Reactive Power Compensation Equipment Research Articles

A comprehensive optimization mathematical model for wind solar energy storage complementary distribution network based on multi-regulatory devices under the background of renewable energy integration

In the context of global energy transformation and sustainable development, integrating and utilizing renewable energy effectively have become the key to the power system advancement. However, the integration of wind and photovoltaic power generation equipment also leads to power fluctuations in the distribution network. The research focuses on the multifaceted challenges of optimizing the operation of distribution networks. It explores the operation and control methods of active distribution networks based on energy storage and reactive power compensation equipment. The stable operation of the distribution network is analyzed under the conditions of wind and photovoltaic integration, with a particular focus on precise regulation to address the limitations of existing methods. Afterwards, the study proposes an improvement plan that combines on load tap changer transformers and reactive power compensation equipment to solve complex power balance problems through second-order cone programming relaxation method. The results of numerical analysis show that the constructed mathematical model maintains a stable voltage of 1 to 1.1 pu at distribution network nodes within 24 h. Especially during peak hours from 15:00 to 24:00, it remains normal without any abnormal fluctuations when the control equipment is not added. These results confirm that precise regulation of multiple devices ensures voltage stability and avoids low or high voltage issues.

Study on overvoltage suppression method of phase modulation of hydroelectric generating units and its cooperative optimization in new energy grid

When a significant portion of renewable energy is transmitted to the power grid through high voltage direct current, when the monopolar blocking occurs, as a result of the converter station’s filter and reactive power compensation equipment’s influence, overvoltage will be generated, which will cause harm to the new energy station, and even lead to large-scale new energy grid disconnection. This paper initially examines the mechanism behind overvoltage in a new energy power grid and then puts forward a method to restrain overvoltage by using phase modulation operation of hydroelectric generating units. To improve the phase modulation capability of hydroelectric generating units and optimize the utilization of new energy sources, this paper proposes a particle swarm optimization to determine the optimal phase modulation capacity. Finally, this paper builds an example of the PSASP platform to verify the correctness and effectiveness of collaborative optimization.

Ultra-Low Reactive Power Operation and Control Strategy of Hybrid Line Commutated Converter Based on IGCT for HVdc Application

Existing line commutated converter (LCC) based high voltage DC (HVDC) systems require large reactive power during operation and reactive power compensation equipment under construction. However, the equipment is expensive and occupies a huge area. In this letter, a novel operation of hybrid line commutated converter based on integrated gate commutated thyristor (IGCT) is proposed to achieve ultra-low reactive power (LR-LCC), and the corresponding control strategy is developed by utilizing IGCT's active blocking and bidirectional voltage withstanding capability. It can almost eliminate the system's extinguishing angle (γ), and the power factor is close to 1. This novel LR-LCC can result in advantages including a much lower manufacturing cost and volume of reactive power compensation equipment for HVDC application.

Analysis of transient electromagnetic force on end windings of 300 Mvar synchronous condenser during dynamic reactive power compensation process

The uneven distribution of renewable energy supply and demand promotes the development of high-voltage direct current transmission. As the critical reactive power compensation equipment for high voltage direct current transmission, the synchronous condenser must have a strong overload capability. One of the critical factors limiting the improvement of its overload capacity is the reliability of the end winding, which depends on the magnitude of the force on end windings during dynamic large reactive power output. Therefore, this paper proposes a coupling model of transient electromagnetic force for the high voltage direct current transmission system and the end zone of the synchronous condenser. The transient response of the synchronous condenser under different fault degrees is calculated, analyzed, and verified by experiments. Based on the current response of the synchronous condenser, the transient electromagnetic force on end windings is calculated. The distribution law of the force on end windings of the synchronous condenser under different degrees of dynamic reactive power compensation process is revealed. Further, the regions on end windings with larger force during strong overload are indicated. The optimizing fixation scheme for end windings is proposed according to the distribution features of the force, which can improve the operational reliability of end windings.

