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This paper proposes a new backup protection scheme, named coordinated backup protection (CBP) scheme, for distribution networks containing distributed generation. The proposed protection scheme takes into account the issues faced by traditional backup protection, such as difficulty in setting parameters and complex cooperation, and considers the features of distribution networks, such as changeable power flow because of high penetration of distributed generation sources and insufficient measuring quantities. The CBP scheme includes two aspects: coordinated substation protection and regional master substation protection, who also work as nearby backup protection and remote backup protection respectively. The two protections support each other by local information coordination and regional information sharing, in order to improve the reliability of fault identification. The configuration principles and performances of the proposed backup protection scheme are addressed in the paper. Different fault conditions in the IEEE 14-node system have been used to illustrate and verify the feasibility of the CBP scheme.

Summary Increasing penetration of distributed generators (DGs) is gradually changing distribution networks from a radial structure into a multi‐source one. In addition, some distribution systems are in slightly meshed structures for the interest of smart grids. The traditional protection philosophy is being challenged because the coordination among protection devices is affected by the bi‐directional power flow and the intermittent nature of DGs. This paper proposes a communication‐based protection algorithm considering the impact of bi‐directional power flow in distribution networks with DGs. The proposed algorithm detects and isolates fault sections by a 2‐step search procedure. In step 1, an injected power calculation, in conjunction with a tabu search algorithm, is used to narrow down the fault‐section search region by using the voltage measurements. Step 2 precisely detects the fault section by comparing current phase angle changes. A typical distribution network in Beijing, China and the IEEE 30‐node system are used to illustrate and validate the proposed method.

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