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最新刊期
卷 44 ， 期 1 ， 2020
- 摘要：Ubiquitous Internet of Things (IoT) based power distribution and consumption system (PDCS) is a cyber-physical-social system (CPSS) formed by the deep integration of smart distribution grid and power IoT. The participants of ubiquitous IoT based PDCS and their cyber, physical and social attributes are analyzed. The mutual interactions of these participants are also discussed from the cyber field, physical field, and social field. The operation features of ubiquitous IoT based PDCS are abstracted in the CPSS perspective. In the physical field, the features include the flexibility of nodes, network, and functions. In the cyber field, the uncertainty of ubiquitous sensing, edge computing, and cybersecurity are essential features. Moreover, new features in the social field include role variability and utility personalization of participants, and diversification of business models. Based on the analysis of domestic and foreign research trends, the difficulties are refined including feature identification of complex power system, social behavior modeling and hybrid simulation, stochastic game theory framework and application with incomplete information, modeling and solving optimization problem with fusion social attributes, scheduling strategy and driving mechanism for edge computing, interactive security mechanism for the terminal IoT based PDCS. The analysis and discussion are provided on the multidisciplinary intersection of information, physics and social systems at the theoretical level, and the technical support is given for the construction of ubiquitous power IoT and smart grid at the application level.关键词：ubiquitous Internet of Things;cyber-physical-social system;prosumer;optimal operation;edge computing18|4|0更新时间：2020-07-14
- 摘要：The ubiquitous power Internet of Things (UPIoT) is a key direction for the development of smart grids. Firstly, the main functions and value of UPIoT are summarized. Secondly, the existing research and application foundation of Internet of Things technology in the field of power are surveyed from each link of smart grid. Furthermore, the development model of UPIoT is conceived and proposed, including the technical development trend of three stages of smart grid at present stage, transparent grid and zero marginal cost grid, which provides some ideas for deepening the construction of UPIoT. Finally, several technical challenges of UPIoT are given, which provides a reference to the future research of UPIoT.关键词：smart grid;Ubiquitous Power Internet of Things;transparent grid;zero marginal cost4|2|0更新时间：2020-07-14
Ubiquitous Electric Power Internet of Things
- 摘要：With the development of DC conversion technologies and the practical need for DC power supply, DC distribution systems attracts more and more attentions around the world. Furthermore, the national criterion GB/T 35727—2017 of China for standard voltages of medium and low voltage dc distribution system is published recently, which is very important for the development of DC distribution system since voltage levels and series are the key points for power system research and design. The background of this criterion is introduced in this paper, followed with the main parts of medium-level nominal voltages, low-level nominal voltages and the corresponding permitted voltage deviations with main factors considered. Finally,this paper puts forward a power supply mode analysis method of DC distribution system based on load distance, which links voltage level, allowable deviation, line parameters, transmission capacity, etc. to provide support for the analysis and design of power supply mode of DC distribution system.关键词：DC distribution system;DC nominal system voltage;DC voltage deviation;load distance;guideline4|2|0更新时间：2020-07-14
Special Report
- 摘要：Climate change has become a core challenge for human sustainable development, and low-carbon energy transition has become a key measure to mitigate climate change. Carbon emission reduction is one of the key benefits of energy transition. If the carbon emission reduction benefit can be evaluated monetarily, the cost-benefit analysis of alternative energy transition goals and paths with the unified currency dimension can be realized. This paper analyzes the mainstream monetary value evaluation method of carbon emission in detail, and proposes the social cost of carbon (SCC) as a more suitable method for the long-term energy transition problems. Furthermore, the sub-modules of SCC assessment are elaborated, including social economy, climate change, damage assessment and discounting modules, and the uncertainty sources of evaluation model are discussed. Finally, a typical SCC assessment model is chosen to calculate the country level SCC (CSCC) in China, and the sensitivity analysis of the key parameter (the discount rate) is provided, which can provide an evaluation methodology of carbon emission reduction benefit for the cost benefit analysis of alternative energy transition plans.关键词：energy transition;carbon emission;cost benefit;monetary value;integrated evaluation model23|2|0更新时间：2020-07-14
