Table of Content

28 February 2024, Volume 57 Issue 2

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Special Contribution

Power Grid Scale Prediction and Optimization Needs Based on Policy Requirements of Modern Infrastructure System

Xin TIAN, Linyu WANG, Xingpei JI, Xinyang HAN

2024, 57(2):  1-8.  DOI: 10.11930/j.issn.1004-9649.202310055

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After the modern infrastructure system policy was put forward, new requirements were put forward for the construction of transportation, water conservancy, energy, and new infrastructure represented by information and communications. Starting from the effectiveness of infrastructure, various industries have proposed optimization directions for layout, structure, function, and system integration. This article starts from the study of the functional role of the modern infrastructure system, analyzes the important role of the power grid infrastructure in the modern infrastructure system, and uses Pearson's correlation coefficient to study the relationship between the power grid infrastructure line length and transformer capacity scale and the electricity consumption of the whole society. The article also forecasts the length of transmission lines and transformer capacity scale in the eastern, central, western, northeastern, and other regions in 2025 and 2035. On this basis, the layout, structure, and function of the power grid infrastructure within the framework of the modern infrastructure system are analyzed, and the logic of system integration optimization is given. In addition, the requirements for power grid layout structure function and system integration optimization in building a modern infrastructure system are put forward, providing a reference for the investment and construction of power grid infrastructure.

Low-Carbon Planning and Operation for New-Type Power Systems

Interactive Operation Strategy for Multi-scenario County-Level Multi-microgrid Based on ADMM

Chongbiao ZHANG, Chenwen QIAN, Hongyan YU, Yanling PENG, Jinwei CHEN

2024, 57(2):  9-18.  DOI: 10.11930/j.issn.1004-9649.202308065

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Under the guidance of the "double carbon" goal, renewable energy has witnessed rapid growth in accommodation demand. In order to realize the complementary advantages of microgrid and renewable energy in the county and improve the accommodation rate of renewable energy, a ADMM-based interactive operation strategy for multi-scenario county-level multi-microgrid is proposed. Firstly, a scheduling model for independent microgrid operation is established to realize the optimal scheduling strategy in the day-ahead pre-scheduling plan. Secondly, a multi-microgrid energy interactive operation model is established, which is iteratively solved with the ADMM algorithm to obtain the global interactive energy between microgrids. Finally, the Shapley value method is used to allocate the benefits of the microgrid group and reduce the system operation cost of each sub-microgrid. The case study shows that the proposed method can not only improve the accommodation rate of renewable energy and realize the economy, but also reduce carbon emissions and realize low-carbon operation.

Economic Dispatch of Microgrid Considering Data Center and Wind Power Uncertainty

Wenfei YI, Weiping ZHU, Mingzhong ZHENG

2024, 57(2):  19-26.  DOI: 10.11930/j.issn.1004-9649.202311122

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The continuing increase of grid-connected wind turbines has brought huge challenges to the power system's wind power consumption. As a highly flexible electrical load, the data center has great potential for wind power consumption in the power grid. Therefore, this article proposes economic dispatch of microgrid considering data center and wind power uncertainty. Firstly, based on the hierarchical structure of the data center, a coupling model is established for the information layer and the power layer. Secondly, aiming at the uncertainty of wind power output, a microgrid economic dispatch model considering data center and wind power uncertainty is proposed. Finally, based on the dual theory and two-stage robust optimization algorithm, the dispatch model is transformed into a robust optimization model and solved using column and constraint generation (C&CG) and dual theory. The case study results show that the participation of data center in microgrid economic dispatch can effectively reduce operating costs and the system operators can flexibly adjust the uncertainty of wind power output according to demand.

Time-based Equivalent Method for Reactive Power Regulation Capacity of Grid-connected Photovoltaic Plant

