A profound transformation of China's energy system is required to achieve carbon neutrality. Here, we couple Monte Carlo analysis with a bottom-up energy-environment-economy model to generate 3,000 cases with different carbon peak times, technological evolution pathways and cumulative carbon budgets. The results show that if emissions peak in 2025, the carbon neutrality goal calls for a 45-62% electrification rate, 47-78% renewable energy in primary energy supply, 5.2-7.9 TW of solar and wind power, 1.5-2.7 PWh of energy storage usage and 64-1,649 MtCO of negative emissions, and synergistically reducing approximately 80% of local air pollutants compared to the present level in 2050. The emission peak time and cumulative carbon budget have significant impacts on the decarbonization pathways, technology choices, and transition costs. Early peaking reduces welfare losses and prevents overreliance on carbon removal technologies. Technology breakthroughs, production and consumption pattern changes, and policy enhancement are urgently required to achieve carbon neutrality.© 2022. The Author(s).

With a substantial fraction of renewable energy integrated into the electrical grid, the new power system urgently requires grid planning scheme displaying adaptability to different energy types and their volatility. Considering the indeterminacy of renewable energy generation output and the different attitudes of decision-makers towards its risk, this paper proposes an adaptability assessment methodology for power grid planning schemes considering multiple decision psychology. First, an evaluation indicator framework is established based on the adaptive requirements of the grid planning for novel power system, and the weights of indicators are calculated based on an improved AHP-CRITIC combination weighting method. Second, improved cumulative prospect theory (ICPT) is adopted to improve to the calculation method of the distance between the evaluation program and the positive and negative ideal programs in the GRA and TOPSIS, which effectively characterize the different decision-making psychologies, and a combination evaluation model is constructed based on a cooperative game (CG), namely, an adaptability evaluation model of grid planning schemes for novel power systems based on GRA-TOPSIS integrating CG and ICPT. Finally, the proposed model serves to evaluate grid planning schemes of three regions in China’s 14th Five-Year Plan. The evaluation results show that the adaptability of the schemes varies under different decision-making psychologies, and under the risk-aggressive and loss-sensitive decision-making psychologies, grid planning scheme of Region 1 with the greatest accommodation capacity of renewable energy is preferable.

为贯彻落实绿色发展理念,提升现有电网工程绿色建造评价方法的全面性、系统性以及客观性,提出了一种基于灰色系统理论的模糊综合评价模型。通过研究影响电网工程设计、施工与交付等环节的重要绿色评价因子,构建了多层次的绿色建造评价指标体系。并基于灰色系统理论确定指标权重,建立了多层级模糊综合评价模型。同时选取电网工程案例来进行验证,证明了该模型能够科学、合理地确定各指标的权重,从而为电网工程绿色建造评价及不断优化提供了支撑。

In order to implement the concept of green development and improve the comprehensiveness, systematicness and objectivity of the existing green construction evaluation methods for power grid projects, a fuzzy comprehensive evaluation model based on grey system theory was proposed. By studying the important green evaluation factors affecting power grid engineering design, construction and delivery, a multi-level green construction evaluation index system was constructed. In terms of the grey system theory, the index weight was determined, and a multi-level fuzzy comprehensive evaluation model was established. At the same time, a power grid engineering case was selected for verification, which indicate that the model can scientifically and reasonably determine the weight of each index, thus providing support for the green construction evaluation and continuous optimization of power grid engineering.

目的 为完善集中-分布式配电网在分层分区和网架规划方面的研究，充分考虑集中-分布式配电网要求等多方面因素，提出了基于Q-learning的分布层分区和网架规划方法。 方法 针对训练过程中出现的有向和无向转换、网架连通性、考虑多因素的分类等问题，根据分层分区和网架规划2个阶段的不同需求，分别对Reward和Agent进行了改进，使模型考虑要素更为全面，并利用实际电网数据进行了仿真验证。 结果 相比于传统电网规划方法，使用所提集中-分布式规划方案在保证一定可靠性的同时有着更好的经济性。 结论 所提方法在高可再生能源发电渗透率配电网中具有较高应用价值，为集中-分布式形态配电网的规划设计提供了一种新的思路和技术手段。

Objectives To improve the research on distribution layer partitioning and grid planning in hybrid centralized-distributed networks, this study fully considers various factors such as the requirements of hybrid centralized-distributed networks and proposes a method for distribution layer partitioning and network planning based on Q-learning. Methods The method addresses issues such as directed and undirected transitions, grid connectivity, and multi-factor classification during the training process. The Reward and Agent are improved based on the different requirements of the two stages: distribution layer partitioning and grid planning. This makes the model more comprehensive by incorporating more elements and is verified through simulations using actual power grid data. Results Compared to traditional grid planning methods, the hybrid centralized-distributed planning scheme using this method provides better economic efficiency while ensuring a certain level of reliability. Conclusions The proposed method demonstrates significant application value in distribution networks with high renewable energy penetration, providing a novel idea and technical approach for the planning and design of hybrid centralized-distributed networks.

相较传统电力系统,含新能源的交直流混联系统结构更加复杂,其稳定评估难度更大,且稳定影响因素的甄别和解释性较差。针对上述问题,首先选择新能源和直流特征量作为稳定评估模型的输入,并由sigmoid函数得到样本预测值与稳定结果之间的关系,提出一种基于极致梯度提升树(extreme gradient Boosting, XGBoost)的交直流混联系统暂态功角稳定评估方法;为进一步分析特征量对系统暂态功角稳定的影响,提出基于SHAP(Shapley additive explanations)的特征量可解释分析方法,从全局说明新能源和直流特征量的重要性,并从全部样本的角度反映各特征量值本身的大小与稳定结果的促进和抑制关系,再从局部得到特征量对单个样本稳定结果的影响;最后在某500 kV实际交直流混联系统上进行仿真验证,证实了该评估方法的准确率较高且SHAP能有效解释新能源和直流特征量对交直流混联系统暂态功角稳定的影响。

Compared with traditional power systems, the structure of an AC/DC hybrid system with new energy sources is more complex, its stability evaluation is more difficult, and the identification and interpretation of stability influencing factors are poor. Given the above problems, this study first selects new energy and DC features as the input of the stability evaluation model and obtains the relationship between the sample prediction value and the stability result using the sigmoid function. A transient power-angle stability evaluation method for an AC/DC hybrid system based on extreme gradient Boosting (XGBoost) was proposed. To further analyze the influence of features on the transient power angle stability of the system, an interpretable analysis method of features based on SHAP is proposed, which explains the importance of new energy and DC features from a global perspective, which reflects the relationship between the size of each feature itself and the promotion and inhibition of stability results from the perspective of all samples, and then obtains the influence of features on the stability results of a single sample from a local perspective. Finally, simulation verification was performed on a 500 kV actual AC/DC hybrid system, which proves that the accuracy of the evaluation method is high and that SHAP can effectively explain the influence of new energy and DC features on the transient power angle stability of the AC/DC hybrid system.