- 摘要：The initial allocation of carbon emission rights for the electric power industry is the basis and key to ensure the effective operation of the carbon trading market. Through the mining of the characteristics of the carbon emissions in the electric power industry, the index decomposition is carried out to extract the multiple correlated factors that affect the carbon emission allocation system. Secondly, based on the knowledge and experience of experts, the subjective weight of each indicator is determined based on the improved analytic hierarchy process. Then, the improved entropy weight method is used to map the indicators, and a new identification parameter system is constructed. The objective weights of each indicator are determined adaptively. Finally, through the optimized combination of subjective and objective weights, the comprehensive weights of each indicator are determined. A case study of a province using comparative simulation analysis is performed to examine the effectiveness of the proposed method. Compared with traditional schemes that consider single factor, the proposed model that considers multiple correlated factors can reflect the actual responsibilities of regional carbon emission reduction more objectively. It can avoid excessively subjective or excessively objective one-sided evaluation results.关键词：multiple correlated factors;carbon emission rights;allocation scheme;analytic hierarchy process;entropy weight method;subjective and objective weighting method5|2|0更新时间：2020-07-14
Energy Transition and Power Support
- 摘要：The emergence of multiple solutions for electricity price will bring difficulties to the clearing of the real-time market. It is necessary to theoretically study the occurrence conditions of happening and establish high efficient judgment method to improve real-time pricing efficiency. In this paper, the judgment mechanism of multiple solutions for electricity price is deeply analyzed and studied. Based on the physical and mathematical characteristics of market clearing problems, a clear and strict relationship between degeneracy, dual problem and multiple solutions of nodal electricity price is proposed. According to the obtained judgment mechanism, a complete and effective judgment process of the multiple solutions for electricity price is established. Finally, the comparison of the judgment methods and the validity and adaptability verification are carried out by the case study.关键词：nodal electricity price;degeneracy;multiple dual solutions;multiple solutions of electricity price;judgment process4|3|0更新时间：2020-07-14
- 摘要：Aiming at the non-negligible impact of time-delay on the stable operation of large-scale interconnected power system, this paper investigates the stability problem of power system with the influence of interval time-varying delay. Firstly, fully considering the influence of delay derivative on the stable region of power system, a new Lyapunov functional with delay-dependent matrix is constructed. Then, new integral inequality is used to deal with the integral terms after delay segmentation in the analytical process, and the less conservative stability criterion with less variables is obtained, which expands the stable operation region of the power system. Finally, simulations of typical second-order time-delay system, single-machine infinite system, two-area four-machine system and load frequency control system are given to illustrate the effectiveness of the proposed method.关键词：power system;Lyapunov functional;interval time-varying delay;delay-dependent matrix;stability criterion3|1|0更新时间：2020-07-14
- 摘要：For the wide-area interconnected power system, considering there exist transmission delays in multiple loops, a power system model with multiple time delays is established. Then a Lyapunov-Krasovskii functional with higher accuracy is constructed, using the integral inequality of auxiliary function to define the integral term in the functional derivative, the stability criterion of the system with with multiple time delays is derived. The newly constructed functional and integral inequality of auxiliary function introduce more boundary information for the system with multiple time delays, and obtains more free solution space, the error caused by the integral definition process is reduced. Finally, by using the linear matrix inequality toolbox in MATLAB software, the stability of typical second-order time-delay system, single-machine infinite bus system and WSCC three-machine nine-node system are simulated and computed by multiple stability criteria. The simulation results show that the stability criterion proposed in this paper can produce more tighter time delay bounds than those in the existing literatures, several delay stability intervals of the system are also revealed, and can more accurately reflect the stability of power system with multiple time delays.关键词：interconnected power system;multiple time delays;integral inequality;stability3|1|0更新时间：2020-07-14
