Online frequency and power regulation scheme of magnetic coupled resonant wireless power transfer

In order to address the issues that the magnetic coupled resonant wireless power transfer （MCR-WPT） system is sensitive to the resonant frequency and that transmission power is difficult to control with the non-resistive load in the MCR-WPT, a single-side regulation scheme for frequency and transmission power online is proposed, which is based on the inherent constraint relationships the among system parameters in the primary side. Thus, the communication between the primary side and the secondary side is avoided. First, the transfer models of resistance-capacitance load and resistance- inductance load are established, respectively. Next, the relationship between the input voltage phasor and the input current phasor is used to recognize the load property and value. Then, the coaxial rotation of the stepper motor and the rotating vacuum variable capacitor is conducted to unify resonant frequency both in the primary side and the secondary side. Finally, the regulations of both frequency and amplitude of input voltage are made to guarantee transmission power under a new resonant frequency point the same as the one when the only pure resistance part of load is accessed under the former resonant frequency point. Both simulation and experimental results indicate that the proposed regulation scheme can track remnant frequency and maintain transmission power constant.

Flexible Power Regulation and Limitation of Voltage Source Inverters under Unbalanced Grid Faults

This paper develops a flexible power regulation and limitation strategy of voltage source inverters(VSIs)under unbalanced grid faults.When the classical power theory is used under unbalanced grid faults,the power oscillations and current distortions are inevitable.In the proposed strategy,the extended power theory is introduced to compute the power feedbacks together with the classical power theory.Based on the combination of the classical and extended power theory,the proposed strategy can achieve the sinusoidal current provision and the flexible regulation between three common targets,i.e.,constant active power,balanced current,and constant reactive power.Meanwhile,the proposed strategy is associated with a power limiter,which is capable to keep the currents under the pre-defined threshold and to compute the maximum apparent power for better utilization of the inverter capacity.With this power limiter,the rated inverter capacity is fully used for both the active and reactive power provisions under unbalanced grid faults.Using the proposed power regulation and limitation,the VSI can avoid overcurrent tripping and flexibly regulate its power under unbalanced grid faults.All the conclusions are verified by the real-time hardware-in-loop tests.

Active power regulation of wind power systems through demand response

With the specific characteristics of low-carbon intensity and economy,wind power has been widely promoted around the world.Due to the variable and intermittent nature of wind power production,the system has to frequently redispatch generators in order to ensure the effective use of wind power whilst maintaining system security.In this way,traditional generation costs are increased and the social benefit of wind power decreases indirectly.In this paper,a new regulation strategy based on power flow tracing was proposed,taking advantage of a comfort-constrained demand response strategy to follow the fluctuations of wind farm output,with the remaining imbalance of active power compensated by traditional generators.Examples showed that compared with conventional regulation,demand response could reduce the gross operating costs of the system,and the rapid response could help maintaining system stability in case of contingency.The strategy in this paper also applies to other large-scale integration problems associated with renewable energy resources which display short-term production variability.

Superconducting Magnetic Energy Storage Integrated Current-source DC/DC Converter for Voltage Stabilization and Power Regulation in DFIG-based DC Power Systems

Unpredictable power fluctuation and fault ridethrough capability attract increased attention as two uncertain major factors in doubly-fed induction generators(DFIGs)integrated DC power system.Present solutions usually require complicated cooperation comprising multiple modules of energy storage,current control,and voltage stabilizer.To overcome the drawbacks of existing solutions,this paper proposes a superconducting magnetic energy storage(SMES)integrated currentsource DC/DC converter(CSDC).It is mainly composed of a current-source back-to-back converter,and the SMES is tactfully embedded in series with the intermediate DC link.The proposed SMES-CSDC is installed in front of the DC-DFIG to carry out its dual abilities of load voltage stabilization under multifarious transient disturbances and power regulation under wind speed variations.Compared with the existing DC protection devices,the SMES-CSDC is designed on the basis of unique current-type energy storage.It has the advantages of fast response,extensive compensation range,concise hardware structure,and straightforward control strategy.The feasibility of the SMESCSDC is implemented via a scaled-down experiment,and its effectiveness for DC-DFIG protection is verified by a large-scale DC power system simulation.

