Stability Of Electric Power System Research Articles

Salp swarm optimizer to solve optimal power flow comprising voltage stability analysis

A new attempt of employing salp swarm algorithm (SSA) to tackle the optimal power flow (OPF) problem is demonstrated in the current study. This aforementioned problem has four fitness functions to be optimized such as (1) the sum of generating units’ fuel costs, (2) total network real power losses, (3) entire sum of voltage deviation of load buses, and (4) static voltage stability (VS) of electric power systems. At initial stage, these objective are solved one by one, and at a later stage, different vector objective functions are solved simultaneously by the SSA. The VS study based on a modal analysis is taken into consideration as an objective function. In this issue, the eigenvalues and eigenvectors of a reduced Jacobian matrix due to the reactive power change are figured. The smaller magnitude of eigenvalues indicates the vicinity to system voltage instability. As the magnitude of eigenvalues increases, the incremental voltage decreases, which means strong VS. The output active power of generating units, their voltages, transformers tap setting, and capacitor devices represent the search field. Two electric grids such as IEEE 57- and 118-bus electric networks are demonstrated to examine the performance of the SSA. The effectiveness of the SSA–OPF methodology is compared with that obtained by using other competing optimization methods. Furthermore, statistical performance measures comprising parametric and nonparametric tests are made and the simulation results are extensively verified which indicate a competition of the SSA with others algorithms in solving the OPF problem.

Influence of moment of inertia on electric power system security and stability control

The moment of inertia is the basic parameter of the generator and also the basic data of PSS parameter tuning. The parameter setting of PSS will increase the damping of the unit and improve the small disturbance stability of the system. When the rotational inertia parameter is not consistent with the real rotational inertia of the unit, the PSS parameter setting will not increase the damping of the unit, but sometimes it will cause the oscillation of the unit. Here, the correlation analysis is carried out with the small signal stability analysis program, and the field test is carried out in Qinghai Kang Yang power plant. The influence of moment of inertia on PSS is analysed by small disturbance analysis and field test.

Voltage Stability Of South Sulawesi Power System Using Fuzzy Logic Method Based On The Linguistic Variable

This study aims to apply a new method for controlling voltage stability in electric power systems, using new modeling with linguistic variables of cryptic logic. The method can easily carry out appropriate control measures in accordance with human thinking and acting. The Fuzzy Logic Stabilizer periodically checks the voltage in real time at each bus and maps into linguistic variables, analyzes its control decisions, then calculates how much stability control is sent to all mobile operator numbers that have been registered at the short message service center, so that appropriate control measures are carried out on the On Load Tap Changer, or On Load Voltage Regulator at each substation, according to the contents of the short message it receives. Application of fuzzy logic stabilizer in the 46 bus electricity system of South Sulawesi will increase the quality of bus voltage from an average of 0.08% to 0.5% of the nominal voltage.

Analysis of Transient Stability in Synchronous Generator Using Nyquist Method

There are two factors that must be considered for the power quality analysis of an electrical power system, i.e. frequency and voltage stability. The system that can return to the initial condition or the steady state after a disturbance occurred indicates that the system is stable. This paper aims to detect the transient stability of three generators, which have identical specification of 2.25 MW 6.6 kV and are operated in parallel, based on the frequency performance. In this paper, the stability analysis is determined by using the nyquist method, where the system stability is indicated by the value of the response curve of the system. The analysis results show that the system of three paralleled generators have the value that far from 1 + j0 and the phase margin value and gain margin tend to be minimum. These values indicate that the system is unstable. The system slowly changes into more unstable because the oscillations are getting bigger until the final state. So, it is necessary to change the parameters of each generator that can affect the system stability during synchronization state.

Improvement of Electrical Power System Dynamic Stability Using Fuzzy Logic

This research has an aim to know the effectiveness of fuzzy logic which takes over the controlling of Proportional Integral Derivative (PID) in repairing the dynamic stability of electrical power system. This research begins with making the mathematic model of electrical power system into a circumstances variable equation and the plant system diagram block model. The structure of fuzzy logic controller system is designed by using 2-input which has three, five, and seven membership functions. The formed system work test is conducted by giving a disruption of increase and decrease electric power, to perceive the result of dynamic order on system variable to rotor speed deviation, angle rotor, voltage terminal, and power electric. Fuzzy logic can increase PIDPSS performance in repairing the electrical power system dynamic stability. The overshoot value decrease to 73.881% - 89.069% and settling time is 57.81% - 67.01% to the rotor speed deviation.

