Dynamic Reactive Power Optimization Model for a Wind Farms and Energy Storage Combined System

Reactive power optimization is a nonlinear, multivariable, multi-constrained programming problem, which makes the optimization process complicated. In this paper, based on the characteristics of reactive power optimization, a mathematical model of reactive power optimization, including comprehensive consideration of the practical constraints and reactive power regulation means for optimization, is established. Also particle swarm optimization (PSO) has been studied, and the method based on improved particle swarm optimization for reactive power is going to be taken in this paper. Optimization for the IEEE 14-bus system proves that the improved PSO algorithm used in this paper for reactive power optimization is effective. The algorithm is simple, convergent and of high quality for optimization, and thus suitable for solving reactive power optimization problems, with some application prospect.

With the development of science and technology, there has been growing the grid size, the growing demand for electricity and the extent of increasing the electricity market.In this paper, a mathematical morphology and genetic algorithm based dynamic reactive power optimization method for distribution network is proposed.By means of constructing mathematical morphology filter, the binary image composed by allelic genes of chromosome is filtered and the problem that deals with the action times of voltage regulating devices for compensation is turned into filtering problem of discrete binary image.With further automate scheduling, distribution automation and unmanned substation reactive power optimization of distribution line running made an urgent request.Reactive power optimization can improve the voltage passing rate, increasing the reliability of the system, the power quality, and the system runs the security and economy of the perfect combination, very broad application prospects.

In view of uncertainties caused by large-scale wind power integration, energy storage system (ESS) is being considered to stabilize the fluctuation of wind power. In this paper, the influence of ESS on power system operation with wind power is analyzed in detail, and an economic dispatch (ED) model with wind power and ESS is proposed based on scenario set. First, the initial scenario set of wind power output is generated by the Monte Carlo sampling. To overcome the shortcoming of heavy dependence on the initial clustering centers, which usually leads to unstable clustering results, the k-means clustering is improved by combining self-organizing feature map neural network and particle swarm optimization (PSO). Then, the initial scenario set is reduced based on this improved k-means clustering method. Finally, an ED model solved by PSO is used to minimize the comprehensive power generation cost based on the reduced scenario set. Taking IEEE-39 bus system as an example, the scenario-set-based ED model is implemented in this paper. The simulation results show that, when solving the ED problem with wind power and ESS, the proposed method considering scenario reduction makes not only the clustering index better, but also the results of ED more reasonable.

Energy storage system is an effective means to overcome the fluctuation of wind power generation and improve electrical network stability. This paper briefly introduces the impact of wind power generation on the grid and different battery energy storage technologies first. Demonstration projects of combined wind power generation and energy storage systems is then discussed. This is followed by an outline of three main operating modes of the combined wind power generation and energy storage using batteries, including smoothing wind power fluctuation, tracking wind power schedule output and load shifting. Current status of control strategies and storage capacity for the combined wind power generation and energy storage systems are then presented. Finally, further research needed for the combined system is discussed and improvement on the economic aspects is concluded to be a key aspect for future research.

Active distribution network active and reactive power coordinated dispatching method based on discrete monkey algorithm

Policy analysis for grid parity of wind power generation in China

Numerous problems have emerged with the rapid development of wind power in Xinjiang. The predominant problem is the inhibition of the healthy development of the wind power industry by wind power curtailment in Xinjiang. In this study, wind power heating and high energy-consuming industries were coupled to increase wind power consumption in Xinjiang on the load side. The feasibility analysis of wind power heating in Dabancheng showed that the heating load characteristics coincide with the wind characteristics and the electric heating technology can fulfill the requirements for wind power heating. A business model innovation achieved a win–win situation. Furthermore, a wind power heating system was designed in Dabancheng, the boiler capacity and the heat storage capacity were calculated, and a heating system model with heat storage technology was established. Wind power heating with heat storage can improve the consumption of wind power and increase the local electric load and system adjustability. Furthermore, heating with curtailed wind power can save 2942 tons of standard coal as well as reduce 5172 tons of CO2, 2.9 tons of SO2, 22 tons of NOX, and 2 tons of soot emissions. Non-grid-connected distributed wind power was applied to the high energy-consuming coal chemical industry to reduce wind power curtailment, expand the consumption market, and reduce pollution. A multifunctional wind-photovoltaic complementary system with hydrogen energy storage coupled with traditional high energy-consuming coal chemical industry was established. The implementation plan using wind and solar energy to produce, store, and apply hydrogen energy was proven beneficial. Wind power consumption was improved on the load side. The wind power curtailment problem was reduced by increasing local load using the curtailed wind power to provide clean heat in Dabancheng and constructing the multifunctional wind–photovoltaic complementary system. This study will contribute to the healthy and sustainable development of the wind power industry in Xinjiang.

