An overview of the policies and models of integrated development for solar and wind power generation in China

Under the goal of “Carbon Emission Peak and Carbon Neutralization”, the integrated development between various industries and renewable energy(photovoltaic, wind power) is of great significance in China. This paper summarizes the relevant policies, integration schemes and typical cases of the integrated development between renewable energy and other industries. First, the development status of wind and solar generation in China is introduced. Second, we summarize the relevant policies issued by the National Development and Reform Commission, National Energy Administration and other departments to promote the integrated development in photovoltaic and wind power generation in China. Third, eight kinds of photovoltaic three-dimensional development models are described, including “photovoltaic + agriculture, industry, environmental protection, transportation, architecture, communication, hydrogen and ecology”. Fourth, eight kinds of wind power threedimensional development models are summarized, including “Offshore wind power + marine ranch, marine energy, marine tourism, marine oil and gas, hydrogen, communication, Energy Island” and “Onshore wind power+ courtyard”. In the future, the promotion and application of the above integrated development projects will be accelerated. This overview aims to provide reference for the design in photovoltaic and wind energy systems and help potential investors to make decisions.

PI-MPC Frequency Control of Power System in the Presence of DFIG Wind Turbines

For the recent expansion of renewable energy applications, Wind Energy System (WES) is receiving much interest all over the world. However, area load change and abnormal conditions lead to mismatches in frequency and scheduled power interchanges between areas. These mismatches have to be corrected by the LFC system. This paper, therefore, proposes a new robust frequency control technique involving the combination of conventional Proportional-Integral (PI) and Model Predictive Control (MPC) controllers in the presence of wind turbines (WT). The PI-MPC technique has been designed such that the effect of the uncertainty due to governor and turbine parameters variation and load disturbance is reduced. A frequency response dynamic model of a single-area power system with an aggregated generator unit is introduced, and physical constraints of the governors and turbines are considered. The proposed technique is tested on the single-area power system, for enhancement of the network frequency quality. The validity of the proposed method is evaluated by computer simulation analyses using Matlab Simulink. The results show that, with the proposed PI-MPC combination technique, the overall closed loop system performance demonstrated robustness regardless of the presence of uncertainties due to variations of the parameters of governors and turbines, and loads disturbances. A performance comparison between the proposed control scheme, the classical PI control scheme and the MPC is carried out confirming the superiority of the proposed technique in presence of doubly fed induction generator (DFIG) WT.

Optimal Control of Wind Turbines under Islanded Operation

In this paper, an optimal control scheme for wind turbine output torque and power regulation under the influence of wind disturbances is presented. The system considered is a dynamic mechanical-based model with pitch and generator torque actuators for controlling the pitch and generator torque. The performance of linear matrix inequality (LMI) formalism of linear quadratic regulator (LQR);linear quadratic regulator with integral action (LQRI) and model predictive control (MPC) were compared in response to a step change in wind disturbance. It is shown by Matlab simulation that the LQRI outperformed both LQR and MPC controllers.

Investigation on Grid Connections of Wind Power and PV Power in China

In order to fully comprehend the developing status of wind power and photovoltaic (PV) power generation, a special investigation on the integration of wind power and PV power was launched by the agencies of the State Electricity Regulatory Commission (SERC) throughout China during July-October 2010. This report is completed based on the investigation along with routine supervisory and management programs. There are totally 573 wind power projects and 94 PV power projects involved. Existing problems in these projects are pointed out and proposals for regulation are put forward.

A Sliding Mode Approach to Enhance the Power Quality of Wind Turbines Under Unbalanced Voltage Conditions

An integral terminal sliding mode-based control design is proposed in this paper to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, and high quality transient characteristics of the integral terminal sliding mode control with the estimation properties of disturbance observers. The controller gains were auto-tuned using a fuzzy logic approach.The effectiveness of the proposed design was assessed under deep voltage sag conditions and parameter variations. Its dynamic response was also compared to that of a standard SMC approach.The performance analysis and simulation results confirmed the ability of the proposed approach to maintain the active power,currents, DC-link voltage and electromagnetic torque within their acceptable ranges even under the most severe unbalanced voltage conditions. It was also shown to be robust to uncertainties and parameter variations, while effectively mitigating chattering in comparison with the standard SMC.

