Grid Control Research Articles

Hybrid smart grid with sustainable energy efficient resources for smart cities

A smart city is a safe and productive metropolitan area that offers its residents a high standard of living through optimized resource planning. The advent of smart cities has allowed consumers to easily and reliably control home resources. In this regard, power control is a challenging activity, involving the optimal scheduling of connected devices to optimize electricity utilization. Therefore, this problem needs to be addressed with considerable attention and dedication. Several solutions are presented for energy optimization in smart cities, but not for real-time energy optimization. This paper introduces a hybrid smart grid that produces electricity from various sources Photovoltaic (PV), hydro and thermal power with a delivery system that satisfies energy optimization of the energy costs in real-time (ECRT) by considering the latency factor (FoL). This research aims to build resources in a smart grid (SG) for efficient control of power operations management. This paper models sustainable energy from all-natural sources and organized the proper energy distribution system at an optimized level for energy efficiency in a smart city. This paper presents various ideas and smart energy solutions that provide more advancement to several disciplines that concentrate on performance enhancement, smart and efficient resource utilization, and sustainable design.

Energy Management System Designed for Residential Grid connected Micro Grid

This paper presents an energy management system supported by PI Controller for a residential grid connected micro grid with renewable hybrid generation (wind and photo voltaic) and battery system. Modeling hybrid system includes non conventional energy sources given at sporadic supply conditions and dynamic energy demand, and to make conceptual energy storage with the help of battery system . Designing an appropriate scheme that dynamically changes modes of renewable integrated system based on the availability of RES power and changes in load. Wind,PV are the primary power supply of the system; battery is going to be act as a substitute.The PI controller is developed and carried out for the aimed hybrid(Wind and PV) energy system to integrate the non conventional energy sources to the serviceability either to grid or to Residential loads.main objective is improvement of transients during switching periods by using an efficient PI controller.maximum power point tracking is also other objective is energy management system designed for the residential grid connected Micro Grid. Simulations are carried out on the proposed Hybrid energy system using MATLAB/ SIMULINK.

Supervised control of hybrid AC-DC grids for power balance restoration

In this paper, the flexibility of hybrid AC-DC distribution networks is exploited to coordinate multiple Distributed Energy Resources (DERs) with the aim of promptly restoring unexpected power imbalances caused by intermittent Renewable Energy Sources (RESs) and loads. Given the potential large-scale nature of the problem, the AC distribution network is decomposed into non-overlapping areas named clusters, equipped with MicroGrids (MGs) and non-dispatchable units, and interconnected also by the DC network. Each cluster is endowed with a Model Predictive Controller designed to compensate the local active power variability by requesting balancing services to the local MGs. A supervisory layer is designed and activated to optimally transfer power through the controllable DC links guaranteeing enough operative margins to each cluster. The designed architecture is tested on a benchmark grid composed of the IEEE 37-bus and 13-bus systems, connected by a multi-terminal DC network. The reported numerical results witness the effectiveness of the proposed approach.

Analysis of IoT-Based Load Altering Attacks Against Power Grids Using the Theory of Second-Order Dynamical Systems

Recent research has shown that large-scale Internet of Things (IoT)-based load altering attacks can have a serious impact on power grid operations such as causing unsafe frequency excursions and destabilizing the grid's control loops. In this work, we present an analytical framework to investigate the impact of IoT-based static/dynamic load altering attacks (S/DLAAs) on the power grid's dynamic response. Existing work on this topic has mainly relied on numerical simulations and, to date, there is no analytical framework to identify the victim nodes from which that attacker can launch the most impactful attacks. To address these shortcomings, we use results from second-order dynamical systems to analyze the power grid frequency control loop under S/DLAAs. We use parametric sensitivity of the system's eigensolutions to identify victim nodes that correspond to the least-effort destabilizing DLAAs. Further, to analyze the SLAAs, we present closed-form expression for the system's frequency response in terms of the attacker's inputs, helping us characterize the minimum load change required to cause unsafe frequency excursions. Using these results, we formulate the defense against S/DLAAs as a linear programming problem in which we determine the minimum amount of load that needs to be secured at the victim nodes to ensure system safety/stability. Extensive simulations conducted using benchmark IEEE-bus systems validate the accuracy and efficacy of our approach.

