Power System Regulation Research Articles

On Stability of Distributed-Averaging Proportional-Integral Frequency Control in Power Systems

Distributed consensus-based controllers for optimal secondary frequency regulation of microgrids and power systems have received substantial attention in recent years. This letter provides a Lyapunov-based proof that, under a time-scale separation, these control schemes are stabilizing for a wide class of lossless and stable nonlinear ODE power system models, and under weak assumptions on (i) the objective functions used for power allocation, and (ii) the graph topology describing communication between agents in the consensus protocol. The results are illustrated via simulation on a detailed test system.

Impact of large photovoltaic power penetration on the voltage regulation and dynamic performance of the Tunisian power system

By the year 2023, the Tunisian power transmission grid has been projected to include photovoltaic pool of power of 937 MW, scattered throughout the whole landscape of the nation. This paper investigates high photovoltaic energy penetration impacts voltage regulation and dynamic performance of the grid. Load flow analysis is implemented to investigate the power system capability for the case of incorporating the desired photovoltaic power. Computer-based simulations have been used for evaluating the upgradation of the grid. Moreover, the study is based on bifurcation diagrams taking the photovoltaic generation as a bifurcation parameter and time response simulations to grid disturbances. Professional PSAT simulation toolbox has been used for the power flow simulation studies. Network- related faults like outage of photovoltaic farm event, three-phase short-circuit at a conventional bus, and voltage dip at the largest photovoltaic station have been considered. It is hoped that the results of the presented study would benefit Tunisian’s utility’s policies on integration of PV systems. Moreover, this comprehensive analysis and study will be a valuable guide for assessing and improving the performance of national grid systems of any other countries also, that gives the huge potential and need for solar energy penetration into the grid systems.

A modified moth flame optimisation technique tuned adaptive fuzzy logic PID controller for frequency regulation of an autonomous power system

ABSTRACT This paper suggests to use an adaptive fuzzy logic PID controller (AFPID) for frequency regulation of an autonomous power system (APS) where the parameters of the AFPID are tuned by a modified moth flame optimization (mMFO) algorithm. The effectiveness of proposed mMFO technique is first equated with similar methods for benchmark test functions using statistical analysis. The effectiveness of mMFO based AFPID controller is then compared with that of an mMFO based classical PID controller as well as MFO, GWO, PSO and GSA based AFPID controller. The robustness of AFPID controller is furthermore investigated against variation of system parameters. Finally the suggested design approach is applied to a widely used two-area system and compared with some recent frequency control approaches.

From Reliability to Resilience: Planning the Grid Against the Extremes

Although extreme events, mainly natural disasters and climate change-driven severe weather, are the result of naturally occurring processes, power system planners, regulators, and policy makers do not usually recognize them within network reliability standards. Instead, planners have historically designed the electric power infrastructure accounting for the so-called credible (or "average") outages that usually represent single or (some kind of) simultaneous faults (e.g., faults on double circuits).

PSO-Based: MARL Approach for Frequency Regulation of Multi-area Power System

In this study, a particle swarm optimization (PSO) based Multi-Agent Reinforcement Learning (MARL) approach for load frequency control (LFC) of multi-area power system over communication network considering communication delay and packet loss is presented. A networked control system (NCS) is framed to model a constant delay and packet loss using Markovian approach. The controller using PSO based MARL technique having two levels of controlled action in each area of power system act as an estimator agent and controller agent respectively. The proposed method for frequency regulation of multi-area power system is studied in detail and verified for different types of load disturbances. In addition, to check the system dynamic performance of electric power system a mean square errors (MSEs) of states with different value of communication delay are computed. The simulation results of this study is validated and compared with some pre-design methods available from literatures, along with capacity of multi agent system (MAS) for application of LFC in power system over communication network.

Study on the Unified Data of Power Regulation System for Guizhou Power Grid

The grid structure of the Guizhou Power Grid is becoming more and more complex, and the deepening of regulatory integration has made the information and work of regulators more and more onerous. Combining artificial intelligence, big data technology and grid control business is an inevitable trend of development. In this paper, a unified data model of the power system is established based on the Guizhou power grid’s regulatory operation requirements. It can analyze the impact of big data on dispatching business and define the power business demand model in the big data environment. This model also integrates and manages the multi-source heterogeneous data of power grid business by reflecting data and relationships of power regulation business. The research results are of great significance to improve the level of safe and stable operation of the power grid, and to promote intelligent operation of regulation and control, and also lay a solid foundation for intelligent dispatch.

