传统高压直流用于大规模陆上风电传输的经济可行性

随着风电在全世界的爆发式发展,大规模风电传输成为研究热点之一。鉴于高压交流和风火打捆特高压直流等输电方案都存在其局限性,更多的传输方案有待研究。提出一种用变功率控制LCC HVDC系统传输大规模陆上风电的方案,即HVDC系统的有功功率实时跟随风功率变化,并基于一个特定案例对该方案进行了全方位的经济和技术可行性研究。为了更好地展现所提出方案的经济性,将定功率控制的LCC HVDC和所提出方案在当前和未来两套价格体系下进行了经济性比较;结果显示,在一定条件下变功率控制HVDC传输方案更具经济竞争力。

基于电力市场条件下的风电传输通道混合性规划模型

针对新能源的快速发展和电力市场的进一步开放,文章基于确定性规划准则和概率性规划准则,提出了一个应用于风能传输通道规划中的多场景混合性规划模型。该规划模型将传输通道的规划问题转化为混合整数问题,通过采用直流潮流模型、最优潮流和最小割集,定义模拟未来电力系统负荷增长的多个场景,通过商业优化软件CPLEX,实现了为风电传输通道寻找最优规划方案的目的。文中,该混合性规划模型通过基于实际电网的测试系统的检验及与传统规划模型的对比,证明了该模型的有效性、灵活性和先进性。

直流孤岛外送风电变电流控制策略

由于风电具有波动性,对于没有足够火电配比的风电系统,尤其是风电孤岛系统,无法采用以往的定功率控制输送风电。为此,提出可以跟踪风电变化、输送可控可变功率的变电流控制策略。根据风电功率的波动性,该策略利用变电流控制方式实时输送波动的风电功率,且可以保证系统的电压电流均在允许范围之内。推导了该策略的控制原理、运行区域,确定了控制模型结构,设计了变电流控制器,搭建了仿真模型。仿真结果验证了所提策略的有效性。

汇集站和集群中心站分级协调的风场群接入系统优化规划

风电消纳难题的根源在于风电与电网规划的不协调,单个风电场的接入系统各自依据其边界条件设计,叠加得到风电场集群的区域接入电网往往难以达到最优效果,甚至是不可行方案。该文提出风电场集群的接入系统协调规划模型,以经济性最优为目标,对接入系统进行汇集站及集群中心站两级综合协调优化。模型考虑风电送出受阻电量的损失、风电送出电量的效益、风电场集群内部升压变电站选址、各个风电场接入线路容量以及风电场集群分组等因素,并利用遗传算法对上述综合协调模型双层分解后进行优化求解,最后通过算例验证了模型和方法的有效性。

Special report on relationship between wind farms and power grids

The installed capacity of a large scale wind power plant will be up to a number of hundreds MW, and the wind power is transmitted to load centers through long distance transmission lines with 220 kV, 500 kV, or 750 kV. Therefore, it is necessary not only considering the power transmission line between a wind power plant and the first connection node of the power network, but also the power network among the group of those wind power plants in a wind power base, the integration network from the base to the existed grids, as well as the distribution and consumption of the wind power generation by loads. Meanwhile, the impact of wind power stochastic fluctuation on power systems must be studied. In recent years, wind power prediction technology has been studied by the utilities and wind power plants. As a matter of fact, some European countries have used this prediction technology as a tool in national power dispatch centers and wind power companies.

Research on Wind Farm Participation in Power Grid AGC Control

Since wind power has the features of being intermittent and unpredictable, and usually needs transmission over long distances, grid integration of large-scale wind power will exert signif icant influence on power grid planning and construction, and will make a heavy impact on the safe and reliable operation of power systems. To deal with the diff iculties of large scale wind power dispatch, this paper presents a new automatic generation control (AGC) scheme that involves the participation of wind farms. The scheme is based on ultra-short-term wind power forecast. The author establishes a generation output distribution optimization mode for the power system with wind farms and verif ies the feasibility of the scheme by an example.

Determination of Weak Points Based on Risk Theory and Application to Transmission Network Planning

In the traditional power transmission network planning,deterministic analysis methods are widely used.In such methods,all contingencies are deemed to have the same occurrence probability,which is not reasonable.In this paper,risk assessment is introduced to the process of transmission network planning considering the probabilistic characteristics of contingencies.Risk indices are given to determine the weak points of the transmission network based on local information,such as bus risk,line overload risk,contingency severity.The indices are calculated by the optimal cost control method based on risk theory,which can help planners to quickly determine weak points in the planning and find solution to them.For simplification,only line overload violation is considered.Finally,the proposed method is validated by an IEEE-RTS test system and a real power system in China from two aspects.In the first case,the original system is evaluated by the proposed method to find the weak points,and then four planning schemes are established,among which the best scheme is selected.In the second case,four initial planning schemes are established by combining the experiences of planners,and after the evaluation by using the proposed method,the best planning scheme is improved based on the information of weak points in the initial schemes,and the risk of improved scheme is reduced from 42 531.86 MW·h per year to 4 431.26 MW·h per year.

On Issues of Large-Scale and Long-Distance Transmission of Wind Power

While having constantly developed for five years,China's wind power meets its bottleneck of further development in fast-growing areas due to the insufficient market accommodation.In contrast,the Central China and the East China have experienced the shortage of coal,oil and natural gas for power generation in recent winters.Hence,how to handle the discrepancy between insufficient accommodation and short energy supply has become the focus of attention both domestically and abroad.Taking Jiuquan Wind Power Base as an example,the reverse distribution between the energy resources and the consumer market,the wind power accommodation and the energy transmission are analyzed;the necessity and feasibility of long-distance power transmission are also discussed,which presents a technical roadmap for the long-distance transmission of thermal and wind power in combination.

Wind Generation Modeling for Transmission Systems Adequacy Studies with Economic Dispatch

In this paper, a strategy is proposed in order to introduce in a realistic way wind generation into a HL11 （bulk power system） non sequential Monte Carlo adequacy study with economic dispatch. Thanks to the implemented solution, wind generation is consequently confronted to operational constraints related to high powered thermal units, nuclear parks or thermal machines with technical minimum value. Moreover, during each simulated system state, a DC load flow is also calculated in order to evaluate reinforcements optimizing the large scale integration of wind power production. The simulation tool modified during the present work is called Scanner and is the property of Tractebel Engineering （Gaz de France-Suez） company. It has been here applied to an academic test system： the Roy Billinton Test System （RBTS）.