The low voltage ride-through (LVRT) capability of the doubly-fed induction generator (DFIG) significantly impacts upon the integration of wind power into the power grid. This paper develops a novel comprehensive control strategy to enhance the LVRT and reactive power support capacities of the DFIG by installing the energy storage system (ESS). The ESS is connected to the DC-link capacitor of the DFIG and used to regulate the DC-link voltage during normal or fault operations. The unbalanced power between the captured wind power and the power injected to the grid during the transient process is absorbed or compensated by the ESS. The rotor-side converter (RSC) is used to control the maximum power production and the grid-side converter (GSC) is used to control the reactive power before participating in the voltage support. When the supply voltage continues to drop, the rotor speed is increased by controlling the RSC to realize the LVRT capability and help the GSC further enhance the reactive power support capability. The capacity of the GSC is dedicated to injecting the reactive power to the grid. An auxiliary transient pitch angle controller is proposed to protect the generator’s over speed. Both RSC and GSC act as reactive power sources to further enhance the voltage support capability with serious voltage sags. Simulations based on a single-machine infinite-bus power system verify the effectiveness of the developed comprehensive control strategy.

Based on the generalized Tellegen theorem, this paper establishes a mathematical model for the sensitivity calculation of power networks and derives the sensitivity formula of power networks. Next, the influence of node reactive power on network loss is studied, combined with the sensitivity of node voltage to network parameters in the generalized Tellegen theorem, a reactive power optimization model is established, a reactive power step function is constructed, and the optimal step is obtained by loop iteration Long, optimize the reactive power of the node to minimize the network loss. The IEEE-11 node and 14node systems are analyzed using the reactive power optimization algorithm proposed in this paper, and the results of network loss before and after optimization are compared. The method proposed in this paper is further verified to be correct.

This paper proposes a transparent and reliable method between the suppliers and consumers for optimal reactive power pricing. The electric power suppliers compute the optimal reactive power using optimal reactive power dispatch problem by considering nodal voltage stability index ‘I’ as one of the constraints. The computed optimal reactive power of the generator is included in the reactive power pricing. The pricing method to the suppliers based on the opportunity cost method is presented and a detailed analysis using 62 bus Indian utility system has been carried out by considering diverse cases. In this proposed pricing method, the services of the cloud technology have been used to provide transparent pricing based on the demands of the consumers. The power demands at the consumers’ site is calculated without the human involvement using the Internet of Things and the same is uploaded in the cloud. In reactive power pricing, the system operator acts as a mediator between the suppliers and consumers. Based on the demand and availability of power, the system operator provides the cost for the service to the consumer through cloud.

Different from conventional generators, wind power is an intermittent energy source, power system dispatch and control is confronted with new challenges. This paper establish the mathematical model of wind power and energy storage system for simulation and analysis, and study the wind power prediction using statistical methods and physical methods, and study the key technologies of automatic generation control and automatic voltage control which were in the large-scale wind power and energy storage system. The results show that the wind power prediction is reasonable for grid, and the power quality and stability of wind farm connected to power grid can be well improved by battery energy storage.

