Electric Power

Comparison of Allowable Harmonic Emission Value Distribution Methods at the Point of Common Coupling of High Voltage System

Shun TAO, Huilin CHEN, Yonghai XU, Shengjun ZHOU, Xiangning XIAO

2025, 58(1): 1-14. DOI: 10.11930/j.issn.1004-9649.202404023

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With a large number of nonlinear loads connected to the power grid, the harmonic problems caused by them are becoming more and more serious. Various countries or organizations have formulated harmonic standards to constrain the harmonic emission values of nonlinear users to ensure the waveform quality of the AC power grid. How to distribute the allowable harmonic emission value fairly and reasonably among power users has become a key issue. By comparing and analyzing the harmonic emission level distribution methods of nonlinear load access to high voltage system in IEC 61000-3-6, GB / T 14549 and IEEE Std.519, the applicability of each standard is evaluated by three principles of fairness, consistency and feasibility, and the consistency of the three is evaluated by comparing the case study results, which can provide some references for the revision of harmonic national standards.

Harmonic Responsibility Division of Grid Asynchronous Monitoring Data Scenarios Based on Correlation Analysis

Shilong CHEN, Tao WU, Cheng GUO, Guihong BI, Yongliang QIAN

2025, 58(1): 15-25. DOI: 10.11930/j.issn.1004-9649.202401107

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In view of the shortcomings of the traditional harmonic responsibility division methods, which require the use of dedicated synchronous equipment monitoring data and the division of harmonic responsibility based on equivalent circuit model, and are complex in engineering application, based on the asynchronous measurement data of the existing harmonic monitoring devices, a harmonic responsibility division method is proposed, which takes into account the asynchronous nature of the data, the division of the scenarios, and the correlation of the data. Firstly, the original asynchronous monitoring data set is preprocessed using piecewise aggregation approximation (PAA) algorithm for noise reduction, and then the ShapeDTW algorithm is used to realize the data matching and alignment. Secondly, the OPTICS algorithm is used to divide the scenarios for dealing with the harmonic responsibility changes in power system caused by switching of the power load and the reactive power compensation devices. Finally, the harmonic responsibility of the scenarios and the total harmonic responsibility indexes are constructed based on correlation analysis, and the factor of scenario duration percentage is introduced in the process of indexes construction to .get a more scientific and reasonable total harmonic responsibility value. The simulation verification and grid example verification show that the proposed method can realize the dynamic harmonic responsibility division of each user in a reasonable time scale based on the existing asynchronous monitoring data, which can provide new ideas and methods for fast harmonic responsibility division in engineering.

Adaptive Control Strategy for Receiving-end Disturbance of Offshore Wind Power through MMC-HVDC System

Jingbo ZHAO, Wenbo LI, Xinyao ZHU, Qingbin SUN, Quanrui HAO

2025, 58(1): 26-38. DOI: 10.11930/j.issn.1004-9649.202404076

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In view of the scenario of disturbance at the receiving end of offshore wind power through MMC-HVDC system, this paper proposes an adaptive control strategy to ensure the operation of the receiving-end converter station within the non-hazardous range independently and realize the reasonable distribution of active power among multiple sending-end converter stations. It includes the operating limit control strategy of the receiving-end converter station and the U_dc-f adaptive droop control strategy of the sending-end converter station. When the disturbance of receiving-end power grid leads to over-limit of internal electrical variables in the receiving-end converter station, the operating limit control will output the reduction coefficient to reduce the reference value of virtual potential, so that the internal electrical variables will return to the limit value. The adaptive droop control strategy is to adjust the droop coefficient adaptively under the constraints of active power margin and DC voltage deviation, so as to reasonably distribute the disturbance power among multiple sending-end converter stations adjusted by the wind farm due to the receiving-end disturbance and reduce the DC voltage deviation. The control strategy of sending-end and receiving-end works together to maintain whole system stability. Finally, a three-terminal MMC-HVDC simulation model is built in PSCAD/EMTDC to verify the effectiveness and accuracy of the proposed method.

