Power System Circuit Research Articles

MATHEMATICAL MODEL AND ALGORITHM FOR THE DETERMINATION OF THE ORIGIN OF ELECTRICITY FROM RENEWABLE ENERGY SOURCES IN THE ELECTRIC POWER SYSTEM

The article deals with the development of a method and algorithm for calculation of individual compo-nents of electricity flows in the branches of an electric power grid circuit caused by generation and con-sumption in its nodes. In particular, it is about estimating the share of renewable energy sources (RES) in the electricity consumption of a given consumer. The method is based on methods and algorithms for the calculation of steady-state modes of power grids, integrating a mathematical model for determining the components of current flows in the branches of the power system circuit. The model employs distribution coefficients of currents in the circuit branches from RES nodes and node voltages to form a matrix of cur-rent distribution coefficients for RES across the power grid branches. Since RES in electric power systems (EPS) use general power grids to transmit the electricity they generate, accurate determination of their power share within overall flows enables the impact of RES on the EPS mode parameters to be considered. The peculiarity of the algorithm for estimating the share of RES in the electricity consumption of a given consumer is its consideration of physical processes in the power system. The input data for the calculation are the power system parameters, the node loads (specified by capacity or schedules), as well as arrays of RES generation and centralized power supply nodes and consumers with a controlled value of the Guar-anteed Origin of electricity from RES. The voltages during the formation of the matrix of power distribu-tion coefficients at nodes along the branches of the power grid are determined by the calculation results of the power grid steady-state modes or by experimental measurement data. The method's efficacy and the accuracy of estimating the RES share in the power consumption of a given consumer are verified and demonstrated through a practical example. Determination of the share of the consumer's electricity con-sumption, which origin from renewable sources can be guaranteed, creates an enabling environment that would foster producers and consumers to increase the use of renewable energy sources and promotes the development of the green energy market. Ref. 18. Fig.3.

Switching attack modeling and vulnerability analysis of generator for dynamics study

This paper presents novel insights about cyber-attacks in the power network and their consequence in terms of stability. Compared to existing cyber-attack related studies in power systems, the work discusses switching attack construction and evaluates the impact on generator dynamics. As such, the study is in two folds: (i) switching attack construction, with selection of switching instants based on system states and (ii) vulnerability analysis of power system components, circuit breaker, governor system and excitation system of generators. The role of inherently present communication delay/state variable delay becomes important as it has direct impact on dynamic performance of the system. The impact of the constant and timedependent delay on the stability is addressed by determining the time-delay margin using Lyapunov-Krasovskii functional. Thereafter, the condition for successful switching attack construction is given in terms of delay margin. The accuracy of the derived condition for successful switching attack is demonstrated via real-time co-simulation (RTDS) and MATLAB software. The vulnerability of power system components in IEEE 3-machine, 9-bus network are analysed as individuals or their combinations when subjected to switching attacks. The adequacy related to power system stability as a consequence of cyber-attacks is investigated with an estimation of RoCoF of generators.

NUMERICAL AND LABORATORY SIMULATION OF TRANSFORMER SATURATION DEPENDING ON THE INITIAL PHASE OF THE CURRENT

In case of short circuits in electric power systems, emergency modes are possible, accompanied by saturation of transformers. With them, significant distortion of current signals occurs in the secondary winding of the transformer with the appearance of an aperiodic component and harmonics, the level of which is comparable to the signal at the main industrial frequency. The requirements for relay protection and automation devices imply the need to determine the time from the onset of the transient process to the onset of distortion of the current signal in the secondary winding.
 
 The purpose of the study is to analyze the saturation of the transformer depending on the initial phase of the transition process.
 
 Materials and methods. The PSCAD platform was used to model the power system section. The model makes it possible to qualitatively describe the saturation of a step-down transformer in the event of a short circuit on the low side, taking into account hysteresis phenomena in the magnetic system. Experimental verification was carried out in laboratory conditions using a measuring (intermediate) current transformer.
 
 Results. It is shown that, depending on the phase of the current at the moment of the beginning of the transient process, the pattern of saturation and, accordingly, the distortion of the current changes significantly. The distortion of the time waveform of the current signal in the secondary winding of the transformer can begin both after fractions of the period of the power frequency signal, and after several periods.
 
 Conclusions. The assessment of transformer saturation modes should be carried out taking into account the fact that the initial conditions for transient processes during short circuits are random. In the analysis of such processes, it is necessary to take into account the phase shift between current and voltage.