Hai QIN, Sheng CHEN, Honglue ZHANG, Tian XIA, Qinfeng MA, Zhanyu DUAN, Wei YAN

2024, 57(2):  27-33.  DOI: 10.11930/j.issn.1004-9649.202303049

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The existing equivalent methods for reactive power regulation capacity of grid-connected photovoltaic(PV) plant do not take into account the voltage security constraints in the plant and the impacts of random fluctuations of grid-connected voltage and photovoltaic output, which makes it hard to meet the requirements of actual engineering. For this reason, a time-based equivalent method for reactive power regulation capacity of grid-connected PV plant is proposed, which can provide an effective decision-making basis for actual engineering management. Firstly, under the given gate voltage and PV output, and with consideration of the static var generator within the PV plant, the reactive power regulation capacity of the PV unit and the upper & lower limits of the reactive power regulation range, an optimal equivalent method for maximum gate reactive power regulation capacity of PV plant is proposed to determine the relationship between the gate reactive power regulation capacity of the PV plant and its active output and gate voltage. Secondly, considering the time period characteristics of the gate voltage and PV output fluctuations, the time-based equivalent scheme for reactive power regulation capacity of PV station is realized through the time period fusion strategy for fluctuation thresholds of similar days. Finally, the simulation analysis of an actual PV plant verified the effectiveness of the proposed method.

Power Quality Disturbance Identification Method Based on VMD-SAST

Bozhi ZHANG, Ru ZHANG, Dongxiang JIAO, Longyu WANG, Yifan ZHOU, Lixia ZHOU

2024, 57(2):  34-40.  DOI: 10.11930/j.issn.1004-9649.202311091

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Complex power quality disturbances (PQDs) caused by large-scale grid-connection of renewable energy and wide application of power electronic equipment will threaten the safe and stable operation of power system. Aiming at the difficulty of accurate detection and recognition of complex PQDs, a PQDs detection and recognition method based on variational mode decomposition (VMD) and synchrosqueezing adaptive S-transform (SAST) is proposed. Firstly, the VMD is used to PQDs signals into multiple modal components, with each component only preserving local disturbance features so as to reduce the complexity of PQDs signals. Secondly, a SAST time-frequency analysis method is proposed to improve the time-frequency resolution, concentrate the energy distribution in the spectrum and improve the detection accuracy of PQDs signals. Finally, the disturbance features are extracted based on VMD-SAST, and the PQDs signals are classified and recognized by 3 algorithms respectively. The simulation results show that the proposed method has high PQDs classification and recognition accuracy, high applicability and strong anti-noise ability.

Fuzzy Partitioned Multi-objective Risk Framework Based Operational Risk Assessment of Cascading Failure for Power Grid

Shi MO, Qiushi XU, Zijing LU, Zishou LI, Hongsheng ZHAO, Li QIAO, Chao LUO

2024, 57(2):  41-48.  DOI: 10.11930/j.issn.1004-9649.202311114

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On the basis of analyzing the difference between the long-term evolution process and the short-term evolution process of the power grid, the concept of power grid cascading failure operation risk is proposed, the relationship between the long-term risk of cascading failure and operation risk is quantitatively analyzed, and a power grid cascading failure operation risk assessment model is established. The Monte Carlo method is used to simulate the evolution of the power grid with a given initial operating mode, and a fuzzy segmentation multi-objective risk framework is introduced to establish an evaluation index system. An example study was conducted in the IEEE 118 node system to analyze the impact of system operating parameters on the risk of power grid cascading failure under a given operating mode.

Active Load Participation in Automatic Balancing of Three-Phase Load Imbalance in Low-Voltage Substation Areas

Zhiqiang HU, Yuanyu YE, Lingang YU, Dongwen WU, Tao HU

2024, 57(2):  49-54.  DOI: 10.11930/j.issn.1004-9649.202212040

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In order to solve the problems of increased losses and reduced power supply quality caused by unbalanced three-phase loads, an automatic equalization method for three-phase load unbalance in low-voltage stations involving active loads is proposed. Based on the high-speed carrier technology of the power Internet of Things, the meter load data of the low-voltage station area is collected, and the load data is monitored and collected in real time. A three-phase load imbalance equalization control terminal is designed and the objective function is established. The pigeon swarm algorithm is used to solve the function to achieve automatic balancing control of three-phase load imbalance in the low-voltage station area, which has good control effects.