Mixed-integer second-order cone programming method for active distribution network

Developing a novel type of power system is an important means of achieving the “dual carbon” goals of achieving peak carbon emissions and carbon neutrality in the near future. Given that the distribution network has access to a wide range of distributed and flexible resources, reasonably controlling large-scale and adjustable resources is a critical factor influencing the safe and stable operation of the active distribution network (ADN). In light of this, the authors of this study propose a mixed-integer second-order cone programming method for an active distribution network by considering the collaboration between distributed, flexible resources. First, Monte Carlo sampling is used to simulate the charging load of electric vehicles (EVs), and the auto regressive moving average (ARMA) and the scenario reduction algorithms (SRA) based on probability distance are used to generate scenarios of the outputs of distributed generation (DG). Second, we establish an economical, low-carbon model to optimize the operation of the active distribution network to reduce its operating costs and carbon emissions by considering the adjustable characteristics of the distributed and flexible resources, such as on-load tap changer (OLTC), devices for reactive power compensation, and EVs and electric energy storage equipment (EES). Then, the proposed model is transformed into a mixed-integer second-order cone programming (SOCP) model with a convex feasible domain by using second-order cone relaxation (SOCR), and is solved by using the CPLEX commercial solver. Finally, we performed an arithmetic analysis on the improved IEEE 33-node power distribution system, the results show that ADN’s day-to-day operating costs were reduced by 47.9% year-on-year, and carbon emissions were reduced by 75.2% year-on-year. The method proposed in this paper has significant effects in reducing the operating cost and carbon emissions of ADNs, as well as reducing the amplitude of ADN node voltages and branch currents.

Operating State Evaluation Method of UHV Oil Immersed Shunt Reactors

The oil-immersed shunt reactor is one of the most important reactive power compensation equipment in the ultra-high voltage (UHV) long-distance transmission and transformation system, which can solve the problem of large power and long-distance transmission that makes the capacitance effect of transmission lines obvious. At present, the commonly used state evaluation methods for UHV oil-immersed shunt reactors are mostly based on a certain factor or several factors to make judgments, without a comprehensive consideration of the overall operating condition information of the shunt reactors. There are various uncertainties in the process of fault diagnosis and state evaluation of the shunt reactors, and the accuracy and timeliness of the diagnosis results are poor. To solve the above problems, this paper combines the key characteristic parameters of oil immersed shunt reactor, such as vibration, chromatography, partial discharge, and oil temperature, and establishes a comprehensive evaluation method for the operating state of oil immersed shunt reactor based on Gaussian Cloud Model (GCM), and verifies its effectiveness through test data, whose R2 over 0.98. The test data show that this method can effectively judge the operation state of the UHV oil-immersed shunt reactor, which accuracy rate of state diagnosis is over 91%. The results of this paper can provide technical support for the application of UHV oil-immersed shunt reactor state assessment and diagnosis, and further improve the level of equipment operation and maintenance.

A novel robust Volt/Var optimization method based on worst‐case scenarios for distribution network operation

The Volt/Var optimization (VVO) problem is used for scheduling the voltage regulation and reactive power compensation equipment in distribution networks to minimize power loss and voltage violation. In order to solve the VVO problem for a forthcoming time horizon, it is necessary to predict some parameters such as load demand and renewable energy production. The prediction of these parameters is always accompanied by uncertainty that robust optimization can be used to solve this concern. This paper presents a scenario-based robust Volt/Var optimization (RVO) method that significantly reduces the number of scenarios required for the worst-case approach. Solving the VVO problem with the worst-case scenarios reduces the computational burden and maintains the voltage security of the distribution network against the severe events. The proposed RVO is formulated based on a mixed-integer second-order cone programming (MISOCP) model in which Volt/Var control (VVC) equipment is scheduled over a two-stage strategy. The proposed method is validated using modified 33-bus and 69-bus IEEE test systems. The results demonstrate that the proposed RVO method maintains the network's voltage profile within the acceptable range against uncertainties.