Predictive Analysis and Correction Control of CCT for a Power System Based on a Broad Learning System

Transient stability is an important factor for the stability of a power system. With improvements in voltage levels, and the expansion of power network scales, the problem of transient stability is particularly prominent. When a power system circuit fails, if the operation time of the relay protection device is higher than the critical clearing time (CCT), the relay protection device cannot cut the fault line in a timely manner. It is essential to forecast and adjust the CCT to improve the stability of the system; therefore, a method is proposed in this paper to predict and evaluate the critical clearing time using the broad learning system (BLS). The sensitivity of the critical clearing time can be easily calculated based on the prediction results of the critical clearing time using BLS. Moreover, the critical clearing time can be modified using the BLS correction control model. The proposed method was verified using a 4-machine 11-node system and a 10-machine 39-node system. According to the experimental results, the proposed model can predict, evaluate, and correct the CCT very well.

Digital twin-oriented multi-physics field simulation analysis of high-voltage SF6 circuit breakers

Circuit breakers are important components for removing short circuits in power systems and ensuring safe operation. The operation of circuit breakers may not be predicted and thus cause accidents, so there is an urgent need to innovate means to assess the operation status of power equipment and monitor the operation status of power grids in full real time, to improve the monitoring capability of major key equipment, and to study key technologies for the digital twin of circuit breakers to support the safe and stable operation of transmission networks and the digital transformation of energy systems. This paper establishes the multi-physics field coupling calculation model of the circuit breaker opening process, completes the simulation calculation of the circuit breaker opening process, gets the distribution and change trend of parameters such as electric field, pressure, temperature, density, and airflow speed inside the interrupting chamber, and analyzes the flow characteristics inside the interrupting chamber in different opening processes. We select the characteristic parameters and provide data support for the establishment of fault diagnosis based on the digital twin of the circuit breaker.

Determination Method of Contact Ablation Degree of Power System Circuit Breaker Based on Power Load Property

In the field of electrical engineering, the stable operation of circuit breaker is one of the important indexes to ensure the safety and stability of power system. Because the influence of load property on electromagnetic wave waveform is not considered, the method to determine the ablation degree of circuit breaker by using the characteristics of radiated electromagnetic wave is not completely accurate. Therefore, this paper proposes a method to determine the ablation degree of circuit breaker considering the load properties. By adding load factor, the ablation degree of circuit breaker contact can be determined more accurately. When the load is resistive load, the load factor is 1, when the load is inductive load, the load factor is 2.5, when the load is capacitive load, the load factor is 3. When the duration of the radiated electromagnetic wave exceeds the corresponding time, it can be judged that the contact is seriously ablated. The method proposed in this paper mainly uses electrical detection means to realize the rapid determination of the ablation degree of the circuit breaker contact and avoid the misjudgment caused by not considering the nature of the load.

Research and Application of Electromagnetic Wave Signal Acquisition Device for Power System Circuit Breaker

Power circuit breaker is an important tool to satisfy the controllability and safety of power system. Therefore, to ensure the stable operation of the circuit breaker is to ensure the normal supply of electric energy. In order to better capture the electromagnetic wave signal radiated by the circuit breaker and better judge the state of the electromagnetic wave radiated by the arc of the circuit breaker, a new type of vibration trigger device specially used for collecting the electromagnetic wave signal radiated by the circuit breaker and its use method are proposed in this paper. This method can collect the electromagnetic wave signal of circuit breaker through the optimized design of vibration trigger device. The device uses all metal integrated cast aluminum shell and independent power supply. This device can effectively resist electromagnetic interference, and is convenient for the acquisition of electromagnetic wave signal. The device developed in this paper and its application method belong to the field of off-line detection of electrical equipment, and are especially suitable for vibration triggering of the device when collecting the radiated electromagnetic wave signal during the action of circuit breaker.

Multi-Output Regression for Analyzing Power System Random States in Reliability Assessment by the Monte Carlo Method

Increasing calculation speed of the electric power system (EPS) reliability of is one of the key issues in their operational management and long-term development planning. Analytical methods to assess the EPS reliability seem to be impossible due to large size of the problem and, as a consequence, essentially the only option for assessing is to use the Monte Carlo method. When it is used both the speed and the accuracy of calculation directly depend on the number of randomly generated system states and the complexity of their calculation in the model. Methods aimed at increasing computational efficiency can relate to two directions - reducing the states under consideration and simplifying the computational model for each state. Both options are performed provided that calculation accuracy is retained.The article presents research on using the machine learning methods and, in particular, the multi-output regression method to modernize the reliability assessment technique via the Monte Carlo method. Machine learning methods are used to determine the power deficit (realization of a random variable) for each random EPS state.The use of multi-output regression enables comprehensive determining of values of all the required variables. The experimental studies are based on the two test circuits of electric power systems: three-zone and IEEE RTS-96 with 24 zones of reliability.