Mid- and High-Frequency Oscillation Suppression Strategy for MMC-HVDC System Based on DC Current Feedback

Yechun XIN, Shangxuan LI, Yanxu WANG, Yihua ZHU, Jiawei YU, Dongxu CHANG

2025, 58(1): 39-49. DOI: 10.11930/j.issn.1004-9649.202309116

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The serious mid-and high- frequency oscillation issue in modular multilevel convertor based high voltage direct current (MMC-HVDC) systems poses a significant threat to the normal operation of power systems. In this paper, we firstly established an AC-side impedance model of the MMC based on its dynamic phase vector model. Secondly, we analyzed the impact of control loops and control parameters on MMC impedance characteristics using the impedance method, and identified the power outer loop, current inner loop and control loop delay as the main factors causing MMC to present negative damping characteristics. And then, based on an analysis of the limitations of existing oscillation suppression strategies that are based on voltage feedforward loops and current inner loops, we proposed an oscillation suppression strategy that adds DC current feedback to the power outer loop, which can greatly eliminate harmonic components in the system and improve MMC impedance characteristics. Finally, the correctness and effectiveness of the theoretical analysis and proposed suppression measures were verified through electromagnetic simulation software.

Strategy Design and Parameter Optimization of High-Frequency Resonance Suppression for Modular Multilevel Converter

Xiao ZHOU, Yuexi YANG, Longze KOU, Yunfeng LI, Xuewei QIAN, Jie HAO, Weizhe JING

2025, 58(1): 50-60. DOI: 10.11930/j.issn.1004-9649.202405143

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Addressing the issue of high-frequency oscillations in converter stations during flexible DC grid integration and transmission, a suppression scheme combining active and passive damping, along with a method for optimizing the design of its parameters, is proposed. This scheme aims to alter the impedance characteristics of the converter station from a passive perspective, thereby achieving reliable suppression of high-frequency oscillations. Firstly, by analyzing the negative damping characteristics within the simplified high-frequency impedance model of the converter station, the principle is revealed that the active damping in the suppression scheme should shift the negative damping of the converter station to higher frequencies. Secondly, based on the impedance model, the principle for selecting the parameters of the active damping controller for virtual series impedance is derived, and appropriate parameters are obtained using a coefficient fitting method. Subsequently, with the goal of reducing investment costs and the constraint of completely eliminating high-frequency negative damping, an optimization algorithm is employed to determine the parameters of the passive filter. By comparing the parameter changes of the passive filter before and after the addition of virtual series impedance, the economic benefits of the coordinated suppression scheme are highlighted. Finally, electromagnetic transient simulations verify the correctness and effectiveness of the suppression scheme under the optimized parameter design method.

Improvement and Comparison of Single-Phase Frequency Locked Loops Based on Second Order Generalized Integrator

Chaobo DAI, Guoliang ZHAO, Zhichang YANG, Jingxin CUI

2025, 58(1): 61-69. DOI: 10.11930/j.issn.1004-9649.202406102

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It is required for grid-connected converters to obtain synchronous information quickly and accurately when a short-circuit fault occurs in the grid. Compared with the phase locked loop (PLL), the second order generalized integrator (SOGI)-frequency locked loop (FLL) promises faster detection of the phase, amplitude and frequency of the grid voltage, but becomes susceptible to the effect of a direct current (DC) offset. Modified schemes based on the suppression method and the filtering method have drawback of slower response. A modified scheme based on the subtraction method is proposed with an addition of a SOGI block in the FLL. The basic scheme based on SOGI-FLL, the modified scheme based on the suppression method and the proposed scheme based on the subtraction method are analyzed and compared by transfer functions theoretically and simulations of PSCAD commercial software. Comparison results illustrate that the subtraction-based scheme promises faster detection of the phase, amplitude and frequency of the grid voltage, and better suppression of the DC offset and low frequency components. Taking account of respective transient and steady-state response characteristics, the subtraction-based scheme has the best comprehensive properties.