Research on Reactive Voltage Control of Distribution Network with Distributed Photovoltaic Sources

Aiming at the problem that the voltage of multiple nodes exceeds the limit after the distributed photovoltaic source is connected, a reactive voltage control method of distribution network is proposed. It modeled the distribution network system with distributed photovoltaic sources, determined the maximum photovoltaic output and adjustable amount, and calculated the power flow. The line loss can be obtained from the node voltage and rated power, and the power distribution of each branch of the whole network can be further obtained. This paper analyzed the influence of photovoltaic power access on the voltage quality of the distribution network from the perspective of power. It calculated the reactive output power of reactive power compensation equipment of upstream and downstream nodes. In this paper, the active power of distributed generation is locally reduced at each out-of-limit node to control the voltage. The experimental results show that the proposed method can effectively improve the relationship between photovoltaic output and voltage, and realize the correction of photovoltaic regulation. Therefore, it can reduce the risk of voltage out of limit and improve the voltage quality.

Optimization of Intelligent Distribution of Distribution Network in the Presence of Distributed Sources

In order to improve the intelligent distribution effect of the distribution network in the presence of distributed generation, this study combines intelligent algorithms to analyze the intelligent distribution of the distribution network in the presence of distributed generation. Moreover, this study establishes an objective function composed of system network loss expectation, voltage stability index, and reactive power compensation equipment investment. In addition, this study improves the artificial bee colony algorithm through tabu search algorithm and genetic algorithm and obtains an improved TS-IABC algorithm. Finally, this study compares and tests the performance of different algorithms in the form of functions and simulations. The simulation results show that the optimal intelligent distribution method of the distribution network in the presence of distributed power generation proposed in this study has a good effect and can promote the intelligent distribution of the distribution network.

A novel optimization method for high-penetration electric vehicles integration to electrical distribution network

With the implementation of China’s “double carbon” strategy, the usage scale of electric vehicles has grown rapidly. Therefore, how to maintain the ideal voltage and energy curve in the distribution network with high penetration of electric vehicles is a challenging problem. In this paper, the random behaviors of fast charging, ordinary charging and discharging modes of electric vehicles have been analyzed and the mathematical formulation of the algorithm has been presented. Then, the strategy of coordinated charging-discharging stack of electric vehicles is proposed. The improved particle swarm optimization algorithm based on mixed real number and binary vector is used to solve the optimization model. The results of several case studies have also been presented in this paper to show that optimum capacitor switching and transformer tap adjustment solutions can be found to minimize the total operation cost including energy consumption, power quality and reactive power compensation equipment action cost. The paper demonstrates that the impact of high-penetration electric vehicles on the energy and voltage control of the distribution network has been solved. The proposed EV coordinated stacking method can make electric vehicles charge and discharge in an orderly queue, and ensure that the line flow does not exceed the limit. Through the proposed control strategy, the voltage curve is obviously improved, and the cost of the distribution system with large-scale EVs can be effectively reduced.

The Vector Electromagnetic Vibration of Magnetically Controlled Reactor Considering the Vector Hysteretic Magnetostriction Effect

Magnetically controlled reactors (MCRs) are widely used as reactive power compensation equipment owing to their favorable properties of smoothly adjusting their inductance value through dc bias. However, the dc bias and the rotational magnetization at corner and T-joint areas make the cores of MCRs saturated, resulting in high magnetostriction and vibration. Thus, the electromagnetic vibration analysis of MCRs must consider the vector hysteretic magnetostriction effect. In this article, a vector hysteretic magnetostriction model of silicon steel is proposed by combining the quadratic domain rotation model with the vector inverse Jiles–Atherton model firstly. Then, based on the measured magnetization and magnetostrictive characteristics curves of silicon steel, the model’s parameters are optimized by velocity controllable particle swarm optimization (VCPSO). Finally, the vector hysteretic magnetostriction model is combined with the finite element method (FEM) to simulate the vector vibration characteristics of MCR under dc bias. The simulation results show that the vector property of electromagnetic vibration and magnetic field at the T-joint area is higher than that at other areas. And the MCR vibration test results are consistent with the simulation results, which verify the accuracy of the proposed model in simulating electromagnetic vibration.

