Applied Mechanics and Materials Vols. 347-350

Abstract: Mobile Ad hoc Network (MANET) is an effective method to solve the bottleneck of information collection and wireless transmission in Smart Grid. The particularity of MANET determines the importance of routing protocols. In order to improve the performance of MANET routing protocol, in this paper we evaluate the routing protocol, i.e., Ad hoc On demand Distance Vector (AODV), from several perspectives that did not draw attention in previous works. Furthermore, we also compare AODV with the routing protocol Dynamic source Routing (DSR). The simulation shows that AODV outperforms DSR in generally, and the former is suitable for larger MANET network. The simulation results in this paper not only provide effective evidence for further optimized routing protocols and the current protocols, but also provide feasible solution for Smart Grid to collect and transmission data by using MANET technology.

Abstract: In order to make a diagnosis of wind turbine failure, the mathematical model of the wind turbine should be prepared. This model can provide a theoretical basis for fault diagnosis. establishing the mathematical model of the main part of the generator being discussed on theoretical ,including the tower vibration, wind wheel and drive chain, the moment of inertia of the wind turbine and the synchronous generator voltage equation model in dq coordinate system. Its main focus on the demand for wind turbine fault diagnosis.

Abstract: Based on the planning data of Henan power grid in 2014, the impacts of 800kV UHVDC from Hami to Zhengzhou on static voltage stability of Henan power grid are analyzed in details. Firstly, this paper introduces the principle of voltage stability analysis, the stability margin index has been established. Secondly, the analysis of static voltage stability for Henan power grid before and after the UHVDC from Hami to Zhengzhou putting into operation is carried out, the weak buses and regions in Henan power grid are pointed out. Finally, the operation patterns of Henan power grid after the UHVDC putting into operation are classified and optimized. Simulation results show that the improper operation pattern may significantly deteriorate the static voltage stability of power grid. The operation patterns of HVDC power multi-channel transferring from Henan to Central China grid combined with partly internal consumption are favorable to improve the static voltage stability of the whole system. The analysis results provide theoretical basis for the future operation of Henan grid.

Abstract: Based on the improved Continuation Power Flow algorithm, this paper investigates the impacts of FACTS on static voltage stability characteristics of AC/DC hybrid power system. This paper introduces the steady-state model of different FACTS devices, and the power flow mathematical model is established about AC/DC power system with FACTS devices. The impacts of FACTS devices with various capacities in different locations on static voltage stability are compared and analyzed. The calculation results of a four-machine two regions AC/DC power system show that FACTS are able to improve the voltage stability and the installation of SVC shunt compensation can possess a better effect to improve the system static voltage stability limit than TCSC series compensation.

Abstract: With widely research and application of microgrid, the effect of the harmonic problems becomes not be ignored. This paper applies one cycle controlled active power filter (APF) to suppress harmonic in microgrid. Compared with traditional methods, one cycle controlled APF omits the harmonic detecting circuit and greatly simplifies the system structure. The one cycle control method in this paper, combining with space vector control, divides the frequency cycle into three control sextants, which simplifies the controller further. This paper builds the model of one cycle controlled APF and microgrid model including wind power system and photovoltaic systems. Then make simulation analysis about microgrid harmonic suppression. Simulation results show that one cycle controlled APF has a good compensation effect in microgrid harmonic suppression.

Abstract: With the HVDC system interconnected to power grid, the voltage stability problem of power grid has become increasingly prominent. This paper establishes the mathematical model of AC/DC hybrid power system and proposed an improved Continuation Power Flow (CPF) algorithm to calculate the static voltage stability limit of AC/DC hybrid system, the characteristics of this algorithm are as following: PQ decoupled power flow algorithm is used; Lagrange quadric interpolation is used in the process of predictor and step control; local parameter method is used in the correction. The iterations of AC/DC calculation alternate to solve power flow equations and select the step control near the critical power limit points to ensure the convergence of power flow solution. In order to verify the correctness of the proposed algorithm, this paper compares the calculation results by the improved algorithm and Matpower on the IEEE 14 bus-system. This paper calculates the static voltage stability limit of AC/DC hybrid power system under different DC control patterns of modified IEEE 14 bus-system and analyzes the impacts of different DC control pattern to the system voltage stability.

Abstract: This paper presents a methodology for solving unit commitment (UC) problem for thermal units integrated with wind power and generalized energy storage system (ESS).The ESS is introduced to achieve peak load shaving and reduce the operating cost. The volatility of wind power is simulated by multiple scenarios, which are generated by Latin hypercube sampling. Meanwhile, the scenario reduction technique based on probability metric is introduced to reduce the number of scenarios so that the computational burden can be alleviated. The thermal UC problem with volatile wind power and ESS is transformed to a deterministic optimization which is formulated as the mixed-integer convex program optimized by branch and bound-interior point method. During the branch and bound process, the best first search and depth first search are combined to expedite the computation. The effectiveness of the proposed algorithm is demonstrated by a ten unit UC problem.

Abstract: In this paper the site selection is researched to new coal-fired plants containing CCS technology. The cost of CO₂ pipeline transport and the income of strengthening oil exploitation with CO₂ are added to traditional model. They are the main factors to effect the site selection. The model is established with the minimum comprehensive cost per year of the system for target function. The optimized site scheme is determined through model solution with BCC optimization algorithm. The geographical area of one region is divided into smaller units and coded. The optimizing result shows that the proportion of power transmission cost is larger,so power plant site is close to load points. Moreover the cost of pipeline transportation holds a sizable proportion. It is needed to balance factors to confirm the best optimized scheme.

Abstract: Optimization of restoration paths of power system after blackout is a multi-stage, multi-target, multi-variable combinatorial problem in the power system restoration. This paper presents a reasonable model and effectually method. The proposed model is considered as a typical partial minimum spanning tree problem from the mathematical point of view which considering all kinds of constraints. Improved data envelopment analysis (DEA) was used to get the weight which considering line charging reactive power, weather conditions, operation time and betweenness of transmission lines. The improved genetic algorithm method is employed to solve this problem. Finally, an example is given which proves the strategy of the line restoration can effectively handle the uncertainty of the system recovery process, to guarantee the system successfully restored after the catastrophic accidents.

Abstract: In order to improve the situation that there is a high pollution emission from coal-fired power plant in China and after a lot of research on inter-regional power generation exchange, we find that pollution emission would be reduced by exchanging power generation in the inter-regional coal-fired power plant. Taking the quantity of coal saving, economic benefit and environmental benefit into account, this paper proposes an analysis model for calculating the quantity of coal saving, added value and pollution reduction in the inter-regional power generation exchange, analyzing the benefit brought by this exchange. The case study shows that by using this model, pollution emission would be reduced in the whole region and economic and environmental benefit would be added in both electricity buyers and sellers. This analysis model has an application value.