Adaptive Assessment of Power System Transient Stability Based on Active Transfer Learning

Chenhao ZHAO, Zaibin JIAO, Chenghao LI, Di ZHANG, Penghui ZHANG

2025, 58(1): 70-77. DOI: 10.11930/j.issn.1004-9649.202404033

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This paper constructs a framework based on active transfer learning. The basic model is built and trained based on the original scene data. The update mechanism is started when the performance of the model decreases due to the change of the running scene. A large number of samples without stable state are generated by short-term time-domain simulation, and a small batch of labeled samples are generated by complete simulation. The active learning method based on variational adversarial is used to learn the potential feature representation space of the data, and the unlabeled samples with the largest amount of information are selected and labeled according to the confidence. The basic model parameters are migrated and fine-tuned with labeled samples to save the update time while ensuring the migration accuracy. The IEEE 39 node verifies the effectiveness of the proposed method.

Collaborative Planning Method of Flexible Interconnection Devices for Multi-Voltage Level Distribution Network Considering Integrated Profits

Chunguang HE, Linfeng WANG, Yuan CAO, Jiakun AN, Zijian LEI, Guanyu SONG, Haoran JI

2025, 58(1): 78-84. DOI: 10.11930/j.issn.1004-9649.202401080

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To avoid the above problems, a collaborative planning method of flexible interconnection devices for distribution networks is proposed considering integrated profits. With the installation location and capacity of soft open point (SOP) optimized in multi-voltage level distribution networks, the operation in normal and the supply restoration in fault are both improved, promoting the system’s integrated indicators of economy and reliability. Finally, the case study is conducted based on an actual distribution network data in Hebei province, verifying the effectiveness of the proposed method and analyzing the improvement of economy, safety, and reliability.

Multi-objective Optimization Control Strategy for Soft Open Point in Distribution Network with High Penetration of DG

Wenjun LIU, Weijie DONG, Yuanyang CHEN, Shuyun HE, Jian CHEN, Dongqiang JIA

2025, 58(1): 85-92. DOI: 10.11930/j.issn.1004-9649.202405027

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A multi-objective optimization control strategy for distribution station SOP is proposed to enhance the distributed generation (DG) consumption capability of the distribution network by utilizing multi soft open point (SOP). By analyzing the access mode of SOP in the distribution network and considering its role in distributed power consumption and peak shaving, a multi-objective model was constructed to maximize the daily consumption of distributed energy, minimize control costs, and minimize the deviation of daily net load of feeder lines. Conduct simulation comparison and verification using an improved distribution network example. The results indicate that SOP integration is beneficial for improving the consumption of new energy and achieving load balancing.

Collaborative Planning Method for Multi-energy Networks Based on Double-layer Game Theory

Hai LU, Hao ZHANG, Xiaoyun CHEN, Suyang ZHOU

2025, 58(1): 93-99. DOI: 10.11930/j.issn.1004-9649.202402068

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The increasing conflict of interests among multiple stakeholders in the integrated energy system has increased the difficulty of system planning and modeling. In the research of integrated energy systems, the system is divided into energy suppliers, integrated energy stations, and user entities. Combining the theory of master-slave game and cooperative game, a two-level game planning model for integrated energy systems applicable to multiple entities is established, and corresponding solving methods are proposed. The effectiveness of the proposed method is verified through simulation examples.

