中文摘要：

电容式电压互感器（CVT）传变特性使继电保护装置获得二次电压和电流瞬时值不再满足被保护输电线路分布参数模型，影响了能量平衡保护的可靠性。该文提出基于虚拟CVT的能量平衡保护新方案。该方案将保护获得的电流量经过虚拟数字CVT传变后，再进行能量平衡保护计算。为论证基于虚拟CVT能量平衡保护的可靠性，文中从理论上分析均匀输电线路分布的电压和电流量经过同样的CVT传变后，暂态电压与电流的相互关系仍满足输电线路分布参数模型，并进一步推论出线路分布电压和电流量经过相同的线性电路传变后其相互关系也不发生改变，这就为输电线路保护应用传变后信息量提供了理论参考。最后用ATP仿真验证基于虚拟CVT能量平衡保护新方案。

英文摘要：

Because of the transfer characteristics of capacitive voltage transformer （CVT）, the interaction between secondary voltage and current, which are input signals to relay protection device, cannot satisfy the distributed parameter model of protected transmission line. Thus the reliability of protection based on energy balance is unavoidably under its influence. A new scheme of the protection of energy balance which applying virtual CVT was presented. The protection energy balance is calculated after currents passing through virtual CVTs. In order to study the reliability of protection based on energy balance of which applying virtual CVT, it was analyzed in theory that the interaction between transient voltage and current still satisfies a uniform transmission line＇ s distributed parameters model after distributed voltage and current pass through the same CVTs. Then the conclusion was deduced that the interaction between distributed voltage and current on a uniform transmission line is changeless after they pass through the same linear circuit. This conclusion provides a theoretic basis for the information of transmission line protection after applying transformer. Finally, simulation results of ATP verify the new scheme of the protection based on the principle of balance of energy which applying virtual CVT.