Rooted Tree Optimization for Wind Turbine Optimum Control Based on Energy Storage System

The integration of wind turbines(WTs)in variable speed drive systems belongs to the main factors causing lowstability in electrical networks.Therefore,in order to avoid this issue,WTs hybridization with a storage system is a mandatory.This paper investigates WT system operating at variable speed.The system contains of a permanent magnet synchronous generator(PMSG)supported by a battery storage system(BSS).To enhance the quality of active and reactive power injected into the network,direct power control(DPC)scheme utilizing space-vector modulation(SVM)technique based on proportional-integral(PI)control is proposed.Meanwhile,to improve the rendition of this method(DPC-SVM-PI),the rooted tree optimization technique(RTO)algorithm-based controller parameter identification is used to achieve PI optimal gains.To compare the performance ofRTO-based controllers,they were implemented and tested along with some other popular controllers under different working conditions.The obtained results have shown the supremacy of the suggested PIRTO algorithm compared to competing controllers regarding total harmonic distortion(THD),overshoot percentage,settling time,rise time,average active power value,overall efficiency,and active power steadystate error.

Control scheme of hexagonal modular multilevel direct converter for offshore wind power integration via fractional frequency transmission system

A fractional frequency transmission system(FFTS)is a promising solution to offshore wind power integration,for which the hexagonal modular multilevel converter(Hexverter)is an attractive choice for power conversion.The Hexverter has recently been proposed to directly connect two three-phase systems of different frequencies and voltage amplitudes,with only six branches in the FFTS in that case.This paper examines for the first time the control scheme of the Hexverter when applied to offshore wind power integration via a FFTS.Firstly,the frequency-decoupled mathematical model of the Hexverter is deduced by introducing the double dq transformation.Then the branch energy of the Hexverter is analyzed in detail and the reactive power constraint equation is obtained.The corresponding control scheme is thoroughly discussed,including the inner loop current control,the outer loop voltage control in both grid-connected mode and passive mode,and a novel optimization method to minimize the circulating current in the Hexverter.Finally,a simulation model of offshore wind power integration via a 4-terminal FFTS based on the Hexverter is built in MATALB/Simulink to verify the feasibility of Hexverter and the effectiveness of the control scheme proposed in this paper.

Dynamic Modeling for Gas-Electricity Combined Systems with Wind Power and its Stability Control

The micro turbine(MT)is scheduled to address wind power uncertainties and thus lead to greater variations in the state of natural gas system(NGS).To meet this challenge,first,a dynamic model of a gas-electricity combined system with wind power is established,the dynamic model of the NGS is based on differential equations,so that it can easily connect with the MT model;and a droop control module is added to the Rowen's MT model,so that the improved model can adjust the output power according to the scheduling instructions.Then,a stability control method based on the variable regulation ratio gas pressure regulator is proposed,the essence of this method is to reduce the variation of natural gas storage in the gas pipeline,so as to ensure the stability of pressure.The simulation results show that the dynamic model is correct and the stability control method is effective.

A two-level hierarchical discrete-device control method for power networks with integrated wind farms

Power systems depend on discrete devices, such as shunt capacitors/reactors and on-load tap changers, for their long-term reliability.In transmission systems that contain large wind farms, we must take into account the uncertainties in wind power generation when deciding when to operate these devices.In this paper, we describe a method to schedule the operation of these devices over the course of the following day.These schedules are designed to minimize wind-power generation curtailment, bus voltage violations, and dynamic reactive-power deviations,even under the worst possible conditions.Daily voltagecontrol decisions are initiated every 15 min using a dynamic optimization algorithm that predicts the state of the system over the next 4-hour period.For this, forecasts updated in real-time are employed, because they are more precise than forecasts for the day ahead.Day-ahead schedules are calculated using a two-stage robust mixedinteger optimization algorithm.The proposed control strategies were tested on a Chinese power network with wind power sources; the control performance was also validated numerically.

