This paper presented a comprehensive coordinated control strategy of centralized condenser in highvoltage DC converter station which participated in automatic voltage control（AVC） to perform the reactive power optimization in high proportion new energy areas of Northwest Power Grid. Firstly, the general control idea of AVC was analyzed, and the three-level voltage control mode based on “soft partition” was given. According to the actual situation of Northwest power grid and Qinghai power grid,the coordinated control variables between them were established. Combined with the optimal power flow model,the comprehensive coordinated control strategy of Qaidam condenser participating in AVC was formed. The good applicability of the control strategy was demonstrated by the example of power grid large disturbance encountered during the AVC joint commissioning test of Qaidam condenser. The presented strategy enhances the condenser’s reactive power source effect in the case of steady-state operation. Meanwhile,it ensures instantaneous strong reactive power support capability in the case of power grid fault. As a result, the strategy gives full play to the performance of the condenser,and improves the level of reactive power and voltage regulation of power grid.

自动电压控制(AVC)已经在各级电网调度中心广泛使用.传统上AVC中的电压限值、功率因数限值等控制参数由人工经验制定.当电网结构发送变化或局部电网区域的负荷特性变化时,经常出现多级电压限值不能适配,影响AVC控制效能.文章提出一种基于大数据分析自动提取的AVC精细规则来优化AVC控制限值参数的方法.首先提出基于控制仿真在环的滚动潮流计算方法来模拟全天的电网自动电压控制过程,并设计了并行快速仿真计算平台,为后续AVC控制规则提取提供海量仿真数据;然后基于海量数据采用人工智能机器学习方法自动学习AVC控制精细规则,自动发现AVC限值参数与电网运行状态指标的内在规律;最后,基于提取的AVC精细规则构建优化模型来自动决策AVC中的母线电压限值、功率因数限值等控制参数,从而实现AVC控制参数的自动优化和辅助决策.

传统自动电压控制为实时反馈控制,缺乏前瞻能力.随着高比例可再生能源的渗透,慢速离散调压设备可能因可再生能源出力波动而频繁动作,损害其工作寿命.为更充分合理地利用慢速设备的调节能力,提出了面向高比例可再生能源电力系统的日前-日内两级无功滚动调度方法.在日前尺度,建立两阶段鲁棒优化提前计划出慢速设备各小时允许的动作次数;在日内尺度,进行滚动优化调度,决定具体动作时刻,引入富余可调次数修正,进一步增加调度灵活性.电网测试效果表明所提方法相比传统方法性能更优越,利用预测信息实现了快慢无功协调,增强了电压控制效果.

分析了传统三级协调模式下AVC系统存在的协调水平不足问题,提出了基于全局无功电压优化控制的AVC-DVC模式,通过采用全局优化控制策略,解决了省地协调过程中存在的无功设备投入率低,无功设备的频繁动作等问题;在执行层面,利用DVC的控制模式,结合目前广泛应用的智能变电站控制系统,实现自动闭环优化控制.该控制模式已在北京电网中实际应用,控制效果良好,高峰负荷期间无功设备投入率得到提升,无功分布得到优化.

近年来,高比例可再生能源发电接入我国电网,通过多条特高压/超高压交直流输电线路实现远距离传输,电网对故障后的暂态电压过程更加敏感,暂态电压安全成为我国电网的核心威胁之一.这已经成为国内外学术界和产业界关注的热点,其中一个焦点是如何通过有效的控制手段降低出现暂态电压不安全的风险.该文设计并研发了面向高比例可再生能源交直流混联电网的动态自动电压控制(dynamic automatic voltage control,DAVC)系统,通过考虑在线预想故障集的预防控制,提升电网故障后的暂态电压支撑能力.阐述了所研制的DAVC系统总体结构、主要功能和系统设计,通过在实际大型电网的应用案例说明其效果.目前,该DAVC系统已经在我国多个网省级电网调度控制中心取得实际在线应用.

发电机自动电压无功控制装置(AVC)是电厂侧自动电压-无功优化控制终端,针对发电机自动电压无功控制装置的性能,本文介绍了一种基于虚拟调度终端环境的电厂AVC子站性能的检测手段.检测时将电厂冗余配备的上位机接入虚拟调度终端,模拟AVC主站发送控制指令和AVC子站行为,模拟发电机励磁系统,根据反馈的调节结果数据对AVC子站性能进行评估,能够有效地发现电厂AVC子站的不足.