Data-driven Efficient Verification Technique for Smart Substations Messages

Rongrong JI, Ganfeng ZHANG, Mengzhi WANG, Yingjie JIN, Hai LI, Ruofan HUANG

2025, 58(1): 100-106. DOI: 10.11930/j.issn.1004-9649.202404028

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To improve the efficiency of remote control and telemetry point verification in substations, a data-driven intelligent station information verification technology is proposed. Aiming intelligent substations, based on the remote information point system architecture, a multi-point random non-repetitive sampling method is used to achieve full coverage of information, an inconsistency verification analysis method is used for information point inspection. The closed-loop processing of remote control and telemetry point verification is realized by using the sampling verification method. efficiency and accuracy of the proposed method are verified by simulation examples.

Fault Mechanism Analysis and One-terminal Protection Method of Flexible DC Transmission Line under the Influence of Multi-type Faults

Zongjun MU, Junhong QIU, Zhenxing LI, Weidong WANG, Dengxin LIU, Bin HU

2025, 58(1): 107-114. DOI: 10.11930/j.issn.1004-9649.202404004

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Multi-terminal flexible DC transmission line protection faces various fault types and is susceptible to factors such as transition resistance and noise. To address this, a fast-action protection method for the entire flexible DC line using single-ended voltage gradient energy values is proposed, which can protect the entire length of the line based solely on single-ended measured voltage. The voltage fault characteristics inside and outside the flexible DC line are analyzed, and an improved voltage gradient algorithm is introduced to construct a protection initiation criterion. Furthermore, a full-line fault protection criterion based on energy value comparison is constructed, and fault pole selection is achieved based on the different ranges of positive and negative energy ratios under unipolar or inter-pole faults. Simulation verification shows that the proposed method can quickly identify faults inside and outside the zone, determine the fault pole, and exhibits good noise immunity and high resistance tolerance.

An Overview of the Evolution of Security and Stability of China’s Power System

Wu DONG, Jian ZHANG, Qinyong ZHOU, Libo ZHANG, Haoyue GONG

2025, 58(1): 115-127. DOI: 10.11930/j.issn.1004-9649.202403003

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In order to take measures in advance to prevent the decline of the safety and stability level of the power system, it is necessary to clarify the impact of the new energy revolution on the evolution of the security and stability of China's power system. According to the scale and growth of the power grid in the process of China's power system development, the security and stability of China's power system is divided into four stages of development. The typical instability problems of the power system at different stages are summarized. The dominant factors affecting the security and stability of the power system at each stage are analyzed, and the mechanisms and causes for the conversion of security and stability are clarified. It is pointed out that under the new energy revolution, the security and stability of the power system appears decoupling from the scale of the power system. Proposals are made to construct a power grid evolution model and establish a comprehensive assessment indexes of stability level to quantify and predict the trend of future changes in the security and stability level of the power system.

Two-Layer Optimization of Regional Integrated Energy System Considering Exergy Efficiency and Multiple Uncertainties

Ling LU, Tao YUAN, Bo YANG, Xin LI, Yang LU, Qiuping PU, Xin ZHANG

2025, 58(1): 128-140. DOI: 10.11930/j.issn.1004-9649.202404018

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In order to realize high quality and efficiency utilization of energy while improving the reliability of system energy supply, the concept of exergy is introduced into regional integrated energy system containing a high proportion of renewable energy, and a two-layer optimization method is proposed considering exergy efficiency and multiple uncertainties. Firstly, a multi-energy coupling model of regional integrated energy system is established for exergy and multi-uncertainties analysis. Multi-scene random planning and range optimization methods are adopted to deal with exergy for different characteristics of solar and wind power uncertainty, along with load and energy price fluctuations. Then, a two-layer collaborative optimization model balances system capacity planning and scheduling operations is constructed, with both exergy efficiency and economy as the optimization goal in the upper layer, and the lowest operating cost as the optimization goal in the lower layer. Finally, an industrial park is selected for example analysis to verify the effectiveness of the proposed method in this paper. Compared with other uncertain factors, the fluctuation of electrical load has a greater impact on the economy and exergy efficiency of the system.