基于主动尾流控制的风电机群协同优化调度

针对机组间尾流效应严重影响风电机组发电效率的问题,提出了风电机组安全偏航约束计算方法、尾流特性混合半机理建模方法以及风电机群多目标协同优化调度方法。基于FAST.FARM平台完善了多自由度可控机组与尾流的动态交互集成仿真环境,对比分析了2台机组串列式排布以及华东地区某海上风电场7台机组实际排布下的协同运行优化性能。结果表明:所建立的集成仿真模型能够合理表征风电机群与空气流场的多领域动态交互特性,所提方法能够有效提升风电机群发电效能,促进经济效益、资源利用和成本控制的均衡优化。

A Multi Input Multi Output Converter for Hybrid Energy Systems

Multi input and multi output converters are becoming popular because they are cost effective and compact. This paper proposes a multi input multi output converter for Grid-Solar power integration for uninterrupted power supply. The proposed converter uses four winding transformer with two primary windings and two secondary windings. The grid supply is connected to the first winding of transformer through rectifier-inverter for controlled power transfer. The solar energy is inverted and applied to the second winding of primary. Two output ports are considered. The circuit is designed to get zero current switching during turn-off and zero voltage switching during turn-on to alleviate the switching losses. The simulation results for the proposed configuration are presented in this paper.

双绕组感应发电机交直流集成发电系统的自抗扰控制策略

针对双绕组感应发电机交直流集成发电系统,为实现简单易调、性能优越、负载适应力强的发电控制,该文提出一种基于线性自抗扰控制器的交直流电压控制策略,通过交流电压和直流电压与控制绕组和功率绕组的传递函数模型,构建交直流电压的线性扩张状态观测器,同时对交流电压有效值、直流电压和电压扰动进行观测,并利用电压和扰动观测值设计线性误差反馈控制律,对交直流电压进行控制。最后,通过仿真和实验验证该控制策略提高电压扰动抑制能力和负载适应性,同时各模块参数可独立设计、控制器结构简单,避免需要较多传感器及降低调参难度。

风电并网的电压稳定性分析与研究

风能作为一种无污染的清洁能源,近些年一直受到世界各国的青睐。但随着大规模的风电场并入电网,风能的随机性和间歇性也给电网的稳定性带来了冲击,因此,研究风电并网的电压稳定性对风电并网的安全运行有着非常重要的意义。本文以双馈异步发电机为例,通过MATLAB仿真,研究虚拟惯量控制、阻尼控制对电压频率稳定性的影响。

基于三端柔性直流的光热储能站与新能源场站功率协同控制策略

新能源基地大多经传统交流方式接入高压交流或直流外送通道,为解决大规模新能源经交流接入方式下并网容量小、损耗大,以及功率波动对电网稳定性影响等问题,构建了一个基于柔性直流输电并网的风电和光伏、光热储能及电网三端柔性直流系统。基于直流电压-有功功率特性,提出一种适用于该系统的站间协调控制策略,根据柔性直流输电系统的直流电压波动情况,调整光热储能机组的出力,以平抑风、光功率波动,降低其对电网的影响。针对光热储能侧换流站,采用直流电压裕度下垂混合控制策略,通过控制器参数配置,抑制控制模式切换过程中的暂态过电压,提高系统响应速度。最后,在PSCAD/EMTDC中搭建三端柔性直流系统仿真模型,验证所提控制策略的有效性。

考虑风光不确定性与灵活性指标的园区综合能源系统最优调度

针对风光高渗透率的园区综合能源系统调度过程中灵活性不足的问题,提出一种考虑风光不确定性与功率型灵活性指标的园区级综合能源系统日前调度策略。在调度模型中通过机会约束理论对风光的不确定性提供备用服务,利用功率型灵活指标对灵活性供给进行量化评价,在此基础上构建兼顾经济成本与灵活性供给的日前优化调度模型,采用混合整数规划的方法求解;仿真结果表明,该调度策略有效保证了系统运行的灵活性与经济性。

