GB/T 20995-2020 in English
VALIDStatic var compensators(SVC)—Testing of thyristor valves
- Issued on:2020-12-14
- Implemented on:2021-07-01
- File Format:PDF
- Delivery:Via email within 5 business days
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《GB/T 20995-2020静止无功补偿装置 晶闸管阀的试验》由TC60（全国电力电子系统和设备标准化技术委员会）归口，TC60SC2（全国电力电子系统和设备标准化技术委员会输配电系统电力电子技术分会）执行，主管部门为中国电器工业协会。
Introduction
Analysis of the core content of the standard
GB/T20995-2020 is the authoritative standard for the testing of thyristor valves for static VAR compensation devices (SVCs) in my country. It is equivalent to the IEC61954:2017 international standard, and focuses on standardizing the testing requirements for thyristor controlled reactors (TCRs), thyristor switched reactors (TSRs) and thyristor switched capacitors (TSCs) valves.
Major Technical Updates
| Main Revision Points | 2007 Edition | 2020 Edition |
|---|---|---|
| Test Safety Factor | 1.3(Partial Test) | Uniformly adjusted to 1.15 |
| Partial Discharge Test | Unspecified Requirements | New Factory Test Requirements |
| Redundant Thyristor Stage Processing | Unspecified Proportional Factor | Added kn=Ntot/(Nt-Nr) Calculation Formula |
Detailed explanation of key test items
1. Insulation test system
The standard constructs a three-level insulation verification system:
- Valve end-to-ground insulation: Including AC withstand (1min/10min) and 1.2/50μs lightning impulse test
- Valve-to-valve insulation: Special requirements for multiple valve units (MVU)
- Valve-to-valve insulation: 20/200μs operation impulse test as the core
2. Innovations in operation tests
The new standard specifically emphasizes:
- The periodic trigger test needs to reproduce the critical period of 0.2ms before current zero crossing to 1ms after current zero crossing
- The loss margin of temperature rise test is increased from 5% to the most severe working condition + 5%
- A fault handling mechanism that allows 3 repair opportunities is clearly defined
Implementation suggestions
Test scheme optimization
Differentiated test strategies are recommended for different types of valve bodies:
| Valve type | Key test items | Special requirements |
|---|---|---|
| TCR valve | 5.4.1 Periodic trigger test | The full control range of αmin~αmax needs to be verified |
| TSC valve | 6.4.1 Overcurrent test | Bidirectional current pulse verification |
| MVU structure | 5.2/6.2 Valve test | Phase-to-phase insulation verification is required |
Technology evolution direction
The standard reflects three major technological trends:
- Stricter electromagnetic compatibility requirements: New 7.2.3 Non-periodic triggered EMC verification
- Quantitative reliability management: Table 2 specifies the number of faulty thyristor stages allowed
- Test efficiency improved: 10min short-time test replaces the original 30min long-time test
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