Event‐triggered based decentralised control for frequency regulation of power systems

The present work focuses on the design of optimal proportional–integral–derivative with filter controller for the frequency regulation in single and multi-area thermal power systems considering effective utilisation of the network resources. The proposed strategy uses global neighbourhood algorithm (GNA), a meta-heuristic algorithm, to obtain optimal controller parameters. Since the controller, in load frequency control (LFC) systems, communicates via open channels there is a need for effective utilisation of channel bandwidth. Therefore, for effective communication, the decentralised adaptive periodic event-triggered scheme is adopted in this study. In order to find the appropriate values of sampling time and to study the effects of time-delay introduced by the communication channel, delay-dependent stability is investigated using Lyapunov theory. The theoretical concepts, developed in this study, are verified using the time-domain simulations carried out using MATLAB which validates the superiority of the GNA-based approach for LFC systems.

Improving Fuel Economy of Spark Ignition Engines Applying the Combined Method of Power Regulation

One of the disadvantages of spark ignition engines, whose power is regulated by throttling, is the increased fuel consumption at low loads and when the engine is idle. The combined method of engine power regulation by switching off the cylinder group and throttling working cylinders is one of the effective ways to improve fuel economy in the above-mentioned modes. This article presents the research results of the combined method of engine power regulation which can be realized by minor structural changes in operating conditions. The method implies the following: at low loads and at idle speed of the engine. Fuel supply to the group of cylinders is switched off with the simultaneous increase of the cyclic fuel supply in the working cylinders. The adequacy of the calculated results has been checked by the indication of operating processes in switched off and working cylinders. The research results of a six-cylinder spark ignition engine with the distributed gasoline injection using the combined power regulation system have been shown. The angles of opening the throttle which provides a non-shock transition from the operation with all cylinders to the operation with the cylinder group switched off have been determined.

Coordinated Control Scheme of Battery Storage System to Augment LVRT Capability of SCIG-Based Wind Turbines and Frequency Regulation of Hybrid Power System

Fixed speed wind turbine-squirrel cage induction generator (FSWT-SCIG)-based wind farms (WFs) are increasing significantly. However, FSWT-SCIGs have no low voltage ride-through (LVRT) and frequency control capabilities, which creates a significant problem on power system transient and steady-state stability. This paper presents a new operational strategy to control the voltage and frequency of the entire power system, including large-scale FSWT-SCIG-based WFs, by using a battery storage system (BSS). The proposed cascaded control of the BSS is designed to provide effective quantity of reactive power during transient periods, to augment LVRT capability and real power during steady-state periods in order to damp frequency fluctuations. The cascaded control technique is built on four proportional integral (PI) controllers. The droop control technique is also adopted to ensure frequency control capability. Practical grid code is taken to demonstrate the LVRT capability. To evaluate the validity of the proposed system, simulation studies are executed on a reformed IEEE nine-bus power system with three synchronous generators (SGs) and SCIG-based WF with BSS. Triple-line-to-ground (3LG) and real wind speed data are used to analyze the hybrid power grid’s transient and steady-state stability. The simulation results indicate that the proposed system can be an efficient solution to stabilize the power system both in transient and steady-state conditions.

A robust optimization method for co-planning of transmission systems and merchant distributed energy resources

This paper presents a new robust co-planning model for transmission investment and merchant distributed energy resources (DERs). The problem is formulated from the viewpoint of power system regulators and planners such that they will build the new transmission facilities and identify optimal locations to direct merchant DERs. The proposed model is a tri-level min-max-min optimization problem where the upper, middle, and lower levels are investment decision of transmission lines and DERs, worst case realization of uncertain parameters, and the best actions in order to minimize the operation costs. The model considers the uncertainties associated with future peak load and generation capacity, the production of renewable units, and the locational marginal price (LMP) of each candidate bus for installing DERs. Results of a case study based on the IEEE RTS 24-bus test system show the usefulness of the proposed model.

