MMC Instantaneous Power Loss Calculation Method Based on Mathematical Model of Virtual Bridge Arm
A mathematical model and calculation method technology, applied in the direction of output power conversion device, AC power input conversion to DC power output, climate sustainability, etc., can solve the comprehensive evaluation of the inapplicable scheme design system and the inability to obtain the MMC switching frequency error , Simulation hardware has high requirements and other issues, to achieve the effect of both speed and accuracy, optimize the design of the scheme, save time and cost
Active Publication Date: 2020-04-28
XI AN JIAOTONG UNIV
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Problems solved by technology
The first type of method can be used to quickly and conveniently estimate the MMC loss, but it can only calculate the average power loss, and the accurate switching frequency of the MMC cannot be obtained under certain modulation and voltage balancing strategies, so there will be problems when calculating the switching loss large error
Although the second type of calculation method can often achieve ideal accuracy, simulation has high requirements on hardware and takes a lot of time, which is not suitable for pre-engineering scheme design and comprehensive evaluation of the system
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Embodiment
[0070] Taking the Kangbao Station of Zhangbei Project as an example analysis, the main parameters of the system are shown in Table 1, and the system structure diagram is shown in figure 2 As shown, the system uses half-bridge sub-modules such as image 3 shown.
[0071] Table 1 Main parameters of Kangbao station system
[0072]
[0073] In the first step, input the main system parameters in Table 1 into VAMM, and set the following operating conditions at the same time: the system works in a full-load rectification state (that is, P=750MW, Q=0), m=0.99, and input them into VAMM, for example To calculate the loss of the upper bridge arm of phase a.
[0074] In the second step, in this example, the system uses the nearest level approach modulation strategy and the traditional capacitance voltage sorting voltage equalization strategy, and inputs these two strategies into the VAMM.
[0075] The third step is to run VAMM to obtain real-time data: i arm and S i . The obtain...
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The invention discloses a method for calculating instantaneous power loss of MMC based on a mathematical model of a virtual bridge arm. Bridge arm mathematical model, at the same time specify the location of the target bridge arm; (2) Determine the modulation and voltage equalization strategy of the MMC system; (3) Run the virtual bridge arm mathematical model to obtain the instantaneous bridge arm current and the i-th sub-module on the bridge arm (4) according to the output result of step (3), judge the on / off state of device in each sub-module, combine the conduction loss characteristic of switch device, calculate the conduction loss of each device of sub-module; (5) According to the output result of step (3), combined with the on / off status of the sub-module devices at the previous moment, it is judged which devices have switched actions, and according to the switching loss characteristics of the switching devices, the switching of each device is calculated. loss.
Description
technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a calculation method for instantaneous power loss of MMC based on a mathematical model of a virtual bridge arm. Background technique [0002] Modular Multilevel Converter (MMC) has the characteristics of flexible control, low switching frequency, and low harmonic content on the AC side. It is widely used in high-voltage and high-power occasions, especially promoting the development of high-voltage direct current transmission technology. For example, the Zhangbei project currently under construction is a flexible DC project with the highest voltage level and the largest transmission capacity in the world, and its capacity has reached ±500kV and 3000MW. Studying the loss calculation of MMC can provide a theoretical basis for device selection and heat dissipation system design, and also lay a foundation for optimizing its topology and control strategy. Therefo...
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IPC IPC(8): H02M7/483
CPCH02M7/483H02M1/0054Y02B70/10
Inventor 王跃尹诗媛尹太元王璋段国朝李凯徐鹏帆
Owner XI AN JIAOTONG UNIV