An investigation on the application and challenges for wide area monitoring and control in smart grid

The complexity and dynamics of the modern power system are continuously changing due to the penetration of a large number of renewable energy sources and changing load patterns. These growing complexities have caused numerous outages around the world, primarily due to the lack of situational awareness about the grid operating states. Rectification of this problem requires advanced sensing technology to accurately capture the dynamics of the system for better monitoring and control. Measurement of synchrophasors is a potential solution to improve situational awareness in the grid. The synchrophasors technology is now widely accepted throughout the world and has the potential to replace the existing SCADA system in monitoring and control of the power system. Their installation enables efficient resolution to substantially improve transmission system planning, maintenance, operation, and energy trading. This paper reviews the state of the art potential applications that the PMU based WAMC offers to the power system. It also includes technical perspectives, challenges, and future possibilities.

Design and performance analysis of PV grid-tied system with energy storage system

With the increasing demand for solar energy as a renewable source has brought up new challenges in the field of energy. However, one of the main advantages of photovoltaic (PV) power generation technology is that it can be directly connected to the grid power generation system and meet the demand of increasing energy consumption. Large-scale PV grid-connected power generation system put forward new challenges on the stability and control of the power grid and the grid-tied photovoltaic system with an energy storage system. To overcome these problems, the PV grid-tied system consisted of 8 kW PV array with energy storage system is designed, and in this system, the battery components can be coupled with the power grid by AC or DC mode. In addition, the feasibility and flexibility of the maximum power point tracking (MPPT) charge controller are verified through the dynamic model built in the residential solar PV system. Through the feasibility verification of the model control mode and the strategy control, the grid-connected PV system combined with reserve battery storage can effectively improve the stability of the system and reduce the cost of power generation. To analyze the performance of the grid-tied system, some real-time simulations are performed with the help of the system advisor model (SAM) that ensures the satisfactory working of the designed PV grid-tied System.

Multi-objective optimization for voltage and frequency control of smart grids based on controllable loads

The output uncertainty of high-proportion distributed power generation severely affects the system voltage and frequency. Simultaneously, controllable loads have also annually increased, which markedly improve the capability for nodal-power control. To maintain the system frequency and voltage magnitude around rated values, a new multi-objective optimization model for both voltage and frequency control is proposed. Moreover, a great similarity between the multi- objective optimization and game problems appears. To reduce the strong subjectivity of the traditional methods, the idea and method of the game theory are introduced into the solution. According to the present situational data and analysis of the voltage and frequency sensitivities to nodal-power variations, the design variables involved in the voltage and frequency control are classified into two strategy spaces for players using hierarchical clustering. Finally, the effectiveness and rationality of the proposed control are verified in MATLAB.

Analysis of a Multi-Timescale Framework for the Voltage Control of Active Distribution Grids

The development of strategies for distribution network management is an essential element for increasing network performance and reducing the upgrade of physical assets. This paper analyzes a multi-timescale framework to control the voltage of distribution grids characterized by a high penetration of renewables. The multi-timescale solution is based on three levels that coordinate Distributed Generation (DG) and Energy Storage Systems (ESSs), but differs in terms of the timescales and objectives of the control levels. Realistic load and photovoltaic generation profiles were created for cloudy and clean sky conditions to evaluate the performance features of the multi-timescale framework. The proposed solution was also compared with different frameworks featuring two of the three levels, to highlight the contribution of the combination of the three levels in achieving the best performance.

