Application and challenge of a direct current network modeling technology

The direct current network is by the interconnected energy transmission system that makes up in the form of direct current of a large number of direct-flow ends, can realize new smooth access of energy, gain merit, inactive power one control independently, the power supply mode with stronger adaptability, the flexible and safe trend is controlled. At present, the development of energy strategy in the world offers the broad space for application of the direct current network. Look from field of transmitting electricity, the traditional power system is accepting the new energy of the super large-scale, high fluctuation and promoting user’s power supply quality, face the technological challenge, and the direct current network depends on one’s own flexible controllable advantage, become a kind of solution with prospect. Look from distribution field, consider the direct-flow load represented by electric automobile, system equipment of information is increasing constantly, can reduce the links of changing flowing through setting up direct-flow distribution network, reduce and loss; And the direct-flow distribution network of city can be reducing to transmit electricity the simultaneous increase of the demand of the corridor transports the capacity, considered to be a kind of attractive solution.

Because the direct current network has a large number of electric and electronic devices, and every device structure is complicated, the attitude is thrown and cutting the device to include a great deal of fast temporarily; Meanwhile, the direct current network runs to need to observe the fairly long trends, so the direct current network builds and imitates the challenge that real technology faces model adaptability, accuracy.

First of all, it has requirement for yardstick of different time that the direct current network analyses and researches, also there is no leading frequency. The looks amount model of the single frequency characteristic can’t meet the demands. So direct current modeling of network need, study detailed accurate model, model on average and allow the intersection of steady state and the intersection of model and 3 model of different levels, used in apparatus one grade of emulation, the project analysis of the control system and artificial analysis of big system separately.

1)Detailed accurate model. The slight switch characteristic that the model can be fully embodied, can make the prompt response in as to the thing that the trouble. The model is accurate, complicated, artificial and slow for modeling.

2)Average model. Model neglect the intersection of switch and detail, increase ideal, suppose, for instance the intersection of three-phase and voltage, electric current balanced, etc, keep the main dynamic characteristic of the apparatus. The main shortcoming of the model is that the accuracy in case of trouble is unsatisfactory.

3)Allow steady state model. The model belongs to the equivalent power model of steady state of great network analysis, the model neglects the electric characteristic of changing the flowing device, use controlling amount of steady state that the control system outputs as the output of the equivalent power directly, suitable for the characteristic analysis of the big system.

Secondly, the model on the basis of the new direct current network apparatus of the electric electron is complicated, there is deficiency on efficiency and precision in the traditional modeling method, need it according to different device characteristics, study the new model fast and accurately, including AC/DC changes direct-flow apparatuses such as flowing device, DC/DC changer, direct-flow circuit breakers, direct-flow choppers and only bending over battery direct current and supporting,etc..

Module much level changes the flowing device (MMC) New for progress of studying and making model great. MMC is the trend that high-power changes the flowing device in the direct current network, the structure is complicated, level counts and reaches level of 250- 500 grades, the artificial efficiency of the detailed accurate model is extremely low, must study the high-efficient fast model. The proposition of David’s south equivalence model is its great progress. The basic thought of MMC model of David’s south equivalence is to describe all switches to be different resistance of hindering value, when it is open to lead in the switch, resistance value is similar to 0, when the switch is shut off, resistance value is very large. Can use the intersection of David and south equivalence accurate the intersection of simulation and every stature internal course of module, can carry on the artificial research of the valve trouble or sub module broken circuit; Meanwhile, MMC circuit of David’s south equivalence is artificial and fast, the artificial precision has no loss.

DC/DC change person who flow apply to already building up high pressure mainly direct-flow circuit interconnected to insert large-scale the intersection of direct current and network with the direct-flow transmission line of electricity of vertically-hung scroll of painting or calligraphy in direct-flow end of grade in different voltage. Detailed modeling has not only faced the problem that structural complicatedness, switch are numerous in quantity, and the uncertainty of the standard scheme has hindered the progress of detailed modeling especially at present. Meanwhile, the equivalent model based on detailed model needs encapsulating and changing the flowing device and touching off the control system, put forward the unified transmission function or circuit, develop more slowly.

Topological structure and movement time of the direct-flow circuit breaker, and protect movements with big influence to the overvoltage of the analyticl system. But because of designing the difference, the topological structure, making and breaking and delaying time, responding to the characteristic inconsistently of the circuit breaker, the accurate direct-flow circuit breaker model really builds and imitates an undecided problem as the direct current network.

Other research focuses also include bending over the array model, the modeling of the storage battery all.