Short-Term Wind Power Forecast Based on CNN&LSTM-GRU Model Integrated with CEEMD-SE Algorithm

Guohua YANG, Xin QI, Rui JIA, Yifeng LIU, Fei MENG, Xin MA, Xiaowen XING

2024, 57(2):  55-61.  DOI: 10.11930/j.issn.1004-9649.202302098

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In order to further improve the accuracy of short-term wind power forecast, a CNN & LSTM-GRU based short-term wind power prediction model using CEEMD-SE algorithm is proposed. First, the original wind power output series are decomposed into several intrinsic mode function components and one residual component by complementary set empirical mode decomposition, and those components of similar mode are reconstructed by sample entropy algorithm. Next, the parallel network structure of convolutional neural network and long short term memory network is set up, and the local and temporal features of the data are extracted. And then the features are fused and input into the gated cyclic unit network for learning and prediction. Finally, the feasibility of the model is verified through case studies. The results show that the forecast accuracy has been improved effectively. The root mean square error and average absolute error, of the proposed model are reduced by 15.06% and 15.22% respectively, while coefficient of determination is up by 1.91%.

Power System

Pilot Protection for Converter-interconnected Lines Based on Multi-stage Mutation of Fault Current

Zhaoyi SHA, Congbo WANG, Rongrong ZHAN, Yue YU, Jianfeng WANG

2024, 57(2):  62-71.  DOI: 10.11930/j.issn.1004-9649.202212059

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The introduction of power electronic converters has altered the fault characteristics of the traditional power grids. Traditional differential protection is inadequate to meet protection requirements when AC lines experience faults, leading to reduced sensitivity and even the risk of refusal to operate. To address this issue, a principle of protection for AC lines based on multi-stage mutation of total fault current has been proposed. This protection is founded on the characteristic changes in the waveform deformation and mutation features of current on both sides of the line after a fault occurs. The matrix gradient algorithm is employed to extract the mutation feature values of total current signals on both sides, describing the degree of mutation in the total current signals and thereby constructing longitudinal protection. In comparison to traditional fast protection based on transient quantities that do not require the extraction of fixed frequency band features, the proposed method overcomes the challenge of accurately extracting fixed transient quantities using the periodic component algorithm under controlled short-circuit current conditions. In contrast to protection using conventional transient signals directly, it exhibits good tolerance to transitional resistance and noise. Finally, a simulation model of the converter grid-connected system is built in PSCAD/EMTDC to validate the effectiveness of the protection. The proposed protection achieves fault identification in less than 7.5 ms and and maintains high sensitivity even in the presence of a transitional resistance fault of 100 Ω, meeting the requirements of fast response and selectivity for inverter-interconnected lines.

IIDG Fault Current Analysis and Calculation Considering Voltage Amplitude Detection Delay and Phase Jump

Meiling LUO, Ying MA, Weibing HUANG, Lingkun MENG, Xiaojun YU, Tao ZHENG

2024, 57(2):  72-81.  DOI: 10.11930/j.issn.1004-9649.202212094

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The volatility, weak feedback, and strong control of inverter interfaced distributed generation (IIDG) make it have different short-circuit current characteristics from synchronous generators under faults, and accurate analysis of them is the basis for the analysis of relay protection adaptability and the research of new protection principles, which is of great significance. Since the existing literature ignores the voltage amplitude detection delay and makes it difficult to accurately analyze the fault characteristics of IIDG, this paper takes the three-phase short circuit of the new energy transmission line as an example, comprehensively considers the influence of the voltage amplitude detection delay and the dynamic response characteristics of the phase-locked loop caused by phase jump, and finely divides the transient process of IIDG fault. It also establishes the fault current analysis expression under voltage and current loop control and current loop control for the two stages of the transient process of the fault. The influence mechanism of voltage detection delay and dynamic response of phase-locked loop on the transient characteristics of IIDG fault current is clarified. Finally, based on the Matlab/Simulink simulation platform, the correctness of the fault current analysis and calculation model proposed in this paper is verified.

Reduced-order Modeling and Control Parameter Design of High-Frequency Oscillation in Low-Voltage DC System

Xiao LIU, Chunfa DONG, Hanbing QU, Guangyuan YU, Shancheng SU

2024, 57(2):  82-93.  DOI: 10.11930/j.issn.1004-9649.202302050

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The interaction between voltage-source converters, DC lines and constant power loads (CPLs) leads to high-frequency oscillation instability in low-voltage DC systems. For this reason, a normalized reduced-order model applicable to the analysis of high-frequency oscillations of the system is established in this paper, with the causes of the high-frequency oscillation instability of the system explained from the perspective of the normalized reduced-order model. On the basis, an analysis method of feasible region of control parameters that can inhibit high-frequency oscillations is proposed. This feasible region cannot only present visually the low-frequency stability or high-frequency instability regions of the system under different control parameters, but also show customized design curves of the system-level dynamic characteristics (oscillation frequency and damping factor) in detail in the stability region. Finally, the simulation example of the low-voltage DC system is built via PLECS software, with the validity of the normalized reduced-order model and the feasible region of control parameters verified by multiple sets of simulation time domain results.