A Two-stage Single-phase Grid-connected Solar-PV System with Simplified Power Regulation

This study focuses on the design and development of a simplified active power regulation scheme for a two-stage single-phase grid-connected solar-PV(SPV)system with maximum power point(MPP)estimation.It aims to formulate and test an improvised new control scheme to estimate the real-time MPP of the PV panel and operate only at either the MPP or on the right-hand side(RHS)of the PV characteristics of the panel.A simple active power regulatory control scheme was formulated to provide frequency control services to a single-phase grid without using an energy storage device.The plant operator provides the reserve fraction as the input for the active power regulation controller.At any time,the reserve fraction is used to determine the magnitude of the reference power to be extracted from the PV panel for injection into the grid.A simple PI controller was used to track the calculated reference power.The different modes of operation of the regulatory scheme are presented in detail.All the above control schemes are integrated and implemented through appropriate switching of the DC-DC converter alone.The DC-AC converter maintains the DC link voltage and unity power factor at the single-phase grid terminals.The proposed control schemes were tested on a 250 Wp solar panel feeding power to a 230 V,50 Hz single-phase grid through a two-stage converter.The entire scheme was modeled using the Matlab/Simulink platform,and the same was validated by hardware experimentation using Chroma Solar Simulator and NI myRIO controller under varied irradiation,temperature,and reserve fractions.The simulation and hardware results are compared and reported.

How to Optimize the Management of Science and Technology Funds in Colleges and Universities Based on the Policy of Streamlining Administration,Delegating Powers,Improving Regulation,and Strengthening Services

To advance the field of science and technology,we need to revitalize the development of science and technology through innovation.The development of science and technology has many beneficial implications on the revitalization of the country.For this reason,universities in China should give full attention to their role as the main propeller of science and technology.“Streamlining administration,delegating powers,improving regulation,and strengthening services”is a policy issued by the Chinese government for the management of science and technology funds in colleges and universities.Based on the policy of“streamlining administration,delegating powers,improving regulation,and strengthening services,”colleges and universities must optimize the management of science and technology funds for their efficient use.In this paper,we analyzed the importance of the policy and put forward an effective management strategy,aiming to improve the management of science and technology funds in colleges and universities.

Regulations and Practice on Flue Gas Denitrification for Coal-Fired Power Plants in China

In China, according to the relative up-to-date regulations and standards, the maincontrol measure for NOX emission of coal-fired power plants is, in principle, low NOXcombustion. However, in recent years, more and more newlyapproved coal-fired plantswere required to install flue gas denitrification equipment. This article expounds if fluegas denitrification is necessary from several aspects, including constitution of NOX, itsimpact to environment, operation ofdeNOXequipment in USA, as wellas the differencein ambient air quality standard between China and World Health Organization. It setsforth themes in urgent need of study and areas where deNOX equipment is necessaryfor new projects, besides a recommendation that the emission standards for thermalpowerplants should be revised as soon as possible in China.

Steady-state voltage-control method considering large-scale wind-power transmission using half-wavelength transmission lines

Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering largescale wind-power transmission.First,the unique voltage characteristics of half-wavelength lines are deduced based on the distributed parameter model.In the secondary voltage-control level,reactive power-transmission limits of half-wavelength lines are introduced as another control objective except for tracing the pilot bus voltage reference.Considering the uncertainty and fluctuation of wind power,the overvoltage risk-assessment method of half-wavelength lines is presented to determine specific voltage-control strategies.Simulation results demonstrate that the proposed voltage-control method delivers superior tracking performance according to a voltage reference value and prevents the overvoltage risk of halfwavelength lines effectively in different wind-power penetrations.

Design of DC regulated power supply based on single chip microcomputer

A DC regulated power supply with numerical control based on single chip microcomputer （SCM） is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage can be obtained through D/A converter （DAC0832） so that different voltages can be provided by operational amplifier. The output voltage varies from 0 V to 12 V with the incremental value of 0. 1 V. The actual output voltage is shown in the nixietube. This DC regulated power supply is characterized by simple structure and easy operation.

A bi-layer coordinated power regulation strategy considering system dynamics and economics for isolated hybrid AC/DC multi-energy microgrid

The isolated hybrid AC/DC multi-energy microgrid(IH-MEMG)offers an effective solution for meeting the electrical,heating,and cooling energy demands of remote and off-grid areas.For an IH-MEMG,system transient dynamics(i.e.,frequency or voltage of the electricity network)and economics are critical aspects that pose the greatest concern to operators.However,these aspects are generally investigated separately owing to their different time scales.To integrate these aspects from the scope of real-time control,this study proposes a bi-layer coordinated power regulation strategy considering system dynamics and economics for the IH-MEMG.First,coupling relationships among multiple sub-networks are analyzed,and a frequency-voltage coupling model between the AC and DC sides is established.Then,a bi-layer coordinated power regulation strategy is developed for the IH-MEMG with output characteristics of different components involved:the primary layer includes a multi-entity power support mechanism used to improve the dynamics of the electricity network,wherein a cooperation principle of the combined cooling,heating,and power(CCHP)unit and energy storage unit(ESU)is designed in detailed;meanwhile,the secondary layer includes a real-time economics-oriented optimization framework used to adjust the power references of multiple units generated from the primary layer for cost efficiency improvement(notably,the primary layer can work independently).Finally,the effectiveness of the proposed strategy is verified through comprehensive simulations under varying operation scenarios.