Study on the Design of Low Voltage Distribution Circuit in Power System

Study on the Design of Low Voltage Distribution Circuit in Power System

A Novel Copper Layer-Based Field-to-Trace Coupling Model and EMS Evaluation Method for DSP-Based Control Circuit in MMC-HVDC System

Underlying control circuit failure problems, especially control signal output failure problems, widely occur in high-voltage large-current modular multilevel converter (MMC) valve towers. The failure mechanism for the digital signal processor (DSP)-based control circuit is studied in this article. This study is based on the combination of low-voltage-level integrated circuit (IC) immunity model and a new perspective on the field-to-trace coupling effect. A novel copper-layer-based field-to-trace coupling model which combines the power system and digital control circuit in the MMC valve tower is proposed. Therefore, the specific electromagnetic interference (EMI) value conducted into the IC can be calculated. Then a new DSP IC electromagnetic sensitivity (EMS) evaluation method is proposed, which can be a guideline in industrial applications. To show the validity and accuracy of the field-to-trace coupling model, an indirect laboratory experiment is designed, then a situation is considered in this article, and the results are compared with PSpice circuit simulations, which show acceptable relative errors. Moreover, based on the situation considered above, one application example of the novel evaluation method is described in detail.

Fault Clearance Ultra Sensing Electronic Circuit Breaker

As Electrical equipments are more sensible, it has to protect them from high current, short circuit occurance. For tripping, fuse, relays and circuit breakers are employed to safeguard the power system components and circuits as well. Due to existence of sensitive components, much attention is taken to care about the protecting system. This paper explains the protection of equipments using suitable circuit breaker. Ultra fast acting electronic circuit breaker(UFECB) is designed to act as an over current protection device. Circuit breakers like fuse or miniature breakers are preferred for breaking the circuit once short circuit is occurred. In case, when overload fault occurs, the time of tripping is slow and which depends on percentage of overload. For instant fault clearance, tripping mechanism is activated for sensitive loads[1]. Time taken for the tripping mechanism is also considered in a great manner for breaking and making the circuit at short instant.

Collaborative Control Of Power System Based On Source Network Load Storage Management

Vertical coordination of charge storage in source network refers to the coordination among energy transmission network, transport resource network and utilization and development of resources and energy through energy flow, information flow interaction and energy conversion technology, which plays a role in unifying user energy demand, expanding power demand side management function and amplifying power demand side operation. In this paper, the differential equations are combined with the power system circuit structure to obtain differential equations, and the differential equations are calculated and park transformed. On this basis, the construction goal of the power system cooperative control model is proposed, and the power grid cooperative storage optimization element is considered to construct the power system cooperative control model. It is proved by simulation experiments that the research method in this paper has higher frequency deviation adjustment capability, can provide more stable power output capability, and has better promotion effect.

Interaction between a DC Traction System and an AC Power System Through Earth-return Circuits

The article describes a problem that occurs in electrified railway transportation, involving the interaction between the earth-return circuits of different power systems. One of the analysed circuits is the earth-return circuit of a high-voltage power grid, the other is the return path of a 3 kV DC traction power supply system. The paper presents the results of the field tests carried out so far and discusses a mathematical model developed in the Matlab-Simulink environment with the aim of determining the interaction between both of the said systems. Keywords: earthing, traction substation, traction return system

Preface

The 2019 3rd International Conference on Electrical, Mechanical and Computer Engineering (ICEMCE 2019) will be held on August 9-11, 2019 in Guizhou, China. The conference report reflects the current interest of the international and Chinese research community, such as Analysis of Power Quality and System Stability, Circuits and electronics, electro-optical phenomena of semiconductors, power electronics technology, remote control and techniques of GPS, smart grid, machinery and agriculture, machinery manufacturing and automation, mechanical engineering and mechanics, algorithms, Artificial intelligence, computer security, digital signal and image processing and wireless sensor networks. 2019 3rd International Conference on Electrical, Mechanical and Computer Engineering is a multi-disciplinary conference bringing together students, young researchers, postdoctoral and experienced researchers working in different research fields to promote the gathering and sharing of interests and achievements, so as to achieve better cooperation.The Conference work was carried out in 3 sections:● Electrical Engineering● Mechanical Engineering● Computer scienceCommittee memberList of Conference Chairs, Program Committee Co-chair, Local Chair, Advisory Committee, Technical Committee also available in this pdf.