Characteristics and Detection Algorithm of Strong and Weak Arc in Low Voltage DC Distribution Network

Guoqiang LIU, Guochun LI, Yanan HAO, Guihai LI, Zhongjie WU

2024, 57(2):  94-102.  DOI: 10.11930/j.issn.1004-9649.202302040

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With no zero-crossing characteristic, DC arc is difficult to extinguish by itself, and is inclined to cause electrical fire, threatening the safety of DC power distribution. The differences of arc characteristics under different voltages are analyzed by building an experimental platform for arc simulation, collecting arc signals under different voltages, and studying the characteristics of arc resistance and voltage. Based on the preferred value of the nominal voltage of the medium and low voltage DC distribution network in GB/T 35727—2017, the differences of the detected arc characteristics at three different voltage levels of 220 V, 750 V and 1500 V are studied, with the frequency domain characteristics such as Fourier transform, wavelet transform and singular value decomposition, as well as the time domain characteristics such as maximum, minimum, average and standard deviation compared, to obtain high-quality criteria for arc detection at different voltage levels, which proves that the frequency domain characteristics at different times are applicable to varied voltage levels. Combined with the neural network model, the arc detection algorithm suitable for 750 V system is designed, and the detection accuracy of the algorithm is 99.12%.

Current-carrying Capacity Probability Prediction of Overhead Transmission Line Considering Conditional Distribution Prediction Errors of Meteorological Parameters

Hanru LI, Zhijian LIU, Liyong LAI, Lingyu HUANG, Shiyin DING, Ren LIU, Bo TANG

2024, 57(2):  103-114.  DOI: 10.11930/j.issn.1004-9649.202310097

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Accurately accounting for the errors in meteorological parameter predictions is essential for the precise forecasting of dynamic current-carrying capacity in overhead power transmission lines. Statistical and computational analyses have revealed for the first time the distinct distribution characteristics of meteorological parameter prediction errors under varying forecasted weather conditions and environmental contexts. Existing methods for probabilistic load capacity forecasting of overhead lines fail to consider the impact of these two critical factors, leading to challenges in achieving accurate predictions. Addressing this gap, the issue of meteorological parameter prediction error analysis is formulated as a problem of solving for the conditional distribution of errors, influenced by both forecasted meteorological conditions and the environment. Incorporating Sklar's theorem, its associated Copula function, and non-parametric kernel density estimation, a novel approach to determining the conditional distribution of prediction errors is established. Further, a new methodology for probabilistic forecasting of transmission line load capacity that integrates the conditional distribution of meteorological parameter prediction errors is proposed, using Monte Carlo sampling techniques. Comparative computational analysis has demonstrated that, relative to two conventional approaches, the proposed method significantly enhances the coverage of prediction intervals by 5.51 and 1.99 percentage points, and concurrently reduces the normalized average width of these intervals by 7.86 and 3.62 percentage points. These improvements confirm the method's heightened accuracy and practicality.

Adaptability Analysis and Countermeasures for Distance Protection of AC Transmission Lines Connected LCC-HVDC Inverter Station

Huixin LI, Xiangwen CHEN, Mingliang JIN, Yang LIU, Haiyang XU

2024, 57(2):  115-126.  DOI: 10.11930/j.issn.1004-9649.202309110

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The AC transmission line fault near the LCC-HVDC inverter station might lead to commutation failure. And fault voltage and current waveforms would be distorted. It will have an adverse effect on the performance of fundamental power frequency phasor based distance protection. Firstly, the performance of traditional distance protection based on positive-sequence voltage polarization which is widely used in practice is analyzed. If the LCC-HVDC inverter station only has the single AC transmission outgoing line, distance protection based on positive-sequence voltage polarization would no longer be applicable. Then, based on the RL model of AC transmission line, a time domain distance protection based on waveform correlation coefficient is proposed. It is not affected by the nonlinear output characteristics of LCC-HVDC inverter station. To solve the fault direction identification problem near the exit area, the index of current distortion is defined to identify the fault direction. Finally, the proposed time domain distance protection is verified by the simulation results.