Quick evaluation and regulation of the maximum instantaneous power and matching resistance for droplet-based electricity generators

Droplet-based electricity generators (DEGs) leveraging triboelectric effects are simple and high-performance devices for harvesting energy from ubiquitous water droplets. Instantaneous power plays a vital role in wide applications of DEGs. However, the governing law of the maximum instantaneous power and matching resistance is lacking and their determination suffers from heavy repetitive experiments, hindering the development of DEGs. Herein, we propose a quick evaluation method for the internal droplet impedance, instantaneous peak power, maximum instantaneous power and matching resistance which exhibits broad universality and excellent accuracy. Moreover, effects of diverse factors pertaining to droplets and devices are fully investigated, highlighting that the maximum instantaneous power and matching resistance can be effectively regulated across multiple orders of magnitudes by controlling the salt concentration. Our findings shed insights into the understanding, evaluation, and regulation of instantaneous power for DEGs, and shall promote the renovation of the DEG technology.

Hierarchical Task Planning for Power Line Flow Regulation

The complexity and uncertainty in power systems cause great challenges to controlling power grids.As a popular data-driven technique,deep reinforcement learning(DRL)attracts attention in the control of power grids.However,DRL has some inherent drawbacks in terms of data efficiency and explainability.This paper presents a novel hierarchical task planning(HTP)approach,bridging planning and DRL,to the task of power line flow regulation.First,we introduce a threelevel task hierarchy to model the task and model the sequence of task units on each level as a task planning-Markov decision processes(TP-MDPs).Second,we model the task as a sequential decision-making problem and introduce a higher planner and a lower planner in HTP to handle different levels of task units.In addition,we introduce a two-layer knowledge graph that can update dynamically during the planning procedure to assist HTP.Experimental results conducted on the IEEE 118-bus and IEEE 300-bus systems demonstrate our HTP approach outperforms proximal policy optimization,a state-of-the-art deep reinforcement learning(DRL)approach,improving efficiency by 26.16%and 6.86%on both systems.

A Parallel-type Load Damping Factor Controller for Frequency Regulation in Power Systems with High Penetration of Renewable Energy Sources

Renewable energy sources(RESs)are rapidly devel-oping and their substitution for traditional power generation poses significant challenges to the frequency regulation in power systems.The load damping factor D characterizes the active power of load that changes with power system frequency,which is an important factor influencing the frequency response.However,the value of D is small,resulting in the limitation in frequency regulation of the power system.This paper proposes a parallel-type load damping factor controller to enhance load damping factor by utilizing static var generators(SVGs)in substations.Additionally,it discusses the configuration method for the relevant parameters of the controller,evaluates its frequen-cy regulation capability,investigates the impact of large-scale application of the controller on static and dynamic loads,and conducts a comprehensive evaluation of the impact of the damping factor control process on the voltage stability of the main grid.The large-scale application of the proposed controller can significantly improve the frequency regulation capability,and almost have no influence on the working status of the load.It can also significantly improve the dynamic performance of system frequency.The proposed controller can provide technical support for the frequency regulation of new power systems with high proportion of RESs.

Multi-Stage Voltage Control Optimization Strategy for Distribution Networks Considering Active-Reactive Co-Regulation of Electric Vehicles

The high proportion of uncertain distributed power sources and the access to large-scale random electric vehicle(EV)charging resources further aggravate the voltage fluctuation of the distribution network,and the existing research has not deeply explored the EV active-reactive synergistic regulating characteristics,and failed to realize themulti-timescale synergistic control with other regulatingmeans,For this reason,this paper proposes amultilevel linkage coordinated optimization strategy to reduce the voltage deviation of the distribution network.Firstly,a capacitor bank reactive power compensation voltage control model and a distributed photovoltaic(PV)activereactive power regulationmodel are established.Additionally,an external characteristicmodel of EVactive-reactive power regulation is developed considering the four-quadrant operational characteristics of the EVcharger.Amultiobjective optimization model of the distribution network is then constructed considering the time-series coupling constraints of multiple types of voltage regulators.A multi-timescale control strategy is proposed by considering the impact of voltage regulators on active-reactive EV energy consumption and PV energy consumption.Then,a four-stage voltage control optimization strategy is proposed for various types of voltage regulators with multiple time scales.Themulti-objective optimization is solved with the improvedDrosophila algorithmto realize the power fluctuation control of the distribution network and themulti-stage voltage control optimization.Simulation results validate that the proposed voltage control optimization strategy achieves the coordinated control of decentralized voltage control resources in the distribution network.It effectively reduces the voltage deviation of the distribution network while ensuring the energy demand of EV users and enhancing the stability and economic efficiency of the distribution network.