Development of a data driven approach to explore the energy flexibility potential of building clusters

With the growing use of renewable energy sources, the stability of electrical power systems can be seriously affected by fluctuations in the available power. As one of the potential solutions for this new challenge, the energy flexibility of buildings has become a focus for research and technological development. Most studies have focused on single buildings, with only a few studies on building clusters in which the building models were usually oversimplified in that they did not consider different building types or their thermal characteristics, their occupancy or their occupants’ behaviour. In this paper, we describe a data driven approach to simulating a generic building cluster that could resemble any mix of building archetypes and occupancy. The energy flexibility potential of apartment building clusters was estimated by using data from surveys and available statistics in Denmark for the worst case scenario, i.e. when the end users do not allow any disturbance when they are at home, so that energy flexibility is only available when residents are not at home. In this scenario, no energy flexibility is assumed when buildings are occupied, which yields a conservative estimation. The uncertainty of the energy flexibility potential due to uncertain occupancy and various archetypes was quantified for different scales of building cluster. The resulting hybrid-model is a combination of a building model and an occupancy model and includes the different factors that influence the potential energy flexibility of buildings. The results show that the uncertainty of the energy flexibility decreases when the aggregated number of buildings increases. The uncertainty of energy flexibility was less than 10%, when about 700 households were aggregated. This approach can be used to simulate building energy flexibility for district or even regional level energy planning when the intention is to use the available flexibility to address the challenges caused by fluctuation in the power available from renewable energy sources.

Synergetic governing controller design for the hydraulic turbine governing system with complex conduit system

The hydraulic turbine governing system plays an indispensable role in maintaining the stability of electrical power system. In this paper, synergetic control theory is introduced to enhance the regulating ability of the hydraulic turbine governing system. For the purpose of describing the characteristics of objective system and deducing the synergetic control rule, a nonlinear mathematic model of a hydraulic turbine governing system with long tail race and two surge tanks is established. Furthermore, the nonlinear characteristic of the hydraulic turbine is described by six variable partial derivatives. For further investigation, the hydraulic turbine governing system is conducted to running under load condition when its coaxial generator connects to an infinite bus. Simulation experiments have been made under both load disturbance and three-phase short circuit fault conditions to compare the dynamic performances of proposed synergetic governing controller and classic PID controller. The results indicate that the proposed synergetic governing controller is an effective alternative in normal condition and a superior one in emergency. Moreover, the robustness of synergetic governing controller has also been discussed at the end of this paper.

Rotor-angle versus voltage instability in the third-order model for synchronous generators

We investigate the interplay of rotor-angle and voltage stability in electric power systems. To this end, we carry out a local stability analysis of the third-order model which entails the classical power-swing equations and the voltage dynamics. We provide necessary and sufficient stability conditions and investigate different routes to instability. For the special case of a two-bus system, we analytically derive a global stability map.

Design of Simulation Product for Stability of Electric Power System Using Power System Stabilizer and Optimal Control

This paper will discuss the use of optimal control and Power System Stabilizer (PSS) in improving the oscillation of electric power system. Oscillations in the electric power system can occur due to the sudden release of the load (Switcing-Off). The oscillation of an unstable system for a long time causes the equipment to work in an interruption. To overcome this problem, a control device is required that can work effectively in repairing the oscillation. The power system is modeled from the Single Machine Infinite Bus Model (SMIB). The state space equation is used to mathematically model SMIB. SMIB system which is a plant will be formed togetherness state variables (State-Space), using riccati equation then determined the optimal gain as controller plant. Plant is also controlled by Power Stabilizer System using phase compensation method. Using Matlab Software based simulation will be observed response of rotor speed change and rotor angle change for each of the two controlling methods. Simulation results using the Simulink-MATLAB 6.1 software will compare the analysis of the plant state in Open loop state and use the controller. The simulation response shows that the optimal control and PSS can improve the stability of the power system in terms of acceleration to achieve settling-time and Over Shoot improvement. From the results of both methods are able to improve system performance.

Проблеми енергетичної залежності держав Центральної Америки і Карибського басейну.