Researching Digital Methods of Generation Signals of Hydroacoustic Phased Antenna Grids

Solving tasks of creation, correction and parametric control of signals excitation hydroacoustic phased antenna grids is actual problem of creating multichannel generated devices, based on switch-mode amplifiers with pulse-width modulation. In this article were reviewed correction methods output signals of hydroacoustic transmission paths, periodic pulse sequence creation and parametric voltage level control of excitation channels of phased antenna grid with abrupt decrease impedance of hydroacoustic converters. Was shown the perspective implementation digital technologies for improvement parameters modes of hydrolocation with deterministic library of signals. Presented digital control methods of output signals in hydroacoustic transmission paths are characterized by scientific novelty and originality of the proposed technical decisions.

Efficiency-driven planning for sizing of distributed generators and optimal construction of a cluster of microgrids

The optimal placement and the sizing of various distribution system components have gained extra significance in the recent past as the concepts of smarter distribution systems, distributed generation, and microgrids blossomed. This paper presents two novel techniques for sizing the Distributed Generators (DGs) in a large-sized radial distribution network. The primary strategy is proposed by considering the bi-directional progression of current in the parts of the circuit that occurs because of the presence of newly installed DGs. The subsequent strategy utilizes the active power sensitivity calculations for sizing the DGs. These strategies are applied on the chosen radial distribution systems to size numerous DGs all at once, with the main objective being the improvement of efficiency, by accomplishing minimization of losses and improvement in nodal voltages. Then, the maximum number of self-adequate and highly reliable microgrids is formed in the distribution network utilizing the “Reverse Current Flow” procedure cited in the literature, for the proposed sizing methods. Finally, a sensitivity analysis is performed by varying the rates of infiltration of the DGs to throw light on the suitability of the newly introduced methods of sizing. This analysis gives a set of operational rules for the controller of the smart grid.

О разработке программно-аппаратного комплекса моделирования электросетевого контроллера и объектов микрогенерации на основе возобновляемых источников энергии в сетях НН 0,4 кВ

The article discusses the issues of connecting microgeneration facilities based on renewable energy sources (RES) to electric networks of low voltage (LV) 0,4 kV. This method of connection will allow the use of microgeneration facilities as network sources of energy, and at the same time unused electrical energy generated by micro-generation facilities can be supplied to a low-voltage network of 0,4 kV. Methods of simulation modeling of the processes of electrical energy distribution in the power supply system with microgeneration objects are proposed; the requirements for the power grid controller used to ensure the connection of micro-generation facilities to the low voltage network are formulated. The problems arising in connection with this are analyzed and the ways of their solution are offered. The proposed methods for the development of software and hardware solutions using modern methods of simulation of electrical energy generation and distribution based on rapid prototyping in the Matlab Simulink environment make it possible to carry out field experiments in order to simulate the processes occurring in 0,4 kV low voltage electrical networks using microgeneration objects prosumers.

Innovative Application of Model-Based Predictive Control for Low-Voltage Power Distribution Grids with Significant Distributed Generation

In past decades, the deployment of renewable-energy-based power generators, namely solar photovoltaic (PV) power generators, has been projected to cause a number of new difficulties in planning, monitoring, and control of power distribution grids. In this paper, a control scheme for flexible asset management is proposed with the aim of closing the gap between power supply and demand in a suburban low-voltage power distribution grid with significant penetration of solar PV power generation while respecting the different systems’ operational constraints, in addition to the voltage constraints prescribed by the French distribution grid operator (ENEDIS). The premise of the proposed strategy is the use of a model-based predictive control (MPC) scheme. The flexible assets used in the case study are a biogas plant and a water tower. The mixed-integer nonlinear programming (MINLP) setting due to the water tower ON/OFF controller greatly increases the computational complexity of the optimisation problem. Thus, one of the contributions of the paper is a new formulation that solves the MINLP problem as a smooth continuous one without having recourse to relaxation. To determine the most adequate size for the proposed scheme’s sliding window, a sensitivity analysis is carried out. Then, results given by the scheme using the previously determined window size are analysed and compared to two reference strategies based on a relaxed problem formulation: a single optimisation yielding a weekly operation planning and a MPC scheme. The proposed problem formulation proves effective in terms of performance and maintenance of acceptable computational complexity. For the chosen sliding window, the control scheme drives the power supply/demand gap down from the initial one up to 38%.