With the development of social economy, the demands for electric power are increasing, and the direct load supply on 10kV side of 220kV transformer substation increasingly common. Under such mode, the difficulty in Automatic Voltage Control (AVC) voltage/reactive power control caused by voltage regulating conflict between the 10kV side and the 220kV and 110kV side is also becoming more prominent. In this article, the effect of AVC strategy and combined strategy on the quality of electric energy is discussed; the voltage regulating problems of direct load supply are classified and discussed; the solution for on-line computation of the sensitivity of tapping point voltage regulation, regulating the main transformer unloaded tap position and adjusting the AVC control parameters are put forward, whose application in the voltage and reactive power optimization and improvement of Yibin's power grid is significantly effective.

To guarantee secure operations in hierarchical systems with large-scale renewable powers, it's essential for the system and operators to determine a voltage secure operational ranges (VSORs) for each bus/station. However, the computation of the VSOR is really complicated especially for large scale systems. Therefore, a hierarchical computational method for the large-scale hierarchical systems is proposed in this paper, which takes into account the HVDC operations and different N-1 contingencies. The VSOR computation is fast and can be applied in hierarchical systems with large-scale renewable powers online, exchanging information between wind farms, wind integrated stations and power grids. The efficiency and accuracy of the VSOR computation has been observed using operation data of Western China Power Grid in case studies.

Wind power changes instantaneously during the control interval of automatic voltage control (AVC) system. To enhance the control effect in voltage-source-converter-based high-voltage direct-current (VSC-HVDC) systems with wind farms integration, this paper proposes a reactive power and voltage control scheme considering the stochastic deviation from baseline wind power. The uncertainties of wind power during the control interval are characterized by state-based generated scenarios. Through a scenario-based optimization, the reduced scenarios are used to optimize expected network losses while the extreme scenarios ensure the voltage security. Case studies based on Monte Carlo simulation show the proposed method decreases the voltage bounds violations with acceptable network losses. In addition, the balance between economy and robustness can be adjusted by parameters in the control scheme.

Integrated Energy System is beneficial for promoting the distributed renewable energy (DRE) consumption, thereby alleviating environmental pollution and energy shortage. In this paper, we propose a virtual power plant (VPP) structure considering the feature of heat and electric power system integration, which is defined as Multi-energy Virtual Power Plant (MVPP). MVPP is allowed to participate in the electricity market; and price information from bulk power market can affect heating system through the coupling devices, thus optimizing the co-operation of electric and heat system. MVPP is also involved in the auxiliary service market, a penalty term is designed for the Utility to charge MVPP service fee so that power fluctuation on transmission line can be reduced. The case study proved the effectiveness of the penalty term and MVPP is able to provide reserve service for Utility in peak load hours by multi-energy flow coupling under the regulation of feed-in tariff.

In this paper, we propose a novel state estimation approach for the steam network to estimate the drainage of each pipe. An equivalent model of the steam pipe is established considering the drainage and condensation processes in steam transportation. Then the state estimation approach is developed, in which parameter uncertainties are taken into account. The proposed approach is tested with simulation data of a real steam network.

The strong coupling of electricity and heat of combined heat and power (CHP) unit in cold season results in the loss of flexibility, which may cause massive wind power curtailment if they are in the same system. This issue could be handled with the thermal storage capability of a district heating network (DHN) that could supply flexibility for CHP to decouple the strong coupling of heat and electric power supplies. In this paper, a wind-CHP generation aggregation(WCGA) model is formulated, which motivates CHP to increase wind power integration by increasing total profit of the system, while considering the additional flexibility supplied by DHN. In WCGA model, DHN is formulated as an energy-storage-like (ESL) model that considers the storage capability of DHN based on dynamic characteristics of temperature and time delay effect of DHN. The potential benefits of the proposed model have been demonstrated by case study in terms of enhancing, wind power integration as well as total profit.

In response to the challenges of energy efficiency, carbon dioxide abatement and renewable energy integration, a concept called multi-energy was presented. Some multi-energy industrial parks have been built or are being built in China. This paper proposes a novel demand response (DR) program of multi-energy industrial park. The mutual conversion between various forms of energy can improve the flexibility of dispatch. Both electricity-based and heat-based DR programs are considered in this paper, where the factories in the industrial park are encouraged to reduce the electricity load and increase the heat load, respectively. The test system in the case studies is designed based on a practical industrial park in southern China. The results of case studies show that the proposed DR programs can effectively reduce the tie line power of industrial park.