- 摘要：Frequency oscillation is a small disturbance stability problem in the active frequency control process. Previous studies have focused on the analysis of generator governors and prime movers. Power system stabilizers can also be used to suppress frequency oscillations. The effect mechanism of the generator excitation system on the frequency oscillation is analyzed. When the load has the voltage regulation effect, the generator excitation system affects the load power by the load voltage, thus affecting the frequency oscillation. The process of frequency deviation affecting electromagnetic power through power system stabilizer, excitation, network and load is given. The damping torque theory is used to calculate the electromagnetic power damping coefficient and the influence of power system stabilizer is analyzed. The evaluation method of the effect of different generator power system stabilizers on frequency oscillation damping in multi-machine system is proposed. It is more effective to improve the frequency oscillation damping by selecting the generator with large influence to optimize the parameters. The analysis results are verified by the simulation on IEEE 4-machine 2-area system.关键词：ultra-low frequency oscillation;power system stabilizer;excitation system;damping torque3|2|0更新时间：2020-07-14
- 摘要：There are a large number of inductive motor loads with different parameters in power systems. In order to study the types of induction motors and the distribution characteristics of their parameters, an analysis is carried out, which is based on the load model parameters of 224 motors obtained from literature, and considers the difference of motor model in transient simulation. Firstly, the missing mechanical torque coefficients and initial slip in the model parameters obtained from literature, are filled by K-nearest neighbor imputation method, load factor or critical slip, respectively. Secondly, the transient power curve of the motor is chosen as the clustering indicator, considering the difference of transient response of different motors. Then, 7 kinds of motors with different transient characteristics are obtained by the K-means algorithm, and the distribution characteristics of their parameters are analyzed. The obtained 7 kinds of typical parameters supplement the motor parameter sets recommended by IEEE and State Grid Corporation of China, and provide a reference for the typical parameters of the induction motor load model.关键词：load model;induction motor types;parameters imputation;K-means clustering;typical parameter values5|0|0更新时间：2020-07-14
- 摘要：It is important to evaluate fast charging network (FCN) of electric vehicle (EV) reasonably for planning decision and the improvement of FCN weaknesses, which is one of the important links to promote the development of EVs. Therefore, a comprehensive evaluation system of FCN of EVs is developed. First, based on the FCN multiple attributes and the coupling relationship of FCN, EV users, traffic network and distribution network, four criteria of FCN are proposed including the operation level, EV user’s experience, traffic operation impact and distribution network impact. Evaluation indices are also constructed to each criterion. Thus, the comprehensive evaluation index system including target layer, criterion layer and index layer is developed. Then, the analytic hierarchy process and entropy weight method are used to determine the index weight of criteria layer and index layer. Combined with recursive fuzzy comprehensive evaluation method, the impact of FCN on each part is quantified and evaluated comprehensively. Finally, four kinds of FCN in a city are evaluated comprehensively to validate the effectiveness of the proposed method.关键词：electric vehicle (EV);fast charging network (FCN);index system;entropy weight method;analytic hierarchy process;fuzzy comprehensive evaluation2|5|0更新时间：2020-07-14
- 摘要：The process noise statistical parameters of state equations are unknown and time-varying in the dynamic state estimation of distribution network. Thus, the real-time estimation of the process statistical parameters is essential for the state estimation process. Inaccurate noise parameters will cause the decrease of performance or divergent filtering of unscented Kalman filter. In this paper, a dynamic state estimation method for distribution network based on improved robust adaptive unscented Kalman filter is proposed. The noise parameter statistical estimator in the method is made up of a biased and an unbiased estimator, which will improve the accuracy of noise parameters estimation during the state estimation process as well as guarantee the semi-positive definiteness of process noise variance matrix. As a result, this method can ensure the robustness of the algorithm. The simulations carried out on the IEEE 33-node system demonstrates that the proposed method can ensure high precision of state estimation when the system runs smoothly, the load changes violently or the initial noise parameters are set improperly.关键词：distribution network;adaptive;robustness;dynamic state estimation3|2|0更新时间：2020-07-14
- 摘要：With the development of the urban distribution network, the difficulty in obtaining the real-time distribution network topology has become an important bottleneck for observing its operational status. To tackle high noise sensitivity and difficult online operation in traditional topology recognition methods, this paper proposes a distribution transformers (DTs) connectivity recognition method based on ensemble deep neural network. Firstly, based on the horizontal and vertical continuity of distribution network measurements, the two-dimension wavelet threshold de-noising method is implemented on historical measurements to reduce the impact of noise on the recognition results. To improve the upper limit of deep learning algorithm, this work proposes the search, generation and evaluation strategy for feature extraction and feature selection. Secondly, we use the extracted features as inputs for the deep neural network with cross-entropy function. The grid search algorithm is used to optimize the hyperparameters of deep neural network. An ensemble learning strategy is utilized to train homogeneous deep neural networks to ensure the ability of online topology recognition. Finally, the experiments implemented on TensorFlow certificate the accuracy and robustness of proposed ensemble deep neural network models in distribution transformers connectivity recognition.关键词：distribution transformers connectivity recognition;two-dimension wavelet threshold de-noising method;ensemble deep neural network;TensorFlow3|0|0更新时间：2020-07-14
