12 Units of LSVR 90 0.4 4 for Voltage Regulation in Licheng Shanxi

1. Project Background & Challenges

1.1 Project Background

Certain rural distribution areas in Licheng County, Changzhi City, Shanxi Province, faced typical "end-of-line voltage quality" issues. With the rapid growth of rural electricity loads and the implementation of distributed photovoltaic (PV) policies, the existing distribution infrastructure faced dual pressures:

• Heavy Load Low Voltage: Due to excessively long power supply radii and small conductor cross-sections, the terminal voltage at consumer premises dropped as low as 200V during peak hours, failing to meet national standards and preventing household appliances from starting.

• PV Overvoltage: During peak PV generation periods with low local demand, reverse power flow caused voltage spikes at access points. This led to frequent tripping of PV inverters, affecting residents' generation revenue.

1.2 Objectives

The power supply company required a low-voltage regulation solution capable of automatic, rapid response and bi-directional adjustment to stabilize terminal voltage within the national standard range (220V ±7%) without large-scale line reconstruction.

2. Technical Solution & Parameters

For the complex conditions of this area, 12 units of LSVR-90-0.4/4 low-voltage automatic voltage regulators were selected. The equipment is strictly designed in accordance with IEC 60076-1:2011 and relevant GB standards. The equipment utilizes series compensation principles, achieving precise voltage adjustment by automatically switching transformer taps.

2.1 Core Technical Parameters

The specific configuration for this project is as follows:

2.2 Drawings

The LSVR Low-Voltage Automatic Voltage Regulator is mainly composed of a compensation transformer, an intelligent regulation switch, a control system and auxiliary systems. Its wiring schematic diagram is shown as follows:

3. Manufacturing & Craftsmanship

3.1 Core Component Selection

• Autotransformer: Adopts S13 or higher energy efficiency core design concepts, using high-permeability oriented silicon steel sheets to ensure a total loss of ≤ 0.5%, significantly enhancing long-term economic operation.
• Intelligent Controller: Integrated microprocessor monitors three-phase voltage in real-time, controlling the on-load tap changer based on logic judgment.
• Protection Design: Tailored for Shanxi's large seasonal temperature variations and dusty environment, the enclosure uses high-corrosion-resistant materials with a protection rating of IP54. The cooling fan inlet is equipped with special dust filters to prevent internal temperature rises caused by fine dust accumulation.

4. Testing & Verification

All 12 units underwent rigorous Routine Tests before leaving the factory:

• Mechanical Operation Test: Verified the accuracy and stability of the 5-tap changer under continuous operation.
• Regulation Logic Verification: Simulated input voltages from 160V to 260V to verify precise triggering of step-up or step-down actions.
• Temperature Rise & Insulation Test: Ensured thermal stability and insulation reliability under high load conditions.
• Automatic Bypass Test: Simulated control power failure to verify the bypass switch's capability to switch within 100ms-200ms, ensuring no sustained power interruption for users.

5. Installation & Summary

5.1 Implementation

The equipment was Pole-mounted, installed directly at the end of the distribution zone or at the start of branches with severe voltage fluctuations. This eliminated the need for additional land acquisition, shortened construction cycles, and reduced overall project costs.

5.2 Results

• Significant Improvement in Voltage Quality:Since commissioning, the terminal voltage—which previously dropped below 200 V—has been stably compensated to over 200 V, achieving full compliance with national grid standards.
• PV Overvoltage Suppression: During midday PV generation peaks, the equipment automatically entered step-down mode, preventing inverter trips caused by overvoltage.
• Load Balancing: The individual phase regulation function mitigated voltage differences caused by single-phase load imbalances, extending the lifespan of the distribution transformer.