Integrated energy systems (IESs) are the physical carriers of energy internet, and have many synergy benefits. Industrial consumes most of the energy in China, so there is much space for energy saving and system optimization. Many big factories in an industrial park have small energy systems and can take part in demand response. Renewable energy is usually installed in IESs, which brings much uncertainty. To deal with above challenges, a smart dispatch system is developed. This smart dispatch system deals with different energy forms, such as electricity, heating and cooling, and enables demand response. The smart dispatch system has a hierarchical framework. It consists of several modules, including situation awareness, risk assessment, optimization, virtual power plant, and demand response. Each module interacts with each other to achieve goals of the smart dispatch system. Case studies show that demand response can improve the integration of renewable energy.

Along with the appearance and rapid development of energy internet,the microgrid with CCHP (Combined Cooling,Heating and Power) system becomes more noticed,which contains multiple renewable energy resources and has high energy utilization rate.An optimal operation model of microgrid with CCHP system is established,which takes the minimum total operational cost as its objective,considers the conversion efficiency among different energy forms and the constraints of different types of power generation and energy storage,and realizes the comprehensive utilization and cooperative optimization of multiple energy flows to satisfy users' demands for different load types.The actual cases of a real district are analyzed and results show that,the established model effectively optimizes the dispatch of heating,cooling and electric energy sources,reduces the operational costs of microgrid and enhances the accommodation of renewable energy resources by the coordination among different energy forms.

Integrated energy system (IES) and relevant research have been the focus of many scholars in recent years. The coupling between different energy systems including electric, heating and natural gas can be optimized together to improve the overall system efficiency. In this paper, we concentrate on heating system dispatch problem and proposes an optimal dispatch model for district heating network (DHN) with combined heating and power (CHP) units, which considers the thermal balance and hydraulic equations in the pipelines. This is a nonlinear optimization problem which can be solved by interior-point method (IPM). The objective is to minimize the cost of fuel consumption for the whole system. A case study based on 20-nodes DHN with 3 CHP units and 19-branches is demonstrated, proving the effectiveness of the proposed model. Moreover, convergence analysis with comparison solved by traditional IPM and primal-dual IPM is discussed and several possible future research directions are proposed.

With further construction and rapid development of the power grid,the East China power grid has an increasing demand for reactive power.At present,all the power plants in East China have been incorporated into the control system of AVC,thus the AVC substation of one power plant has increasing impacts on the voltage regulation of the whole power grid.This paper presents a detection system of power plant AVC substations based on the integrated power grid digital simulation technology,which can evaluate the voltage control algorithms and software functions beforehand so that shortcoming of AVC substations can be detected and overcome before the close-loop control so as to improve the whole quality of automatic voltage control of the power grid.

In order to transmit wind powers to the long-distance load centers in China, large-scale wind power centralized integrated into the weak sending-side systems becomes a major way to use wind energies, which causes a lot of voltage-related challenges. Dynamic reactive power (DRP) plays an important role in voltage problems due to the fast response in terms of the disturbances and contingencies. How to optimize the DRP devices to provide fast voltage support is crucial to the sending-side system. Therefore, this paper proposes a DRP optimization method for large-scale wind farms to compute the set value of all the DRP devices under normal conditions. The DRP computation can be completed by four steps exchanging information between the integrated stations and wind farms. The wind farms in Gansu Power Grid are used to test the proposed method, and the simulation results shows the effectiveness of the proposed method.

Large-scale application of multi-energy flow system (MEFS) brings flexibility and economic benefits. To manage it effectively, analyzing the dynamic power flow and predicting the response is an important work when the mass flow rate and temperature are variable. The steady-state network model does not fully consider the dynamic process of heat transfer. To solve the problem, a quasi-dynamic network model based on forward method is proposed for the heating system in the MEFS. According to the simulation results, the quasi-dynamic model can track dynamic thermal process and transport delay.

冀北电网AVC系统采用基于最优潮流计算和在线软分区的三级电压优化控制模式,以全网网损最小、电压裕度最大、电压波动最小为目标,综合考虑电网安全约束条件,省地协调控制,闭环控制本地区内无功补偿设备,实现电网无功电压的自动调节,有效降低了网损,提升了全网电压控制水平.对于电网经济运行,确保特高压电网运行下的安全性,以及风电富集、对电压控制水平要求高的地区具有重要意义.