Energy reserves show potential

China has great potential in developing itspetroleum and natural gas industries,said Vice-Minister Zhang Guobao in charge of the National De-velopment and Reform Commission(NDRC).

Coalbed Reserves to be Exploited for New Energy

ＣｏａｌｂｅｄＲｅｓｅｒｖｅｓｔｏｂｅＥｘｐｌｏｉｔｅｄｆｏｒＮｅｗＥｎｅｒｇｙＤｕＭｉｎｇ，（ＣｈｉｎａＵｎｉｌｅｄＣｏａｌｂｅｄＭｅｔｈａｎｅＣｏ．，Ｌｔｄ．）ＡｐｐｒｏｖｅｄｂｙｔｈｅＳｔａｔｅＣｏｕｎｃｉｌｏｆＣｈｉｎａｉｎＭａｒｃｈ１９９６...

Distributed Robust Energy and Reserve Dispatch for Coordinated Transmission and Active Distribution Systems

The increasing penetration of renewable energy sources introduces higher requirements for the operation flexibility of transmission system(TS) and connected active distribution systems(DSs). This paper presents an efficient distributed framework for the TS and DSs to work cooperatively yet independently. In addition to conventional power interaction, upward and downward reserve capacities are exchanged to form the feasible access regions at the boundaries that apply to different system operation situations. A distributed robust energy and reserve dispatch approach is proposed under this framework. The approach utilizes the supply-and demand-side resources in different systems to handle various uncertainties and improve overall efficiency and reliability. In particular, integrated as aggregated virtual energy storage(AVES) devices, air-conditioning loads are incorporated into the optimal dispatch. In addition, a reserve model with charging/discharging-state elasticity is developed for AVESs to enhance system flexibility and provide additional reserve support. Different cases are compared to verify the effectiveness and superiority of the proposed approach.

Probabilistic Energy and Reserve Co-dispatch for High-renewable Power Systems and Its Convex Reformulation

This paper proposes a probabilistic energy and reserve co-dispatch(PERD) model to address the strong uncertainties in high-renewable power systems. The expected costs of potential renewable energy curtailment/load shedding are fully considered in this model, which avoids insufficient or excessive emergency control capacity to produce more economical reserve decisions than conventional chance-constrained dispatch methods. Furthermore, an analytical reformulation approach of PERD is proposed to make it tractable. We firstly develop an approximation technique with high precision to convert the integral terms in objective functions into analytical ones. Then, the calculation of probabilistic constraints is equivalently transformed into an unconstrained optimization problem by introducing value-at-risk(Va R) representation. Specifically, the Va R formulas can be computed by a computationally-cheap dichotomy search algorithm. Finally, the PERD model is transformed into a convex problem, which can be solved reliably and efficiently using off-the-shelf solvers. Case studies are performed on IEEE test systems and real provincial power grids in China to illustrate the scalability and efficiency of the proposed method.

Risk-Averse Two-Stage Distributionally Robust Economic Dispatch Model Under Uncertain Renewable Energy

With the participation of large quantities of renewable energy in power system operations,their volatility and intermittence increases the difficulties and challenges of power system economic scheduling.Considering the uncertainty of renewable energy generation,based on the distributionally robust optimization method,a two-stage economic dispatch model is proposed to minimize the total operation costs.In this paper,it is assumed that the fluctuating of renewable power generation follows the unknown probability distribution that is restricted in an ambiguity set,which is established by utilizing the first-order moment information of available historical data.Furthermore,the theory of conditional value-at-risk is introduced to transform the model into a tractable model,which we call robust counterpart formulation.Based on the stochastic dual dynamic programming method,an improved iterative algorithm is proposed to solve the robust counterpart problem.Specifically,the convergence optimum can be obtained by the improved iterative algorithm,which performs a forward pass and backward pass repeatedly in each iterative process.Finally,by comparing with other methods,the results on the modified IEEE 6-bus,118-bus,and 300-bus system show the effectiveness and advantages of the proposed model and method.

Relationship between copulation and cold hardiness in Ophraella communa(Coleoptera: Chrysomelidae)

Ophraella communa(Coleoptera: Chrysomelidae), the ragweed leaf beetle, is a biological control agent of the invasive common ragweed, Ambrosia artemisiifolia(Asterales: Asteraceae). Adults can survive cold conditions that occur during winter. The adults mate before entering overwintering. Understanding the connection between copulation and overwintering will be useful for determining O. communa seasonality. Determining the relationship between overwintering and copulation required comparison of mated and unmated beetles at mean lethal temperature(LTemp_(50)) exposures for 2 h. Cold-related physiological indices, including the water ratio, super cooling point(SCP), cryoprotectant levels, and energy reserve levels, were also measured. Mating treatment decreased the LTemp_(50) of both sexes by reducing their mean SCP and water ratios. Although the changes of cryoprotectant levels in mated adults were not precisely consistent in between the genders, they increased greatly in both males and females. Body sugar may play a role in copulation and may also elevate cold hardiness in O. communa.