- 摘要：Linear power flow equations are widely used in scenarios such as economic scheduling, planning optimization, and probability analysis. The fundamental difference between different linear power flow equations lies in the selection of the state variable function form. In this paper, the linearization error of power flow equation is decomposed into linearization errors related to voltage angle and voltage magnitude, which are quantitatively analyzed separately. A normalized analysis method for state space transformation of power flow equation is proposed to obtain the general characteristics of linearization error of power flow equation. Based on this theory, this paper designs a method for selecting the optimal state space of the power flow equation, and the selection of the optimal linear power flow model is analyzed in the actual application scenario.关键词：linear power flow model;state space transformation;state variable function form;Taylor series expansion;error analysis3|0|0更新时间：2020-07-14
- 摘要：Under the background of large-scale wind power integration, the power system raises the deep peak regulation (DPR) of the thermal power unit to fully exploit the existing downward spinning reserve capacity, which will be one of the effective ways to deal with the uncertainty of wind power. Considering the additional coal loss and unit life loss of the thermal power units which work in the DPR state, a robust optimal dispatching model taking the DPR cost of the thermal power unit into account is established in this paper. Considering the uncertainty of wind power output, a two-stage robust optimal model consisting of the main scheduling problem in forecasting scenes and the control sub-problem in extreme scenes is established, and the uncertain parameter is introduced to control the conservativeness of scheduling scheme. Finally, the economical optimal robust day-ahead scheduling plan is obtained. The rationality and effectiveness of the model are proved by case analysis.关键词：deep peak regulation (DPR) cost;additional coal loss;unit life loss;robust optimization3|1|0更新时间：2020-07-14
- 摘要：Soft open point (SOP) has become a research hotspot in the field of distribution network, which can realize flexible regulation of feeder flow of distribution network, improve voltage distribution level, and promote the ability of distribution network to consume distributed generation. The three-port SOP is studied and the corresponding mathematical model is established in this paper. According to the strong coupling and nonlinearity of the mathematical model, the feedback linearization model is obtained by coordinate transformation, and the sliding mode controller is designed for the model. In this paper, the feedback linearization control and sliding mode control are combined, and the composite control is used to replace the current inner loop of the traditional dual closed-loop proportion-integral (PI) control. Compared with the traditional PI control, the composite control can reduce the PI control link and the difficulty in PI parameter setting. According to the requirements of different operation modes of SOP, the feedback linearization sliding mode control algorithm in constant DC voltage and reactive power mode, constant active and reactive power mode and constant AC voltage mode are realized, respectively. A three-port SOP system is built in MATLAB/Simulink, and simulation results show that the proposed control strategy has good dynamic performance and robustness compared to the traditional PI control. Finally, the effectiveness of the proposed control strategy is further verified by simulation of several typical operation conditions.关键词：distribution network;soft open point (SOP);feedback linearization;sliding mode control3|0|0更新时间：2020-07-14
- 摘要：Joint control of active and reactive power for distribution static synchronous compensator embedded with battery energy storage system (B-DSTATCOM) can effectively mitigate problems caused by large-scale distributed generators with high volatility integrated into distribution network, such as voltage violation, increased network loss and three-phase unbalance. Therefore, this paper proposes a real-time joint optimization control strategy of active and reactive power for B-DSTATCOM in unbalanced active distribution networks considering the impacts of photovoltaic generation. Firstly, the operation principle of B-DSTATCOM within four quadrants is studied. On this basis, a real-time multi-objective optimization control model of active and reactive power for B-DSTACTOM is established, in which the voltage deviation, network loss, voltage unbalance and operation cost are used as sub-objective functions. Then, the optimal control scheme is jointly solved by the weighted sum method, improved particle swarm optimization method and direct load flow algorithm. Finally, the effectiveness, practicability and robustness of the proposed control strategy are verified based on MATLAB simulation of an actual unbalanced distribution network with photovoltaic sources in Australia.关键词：distribution static synchronous compensator (DSTATCOM);battery energy storage system (BESS);unbalanced active distribution network;multi-objective optimization;improved particle swarm optimization;direct load flow3|1|0更新时间：2020-07-14