The article is devoted to the analysis of the energy dependence issue of Central American and Caribbean States. On the basis of statistical and analytical data the authors try to find peculiarities and specific nature of the development of energy sector of the studied countries, to analyze positive and negative trends and to define prospects of making the states more independent in energy sector. Particular attention is paid to the issues of energy security and their solution. The authors also scrutinize the problem of poor access to electricity among the citizens of researched countries. The work analyzes the level of region’s dependence on oil, oil products, natural gas and coal import. In addition, the main sources of providing traditional fossil fuels to the countries of the region are identified. There has been an attempt to divide the countries into risk groups according to the level of hydrocarbon import dependence. The article also examines implementing common projects considering the increase of the level of energy independence and safety within integration associations. The authors particularly make evaluation of the project for integrating the electric networks of the Central American States and the implementation of Mercado Electrico Regional, which contributed to strengthening of electric power system stability in the region. Joint policies of the Caribbean States in energy scene are given consideration as well. Furthermore, the Renewable Energy Development Programme of the Caribbean Community (CARICOM) is studied. The authors evaluate the effectiveness of the programme implementation in the context of current status of the energy sector in the Caribbean States. Besides, the article considers the activity of some global international institutions in the energy sector of the researched countries. For instance, the projects of The International Renewable Energy Agency (IRENA) and The World Bank are examined.

Smart Grid Simulations and Their Supporting Implementation Methods

In this tutorial we present the state-of-the-art as well as new methods for simulating various planning, operation, stability, reliability, and economic models of electric power systems. The discussion is driven by both first-principle models and empirical models. First-principle models result from the fundamental physics and engineering principles that govern the behavior of various components of a grid. Empirical models, on the other hand, are models that result from statistics and data analysis. We overview a wide spectrum of applications starting from planning models with a time-scale of simulation in years to real-time models where the time-scale can be in the order of milliseconds. We present a list of simulation software popularly used by the power engineering research community across the world. The increasingly important roles of power electronics, communication and computing, model aggregation, hybrid simulation, faster-than-real-time simulation, and co-simulation in emulating the daily operation of a grid are enumerated. The importance of research testbeds for testing, verification and validation of complex grid models at various temporal and spatial scales is also highlighted. The overall goal is to provide a vision on how simulations and their supporting implementation methods can help us in understanding the evolving behavior of tomorrow’s power networks as a truly intelligent cyber-physical system.

Power management system implementation on off-shore gas platforms

Electrical power production system of Ivana A&K platforms consists four three-phase generators driven by gas motors. Besides, there are two emergency diesel generator sets for emergency power supply. Generators are feeding power motor control centre board and essential user board on each platform. Due to the reliability, security, efficiency and stability of this islanded industrial electric power system, it was decided to implement a comprehensive power management system which should provide load-shedding solution and protect the plant against blackouts and power source outages due to system disturbances. Selected system consists of a power management intelligent electronic device with remote I/O and measuring devices deployed throughout the power system. System relies on IEC 61850 GOOSE communication for fast and accurate data exchange. In this study, the process of the system selection and implementation has presented and described according to the conducted procedure.

Application of hybrid real‐time power system simulator for research and setting a momentary and sustained fast turbine valving control

The stability of electric power system (EPS) insures energy security of consumers. Therefore, saving the stability of EPS is the main task for professionals around the world. For its solution, a variety of activities is used. This publication deals with the description of the authors' experience for solving the task in the Tyumen power system. The hybrid real-time power system simulator (HRTSim) developed in Tomsk Polytechnic University was used as a platform for research carrying out. The study presents the research result fragments of the momentary and sustained fast turbine valving control (FTVC) which is one of the most effective ways of an automatic emergency control of power units in the thermal power station. Using the simulator HRTSim, one of the greatest challenges of electric power industry in Russia has been solved, i.e. FTVC adequate setting of the power units in the thermal power station Surgut GRES-2 in the Tyumen power system. An FTVC operation largely determines the reliability and stability of the EPS. Therefore, an incorrect setting may result in substantial disturbance or disruption of the stability that already occurred in the past. The adequacy of turbine and FTVC simulations is verified by comparing it with the real data.

Variable speed and constant frequency control of hydraulic wind turbine with energy storage system

To eliminate the adverse effect of the fluctuation and intermittence of wind power on the quality and stability of electrical power system, an energy storage system is introduced into the closed-lo...