A Source-load Low Carbon Optimization Methodology Considering Carbon Responsibility for Direct Carbon Emissions from Cement Plants

Jiang LI, Yuanzheng FAN, Bo LIU

2025, 58(1): 141-152. DOI: 10.11930/j.issn.1004-9649.202401019

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Under the background that the new power system presents higher low-carbon requirements on both source and load, reasonable carbon responsibility allocation of the power system has important guiding significance for the collaborative low-carbon optimization of the source and load. Therefore, this paper proposes a source-load low-carbon optimization operation method that takes into account the direct carbon emission carbon responsibility of the cement plant to further improve the carbon responsibility apportionment. Firstly, the characteristics of direct carbon emissions from production and indirect carbon emissions from electricity consumption are analyzed, and the source and load are thus connected on the basis of the bidirectional carbon emission characteristics. A bidirectional carbon flow model is established for cement plant based on the theory of carbon emission flow, and a new carbon responsibility allocation method is proposed. And then, based on an analysis of the bidirectional carbon flow characteristics of source and load, a grid bidirectional carbon flow optimization model is built to evaluate the carbon reduction capability of users and power grid with the objective to minimize the overall carbon emissions. Finally, the IEEE33 node is used to verify the proposed low-carbon optimization operation method of source-load bidirectional carbon flow, and the results show that the proposed method has practical carbon reduction benefits and carbon reduction effectiveness without affecting the production of cement plants.

Evolutionary Game Study of the Cooperation Mode Between Renewable Energy Generation Enterprises and Energy Storage Companies Considering Government Intervention

Xiaoyan ZOU, Ruihong ZHANG

2025, 58(1): 153-163. DOI: 10.11930/j.issn.1004-9649.202404001

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Driven by the policy of new energy distribution and storage, renewable energy generation enterprises are equipped with energy storage facilities to improve the stability of energy supply, but the actual utilization efficiency of energy storage power stations often fails to meet expectations. By introducing the local government as the main body, this paper constructs a tripartite evolutionary game model of local government, renewable energy generation enterprises and energy storage companies, studies the influence of local government intervention on promoting the cooperation between renewable energy generation enterprises and energy storage companies, analyzes the dynamic evolution process of the tripartite strategy and its game equilibrium strategy, and conducts simulation analysis. The results show that: firstly, the appropriate intervention of local government is helpful to promote the cooperation mode of "crowdfunding co-construction" and "capacity leasing" between renewable energy generation enterprises and energy storage companies; secondly, local government can flexibly adjust the subsidy intensity according to the changes in the cooperation willingness of both parties; thirdly, local government's intervention can effectively promote the establishment of cooperation between the two sides. With the in-depth development of cooperation, local government should reduce direct intervention in due course and let market mechanisms play a greater role. This research result has theoretical and practical significance for optimizing new energy distribution and storage policies and promoting the healthy development of renewable energy industry.

Rental Price Decision of Shared Energy Storage Capacity Based on Supermodular Game

Yuqing WANG, Min ZHANG, Jiaxing WANG, Bohao LI, Tianyang YANG, Ming ZENG

2025, 58(1): 164-173. DOI: 10.11930/j.issn.1004-9649.202312059

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Under the background of construction of new power system, newly-constructed renewable energy stations are required to be equipped with energy storage system in many provinces in China. Shared energy storage capacity lease is a new model for renewable energy stations to meet the requirements with energy storage. However, its pricing mechanism is immature. In view of this, this paper proposes two energy storage allocation modes for renewable energy stations, namely self-construction and lease. Aiming at the competitive market of energy storage allocation composed of shared energy storage capacity leaseholders and energy storage equipment integrators, a decision model of shared energy storage capacity rental price based on supermodular game is constructed, which can solve the optimal price strategy of shared energy storage capacity lease under the equilibrium state of the market. A regional market with new energy stations equipped with energy storage system is used as an example to carry out pricing simulation. The results of the example have proved the effectiveness of the proposed model, which can provide a decision-making support for the price formulation and investment planning of shared energy storage.