A Multi-time Scale Tie-line Energy and Reserve Allocation Model Considering Wind Power Uncertainties for Multi-area Systems

Continued expansion of the power grid and the increasing proportion of wind power centralized integration leads to requirements in sharing both energy and reserves among multiple areas under a hierarchical control structure,which successively requires a correction between schedule plans within multi-time scale.In order to address this problem,this paper develops an information integration method integrating complicated relationships among fuel cost,total thermal power output,reserve capacity,owned reserves and expectations of load shedding and wind curtailment,into three types of time-related relationship curves・Furthermore,a multi-time scale tieline energy and reserves allocation model is proposed,which contains two levels in the control structure,two time scales in dispatch sequence and multiple areas integrated within wind farms as scheduling objects・The efficiency of the proposed method is tested in a 9-bus test system and IEEE 118-bus system.The results show that a cross-regional control center is able to approach the optimal scheduling results of the whole system with the integrated uploaded relationship curves.The proposed model not only relieves energy and reserve shortages in partial areas but also allocates them to more urgent need areas in a high effectivity manner in both day-ahead and intraday time scales.

Biding strategy of vehicle parking for participating in energy and spinning reserve markets

In this paper a model for suggesting a smart parking that involves a set of electric cars is presented to auction the management ability and correct parking planning in reserve spinning market, secondary energy market and grid. Parking interest under various scenarios is analyzed and its effective results are presented by a valid model. Besides, particle swarm optimization algorithm is used for calculating maximum benefit.

Lipid reserves and immune defense in healthy and diseased migrating monarchs Danaus plexippus

Recent studies suggest that the energetic demands of long-distance migration might lower the pool of resources available for costly immune defenses. Moreover, migration could amplify the costs of parasitism if animals suffering from para- site-induced damage or depleted energy reserves are less able to migrate long distances. We investigated relationships between long-distance migration, infection, and immunity in wild fall-migrating monarch butterflies Danaus plexippus. Monarchs migrate annually from eastern North America to central Mexico, accumulating lipids essential for migration and winter survival as they travel southward. Monarchs are commonly infected by the debilitating protozoan parasite Ophryocystis elektroscirrha （OE）. We collected data on lipid reserves, parasite loads, and two immune measures （hemocyte concentration and phenoloxidase activity） from wild monarchs migrating through north GA （USA） to ask whether （1） parasite infection negatively affects lipid reserves, and （2） greater investment in lipid reserves is associated with lower immune measures. Results showed that monarchs sampled later in the fall migration had lower but not significantly different immune measures and significantly higher lipid reserves than those sampled earlier. Lipid measures correlated negatively but only nearly significantly with one measure of immune defense （phenoloxidase activity） in both healthy and infected monarchs, but did not depend on monarch infection status or parasite load. These results provide weak support for a trade-off between energy reserves and immune defense in migrants, and suggest that previously-demonstrated costs of OE infection for monarch migration are not caused by depleted lipid reserves .

Performance testing of a heat pump system with auxiliary hot water under different ambient temperatures

In recent decades,solar collector and heat pump combinations have been widely applied to supply heat and hot water,such as in heat supply and power generation for domestic and commercial buildings and relevant applications in the manufacturing and agricultural industries.However,the solar-assisted heat pumps already in extensive use may undergo system performance deterioration in a cold environment.To solve this problem,we designed a heat pump system assisted with hot water where a water medium was used to store energy to assist the operation of the heat pump at low temperatures.Three factors were comprehensively considered:the opening degree of the electronic expansion valve,the temperature of the low-temperature heat source,and the auxiliary hot water temperature.Crossover experiments were designed with three levels for each factor,and 36 groups of experiments were carried out.The results showed that as the auxiliary hot water temperature increased,the heating capacity and the coefficient of performance also increased.Thus,the overall working efficiency of the system improved.According to the orthogonal test,the most important influencing factor of system performance was the auxiliary hot water temperature,followed by the ambient temperature and opening degree of the electronic expansion valve.These results fully demonstrated that the addition of auxiliary hot water could dramatically improve system performance.In addition,optimization of the opening degree of the electronic expansion valve produced different results,indicating that the optimal value ranged from 50%−75%.