STATCOM Wye Topology Eliminates Phase Reactors

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Solution Overview

Problem

Current STATCOM stations with delta topology require phase reactors, which increase the physical footprint and maintenance complexity, and are costly due to the need for additional components like busbars and supports.

Innovation Solution

Implementing a wye-connected STATCOM topology that utilizes transformer leakage reactance instead of phase reactors to provide impedance, reducing the number of components and footprint, and allowing for a more compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phase reactors are used in delta topology STATCOM, then required impedance is provided for reactive power generation, but physical footprint and device complexity increase

Engineering Contradiction:
Improvereactive power generation capabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the function of the phase reactor with the transformer by utilizing the transformer's leakage reactance to provide the required impedance. This eliminates the need for separate phase reactors and reduces the number of components in the STATCOM system.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The transformer is given a dual function: it not only performs voltage transformation but also provides the impedance necessary for reactive power generation through its leakage reactance. This multi-functionality reduces the overall component count and simplifies the system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If phase reactors are used in delta topology STATCOM, then impedance is provided, but physical footprint and area increase

Engineering Contradiction:
Improveimpedance provisionVSAvoidstation footprint
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the function of the phase reactor with the transformer by utilizing the transformer's leakage reactance to provide the required impedance. This eliminates the need for separate phase reactors and reduces the number of components in the STATCOM system.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If delta topology with phase reactors is used, then reactive power control is achieved, but maintenance complexity and cost increase

Engineering Contradiction:
Improvereactive power controlVSAvoidmaintenance complexity
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent extracts and eliminates the phase reactor component from the system by using the transformer's leakage reactance instead. This removal of the phase reactor directly reduces maintenance complexity and associated costs.

Inventive Principle:
Principle #2Taking out (Extraction)

4Object-affected harmful factors

If phase reactors are placed outside the valve hall, then electromagnetic interference with steel beams is avoided, but device complexity and footprint increase

Engineering Contradiction:
Improveelectromagnetic interferenceVSAvoidsystem configuration
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the phase reactor component from the system by using the transformer's leakage reactance instead. This removal of the phase reactor directly reduces maintenance complexity and associated costs.

Inventive Principle:
Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly reduces the size, complexity, and cost of the STATCOM station while simplifying the circuitry and eliminating the need for external phase reactors, thereby minimizing maintenance and electromagnetic interference.

Implementation Method 1

the transformer leakage reactance provides the impedance for the necessary voltage difference between the grid and the MMC

Methodology Applied
Scientific EffectTransformer leakage reactance: Electromagnetic Induction

Data Source

PatentEP3888218B1Statcom arrangement without phase reactors
Publication Date: 2022.11.09 HITACHI ENERGY SWITZERLAND AG
  • EP3888218B1 patent drawingFigure 1~2
  • EP3888218B1 patent drawingFigure 3a~4
  • EP3888218B1 patent drawing

AI summary

The present disclosure relates to a STATCOM arrangement (1) comprising an MMC (2) and a transformer arrangement (3) arranged to be an interface between the MMC (2) and an AC grid. The MMC (2) is connected in a wye topology with a plurality of converter arms, one for each phase of the AC grid, each arm comprising a plurality of chain-linked converter cells. The transformer arrangement (3) is arranged to interface each of the arms of the MMC (2) with a respective phase of the grid, and arranged to for each of the converter arms produce leakage reactance resulting in reactance in series with the arm which obviates the need for a phase reactor connected in series with said arm.