Key Resonance Component Evaluation of Medium-Voltage Power Systems

Zikang ZHOU, Shun TAO, Chaofan XUE, Wei YUAN, Yonghai XU

2024, 57(2):  127-137.  DOI: 10.11930/j.issn.1004-9649.202308069

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Modal analysis techniques can capture the most comprehensive harmonic resonance data. Although current sensitivity analysis methodologies can rank the impact that each electronic component has on resonance, they fall short in precisely pinpointing the key resonant components and circuits. Initially, an explanation of the physical significance of the contributing factors is offered following the derivation, and two existing sensitivity analysis methods are summarized. Subsequently, taking into account the diversity in the value ranges of components with different attributes, as well as the effects of the external characteristics of inverters, a novel identification method is introduced. This method is tailored for pinpointing critical resonant elements and circuits within power distribution networks. The method's precision in identifying vital resonant components is corroborated through analytical examples and PSCAD simulation outcomes. This technique provides an accurate means to discern the critical components that drive systemic inherent resonance, serving as a valuable resource for the study and mitigation of harmonic resonance issues, as well as for post-incident analyses.

Division of Multi-harmonic Responsibilities Based on DBSCAN Clustering and Interval Regression

Shilong CHEN, Tao WU, Cheng GUO, Zirui ZHANG, Jinghao SUN

2024, 57(2):  138-148.  DOI: 10.11930/j.issn.1004-9649.202303072

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The traditional harmonic responsibility division methods are not applicable to the existing statistical harmonic monitoring data in the context of background harmonic impedance changes and background harmonic voltage fluctuations. Therefore, this paper proposes a multi-harmonic responsibility division method based on monitoring data under background harmonic changes. Firstly, a harmonic monitoring data interval sample set is constructed, and a mathematical model of multi-harmonic source interval harmonic responsibility division under background harmonic changes is established. Secondly, the collected statistical harmonic data set is clustered as the evaluation period by DBSCAN, and the data satisfying the linear relationship threshold requirement is screened by sliding window dynamic correlation analysis. Finally, the equation parameter and the optimal sample division scheme are obtained with the PM algorithm-based interval linear regression method, and the harmonic responsibility in the medium and long term time scope is calculated on the basis of the constructed interval harmonic responsibility division. The harmonic monitoring data of an actual power grid is used to verify the proposed method, and it is proved that the proposed method can use the existing statistical harmonic monitoring data to allocate the harmonic responsibility of each harmonic source in a reasonable time scale under background harmonic changes, which can provide new ideas for the division of responsibility for multiple harmonics during the operation of the actual power system.

New Energy

Evolutionary Game on Development Decision of Poverty Alleviation Photovoltaic in Northwest China

Ning LIU, Chi ZHANG, Dong WANG, Mingjie YANG

2024, 57(2):  149-160.  DOI: 10.11930/j.issn.1004-9649.202212047

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Despite the fact that the new model of distributed photovoltaic development in the whole county has offered a fresh approach to solving the problems such as difficult absorption, serious abandonment of photovoltaic power and decentralized poverty alleviation efforts amid the commitment to "carbon peak and carbon neutrality", the problem of multi-subject decision-making among all stakeholders in photovoltaic poverty alleviation in the whole county market has become the top priority of the current poverty alleviation power station market operation. Based on the evolutionary game theory, a four-party evolutionary game model involving users, state-owned enterprises (including the State Grid), photovoltaic enterprises and the government is constructed, with the multi-subject decision-making evolution and parameter influence of photovoltaic poverty alleviation market in Gansu Province, Qinghai Province and Ningxia Hui Autonomous Region studied. The results show that the equilibrium strategies of state-owned enterprises and photovoltaic enterprises are all positive, but the equilibrium results and time between users and the government are also different due to the differences in light resources, electricity prices and electricity consumption in various areas. The photovoltaic market in Gansu Province is balanced in the strategy set built by users without government subsidies. Areas with more abundant sunshine and significant government subsidies report considerable income from photovoltaic poverty alleviation, which means stronger users interest in investment and shorter time to achieve equilibrium; cost saving and rent reduction are effective measures to improve the equilibrium path in Northwest China.