Research on trading patterns of large users' direct power purchase considering consumption of clean energy

In order to reduce the stochastic volatility of supply and demand, and maintain the electric power system's stability after large scale stochastic renewable energy sources connected to grid, the development and consumption should be promoted by marketing means. Bilateral contract transaction model of large users' direct power purchase conforms to the actual situation of our country. Trading pattern of large users' direct power purchase is analyzed in this paper, characteristics of each power generation are summed up, and centralized matching mode is mainly introduced. Through the establishment of power generation enterprises' priority evaluation index system and the analysis of power generation enterprises' priority based on fuzzy clustering, the sorting method of power generation enterprises' priority in trading patterns of large users' direct power purchase is put forward. Suggestions for trading mechanism of large users' direct power purchase are offered by this method, which is good for expand the promotion of large users' direct power purchase further.

Impact of Distributed Generation Grid Code Requirements on Islanding Detection in LV Networks

The recent growing diffusion of dispersed generation in low voltage (LV) distribution networks is entailing new rules to make local generators participate in network stability. Consequently, national and international grid codes, which define the connection rules for stability and safety of electrical power systems, have been updated requiring distributed generators and electrical storage systems to supply stabilizing contributions. In this scenario, specific attention to the uncontrolled islanding issue has to be addressed since currently required anti-islanding protection systems, based on relays locally measuring voltage and frequency, could no longer be suitable. In this paper, the effects on the interface protection performance of different LV generators’ stabilizing functions are analysed. The study takes into account existing requirements, such as the generators’ active power regulation (according to the measured frequency) and reactive power regulation (depending on the local measured voltage). In addition, the paper focuses on other stabilizing features under discussion, derived from the medium voltage (MV) distribution network grid codes or proposed in the literature, such as fast voltage support (FVS) and inertia emulation. Stabilizing functions have been reproduced in the DIgSILENT PowerFactory 2016 software environment, making use of its native programming language. Later, they are tested both alone and together, aiming to obtain a comprehensive analysis on their impact on the anti-islanding protection effectiveness. Through dynamic simulations in several network scenarios the paper demonstrates the detrimental impact that such stabilizing regulations may have on loss-of-main protection effectiveness, leading to an increased risk of unintentional islanding.

Approach in the modeling of wind turbines for power system stability studies and evaluation of their impact on electric power systems

Wind power - one the fastest evolving in renewable energy industry. From year to year the share of wind energy in power systems are increasing as well as increasing the size of wind farms. A large-scale wind farms that produce hundreds of megawatts of electricity have a serious impact on the power grid. This paper discusses proposed approaches to modeling wind farms using the Hybrid Real-Time Power System Simulator (HRTSim), to study stability and transient processes in electric power systems.

Выбор места установки и законов регулирования устройств продольной емкостной компенсации для повышения устойчивости электроэнергетической системы

Выбор места установки и законов регулирования устройств продольной емкостной компенсации для повышения устойчивости электроэнергетической системы

Neural Network pada Koordinasi PSS dan TCSC untuk Meningkatkan Kestabilan Sistem Tenaga Terinterkoneksi

This paper develops a design procedure for adaptive coordination among power system damping controllers (i.e. power system stabilizers and supplementary damping controller of thyristor-controlled series capacitor) for improving the stability of an interconnected electric power system. The design is based on the use of neural network which identifies the optimal controller parameters online. The inputs to the neural network include the active- and reactive- power of the synchronous generators which represent the power loading on the system, and elements of the reduced nodal impedance matrix for representing the power system configuration. The neural network-based adaptive controller is trained offline with a wide range of credible power system operating conditions and configurations. The controller parameters obtained from the trained neural network are verified by both eigenvalue calculations and time-domain simulations, which confirms that good dampings of the eletromechanical modes and stability are achieved.

Steam Production and Electric Power System Stability: Striking a Balance Using a Comprehensive Electric Dispatch Control Strategy

Steam production and electric power system stability are often competing interests in an industrial refinery. Optimal control of steam production is required to meet the plant process operating requirements, and electrical grid stability is required to prevent power system blackouts. For many industrial plants connected to a utility grid, both of these operating criteria cannot be met simultaneously, placing the power system in serious jeopardy of a blackout.