SC for Power Distr

SC for Power Distribution

Engineering case


The SC can be used to enhance the terminal voltage after long-distance power transmission for corridors (10kV,35kV,66kV etc.) in order to optimize the power quality of enterprises and civil use. It is mainly used for long-distance power distribution lines. Taking 35kv or 10kv power distribution as an example. The terminal voltage becomes weaker and weaker resulting in negative effects for civil use and loads of enterprises under abnormal operation,which is attributable to long power transmission line far outstrips normal power transmission radius.Conventional parallel capacitance compensation (pole-mounted capacitor) or regulating transformer (1:1) cannot solve the problem radically under such circumstances, and furthermore, the compensation effect may rapidly worsen as the terminal power load increases, RXPE's SC can solve this via shortening equivalent electric distance so as to enhance the terminal voltage of power transmission lines effectively.

Pole-mounted 10kV medium-voltage series compensator


Container-type 10kV medium-voltage series compensator

After SC is inserted, the terminal voltage (light load or heavy load) can remain within a qualified range, which guarantees the normal terminal voltage of distribution network in remote areas. The diagram below shows voltage distribution status of Qinggouzi 10kV power distribution project (58km),in which the voltage distribution is improved greatly and the line losses are reduced remarkably after SC is inserted.
Line voltage comparison with series/no series compensation:

Typical Performance
	CSG Honghe10kV SC，10kV，2Mvar， 2sets，2014
	SGCC Yanbian 10kV SC，10kV，2Mvar， 2sets，2013

CSG Yunnan 10kV MVSC Project

Customer Needs

In rural areas, electric power is mainly transmitted via 6kV~35kV overhead lines, the voltage declines severely along the line if such distribution network is too long. Take 10kV distribution networks for example, usually the normal radius of a 10kV line is around 7~8km, however in some cases this length can reach 20km or even longer as loads are far away from each other.
Theoretically it is suggested to increase the line voltage to transmit to longer distances, however this is normally not economic as the total loads are merely 1MW, resulting as a bad investment.
MV SC is the best solution for such 6kV~35kV long distance transmission lines. It is cost-effective, easy to install and operate, and maintenance free.

10kV SC Introduction

Overhead lines are inductive, when current flows along the line, voltage declines at the same time. If the reactance could be reduced by MV series capacitors, the voltage will then be raised up.The MV SC is usually installed at the middle of the line, and X_C is usually 50% ~100% of X_L. If a MV SC is installed in the line, the voltage along the line will be improved like this：

CSG Yunnan 10kV SC

Yunnan is a province with much mountains and villages located far away from each other, also suffering from low voltage problems due to long distance distribution lines. RXPE had delivered one set of 10kV/ 450kvar SC (50% compensation degree). The SC protection scheme is designed as spark gap and bypass circuit breaker. Assuming if aline fault occurred, the spark gap will be triggered and circuit breakers bypassed to protect the SC.

The SC is designed of a containerized solution, with all the equipments assembling and testing done within factory, makes it very easy to ship, install and commission at site, just plug and play.The MV SC is equipped with a remote event report system that automatically sends operation events to customer staff at preset cell phone numbers. The only thing to do is just receiving operation status at mobile phones and maintain only in case if needed.

Customer Benefits

CSG Yunnan MV SC had been commissioned and put into commercial operation in the year 2015. It had completely solved the low voltage problems and significantly reduced the line loss of their 10kV distribution networks.

SC for Power Distribution

Technical principle

Typical references

Engineering case