The application and challenges of 2 direct current networks of artificial technology

The development of the direct current network needs support of artificial ability too, has proposed the requirements of two respects of steady state and temporary attitude. The requirement for the artificial ability of the steady state mainly reflects in calculating in trend. The trend of the direct current network calculates and exchanges the electric wire netting there are greater differences. The changing the flowing device of direct current network has stronger control abilities, can be deemed the constant pressure source, the source or permanent power source flows permanently. In case of constant pressure source, the trend equation of the circuit can be simplified as the linear equation. Under the circumstances that the permanent power controls the mode, the trend equation can’t be simplified as the linear equation. The direct current network controls the mode to have direct influence on calculating model and computing technology in trend. According to different control modes, need to increase the corresponding parameter in the trend equation, and study different nodal types of direct current and it is the most key challenge to promote precision and speed that the trend disappears. The requirement for the artificial ability of the attitude mainly reflects in electromagnetic temporary attitude emulation (EMTP) temporarily Field. The direct current network changed more flowing device and many switcheses to lead to the fact the unsatisfactory and artificial speed of accuracy of existing EMTP is slow.

In switch algorithm, algorithm of inserting etc. and it asks solutions and little steps to be can in case of not reduced the precision in algorithm in long switch at the same time, the step of promoting EMTP is long, thus promote efficiency. Person who insert algorithm face from the intersection of line and artificial the intersection of analysis and tool mainly, and little the intersection of step and long switch algorithm face the real-time artificial analysis tool.

Meanwhile, parallel computation is the best means to promote artificial efficiency. The main thinking of parallel computation is to divide the interface of the network to divide the whole electric wire netting into different sub electric wire netting through running side by side, assign on independent CPU to calculate. A existing one run side by side computing technology have long to transmit electricity mainly line solve the intersection of coupling and law and node, split law. It is long to transmit electricity in the line and solve coupling law and utilize the equation of fluctuating to describe that transmit electricity in the line at a long distance, solve the coupling network naturally, its limitation lies in: Dividing the network needs utilizing and is distributed in the parameter circuit long, lack universality. Node split law some divide the network into two in border, get the leading and receiving burst and nodal relation matrix of border of each sub network, this law has not divided the restriction of the network, have commonability, but efficiency is lower than to transmit electricity in the line and divide the network.

The direct current network has dynamic course as making and breaking the electric electronic element fast soon at the same time and if the steam turbine adjusts speed, slow dynamic course which the electric automobile charges etc., can ask and solve dynamic course and slow dynamic course soon respectively, carry on much speed emulation. Mixed emulation of the attitude temporarily of electromagnetism while including attitude and electromagnetic mixed emulation, little step of the attitude temporarily temporarily of the electromechanics long and long with vigorous strides in many speed emulation. The artificial technology of mixing of the attitude has already been applied to the field of transmitting electricity of direct current conventionally in the attitude and electromagnetic temporarily temporarily of the electromechanics, and many speed is electromagnetic temporarily the mixed emulation of the attitude is the new product of the direct current network. The electromagnetic artificial system of many speed resolves a certain network into two parts, among them change the flowing device (VSC, MMC) with high-speed switch one Wait for, put into artificial system of the high speed, include with close power, electrical machinery of coupling it,etc. at the same time, and the external power system can be adopted and imitated long more than the great artificial step. The electromagnetic emulation of much speed is worse than generally electromagnetic and artificial stability, the error is great too, it is a kind of speed and compromise of precision.

In addition, the real-time simulation emulation of the direct current network is in the ascendant too. The research of the physical analogy platform adopts the simulation experiment to carry on artificial research to the relevant characteristic of the direct current network, realize the emulation of the direct current network through the simulation experiment under the little electric current situation of the low-voltage, have already found relevant application in Britain, Continental Europe and Japan. Count mould mix artificial technology include, connect hardware of controller in ring technology (HIL) Connect technology with the power. Because there are many switch components of the direct current network, precision and speed that HIL needs to promote I/O control signal notably are required, only introduced to the scene and can programme a array (FPGA) Wait for the microelectric technique to meet its requirement. Connect in the power technically, it is the greatest challenge to put the apparatus in high-power work.

3 concludes the speech

Modeling technology? ? ? The artificial algorithm will play an important role in research and application of the direct current network. The modeling of the network key equipment of direct current, including AC/DC changes flowing device and DC/DC changer, direct-flow switchgear and direct current to support etc., it is a subject for research of the artificial modeling technology of the direct current network. At the same time, because of the emergent novelty of the direct current network, need to carry on the technological innovation in fields such as the artificial algorithm, attitude artificial technology and real-time simulation emulation temporarily of steady state,etc. to the direct current network, meet the artificial requirement for the large-scale complicated power system including the direct current network in the future.