADR controlled devices have been confirmed in numerical evaluations.

Application of Stochastic Decentralized Active Demand Response (DADR) System for Load Frequency Control

Reliable operation of the smart grid requires assurance of the electromagnetic compatibility of sensitive smart metering systems and power electronic converters, which introduce high-level electromagnetic interference. As it has been experimentally shown, currently available, normalized, and frequency domain tests are ineffective for the evaluation of data transmission error hazards. The mathematical time-domain model proposed in this paper enables assessment of the probability of errors occurring in a given transmission signal for known interference parameters. The validity of the model and its practical applicability have been experimentally verified.

Time-Domain-Based Assessment of Data Transmission Error Probability in Smart Grids With Electromagnetic Interference

The paper considers the use of an automated decentralized system, the DADR (Decentralized Active Demand Response), for reduction of peak power in the Polish Electrical Power System (EPS) This issue is especially important from the point of view of improving the efficiency and reliability of the Polish EPSfor which purpose the aim is to reduce peak power by 1 GW, which represents about 4% of typically peak power value Among the known methods of reduction of peak loads today, the tariff programs are commonly used; however, they do not achieve the desired results With this in mind the article includes an assessment of the possibility of using a Decentralized Active Demand Response system for activities related to the reduction of peak loads The article discusses the principle of operation of the DADR device in cooperation with thermostatic loads (fridge-freezer), in which there is a possibility to modify their characteristics of power versus time on the supply side Analysis of the aggregated impact of the actions of such a solution on the daily load curve is shown in the simulation results The simulation results have showed that the use of a DADR system involving thermostatic devices (fridgefreezers) available in Poland allows for a significant reduction in peak power of about 037 GW (16% of the targeted 4%) a reduction of energy consumption at peak hours of about 065 GWh and a shift to the night valley The stochastic algorithm that was used reduced peak energy consumption without any negative impact on the electrical power system (there are no power overshoot and oscillations) It has also been shown that the new formula developed by the authors allows for calculation of the amount of reduced energy for various parameters of thermostatic devices and various durations of peak power

Demand side management using DADR automation in the peak load reduction

To improve energy quality in distribution systems, many different solutions there are implemented, for example: (i) active power filters (APF); (ii) unified power flow controllers (UPFC); (iii) unified power quality conditioners (UPQC); (iv) interline power flow controllers (IPFC). Interline power flow controllers are the classical series or series-parallel filters applied to given number of independent lines with common, for all lines, DC element. Their possible functions are enlarging and include power flow control between lines, reactive power compensation and distribution system stability improvement. In the paper, the authors show that using probabilistic approach to the distribution system one can considerably decrease power rating of the parallel active power filter's when it is a component of the interline power flow controller.

Jacek Bojarski

Papers

Application of Stochastic Decentralized Active Demand Response (DADR) System for Load Frequency Control

Time-Domain-Based Assessment of Data Transmission Error Probability in Smart Grids With Electromagnetic Interference

Demand side management using DADR automation in the peak load reduction

Interline power flow controller-probabilistic approach

Decentralized Active Demand Response (DADR) system for improvement of frequency stability in distribution network