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Multi-target current reference instruction calculation method and system suitable for non-ideal power grid

A technology of current reference and calculation method, which is applied in the direction of single-net parallel feeding arrangement, multi-phase network asymmetry reduction, multi-phase network elimination/reduction of asymmetry, etc., can solve problems such as unsatisfactory suppression of power pulsation, and achieve easy Digital implementation, improvement of grid-connected power quality, simple and reliable method

Inactive Publication Date: 2020-01-10
NANJING UNIV OF SCI & TECH
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, most of the actual power grid conditions are non-ideal. In addition to the fundamental frequency positive sequence component, the common non-ideal grid voltage also contains fundamental frequency negative sequence components, 5 times frequency negative sequence components and 7 times frequency positive sequence components, etc. , which causes multiple frequency pulsations in the active power and reactive power. At this time, the sinusoidal current setting cannot meet the demand for suppressing power pulsation

Method used

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  • Multi-target current reference instruction calculation method and system suitable for non-ideal power grid
  • Multi-target current reference instruction calculation method and system suitable for non-ideal power grid
  • Multi-target current reference instruction calculation method and system suitable for non-ideal power grid

Examples

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Embodiment 1

[0112] This example builds the figure 1 The simulation model of the multi-objective current reference command calculation system suitable for non-ideal power grids is shown, and the control method is finite set model predictive control. The grid-connected control target of Embodiment 1 is that the three-phase grid-connected current is sinusoidal and balanced, and the specific parameters are shown in Table 1 below. In this example the active power reference value P * 0 =10(kW), reactive power reference value Q * 0 =0(Var). The simulation result of embodiment 1 is as Figure 4 as shown, Figure 4 (a)~(d) are the simulation results of the three-phase reference current, grid current, FFT analysis of grid current, grid instantaneous active power, and grid instantaneous reactive power respectively. Figure 4 It can be seen from the figure that the current reference command calculation system suitable for non-ideal power grids can give the current reference that meets the cont...

Embodiment 2

[0116] This example builds the image 3 The simulation model of the multi-objective current reference command calculation system suitable for non-ideal power grids is shown, and the control method is finite set model predictive control. The goal of the grid-connected control in Example 2 is to eliminate the 2nd, 4th, and 6th fluctuations of reactive power. The specific parameters are shown in Table 1. In this example the active power reference value P * 0 =10(kW), reactive power reference value Q * 0 =0(Var). The simulation result of embodiment 2 is as Figure 5 as shown, Figure 5 (a)~(d) are the simulation results of three-phase reference current and grid-connected current, grid-connected instantaneous active power, grid-connected instantaneous active power FFT analysis, and grid-connected instantaneous reactive power, respectively. Figure 5 It can be seen from the figure that the current reference command calculation system suitable for non-ideal power grids can giv...

Embodiment 3

[0118] This example builds the image 3 The simulation model of the multi-objective current reference command calculation system suitable for non-ideal power grids is shown, and the control method is finite set model predictive control. The grid-connected control goal of Example 3 is to eliminate the 2nd, 4th, and 6th fluctuations of reactive power. The specific parameters are shown in Table 1. In this example the active power reference value P * 0 =0(W), reactive power reference value Q * 0 = 10 (kVar). The simulation result of embodiment 3 is as Figure 6 as shown, Figure 6 (a)~(d) are the simulation results of the three-phase reference current and the grid-connected current, the grid-connected instantaneous active power, the grid-connected instantaneous reactive power, and the grid-connected instantaneous reactive power FFT analysis respectively, from Figure 6 It can be seen from the figure that the current reference command calculation system suitable for non-idea...

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Abstract

The invention discloses a multi-target current reference instruction calculation method and system suitable for a non-ideal power grid. The system comprises a three-phase three-level grid-connected inverter and a digital calculation processing module. The digital calculation processing module comprises a sampling unit, a phase locking unit, a harmonic component extraction unit and a current reference instruction calculation unit. The method comprises the following steps of using the sampling unit to collect three-phase power grid voltage information; acquiring power grid voltage phase information through the phase locking unit; extracting harmonic component information in a non-ideal power grid voltage through the harmonic component extraction unit; and then calculating a current referenceinstruction under three power and current control targets in a current reference instruction calculation unit based on an instantaneous reactive power theory. In the invention, hardware cost is low,current reference calculation of various control targets of an NPC three-phase three-level inverter under a non-ideal power grid condition can be realized, the method and the system are suitable for various power application occasions, and network access electric energy quality of the inverter is improved.

Description

technical field [0001] The invention relates to the technical field of DC-AC converters of electric energy conversion devices, in particular to a method and system for calculating multi-target current reference commands applicable to non-ideal power grids. Background technique [0002] NPC (Neutral Point Clamped) three-phase three-level grid-connected inverter acts as an energy conversion interface in a distributed grid-connected power generation system, and its working status has a great impact on the quality of power entering the grid. Under ideal grid conditions, the grid voltage only contains the fundamental frequency positive sequence, and the existing current reference commands generally use sinusoidal current reference directly. [0003] However, most of the actual power grid conditions are non-ideal. In addition to the fundamental frequency positive sequence component, the common non-ideal grid voltage also contains fundamental frequency negative sequence components,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/18H02J3/24H02J3/26
CPCH02J3/18H02J3/24H02J3/26H02J3/38Y02E40/30Y02E40/50
Inventor 闫涵王新杰芮苏媛
Owner NANJING UNIV OF SCI & TECH
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