Evaluation of intermittent-distributed-generation hosting capability of a distribution system with integrated energy-storage systems

The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency and variability of power outputs from numerous distributed renewable generators could significantly jeopardize the secure operation of the distribution system.Therefore,it is necessary to assess the hosting capability for intermittent distributed generation by a distribution system considering operational constraints.This is the subject of this study.An assessment model considering the uncertainty of generation outputs from distributed generators is presented for this purpose.It involves different types of regulation or control functions using on-load tap-changers(OLTCs),reactive power compensation devices,energy storage systems,and the reactive power support of the distributed generators employed.A robust optimization model is then attained It is solved by Bertsimas robust counterpart through GUROBI solver.Finally,the feasibility and efficiency of the proposed method are demonstrated by a modified IEEE 33-bus distribution system.In addition,the effects of the aforementioned regulation or control functions on the enhancement of the hosting capability for intermittent distributed generation are examined.

大规模风电接入吉林电网风电消纳能力分析

针对风电大规模并入电网后,消纳风电能力受制约问题,基于吉林电网的电源负荷特性及峰谷差情况分析,在充分考虑尖峰电源备用、低谷火电机组深度调峰的情况下,提出了考虑电力平衡的最大风电消纳能力的计算方法,计算得出了2014年、2016年吉林电网最大风电可接纳容量,并分析了制约风电消纳能力的主要因素,最后提出了加快风电外送通道和加强抽水蓄能电站建设、推广电能替代工作、提高风电储能技术的实用化水平以及健全火电调峰补偿机制具体建议。

我国网络舆论监督权力的法律规制历程

我国网络舆论监督权力的法律规制是个渐进的过程,它与舆论所依赖的网络平台的发展状况以及人们对网络法律规制的认知有着紧密的关系,与我国总体的法治状况直接相关。网络舆论监督权力的法律规制历程迄今为止大致可分为3个主要阶段:即网络舆论监督权力的法律规制初建阶段、逐步完善阶段和深入推进阶段。在规制理念上分别体现为网络自由主义、网络管制主义和中国特色社会主义法治理念。网络舆论监督权力的法律规制总体呈现出不断进步的同时,也暴露了一些普遍存在的影响法律规制效果的问题,这些问题的存在及网络舆论监督法治实践的不断变化决定了网络舆论监督法律规制任重道远。

The Design and Simulation Analysis of Adjustable DC Source Circuit based on AD 13 Software

DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising, the paper simulate and compare common DC regulated power with adjustable DC regulated power by Altium Designer software, intuitively demonstrates the stabilizing effect of the circuit, and introduces the characteristics of adjustable DC regulated power. Using AD13 software simulate and design DC stabilized power supply circuit, calculated the main parameters of the circuit, simulated and analyzed the circuit working simulation process and the working state of the circuit, it can visually verify the results of the theoretical analysis, and get relevant conclusions.

Coordination control method to block cascading failure of a renewable generation power system under line dynamic security

The large application of renewable energy generation(REG)has increased the risk of cascading failures in the power system.At the same time REG also provides the possibility of new approaches for the suppression of such failures.However,the capacity and position of the synchronous generator(SG)involved in regulation limit the power regu-lation speed(PRS)of REG to the overload line which is the main cause of cascading failures,while the PRS of SG is related to the position and shedding power.REG and SGs have difficulty in achieving effective cooperation under constraints of system power balance.Particularly,the dynamic variation of line flow during power regulation causes new problems for the accurate evaluation of line thermal safety under overload.Therefore,a new strategy for quan-titatively coordinating shedding power and power regulation to block cascading failures in the dynamic security domain is proposed in this paper.The control capability and dynamic security domain of the overload line are mod-eled,and the coordination control method based on power regulation is then proposed to minimize shedding power.The algorithm for the optimal control scheme considers the constraints of load capacity,power source capacity and bus PRS.The correctness of the proposed method is verified using case studies.