Multi-stage expansion planning of energy storage integrated soft open points considering tie-line reconstruction

Protection and Control of Modern Power Systems

Table 5 Cost–benefit result in multiple stages

Annual cost (10⁴RMB)	Electricity purchase cost	Power loss cost	Voltage deviation cost	DG curtailment cost	Total investment cost	Total cost
Stage I
Case I	2556.12	38.79	6.29	2.88	130.24	2695.53
Case II	2730.63	44.93	8.04	38.50	–	2822.10
Stage II
Case I	2440.32	41.56	6.20	9.12	178.29	2633.93
Case II	2628.55	52.09	8.37	36.01	–	2725.02
Stage III
Case I	1936.37	45.34	5.40	2.06	304.37	2248.20
Case II	2485.24	56.23	8.38	80.15	–	2630.00
Stage IV
Case I	1122.13	63.25	4.09	0.98	688.89	1816.09
Case II	2511.90	61.26	8.46	196.30	–	2777.92
Total stages
Case I	8,054.94	188.94	21.98	15.04	1,301.79	9,393.75
Case II	10,356.32	214.51	33.25	350.96	–	10,955.04