- 摘要：DC distribution networks have many intensive branches and few measuring points that support data high-speed communication. Meanwhile, the fault characteristics are greatly affected by the control strategy of power electronic equipment, which makes the fault location method of the traditional distribution network difficult to be applied to DC distribution network. Based on this, the paper proposes a new bipolar short-circuit fault location algorithm for DC distribution networks. According to the transient high-frequency current loop, the high-frequency impedance equivalent models of modular multilevel converter and DC/DC converter not affected by the control strategy are constructed. Then, the wavelet transform is used to extract the fault high-frequency voltage of the sparse measurement point, which is used to form the node high-frequency voltage equation. Finally, combining the equation with the Bayesian algorithm based compressed sensing theory, the node high-frequency current sparse vector is solved and fault location is achieved accurately based on sparse voltage measurement. The proposed algorithm has low requirements on the number of measuring points and is not affected by the control strategy of converters. It does not need strict data synchronization measurement and is not theoretically affected by the transition resistance. The simulation model of the 32-node DC distribution network is built in PSCAD and the location effectiveness of the proposed algorithm is verified by the test data.关键词：DC distribution network;high-frequency current;sparse measurement;fault location3|0|0更新时间：2020-07-14
Basic Research
- 摘要：Security and stability control (SSC) system is very important to ensure the safe operation of power grid. In view of the insufficiency that the current open-loop test method cannot fully test the on-site SSC system, a remote closed-loop test method is proposed based on real-time simulation. The solutions of key techniques such as information interaction, remote communication and signal conversion in remote test system are studied. Then the platform architecture and standard interface of the remote test system are designed. A remote test platform for SSC system is developed, and the application modes of the platform are deeply analyzed. Finally, taking SSC system of AC output interface in Yunnan as a pilot application, on-site joint remote tests of two main substations are carried out. The results in the practical project further prove the effectiveness of the proposed method.关键词：security and stability control;remote closed-loop test;standard interface;signal conversion;remote test platform12|1|0更新时间：2020-07-14
- 摘要：In the DC grid, the use of high voltage DC circuit breakers to remove faulty lines can effectively eliminate DC faults, but the existing DC breakers have high investment costs and redundant power electronics during normal system operation. A novel multi-port DC circuit breaker (MP-DCCB) topology is proposed in this paper, which uses a single main circuit breaker to protect multiple DC lines. Thyristors with large current capacity are utilized as control unit to selectively cut off the faulty line between main circuit breaker and DC lines. Then, an energy transfer path which is capable of absorbing the energy of the current limiting inductor is designed to reduce the energy that the arrester needs to absorb, the open circuit of MP-DCCB, energy consumption, control method of reclosing stage and electrical processes are theoretically analyzed, and an equivalent mathematical model is established to study the relationship between voltage, current stress, economic characteristics and key parameters of MP-DCCB. The four-terminal bipolar DC grid is built in PSCAD/EMTDC for simulation verification. MP-DCCB can effectively reduce the investment cost of circuit breakers and has the engineering value applied to flexible DC grids.关键词：DC grid;DC circuit breaker;multi-port;thyristor;energy transfer3|0|0更新时间：2020-07-14
- 摘要：At present, the last breaker protection for converter has the problems of poor reliability, complex logic or insufficient early warning, and there is an undesired tripping event of the last breaker protection for converter in practical project. Therefore, the realization strategy of last breaker protection in practical project is firstly sorted out. Based on the analysis of current loop characteristics of last breakers for converter in the paper, the current network of virtual AC line and virtual bus are constructed. Then, an algorithm of last breaker protection for converter is proposed based on the virtual current networks, which can solve the problem of identifying the last breaker for converter in principle. The proposed algorithm is compared with the algorithm used in practical engineering application, and the results demonstrate that the proposed algorithm can correctly identify the last breakers with clear and reliable principle, and avoid the problems of complex logic and the demand of traversing all working conditions.关键词：last breaker protection;3/2 wiring;virtual current network;DC transmission3|1|0更新时间：2020-07-14