Expandable deep width learning for voltage control of three-state energy model based smart grids containing flexible energy sources

The article establishes a three-state energy (TSE) model for flexible energy sources (FESs) connected to smart grids. The article proposes a unified time-scale (UTS) coordinated primary voltage control framework and a UTS coordinated primary voltage controller for voltage control of smart grids containing a high proportion of FESs. To mitigate uncoordinated voltage, the proposed control framework integrates traditional secondary and primary voltage control into a UTS. The article proposes an expandable deep width learning (EDWL) for the proposed controller. The proposed controller applies the EDWL for predictive control; the proposed controller outputs the reactive power reference value of each TSE unit in smart grids with the real-time voltages of smart grids pilot buses. The proposed algorithm is numerically simulated with the proportional-integral-derivative (PID) algorithm and deep neural networks (DNNs) in IEEE 118-bus, 300-bus, 1354-bus, and 2383-bus systems. The simulation results show that the proposed framework and controller can quickly and accurately control the grid voltage, and verify the feasibility and effectiveness of the proposed approach. The integral of squared error control performance index is 0.47% smaller than the PID and 0.06% smaller than DNNs.

Event‐triggered load frequency control of smart grids under deception attacks

This paper shows a result for the load frequency control with event-triggering mechanism under deception attacks. Specifically, the event-triggering mechanism and deception attacks are considered in the dynamic model of power systems. The event-triggering is used to reduce the frequency of controller update and communication between nodes. The H ∞ controller is designed and the stability of the system is guaranteed by utilising the Lyapunov–Krasovskii functional method and truncated Bessel–Legendre inequality. Finally, a three-area interconnected networked power system is given and the simulated results are presented to show the effectiveness of the developed theoretical results.

Passivity Enhancement of Voltage-Controlled Inverters in Grid-Connected Microgrids Considering Negative Aspects of Control Delay and Grid Impedance Variations

With growing environmental concerns, the installation of distributed generation systems forming microgrids in power systems has received much attention recently. This panacea, however, has always some challenges with itself. The delay in digital control systems, grid impedance variations in weak grids, and the interaction between paralleled converters in a microgrid, which can threaten the expectable operation of microgrids, are notable examples. Thus, this article formulates these challenges in microgrids and then addresses them so that guarantee the stable operation of the microgrid. To this end, this article first offers a delay compensation method and elaborates it so that the control system achieves high robustness against grid impedance variations. Then, a feedforward loop is introduced to the control system that makes the system immune against the interaction of inverters in microgrids. Using these methods, the system can survive irrespective of the abovementioned nonideal conditions. The grid-forming control approach is selected as the operation mode of the microgrid in this article since it could be used for both grid-connected and islanded scenarios. The experimental results of a laboratory prototype show the correctness of the theoretical conclusions and confirm the efficiency of the suggested technique.

Performance Analysis of Maximum Power Point Tracking for Two Techniques with Direct Control of Photovoltaic Grid -Connected Systems

ABSTRACT The present study presents two techniques of Maximum Power Point Tracking (MPPT) via DC/DC converter to enhance the performance of the grid-connected Photovoltaic (PV) generation system to participate effectively within microgrids. The two techniques of MPPT are Perturb-Observe (P&O) and Incremental Conductance (IC). The variation of the solar radiation and temperature is considered during employing the two MPPT techniques. Besides, the performance of the system under the random variation of solar radiation was investigated. The authors used two types of controllers at the three-phase inverter, Proportional Integral (PI) and H-infinity Control (H∞C). The output voltage, current, and power at each type of inverter controller are compared along with the two techniques of MPPT. The effectiveness of the developed controllers together with MPPT techniques is demonstrated by comparing the obtained results with some previously reported research in the literature. In the case of MPPT via P&O and IC techniques along with the H∞C controller, the results show that the technique of IC is more robust, and the obtained output power is well matched with the references one as compared with the P&O technique which records a 7% error from MPP. Besides, the P&O technique has a high voltage and current ripple with a percentage of 20% at the starting time of the simulation.