Ant lion optimized hybrid intelligent PID-based sliding mode controller for frequency regulation of interconnected multi-area power systems

In this article, a novel hybrid intelligent Proportional Integral Derivative (PID)-based sliding mode controller (IPID-SMC) is proposed to solve the LFC problem for realistic interconnected multi-area power systems. The optimization task for best-regulating parameters of the suggested controller structure is fulfilled by the ant lion optimizer (ALO) technique. To assess the usefulness and practicability of the suggested ALO optimized IPID-SMC controller, three test systems – that is, four-area hybrid power system, two-area reheat thermal-photovoltaic system and two-area multi-sources power system – are employed. Different nonlinearities such as generation rate constraint (GRC) and governor dead band (GDB) as a provenance of physical constraints are taken into account in the model of the two-area multi-sources power systems to examine the ability of the proposed strategy for handling the practical challenges. The acceptability and novelty of the ALO-based IPID-SMC controller to solve the systems mentioned above are appraised in comparison with some recently reported approaches. The specifications of time-domain simulation disclose that the designed proposed controller provides a desirable level of performance and stability compared with other existing strategies. Furthermore, to check the robustness of the suggested technique, sensitivity analysis is fulfilled by varying the operating loading conditions and plant parameters within a particular tolerable range.

Automatic Generation Control of Multi-area Power System with Network Constraints and Communication Delays

Newly proposed power system control methodologies combine economic dispatch (ED) and automatic generation control (AGC) to achieve the steady-state cost-optimal solution under stochastic operation conditions. However, a real power system is subjected to continuous demand disturbance and system constraints due to the input saturation, communication delays and unmeasurable feed-forward load disturbances. Therefore, optimizing the dynamic response under practical conditions is equally important. This paper proposes a state constrained distributed model predictive control (SCDMPC) scheme for the optimal frequency regulation of an interconnected power system under actual operation conditions, which exist due to the governor saturation, generation rate constraints (GRCs), communication delays, and unmeasured feed-forward load disturbances. In addition, it proposes an algorithm to handle the solution infeasibility within the SCDMPC scheme, when the input and state constraints are conflicting. The proposed SCDMPC scheme is then tested with numerical studies on a three-area interconnected network. The results show that the proposed scheme gives better control and cost performance for both steady state and dynamic state in comparison to the traditional distributed model predictive control (MPC) schemes.

Determination of the Optimum Hybrid Renewable Power System: A case study of Istanbul Gedik University Gedik Vocational School

In this study, Hybrid Renewable Power System (HRPS) has been designed to meet the energy requirement of Istanbul Gedik University Vocational School (IGUVS) in an optimum way. The energy requirement will be achieved mainly with wind and solar power generation system. The hybrid regenerative power system will be requested from the network when it can’t meet its energy needs. The optimum configuration of grid-connected solar/wind hybrid power generation system will be determined by considering the wind speed data and solar radiation data of the location of IGUVS. Moreover, sensitivity analysis will be carried out taking into consideration the wind speed and solar radiation values. If the optimum hybrid power generation system specified is used, the carbon emission values obtained will be examined.

Полигон для тестирования алгоритмов автоматического вторичного регулирования частоты и активной мощности в энергосистеме

The purpose of this article is to present the development results of a test site for testing algorithms of automatic secondary control of frequency and active power in the electric power system. The instrumental basis is formed by a hybrid real time simulator of electric power systems where the test electric power system circuit is implemented, while the model of the system of automatic secondary regulation of frequency and active power is implemented in the MATLAB software package using the Simulink Desktop Real-Time library. Software in the C# programming language is developed for the testing ground in order to organize the data exchange between the modeling complex and MATLAB/Simulink. To test the ground the authors have prepared and carried out the experiments on reproduction of frequency and active power regulation processes that occur in case of disturbances in the electric power system, in particular, the increase in power consumption which leads to the imbalance of active power when using different types of automatic regulators of the automatic secondary frequency and power regulation system. In experiments, the primary power imbalance created decreases frequency that does not actuate automatic emergency response system. In the process of frequency control generators and elements of the electrical network are loaded in different ways depending on the types and settings of the regulators used. Therefore, the regulators can be adjusted in accordance with the research results to ensure compliance with the standards applicable in the territory of the Russian Federation. The obtained results reflect the correctness of the testing ground operation and the possibility of its use to solve the problems of modernization and testing of algorithms for automatic secondary control of frequency and power flows.

An ab initio issues on renewable energy system integration to grid

With the introduction of new technologies such as Renewable Energy Resources (RER), Energy Storage Systems (ESS), Smart Grid technologies, Micro-Grid technologies, Distributed Generation (DG), etc., in the generation, transmission and distribution sectors, slowly but surely the entire power system scenario is changing, and it is up to the power system planners, researchers, regulators, operators and policy-makers to ensure that the power system adapts to the changes as smoothly as possible; which is easier said than done. With change comes the unknown (issues and challenges) and unless a majority of these unknowns are identified, analyzed and addressed properly, the system cannot achieve its maximum potential. The proper management, operation and integration of renewable and alternate sources of energy to existing grid is one of the promising ventures to increase the capacity of grid and at the same time make the grid more eco-friendly. This paper presents a review of the challenges and issues associated with renewable energy integration to grid and some of the existing techniques that are in use to address these issues. In order to make this review paper as detailed as possible, we have tried to identify the many issues and their corresponding solutions as much as possible.