Dual-Layer Optimization of Distribution Transformer Side Energy Storage Configuration and Dispatching for Short-Term Overload and Long-Term Light Load

Xu ZHANG, Chun WANG, Yitao HU, Ruikai CHEN, Kun LIU, Zhidong GUO, Junxun ZHONG

2025, 58(1): 174-184. DOI: 10.11930/j.issn.1004-9649.202310048

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Aiming at the problem of short-term overload and long-term light-load operation of rural distribution transformers, a bi-layer optimization method for optimizing energy storage configuration and scheduling on distribution transformer side based on economic benefit evaluation is proposed in this paper. The upper model aims at the optimal economic benefit of the system, and decides the rated power and capacity of the energy storage system by Levy flying particle swarm optimization. The lower layer model, embedded in a simple calculation model of energy storage life consumption, aims at minimizing active power fluctuation on the low voltage side of distribution transformer, minimizing energy storage life consumption and optimizing dispatching economic benefits, and decides the scheduling strategy of energy storage system by commercial solver Gurobi. When constructing the economic benefit evaluation model of energy storage system on the side of distribution transformer, taking into account the influence of battery life consumption and dynamic load rate of distribution transformer on economic benefit, the investment cost model of lithium iron phosphate energy storage system based on equivalent total cycle number and the fault risk-return model of distribution transformer considering the effect of dynamic load rate on fault probability are established. The results of numerical examples show that the proposed method can improve the economy of the distribution transformer side connected to the energy storage system while ensuring the safe and stable operation of the distribution network.

Capacity Allocation and Operation Optimization Model of Household Photovoltaic-Storage System Based on MPC

Guomin QI, Tianye LI, Hong YU, Bolun LU, Baozhong MA, Wenxin ZHANG, Entong WU, Xianyao XIAO

2025, 58(1): 185-195. DOI: 10.11930/j.issn.1004-9649.202404034

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Distributed photovoltaic (PV) is crucial to meeting the "double carbon" objective and establishing new power system with new energy sources as the main body. This research examines home PV-storage system construction and operation under the present stepped-peak-valley tariff system. Firstly, the household PV-energy storage system structure and tariff system are introduced. Secondly, the optimal capacity allocation model of PV and storage is established to minimize the investment cost and annual operation and maintenance cost of the household PV-storage system. Then, and a two-layer rolling optimization operation algorithm based on model predictive control is proposed considering the stepped-peak-valley tariff's effect on users' long-term energy use strategy. Among them, the upper model maximizes annual integrated return using a stepwise tariff-based annual rolling optimization, and the lower model is a daily rolling optimization based on a peak-valley tariff with the objective of minimizing daily operating costs. In the lower model, the operation scheme of PV-energy storage is based on the optimization results of the upper model, corrects the system state deviation caused by uncertainty factors. Finally, the algorithm's simulation findings suggest that it can delay high electricity tariff utilization and increase residential customer revenue.

Estimation of Model Parameters of Lithium Batteries Based on Kalman Filtering Optimized by Dung Beetle Algorithm

Tian XIA, Daifei LIU, Jiahui YUE, Laien CHEN, Yiliang Li

2025, 58(1): 196-204. DOI: 10.11930/j.issn.1004-9649.202401111

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The identification of parameters for lithium batteries is an important basis for battery state prediction. An improved kalman filtering (KF) based on dung beetle optimizer (DBO) is proposed for online identification of battery model parameters. This method utilizes the rapid global search for optimal solutions characteristic of DBO to optimize the covariance matrices of process noise and observation noise in KF, thereby improving the accuracy of identifying battery model parameters. Simulation experiment data shows that compared to the parameter identification results based on unoptimized KF, the variance that the identification results of this method compared to the true values are significantly reduced, resulting in the predicted parameter values are closer to the true values.

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