Performance Analysis of Combined Cooling, Heating and Power System Integrated with Energy Storage Battery at Comprehensive Conditions

Fuguo ZHANG, Zepeng LI, Peng WU, Xue WANG, Xiaoen LI

2024, 57(2):  161-170.  DOI: 10.11930/j.issn.1004-9649.202301046

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The combined cooling, heating, and power system (CCHP) boasts efficient energy use and flexible operation. The CCHP integrated system for energy storage battery was designed, with the refined mathematical models of the key components established, and the influence of the compressor and turbine efficiency and ambient temperature on CCHP performance studied. The thermodynamic performance of the CCHP at comprehensive conditions and the charging-discharging characteristics of the battery energy storage system were investigated according to the typical modes of chilling and heating. The results show that the ambient temperature has a significant influence on the performance of CCHP. The maximum heat supply decreases with the decrease in the ambient temperature, and the maximum chilling supply decreases with the increase in the ambient temperature. The cooling load and electric load fluctuate greatly throughout the day in the chilling mode, with the average value for cooling load and electric load representing only about 39.9% of the rated load, and an average energy utilization coefficient of 0.712. In the heating mode, there is insignificant fluctuation of power generation efficiency, heating coefficient and energy utilization coefficient on the typical day, which are all higher than the corresponding indexes in the chilling mode.

Two-Stage Dispatch of CCHP Microgrid Based on NNC and DMC

Suhao CHEN, Yue WU, Wei ZENG, Xiaohui YANG, Xiaopeng WANG, Yunfei WU

2024, 57(2):  171-182.  DOI: 10.11930/j.issn.1004-9649.202212079

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The combination of combined cooling, heating and power (CCHP) and microgrid promotes the consumption of renewable energy. In order to improve the economy, environmental protection and stability of CCHP microgrid, a two-stage optimal dispatching model is proposed. The offline optimization stage is based on the demand response strategy, and the multi-objective model based on the normalized normal constraint method is established, and the optimal results are screened by the entropy-TOPSIS method. In the online optimization stage, a finite-time domain optimization model based on dynamic matrix control algorithm is established to track and optimize the offline optimization results with feedback correction to reduce the influence of uncertainty factors. Finally, a comparison scheme is designed to for analysis verify the effectiveness of the proposed optimization model.

Dispatching Strategy of Park-Level Integrated Energy System Considering Carbon Trading Mechanism and Hydrogen Blending Natural Gas

Dongshun ZHANG, Hengli QUAN, Hua XIE, Zhihong XU, Yayun TAO, Huisheng WANG

2024, 57(2):  183-193.  DOI: 10.11930/j.issn.1004-9649.202210011

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The integrated energy system is conducive to the realization of multi-energy mutual benefit and efficient use of energy. This paper focuses on a comprehensive energy system in a park that incorporates electricity, heat, cold, and hydrogen loads. The study analyzes the coupling and cascade utilization characteristics of multiple energy sources in the operation of a renewable energy hydrogen production system and hydrogen-blended gas turbine. The impact of hydrogen blending ratio on gas turbine efficiency and the thermoelectric ratio is considered. With the objective of minimizing the operational cost of the system, an optimization and dispatching model for the park’s comprehensive energy system is established under a tiered carbon trading mechanism. Segmented linearization and the big M method are employed to transform a nonlinear model containing multiple 0-1 variables and continuous variables into a mixed-integer programming model. The model is then solved using the Cplex solver to achieve fast solutions. Case analysis shows that the dispatching strategy designed in this paper can effectively improve the economic performance of the park’s energy system. Properly controlling the hydrogen blending ratio in gas turbine helps reduce carbon emission in the park’s system.

Frequency Regulation Strategy of Isolated Island Microgrid Based on Fusion Expert Knowledge DDPG

Kun HUANG, Ming FU, Jiaben LIANG

2024, 57(2):  194-201.  DOI: 10.11930/j.issn.1004-9649.202302031

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With the wide access of intermittent renewable energy such as wind and PV to island microgrid, it is difficult for traditional control methods to effectively coordinate multiple resources such as source-charge-storage in frequency regulation to deal with the frequency deviation caused by random fluctuations of source-charge. In this paper, a frequency regulation algorithm for island microgrid based on the fusion of expert knowledge and deep deterministic policy gradient (DDPG) is proposed to solve the above problems. The algorithm guides the efficient interaction between the regulatory equipment and the environment through the empirical rules of expert knowledge and improve the performance of multi-resource collaborative frequency adjustment. The simulation results show that the frequency regulation strategy can make full use of multiple resources in the microgrid for frequency regulation and effectively improve the frequency regulation performance.