吉林油田风光发电项目探索与实践

“双碳”目标下,吉林油田加快绿色低碳转型,推进油气与新能源融合发展,着力打造原油、天然气、新能源“三分天下”新格局。针对油气生产用能特点和清洁替代实际需求,充分利用域内风光资源、油田电网、电力消纳及土地资源等优势,以需求和消纳为导向,组织建设15×10^(4)kW自消纳风光发电项目。合理规划风光发电建设类型和装机规模,建成分散和集中式光伏400余处共7.1×10^(4)kW,集中和分散式风机18台共7.8×10^(4)kW,年发电能力3.6×10^(8)kW·h,绿电替代网电比例达29.3%,有效改善了用能结构,大幅降低用能成本。油气田企业发展风光发电业务,建议提高自消纳绿电项目建设规模,北方地区尽量避免冬季施工,分散式风光发电需加大在线计量管理,自消纳项目单独论证便于开发碳资产。

基于开绕组电机的电动汽车双电池集成充电系统准直接功率控制

针对基于开绕组永磁同步电机和双电池组驱动的电动汽车提出一种集成化充电拓扑,充电运行时将双逆变器和电机绕组复用为双PWM整流器及其输入侧滤波电感。在三相电压源型整流器(VSR)和开绕组永磁电机数学模型的基础上,将电网坐标系和电机坐标系相统一,分析了充电状态下的电磁转矩。实际运行时存在双电池剩余电量不相等的情况,导致充电时双通道功率不平衡,因此设计了一种准直接功率控制策略,以解决功率不平衡带来的转矩脉动问题。最后通过仿真和实验验证了该集成化充电拓扑的可行性。

考虑氢能储运特性的配电网集群划分与氢能系统选址定容策略

电-氢能源系统(IEHS)的合理规划对能源结构转型具有重要意义,充分利用氢储能的可移动特性可降低IEHS综合成本,提出一种考虑氢能储运特性的配电网集群划分与氢能系统规划策略。首先,将氢能系统拆分为多个氢能子系统(HES),建立多个HES之间的气氢拖车交通运输及储运成本模型;其次,基于电力-交通网架结构与新能源分布情况提出配电网集群划分方法;最后,根据集群划分结果,建立HES双层选址定容模型,该模型以IEHS年综合成本最低为目标,分层解决单个集群内HES的容量配置问题、各集群内部HES选址定容及气氢拖车配置问题。结果表明:提出的策略可以减小氢能储运压力、降低IEHS综合成本,提升风、光消纳水平,加快系统潮流计算迭代收敛速度。

基于储能SOC和风光功率裕度调节的风光储联合调频策略

利用储能主动参与风光储场站内部调频控制方法,及风电机组和光伏机组配合储能参与风光储场站内部联合控制,以解决风电机组和光伏机组单独控制时带来的电压和频率稳定问题。对风光储各单元采用虚拟同步机(virtual synchronous generator,VSG)控制技术,基于储能的荷电状态(state of charge,SOC)实时调整储能的p-f下垂系数,同时根据风/光机组的功率裕度配合储能调整各自的p-f下垂系数,通过风/光/储联合控制实现系统频率调整。此外,为实现风光储场站系统的二次调频,对VSG技术中的频率-有功控制部分进行了修正,通过实时检测系统频率,对有功功率参考值进行自适应调整;最后,通过阶跃负荷扰动下对比储能单一调频、光储联合调频、风储联合调频及风光储联合调频4种场景来验证所提控制方法的有效性。

水风光综合基地多风险量化及长期多目标协调优化调度方法

水风光一体化运行可以发挥多种能源优势,提高综合效益。风光能源大规模并入水电基地,因不确定性增加致使系统能源消纳和电力供应问题更加突出,将面临更高弃水和缺电风险。针对该问题,提出了一种评估各时段蓄水状态的风险量化方法。基于该方法构建了考虑弃水量、发电量、弃水风险和缺电风险的多目标调度模型,基于双层优化,采用动态规划、离散微分动态规划和逐步优化相结合的算法进行高效求解,将分层序列法与线性加权和法嵌入算法中,以协调多目标矛盾。最后,以中国某水风光综合基地为工程背景模拟调度,并将所提模型与传统模型进行对比验证。研究结果表明,所提模型能较好地刻画运行风险,通过调整水电运行方式能合理消纳新能源,并获得更高稳定收益;模型能以较高效率完成求解,并满足实际调度时效性要求;在实际场景与预测场景出现偏差时,能显著降低弃水损失,通过改变水电运行方式以适应新能源日益增长带来的运行风险。