- 摘要：The scheme that arc-suppression coils are in parallel with low resistances is increasingly utilized in 10~35 kV medium voltage distribution networks in China whose neutral node is grounded through arc suppression coil. The parallel low resistance will be connected after a permanent single-phase-to-ground fault occurs, which increases the fault current and the protection device is reliably operated to trip the fault line. Therefore, the researches on the fault location technology of single-phase-to-ground fault on the basis of the above have great development prospects and necessity. After the parallel low resistance is connected, the current traveling wave is generated and reflected when reaching the fault point. The current traveling wave has high amplitude and obvious characteristics. Based on these features, this paper proposes a fault location method using the current traveling wave generated by the parallel low resistance. The propagation characteristic of the current traveling wave along the line is analyzed in deep and the single terminal fault location method based on the zero-mode and aerial-mode components is presented. According to the characteristics of distribution network, the solutions of hybrid networks with overhead lines and cables as well as the integrated fault location technology using multiple detection devices are studies. Finally, the simulation results of ATP/EMTP software confirm the accuracy and practicality of the proposed fault location method.关键词：medium voltage distribution network;single-phase-to-ground fault;traveling wave;fault location;arc-suppression coil3|0|0更新时间：2020-07-14
- 摘要：According to the optimal reconfiguration issues of switch type fault current limiter (FCL), a mathematical relevance model of maximum braking current of circuit breaker (CB) and reconfiguration of FCL is established to precisely evaluate the limiting effect after fault current limiter operates. On this basis, taking reactance values of FCL installed on two sides of each branch as optimal variables, and the best current limiting effect of per unit cost of FCL as an objective function,an configuration optimal model of FCL is constructed, in which the constraints of short-circuit current of buses, the maximum breaking current of CB and the maximum reactance of each FCL are considered. After that, the biogeography-based optimization (BBO) algorithm based on sinusoidal migration model and Cauchy mutation is adopted. Considering that the adjacent dimensions in optimization variables have similar influence on objective function, the second mutation operation between adjacent dimensions is introduced into the optimal algorithm and an improved BBO algorithm based on second mutation is proposed. Finally, in order to verify the performance of the proposed improved BBO algorithm, different optimization algorithms are applied to solve the optimal configuration model of FCL which takes a 500 kV regional power grid as an example. The results show that the improved BBO algorithm has better convergence rate, stability and searching ability.关键词：optimal configuration of fault current limiter (FCL);biogeography-based optimization algorithm;maximum breaking current of circuit breaker (CB);short-circuit current3|1|0更新时间：2020-07-14
- 摘要：Supraharmonic is an inevitable power quality problem in the rapid development of power electronic technologies, which attracts more and more attention. In order to reveal the supraharmonic resonance characteristics with integration of multiple inverters, this paper proposes an analysis method of supraharmonic resonance characteristic. Firstly, taking the single-phase grid-connected inverter as an example, the supraharmonic distribution characteristics with the control of unipolar and frequency multiplication sinusoidal pulse width modulation (SPWM) are analyzed to reveal the supraharmonic emission mechanism of power electronic devices based on unipolar and frequency multiplication SPWM control. Secondly, an equivalent circuit model of grid-connected inverter is established. On this basis, the supraharmonic equivalent circuit model of multi-inverter grid-connected system is obtained. Thirdly, according to the equivalent circuit model, the equivalent impedance at the point of common coupling (PCC) is given, and the concept of supraharmonic resonance amplification factor is proposed. Then the control variable method is used to analyze the supraharmonic resonance characteristics of the grid-connected system when the filter parameters, the number of grid-connected inverters and the grid impedance change. Finally, the correctness of the model and theoretical analysis is verified by simulation.关键词：supraharmonics;emission mechanism;LCL-type grid-connected inverter;supraharmonic resonance;equivalent circuit;resonance amplification factor3|0|0更新时间：2020-07-14