According to the characteristics of double fed asynchronous generator rotor energy flow, research and design based on the DSP control with two-way flow of energy function of Dual PWM converter and discusses the grid side converter control method of Dual PWM converter in particular. The wind turbine simulation model is established by using the electromagnetic transient PSCAD/EMTDC software. The simulation system is used to simulate the P, Q decoupling control and maximum wind energy tracking control of the generator. Wind is a natural phenomenon generated by the solar radiation heat, the earth's surface caused by uneven heating of the atmosphere. It is estimated that only 1% of the wind on the ground will be able to meet the needs of the world's energy. With the continuous improvement of the level of wind power generation technology, the cost of wind power gradually reduced, considering environmental benefits, the cost will be close to the cost of coal-fired power generation. Therefore, great efforts to develop wind energy as the representative of the renewable energy and new energy, to achieve sustainable development, has become the consensus of the whole society, strategic choice to solve the energy crisis and environmental problems. 2.Overview of control technology of doubly fed wind power gener ation Wind power is the kinetic energy contained in the natural wind into electrical energy in the process, the wind turbine wind energy capture and convert it into mechanical energy, driven by rotary generator, and the generator for converting mechanical energy conversion into electrical energy. As countries around the world pay more attention to wind power, wind power has become the world's fastest, most widely studied and applied new energy technology. With the development of wind power technology, wind turbine, wind turbine generator, converter and its control system and the way of the wind turbine, there are different types of. Among them, the doubly fed wind power generation system due to the converter control capacity is small, the speed of operation range wide characteristics become currently the world's most widely used VSCF wind power generation system. Variable speed constant frequency generator in asynchronous generator rotor side applied three-phase low frequency current to realize AC excitation, the output power is constant frequency and constant voltage amplitude, frequency, phase of the exciting current control. At the same time, the active power and reactive power decoupling control of the generator is realized by using the vector control technology. Control active power capable of adjusting the rotation speed of the wind turbine, to capture the maximum wind power tracking control; regulation of reactive power adjustable power factor and improve the dynamic and static stability of the wind turbine and power system operation. In addition, the VSCF wind power generation technology, so to achieve good flexible connection between the generator and power grid system, compared with the traditional constant speed constant frequency generation system easier to achieve grid connected operation and operation

Offshore oil and gas platforms can accelerate their shift towards lower greenhouse gases emissions by combining wind power generation and energy storage systems. However, the variability of the wind resources and power demand, and the limited storage capacity make the design of the system particularly challenging. We present a modelica library at its early stage of the development and yet with promising results. The model will be used to simulate the dynamic of the whole system for a long period of time using simplified power components and balanced micro grid. This paper shares some preliminary results by applying the model on a data set of wind resources and power demand from the North Sea. The results are the power system dynamics and an approximation of the mass of greenhouse gas emissions. On the long term the model will be applied to determine the right control and optimization strategy to control the energy system towards lower greenhouse gas emissions without compromising the balance between the power supply and demand.

Hydrogen energy, as a medium for long-term energy storage, needs to ensure the continuous and stable operation of the electrolyzer during the production of green hydrogen using wind energy. In this paper, based on the overall model of a wind power hydrogen production system, an integrated control strategy aimed at improving the quality of wind power generation, smoothing the hydrogen production process, and enhancing the stability of the system is proposed. The strategy combines key measures, such as the maximum power point tracking control of the wind turbine and the adaptive coordinated control of the electrochemical energy storage system, which can not only efficiently utilize the wind resources but also effectively ensure the stability of the bus voltage and the smoothness of the hydrogen production process. The simulation results show that the electrolyzer can operate at full power to produce hydrogen while the energy storage device is charging when wind energy is sufficient; the electrolyzer continuously produces hydrogen according to the wind energy when the wind speed is normal; and the energy storage device will take on the task of maintaining the operation of the electrolyzer when the wind speed is insufficient to ensure the stability and reliability of the system.

This paper presents a reactive power optimization model that is based on successive quadratic programming (SQP) methods. Mathematical formulation and unified algorithm suppose different objective functions (OF) of reactive power optimization, depending on type and purposes of current reactive power control or planning problem. A bicriterion reactive power optimization model, that represents compromise between economical and security objective functions, is proposed. An efficient algorithm for approximation of initial problem by quadratic programming problem is described. The quadratic programming problem (QP) is solved on the basis of the Newton type quadratic programming method. A modified successive quadratic programming method was developed, that provides reliable convergence of the SQP method.