Application Prospects of the Superconducting Dynamic Synchronous Condenser

The new power system based on renewable energy sources may bring the problems of voltage and frequency stability due to the high-level power electronic-based interfaced generation. As a reliable reactive power compensation equipment, dynamic synchronous condensers (DSCs) have the merits of short response time and high overload capacity. They can also improve the system inertia and short-circuit current capacity, and play the role of voltage and frequency stabilizer in the power system. Compared with the conventional DSCs, the superconducting DSCs have higher efficiency, stronger voltage support ability and more excellent reactive compensation performance. In 2018, a research project was launched to explore the feasibility of the superconducting DSC in power grid. The project has achieved significant progress. A hundred-kW prototype was designed and made for technical verification, and the design procedure of the 10 Mvar one is being carried out.

Siting and sizing of synchronous compensator based on electromagnetic transient simulation

With the increasing load of power grid and the access of new energy sources and direct current lines, power grid voltage stability becomes increasingly prominent. Installing synchronous compensator is an option to supplement reactive power and improve voltage stability. Compared with other reactive power compensation equipment (SVC, SVG, etc.), synchronous compensators have advantages in service life, size, easy to maintenance and etc. Siting and sizing of synchronous compensator are critical for investment and voltage stability adjustment performance of the equipment. Considering that the power grid contains new energy and HVDC equipment, it is necessary to use electromagnetic transient (EMT) simulation to evaluate transient stability of a power system when the siting and sizing of a synchronous compensator was determined. In this paper, a method of siting and sizing the synchronous compensator based on voltage sensitivity index (VSI), severity index (SI) and EMT simulation is proposed. VSI of different bus in the system is calculated by injecting reactive power into each bus, and the suitable candidate bus location for compensator is obtained. Furthermore, the calculation of power grid fault severity index is designed, and the synchronous compensator sizing method with the SI as optimization objective is designed. An actual AC–DC hybrid power grid system with 1343 buses was used to test the proposed methods and testing results demonstrate the performance of the proposed method.

Research on Reactive Power Compensation Based on Magnetic Saturation Controllable Reactor

With the improvement of the automation level of the power system and the development of power electronic equipment, the magnetic saturation controllable reactor will surely become indispensable reactive power compensation equipment. But there are few researches on it at home and abroad. In the power system with its superior performance the magnetic saturation controllable reactor studied in this article is a static dynamic reactive power compensation device, which mainly uses lagging inductive reactive power to offset the leading capacitive reactive power. In this paper, its structure and working principle are studied in detail, electromagnetic calculation and simulation analysis are carried out, and genetic algorithm is introduced to optimize it. From theory to practice, a thorough discussion is made to make up for the blank of this direction.

Capacity Optimization and Maintenance of Low Voltage Reactive Power Compensation Equipment in Distribution Netw

Low-voltage distribution network has the characteristics of large number of nodes and branches, radial network and three-phase asymmetry in normal operation, which directly affects the power quality of users. In this paper, the load variation, the three-phase asymmetry and the capacity attenuation of capacitors are considered, and the state evaluation and three-phase capacity planning of LV reactive power compensator are studied. Genetic algorithm is used to realize economical and efficient control effect of bus voltage stability through reasonable planning of finite compensation equipment in multi-node system. Experimental results show that the proposed method can effectively optimize the location and capacity of the compensation device, and can improve the overall voltage level of distribution network economically and reasonably.

Research on Dynamic Reactive Power Compensation Scheme for Inhibiting Subsequent Commutation Failure of MIDC

Commutation failure at the inverter side of an MIDC (multi-infeed HVDC) is usually caused by AC system faults. Suppose the converter bus voltage cannot recover to the normal operation level in time: in that case, the commutation failure will then develop into more severe subsequent commutation failures or even DC blocking, which will severely threaten the security and stability of the system. Dynamic reactive power compensation equipment (DRPCE) can offer voltage support during accident recovery, stabilize voltage fluctuation and inhibit any subsequent commutation failure risk. This paper proposes the optimal DRPCE configuration scheme for maximizing both inhibitory effect and economic performance. The simulation results on MATLAB-BPA prove the scheme’s correctness and rationality, which can effectively inhibit the risk of subsequent commutation failure and obtain economic benefits.