- 摘要：In order to improve the dynamic response speed and control accuracy of three-phase voltage source pulse width modulation (PWM) rectifiers, this paper proposes a model predictive power control (MPPC) algorithm based on dynamic component optimization of input-port voltage. Firstly, a power mathematical model of three-phase PWM rectifiers is built in dq rotating frame, and the working principle of the conventional direct power control (DPC) based on proportional-integral (PI) controller is analyzed. Then, from the perspective of dynamic component optimization of input-port voltage, this paper uses the model predictive control idea to predict the optimal dynamic component through the evaluation function, to overcome the drawbacks of the inner-loop power-based PI controllers in PI-DPC, such as complicated parameter design and slow dynamic response. The proposed MPPC scheme can achieve fast dynamic response and high control precision, while avoiding the use of the inner-loop power-based PI controllers. Finally, the proposed MPPC and PI-DPC schemes are compared in hardware-in-loop experiment platform, and the experimental results have verified the validity and effectiveness of the proposed algorithm.关键词：pulse width modulation (PWM) rectifier;direct power control (DPC);proportional-integral (PI) controller;model predictive control (MPC);dynamic component optimization3|0|0更新时间：2020-07-14
Application Research
- 摘要：With the maturity of renewable energy generation technology and the reduction of installation and operation costs, the distributed generation have been rapidly developed, and a large number of electricity prosumers have been generated. However, due to the characteristics of small capacity, high volatility and scattered distribution, the distributed generation is not suitable for participating in the existing electricity market. Combined with the research of foreign electricity retail market and the current distributed generation trading situation in China, this paper proposes a decentralized electricity market (DEM) mode at the level of distribution network. The framework design of DEM is carried out from the aspects of market definition, participants, trading methods, time scale and clearing methods. Aiming at the problem that the DEM trading platform is difficult to establish, this paper studies the feasibility and transaction realization process of blockchain technology applied in DEM. Finally, from the perspectives of policies, regulations and key points of market construction, the issues to be paid attention to in the construction of DEM are analyzed.关键词：distributed generation;electricity prosumer;retail market;decentralized electricity market (DEM);blockchain technology3|0|0更新时间：2020-07-14
Discussion
- 摘要：With the in-depth development of power market reform in China, renewable energy sources such as wind power need to compete with traditional power sources such as thermal power, while the uncertainty of renewable energy sources greatly increases their gaming difficulty in the market. By focusing on the benefit gaming problem of wind farms with energy bidding mode and considering the uncertainty and forecasting error of wind power, the analytical formula of the market gaming equilibrium is deduced with different bidding combinations of wind farms based on the day-ahead and intraday two-stage spot market model, and actual wind power output and forecasting data are used for market simulation to verify the formula. The wind power bidding results with market equilibrium are analyzed. The results show that optimal bidding strategy of wind farms with energy bidding mode is related to their wind power forecasting value as well as forecast error, and wind farms can reduce the risk of bidding revenue by improving forecasting accuracy. Meanwhile, the bidding strategy of wind farms appears energy withholding in the day-ahead market, which aggravates the speculative behavior of wind farms and increases the risk of market operation.关键词：spot market;wind farm;forecasting error;energy bidding;gaming3|0|0更新时间：2020-07-14
- 摘要：In order to weaken the dependence on fossil energy and develop renewable energy sources, the installed capacity of wind power in Xinjiang in China has been increasing year by year. At the same time, the impact of large-scale wind power integration on the traditional distribution network is increasingly significant, especially the short-circuit current when the short-circuit fault occurs, which reduces the reliability of the relay protection and result in instability of the power system. The 110 kV artificial short-circuit test of Xinjiang Power Grid not only carries out the preparation of detailed test plan, but also analyzes the influencing factors of short-circuit current. The analysis of calculated value and test value error based on PSASP power flow mode is implemented. At last, the degree of fit between the different types of wind turbine calculation models of the current power system and the actual situation of the power grid. The error ratio between the calculated current and the measured current with different fault types are obtained, and the influencing factors of the calculated values and the measured values are summarized.关键词：wind power;relay protection;artificial short-circuit test;calculation model;short-circuit current3|0|0更新时间：2020-07-14
Engineering Application
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