Technology and Economics

Influence Mechanism of Time-of-Use Electricity Prices on Industry Load Characteristics Based on Multi-dimensional Price Elasticity Coefficient Matrix

Wensheng TANG, Yang WANG, Yu ZHANG, Xiyang LIU, Qingkun TAN, Peng WU, Songsong CHEN, Jing YANG

2024, 57(2):  202-211.  DOI: 10.11930/j.issn.1004-9649.202304028

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Based on the load curves of fixed user groups of various industries in 23 provinces, a multi-dimensional price elasticity coefficient is proposed to evaluate the impact of time-of-use electricity price adjustment on the peak and valley electricity consumption of various industries in various provinces, and the sensitivity of peak-valley power demand to multi-dimensional price indicators is analyzed. The multi-dimensional price elasticity coefficient was used to quantitatively evaluate the sensitivity of the three-dimensional power indicators of various industries in different regions, including reducing peak electricity, increasing valley electricity and reducing the load peak-valley difference rate, to the three-dimensional price indicators, including increasing the peak electricity price, reducing the valley electricity price and increasing the peak-to-valley electricity price ratio. The time-of-use electricity price optimization and adjustment strategies can be proposed for different regions, industries and time periods according to the analytical results of multi-dimensional price elasticity coefficient.

Market Trading Strategy for Thermal Power Enterprise in New Power System Based on Agent Modeling

Chaoying LI, Qinliang TAN

2024, 57(2):  212-225.  DOI: 10.11930/j.issn.1004-9649.202303088

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It is of great significance to study the bidding strategy of thermal power enterprises under the scenario of high proportion of new energy penetration for guaranteeing the normal operation of thermal power enterprises and promoting the construction of new power system. Based on the multi-agent modeling framework, this paper establishes a power spot market simulation model and an unit self-learning decision model. In the environment module, a spot market clearing model with multiple participation of wind-solar-fire-storage is established considering the uncertainty of both sources and loads. The bidding decision-making process of thermal power units is described as a partially observed Markov decision-making process in the agent module and solved by improved Deep Deterministic Policy Gradient algorithm. Finally, a HRP-38 node system is simulated to clarify the market trading strategy for thermal power enterprises under a high proportion of new energy. The results show that, when the auxiliary services provided by thermal power units are not considered, with the increase of new energy penetration, some thermal power units with unique locations and cost advantages are still competitive; the increase of prediction error will make the bidding strategy of large-capacity thermal power units tend to be conservative, while the bidding strategy of small-capacity units is opposite; the thermal power units have implicit collusion tendency in all kinds of scenarios, that is, they will increase the quotation at the same time while hiding information from each other.

Investment Game Strategy for Power Access Projects under Extension of Investment Interface

Yiqiong CAO, Xuejie WANG, Xin TIAN, Keyao LIN, Zhenda HU, Huiru ZHAO

2024, 57(2):  226-234.  DOI: 10.11930/j.issn.1004-9649.202303083

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In order to effectively reduce the cost of power supply for users, the grid investment interface is required to extend to the user's red line. However, there is no uniform and reasonable standard on how to allocate the extension cost among the government, power grid enterprises and users. This paper firstly expounds the extension of the power grid investment interface and the interest demands of investment entities, and analyzes the investment cost of power access project. Secondly, aiming at maximizing the gap between the investment proportion of each entity and its least ideal proportion, the Nash-Harsanyi bargaining game model is constructed. The bargaining power is quantified through the initial investment proportion, risk sharing ratio and cooperation ability, so as to seek a fair and reasonable government-enterprise sharing strategy for power access costs. Finally, a study is conducted for a power access project in an economic development zone. The results show that the investment proportion among power grid enterprise, users, and government has been optimized from 0.65∶0.14∶0.21 to 0.61∶0.12∶0.27, and the satisfaction degree of all three entities has been improved. The satisfaction degree of power grid enterprise has been greatly improved due to its high bargaining power, which is helpful to promote the extension of the investment interface and further optimize the business environment.