Hybrid Control of Grid-Feeding and Fuzzy Logic Fault Detection in Solving Voltage Dynamic Problem within the Malaysian Distribution Network

The stochastic behavior of PV together with high PV penetration have given rise to power quality concerns involving voltage dynamic issues such as undervoltage, overvoltage, sag and swell. To ensure the grid’s stability, various methods have been practiced such as a proper sizing of the grid lines and the installation of power quality compensation equipment. However, these measures often require high costs and high control complexity due to additional equipment being involved such as multiple transformers and inverters. Moreover, the current available reactive power compensation equipment has a lesser impact on distribution level networks. Therefore, this work proposes a hybrid control of grid-feeding mode and energy storage with Direct Current (DC) fault detection scheme utilizing fuzzy control to mitigate high PV penetration problems, PV intermittency and faults via active power compensation to maintain the system’s voltage within its nominal range. This hybrid control works on two mode of operations: strategic power dispatch by the grid-feeding mode to solve under and overvoltage caused by inconsistent PV generation. Meanwhile, the utilization of fuzzy control aims to solve PV intermittency and line faults. The novel hybrid control has proven its capability to solve voltage dynamic problems caused by high PV penetration, intermittency and faults in the network within a shorter timeframe.

New research progress of large capacity new synchronous condenser

With the increase of HVDC(high voltage direct current) transmission system, the new large-capacity synchronous condenser is the most suitable device to meet the dynamic reactive power demand of the power grid system. Therefore, it has gradually become one of the research hot topics. Based on this, the paper systematically summarizes the research status of the new synchronous condenser. Firstly, the operation principle of the synchronous condenser is introduced from four aspects: its reactive power characteristics, operation state and the typical type and control strategy. Secondly, by comparing it with power electronic reactive power compensation equipment, the superior dynamic reactive power output characteristics of the new synchronous condenser are expounded, and the influence factors are analysed, the example that stable grid voltage is given. Finally, the latest development of the state monitoring technology of the synchronous condenser is summarized from both the existing fault diagnosis technology and parameter identification technology. In this paper, the basic theory, control strategy and operation state monitoring of the new synchronous condenser are summarized, which could provide reference for the further research.

Design of LQR Excitation Controller of Synchronous Condenser in HVDC System

As a kind of reactive power compensation equipment,a synchronous condenser is widely used in High Voltage Direct Current(HVDC) transmission system due to its small influence on the regulation ability and high strong excitation ability. In this paper,the practical state space model of the synchronous condenser is established and the parameters of the model are calculated. The linear quadratic regulator ( LQR) Controller for excitation system is designed and the controllability and stability are analyzed. In order to verify the voltage support ability and dynamic response performance of LQR excitation controller,the simulation is carried out in MATLAB/SIMULINK. The simulation results show that the grid voltage fluctuation can be quickly quelled and the strong excitation function of synchronous condenser is quickly exerted.

Edge Computing Regulation Optimization Technology Based on Power Internet of Things

In the long-term operation of the power grid, local faults sometimes occur, which are mainly caused by excessive load of users, excessive power consumption, insufficient reactive power compensation and other reasons, resulting in low node voltage and large system loss. To solve this problem, based on the edge computing of power Internet of Things, the regulation optimization technology is studied. In this paper, firstly, the development status of edge computing in power Internet of Things is summarized, the importance of reactive power compensation in power grid under edge computing environment is introduced, and the application of improved particle swarm optimization (GPSO) algorithm in reactive power compensation in power grid is studied. GPSO algorithm is used to compensate the system with local faults, and the compensation effect is compared with that of particle swarm optimization algorithm and genetic algorithm. Then, the power flow calculation and reactive power compensation of the power grid are analyzed theoretically, and the reactive power loss, reactive power compensation device and reactive power compensation mode of the power grid are studied, and some mathematical models and practical working methods are summarized. In addition, according to an actual network example in a certain area, particle swarm optimization, genetic algorithm and GPSO algorithm are used to calculate the reactive power compensation of the power grid, and the reactive power compensation equipment is connected to the power grid reasonably, thus increasing the node voltage and reducing the network loss. Finally, by comparing the grid node voltages of the three algorithms under edge computing conditions, it is proved that GPSO algorithm has improved the power Internet of Things, that is, it is a good regulation and optimization technology to compensate the reactive power of the grid by using GPSO algorithm.