Charging and discharging strategy optimization of linear machine gravity energy storage systems

doi:10.19799/j.cnki.2095-4239.2025.0138

Abstract

Abstract:

To reduce the charging and discharging costs of gravity energy storage systems, this paper proposes a dynamic adjustment method and an initial sequence recombination method based on a linear machine gravity energy storage system (LMGESS). First, the structure and operational mechanism of the LMGESS are described. Then, considering the relationship between energy storage demand and photovoltaic power generation capacity, as well as the relationship between rated charging power and photovoltaic output power, the photovoltaic output is categorized into three cases. Subsequently, a comparative analysis of the charging cost per unit capacity is conducted between the dynamic adjustment method and the traditional rated power charging method in these cases. Finally, taking into account the state transition characteristics of the LMGESS, the initial sequence recombination method was introduced to optimize its participation in automatic generation control (AGC) auxiliary services. The results show that the dynamic adjustment method achieves a lower charging cost per unit capacity compared to the rated power method during LMGESS charging. Even when the charging costs per unit capacity of both methods are the same, the energy storage capacity realized by the dynamic adjustment method is significantly higher. Moreover, the initial sequence recombination method substantially reduces the discharging cost of the LMGESS. After optimization, the discharging cost of the LMGESS participating in AGC is reduced by 31.3%, and the minimum discharging cost under different initial heavy object sequences is 57.5% lower than the maximum discharging cost.

Key words: energy storage technology, linear machine, gravity energy storage, charging-discharge cost

CLC Number:

TK 02

Liwang AI, Weiwei WANG, Siyuan JIANG, Haichao FENG, Lei XIAO, Xiaozhuo XU. Charging and discharging strategy optimization of linear machine gravity energy storage systems[J]. Energy Storage Science and Technology, 2025, 14(9): 3476-3487.

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参数	数值	参数	数值
系统高度	120 m	能量箱数量	14
高度差	100 m	安全距离	20 m
重物循环周期	4 min	运行速度	1 m/s
能量箱质量	5000 kg	额定充电功率	2.45 MW
重物质量	45000 kg	效率	0.87

曲线	1	2	3
额定功率法	0.23	0.26	0.479
动态调整法	0.23	0.23	0.409

曲线	1	2	3
额定功率法	18.12	18.12	18.12
动态调整法	21.65	18.45	18.12

方案	1	2	5
偏差成本/元	2.52	4.07	1.73
C-C_min/元	0.79	2.34	0
降低	31.3%	57.5%	0

字母	含义	单位	字母	含义	单位
C	充电成本	元	P_Bd	电池放电功率	kW
C_c	电池储能初始投资费用	元	P_Bc	电池充电功率	kW
C_d	电网电价	元/kWh	P_G	光伏出力功率曲线	MW
C_g	光伏电价	元/kWh	P_Gt	t时刻光伏出力功率	MW
C_x	单位容量充电成本	元/kWh	P_N	额定充电功率	MW
C_z	电池折旧成本	元/kWh	P_i	i块重物的充电功率	MW
ΔE	弥补容量	MWh	P_t	t时刻指令功率	MW
E	储能容量	MWh	P_z	单块重物充电或放电功率	MW
E ′	非额定充电功率时的储能容量	MWh	Q	电池额定容量	kWh
E_d	电网提供的容量	kWh	SOC	荷电状态	—
E_g	光伏电站提供的容量	kWh	T	额定充电功率下的充电时长	h
E_N	系统的最低储能容量	MWh	T ′	P_G>P_N的时长	h
E_q	容量缺额	MWh	T_cd	充放电时间	h
η₁	电池储能效率	—	T_i	P _i 的充电时长	h
n	重物数量	块	x	电池充放电状态	—
N	井道内重物数量	块	y	系统是否存在充放电过程	—
N_d	电池寿命	年