Experimental evaluation of an energy storage system for medium voltage distribution grids enabling solid‐state substation functionality

“Smart grids” is a new concept of managing the power transfer in modern grids that will rely not only on the on-line processing of a variety of consumption and generation power data but will also need new hardware to facilitate a flexible and efficient conversion and storage of electrical power to maintain grid stability under fast changing operating conditions. This paper presents the results of the experimental evaluation of a 1.5MJ/25kW energy storage system connected directly to a medium voltage grid to provide fast and flexible grid control capabilities. The demonstrator consists of a supercapacitor stack connected to a low-voltage DC bus via interleaved converters whilst connection to the medium voltage grid is done either via a low voltage inverter and step-up 50Hz transformer or via a cascaded modular multilevel converter fed by dual active bridge converters isolated by medium frequency transformers. The experimental features demonstrated are fast power peak levelling, reactive current injection, grid fault ride through whilst maintaining a high round trip efficiency over a wide power range. The concept on which the demonstrator was designed facilitated the implementation of the solid-state substation with integrated energy storage concept that can further increase flexibility and reliability of future grids.

Decentralized Voltage Stability Monitoring and Control With Distributed Computing Coordination

The computing infrastructure to support the power grid monitoring and control evolves with the increasing system complexity and integration of distributed energy resources (DERs). The integration of DERs requires a stability assessment application to monitor and control at a faster rate compared to the legacy system. Distributed computing architecture provides opportunities for managing these key changes by introducing solutions within substation computers and digital devices such as phasor measurement unit. The proposed decentralized voltage stability using a distributed coordination platform is a secondary emergency control mechanism utilizing large amounts of data in real-time for faster monitoring and control with the legacy system. The developed algorithms have been validated using the IEEE 30, 57, 118, and 300 bus systems using offline and real-time hardware-in-the-loop testbed modeling and simulation. To demonstrate the flexibility of the distributed coordination blocks, multiple case studies and implementation are presented. With control decisions required under changing operating conditions, the IEEE 30 bus system is simulated in real-time using a digital simulator and a network simulator (NS-3). The impact of the SYN flood cyberattack and tolerance of the computing infrastructure to resulting missing data have also been illustrated.

Current mode control of single phase grid tie inverter with anti-islanding

The aim of this paper is to explore the use of various current mode control (CMC) techniques to design a single phase grid tie inverter integrated with anti-islanding protection. Three types of CMC techniques have been discussed, namely current hysteresis control (CHC), constant frequency control (CFC) and average current mode control (ACMC). The performance of the grid tie inverter in the event of grid voltage failure is also studied to help install an anti-islanding mechanism. The proposed control techniques shall eliminate the use of Phase locked loop (PLL) control as the current reference is generated from the grid voltage itself. All three current mode control techniques of an inverter have been simulated in MATLAB/Simulink to evaluate the performance of the designed inverter. The simulated results show a current THD of less than 5% in all three methods and a good anti-islanding response.

Step Coordination Control Strategy Based on WAMS for AC/DC Hybrid System

The power system’s stability is judged through the processing and analysis of wide-area information, and matching and executing the corresponding control measures based on data can be used as an effective backup and supplement to the security and stability control devices. This paper proposes an online additional emergency control strategy based on energy function for the situation that the security and stability control strategy formulated offline may have mode mismatch. This strategy relies on the energy function index that describes the unstable situation of the power system. Based on the real-time data from SCADA and PMU, it combines the energy function method and the trajectory prediction to achieve the function of additional control of the power grid in an emergency. The cases are analyzed to verify the effectiveness of the proposed method. The simulation results demonstrate that the step coordination control strategy could be realized, and the practicality is improved.