Parallel Fuzzy Logic and PI Controller for Transient Stability and Voltage Regulation of Power System Including Wind Turbine

Parallel Fuzzy Logic and PI Controller for Transient Stability and Voltage Regulation of Power System Including Wind Turbine

A Coordinated Controller Design for DFIG-Based Multi-Machine Power Systems

This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly-fed induction generators, synchronous generators, and static compensator devices. The proposed adaptive zero dynamics based approach aims at enhancing the transient stability and improving the voltage regulation of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to Kundur's four-machine two-area and the IEEE 39-bus power systems. Its performance was assessed in the presence of various faulty scenarios and disturbances. Eigen-value analysis, time domain simulations, and transient stability margin analysis (measured by critical clearing time) were carried out in the performance assessment. Comparison analysis with other control approaches was also conducted to highlight the effectiveness of the proposed approach. Enhancing the power and voltage stability of large scale multi-machine power systems, damping inter-area power oscillations, and providing faster post-fault recovery time are among the positive features of the proposed approach.

Improvement in Frequency Regulation of Interconnected Thermal Power System with Optimal SSSC and SMES Controllers

The level of real and reactive power reserve with only contribution from rotor inertia of generators provides a very small margin of maneuverability in system operation. The use of energy storage device and “Flexible AC Transmission systems (FACTs)” devices solves the problem to a large extent particularly in larger interconnected system. In this work energy storage devices like “Superconducting Magnetic Energy Storage (SMES)” system and “Static Synchronous Series Compensator (SSSC)”, are operated together in different combined two-area thermal system.

Power Quality Services Provided by Virtually Synchronous FACTS

The variable and unpredictable behavior of renewable energies impacts the performance of power systems negatively, threatening their stability and hindering their efficient operation. Flexible ac transmission systems (FACTS) devices are able to emulate the connection of parallel and series impedances in the transmission system, which improves the regulation of power systems with a high share of renewables, avoiding congestions, enhancing their response in front of contingencies and, in summary, increasing their utilization and reliability. Proper control of voltage and current under distorted and unbalanced transient grid conditions is one of the most critical issues in the control of FACTS devices to emulate such apparent impedances. This paper describes how the synchronous power controller (SPC) can be used to implement virtually synchronous FACTS. It presents the SPC functionalities, emphasizing in particular the importance of virtual admittance emulation by FACTS devices in order to control transient unbalanced currents during faults and attenuate harmonics. Finally, the results demonstrate the effectiveness of SPC-based FACTS devices in improving power quality of electrical networks. This is a result of their contribution to voltage balancing at point of connection during asymmetrical faults and the improvement of grid voltage quality by controlling harmonics flow.

Salp swarm algorithm-based model predictive controller for frequency regulation of solar integrated power system

Global analysis of power system markets project frequency regulation as one of the most profitable ancillary services. It is associated with second-to-second balance of load and frequency within a control area and acquires a principal role in enabling power interchanges while offering better conditions for electricity exchange. In the light of the above, a novel control strategy, namely salp swarm algorithm (SSA)-based model predictive controller, is proposed for frequency regulation of an unequal two-area realistic power system, incorporating solar thermal power plant and conventional thermal plant. Governor dead band, generation rate constraint and transport delay are considered in each control area. Over the past few years, model predictive controller (MPC) has come forward as a prediction-based control strategy for stabilizing dynamical systems while considering non-linearities, system uncertainties and constraints. The MPC parameters are optimized using SSA. The performance of the proposed approach is validated by comparing the dynamic time responses of SSA-optimized MPC with the other SSA-optimized conventional controllers, namely PID, FOPID and cascade PIDN-FOPID controller. The simulation result analysis shows that the proposed optimal MPC outpaces the conventional controllers with respect to peak overshoot, undershoot and settling time of the time responses. A comparative study of various objective functions indicates that, as compared to other indices, integral square error is better for the considered test system. Further, sensitivity analysis reveals the robustiousness of MPC parameters obtained at nominal values and hence is not required to be retuned, against variations in system loading and inertia constant.