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.

Influence of SDR Resistance Value on Low Voltage Ride Through Capability of Doubly Fed Induction Generator

For the increasing rate of wind generation capacity, the grid codes for grid connected wind turbines evolve continuously and demand that the wind power generator has to ride through the grid faults. In this paper, the new LVRT scheme which based on SDR is presented. Analyzing the new LVRT topological structures of DFIG with SDR circuit topology and the effect of the DBR circuit during grid voltage dip, The mathematical models of the equivalent circuit of DFIG power system during normal voltage and grid voltage dip are established. Through analyzing the mathematical models of DFIG power system during normal voltage and grid voltage dip, the feasibility of the new LVRT scheme is verified. The DFIG power system mode is built with Matlab/Simulink to validate its effectiveness. Simulation results show that DFIG can operate in connection with grid to stabilize the grid voltage during fault and SDR resistance selection could guarantee to limit the rotor current and consider rotor overvoltage.

The circuit design of solar electric vehicle

According to the characteristics of ultracapacitor (UC) and lead-acid battery, a novel and simple circuit of hybrid power system (HPS), which is consisted of UC group and battery set, is designed to realize the basic strategy: to use the UC group to process all solar energy and most of the peak current. However, since the battery set has a much higher energy density than the UC group, it is used to supply power when vehicle run on cruise speed. Both UC group and battery set supply the driving power for vehicle start-up, acceleration and climbing. The results of simulation show that the proposed novel and simple circuit, which is composed of UC group and battery set in parallel, can realize the reasonable energy use of vehicle.

Stability Analysis and Oscillation Mechanism of the DFIG-Based Wind Power System

The interaction between the DFIG (doubly fed induction generator)-based wind farm and the ac grid makes the traditional positive-sequence subsystem and negative-sequence subsystem no longer decoupled, so the single-input single-out (SISO) characteristic in the frequency domain no longer holds. In this paper, the admittance models of the DFIG and ac grid are established by using the small-signal analysis method. On this basis, first the admittance relationship of the entire DFIG-based wind power system in polar coordinates is obtained. Second, the multi-input multi-output (MIMO) system is simplified into an SISO system by the matrix transformation. Then, the characteristic equation and the equivalent circuit of the DFIG-based wind power system are provided. In cases of a weak ac grid, low wind speed and a high proportional coefficient of the phase-locked loop (PLL) controller, the stability of the DFIG-based wind power system will be weakened, and the oscillation among different coupling frequencies will occur based on Nyquist criterion. Finally, the simulation results show the correctness of the theoretical analysis.

Performance Evaluation of BESS for Korean Power System Using Equivalent Power System Circuit Model

Abstract This paper describes a method of modeling power system elements involved in frequency-active power control using frequency data of south Korea power system. A particle swarm optimization method is used for estimating the parameters of the transfer function which illustrates the relationship between frequency and active power deviation. To obtain the optimal parameter estimation, we use the mean absolute percentage error (MAPE) index for evaluating the accuracy of estimation compared to real data. Real frequency and power data from KPX were used for comparison studies. From the proposed equivalent power system circuit model, we achieved 0.0052% MAPE compared to real data. To evaluate the BESS frequency regulation performance, we considered the BESS control algorithm which is based on the data of Korea electric power corporation (KEPCO). From this case study, we confirmed that the BESS which is operated in south Korea can improve frequency regulation in case of frequency event by increasing nadir frequency up to 0.0335Hz.

Многополюсный контроллер нечеткой логики для усовершенствования управления шунтирующими реакторами

The article considers the problem of achieving more efficient operation of a multipole fuzzy logic controller (MFLC) intended to control the shunting reactor reactive power for stabilizing the voltage at the buses of high-voltage electric networks and for enhancing the operational reliability under the conditions of uncertain variations of power system circuit and operating parameters. A new algorithm for controlling the shunting reactor’s reactive power or inductive reactance depending on the load impedance, on the load variation rate, and voltage at the network buses is proposed. The results from a numerical experiment carried out by means of computer modeling confirm the efficiency of the proposed control algorithm for the MFLC with using the fuzzy logics theory.